Female & Male Reproductive Organs and Sexual Anatomy

What is reproductive and sexual anatomy?

Reproductive and sexual anatomy includes your genitals and your internal sex and reproductive organs. Everyone’s reproductive and sexual anatomy looks a little different.

What parts of our bodies are sexual?

Reproductive and sexual anatomy (also known as sex anatomy) includes the sex organs on the outside of your body and the sex and reproductive organs on the inside of your body. Some examples of sex organs are the vulva (which includes your vagina) and penis. Reproductive organs include things like the uterus and testicles.

That being said, any part of your body can be sexual. You might have heard that your brain is your most important sex organ. That’s because it controls your sexual response — how your body reacts to arousal, sex, or masturbation. It’s also where your sexual fantasies and identities are.

You can also think of your skin as one big sex organ, with its millions of sensitive nerves. Parts of your body that when touched make you feel aroused are called “erogenous zones.” Not everyone has the same erogenous zones, but common ones are breasts and nipples, the anus, neck, lips, mouth, tongue, back, fingers and toes, hands, feet, earlobes, and inner thighs. You get the idea: Any part of your body can be considered sexual depending on how it makes you feel.

Does everyone have the same sexual anatomy?

Everyone’s sexual anatomy is a little bit different. Most people have either a penis and scrotum or a vulva, but each person’s genitals are uniquely their own.

When you were born, your doctor probably assigned you a sex — male or female — based on your sex anatomy. But that doesn’t necessarily say anything about your gender identity.

Some people’s assigned sex and gender identity are pretty much the same, or in line with each other. These people are called cisgender. Other people feel that the sex they were assigned at birth doesn’t match their gender identity. So, for example, a person could be born with a penis, but identify as female. These people often call themselves transgender or trans.

Other people have sex anatomies that don’t fit the typical definition of female or male. They may be described as intersex. There are lots of different combinations of body parts and hormones that fall under the intersex umbrella. Being intersex doesn’t necessarily have any connection with a person’s gender identity.

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Vital Statistics of the Male Human Body

The composition of the average human man can be broken down into a series of specific physical measurements and statistics—some of which might surprise you. For example, an average man’s head is about 7% of his body weight. That means the average man with a weight of 172 pounds has a head that weighs more than 12 pounds!

By identifying these standard stats and measures, some health issues can be more easily identified when a specific measure skews outside of these averages; however, also being averages, variations do not necessarily mean there is a health issue.

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Average Height

5 feet, 8 inches

Average Weight

174.6 lbs to 201.7 lbs, depending on age

Average Weight Distribution by Tissue Type

• 43% muscle
• 14% fat
• 14% bone and marrow
• 12% internal organs
• 9% connective tissue and skin
• 8% blood

Average Body Weight Distribution

• 47% trunk and neck
• 34% legs
• 12% arms
• 7% head

Water Content

60% of the average man’s body is water. 

Average Area of Skin

Body surface area for a 69-inch-tall male weighing 172 lbs is about 21.2 sq ft.

Average Lifetime Heart Beats

Approximately 3,363,840,000 times if you live to be 80 years old, at an average of 80 beats per minute.

Total Number of Bones

206

Average Number of Sperm Produced

The average man can produce 3,000 sperm a second.

Average Number of Sperm Per Ejaculation

200 to 300 million. But it only takes one at the right place at the right time to make a baby. A low sperm count is considered to be less than 20 million sperm per milliliter of semen. An average ejaculation volume is 1.5 to 5.0 milliliters.

Average Male Voice Audibility

The average man can be vocally understood at a distance of up to 200 yards; however, measured at night over still water, the maximum distance is 10.5 miles.

Average Penis Size

When flaccid, the average penis length ranges from 2. 8 to 3.9 inches (7 to 10 centimeters) and the average circumference is 3.7 inches (9.3 centimeters). When erect, the average penis length for a human male was estimated as 6 inches (15.2 cm) and circumference as 5 inches (12.7 cm). Measuring your erect penis length and girth is useful for selecting the correct size of a condom.

Average Breakdown of Man in Elements

• 65% oxygen
• 18.5% carbon
• 9.5% hydrogen
• 3.3% nitrogen
• 1.5% calcium
• 1% phosphorus
• 0.35% or less of potassium, sulfur, chlorine, sodium, and magnesium
• There are also traces of iron, fluorine, iodine, zinc, and a few others and a few others

Male Reproductive System – Explore Anatomy with Detailed Pictures

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Continued From Above…

Anatomy of the Male Reproductive System

Scrotum

The scrotum is a sac-like organ made of skin and muscles that houses the testes. It is located inferior to the penis in the pubic region. The scrotum is made up of 2 side-by-side pouches with a testis located in each pouch. The smooth muscles that make up the scrotum allow it to regulate the distance between the testes and the rest of the body. When the testes become too warm to support spermatogenesis, the scrotum relaxes to move the testes away from the body’s heat. Conversely, the scrotum contracts to move the testes closer to the body’s core heat when temperatures drop below the ideal range for spermatogenesis.

Testes

The 2 testes, also known as testicles, are the male gonads responsible for the production of sperm and testosterone. The testes are ellipsoid glandular organs around 1.5 to 2 inches long and an inch in diameter. Each testis is found inside its own pouch on one side of the scrotum and is connected to the abdomen by a spermatic cord and cremaster muscle. The cremaster muscles contract and relax along with the scrotum to regulate the temperature of the testes. The inside of the testes is divided into small compartments known as lobules. Each lobule contains a section of seminiferous tubule lined with epithelial cells. These epithelial cells contain many stem cells that divide and form sperm cells through the process of spermatogenesis.

Epididymis

The epididymis is a sperm storage area that wraps around the superior and posterior edge of the testes. The epididymis is made up of several feet of long, thin tubules that are tightly coiled into a small mass. Sperm produced in the testes moves into the epididymis to mature before being passed on through the male reproductive organs. The length of the epididymis delays the release of the sperm and allows them time to mature.

Spermatic Cords and Ductus Deferens

Within the scrotum, a pair of spermatic cords connects the testes to the abdominal cavity. The spermatic cords contain the ductus deferens along with nerves, veins, arteries, and lymphatic vessels that support the function of the testes.

The ductus deferens, also known as the vas deferens, is a muscular tube that carries sperm superiorly from the epididymis into the abdominal cavity to the ejaculatory duct. The ductus deferens is wider in diameter than the epididymis and uses its internal space to store mature sperm. The smooth muscles of the walls of the ductus deferens are used to move sperm towards the ejaculatory duct through peristalsis.

Seminal Vesicles

The seminal vesicles are a pair of lumpy exocrine glands that store and produce some of the liquid portion of semen. The seminal vesicles are about 2 inches in length and located posterior to the urinary bladder and anterior to the rectum. The liquid produced by the seminal vesicles contains proteins and mucus and has an alkaline pH to help sperm survive in the acidic environment of the vagina. The liquid also contains fructose to feed sperm cells so that they survive long enough to fertilize the oocyte.

Ejaculatory Duct

The ductus deferens passes through the prostate and joins with the urethra at a structure known as the ejaculatory duct. The ejaculatory duct contains the ducts from the seminal vesicles as well. During ejaculation, the ejaculatory duct opens and expels sperm and the secretions from the seminal vesicles into the urethra.

Urethra

Semen passes from the ejaculatory duct to the exterior of the body via the urethra, an 8 to 10 inch long muscular tube. The urethra passes through the prostate and ends at the external urethral orifice located at the tip of the penis. Urine exiting the body from the urinary bladder also passes through the urethra.

Prostate

The prostate is a walnut-sized exocrine gland that borders the inferior end of the urinary bladder and surrounds the urethra. The prostate produces a large portion of the fluid that makes up semen. This fluid is milky white in color and contains enzymes, proteins, and other chemicals to support and protect sperm during ejaculation. The prostate also contains smooth muscle tissue that can constrict to prevent the flow of urine or semen.

Unfortunately the prostate is also particularly susceptible to cancer. Thankfully, DNA health testing can tell you whether you’re at higher genetic risk of developing prostate cancer due to your BRCA1 and BRCA2 genes.

Cowper’s Glands

The Cowper’s glands, also known as the bulbourethral glands, are a pair of pea-sized exocrine glands located inferior to the prostate and anterior to the anus. The Cowper’s glands secrete a thin alkaline fluid into the urethra that lubricates the urethra and neutralizes acid from urine remaining in the urethra after urination. This fluid enters the urethra during sexual arousal prior to ejaculation to prepare the urethra for the flow of semen.

Penis

The penis is the male external sexual organ located superior to the scrotum and inferior to the umbilicus. The penis is roughly cylindrical in shape and contains the urethra and the external opening of the urethra. Large pockets of erectile tissue in the penis allow it to fill with blood and become erect. The erection of the penis causes it to increase in size and become turgid. The function of the penis is to deliver semen into the vagina during sexual intercourse. In addition to its reproductive function, the penis also allows for the excretion of urine through the urethra to the exterior of the body.

Erectile dysfunction is a common reproductive issue; in each decade of men’s lives, it affects about an equivalent percentage of peers. For instance, roughly 20% of men in their 20s experience a degree of erectile dysfunction. The rate rises to 30% of men experiencing ED symptoms in their 30s, and 50% of men in their 50s (and so on). Because it’s so common, the medical community has responded with increasingly convenient ways to treat ED. Read our Hims ED review for more information.

Semen

Semen is the fluid produced by males for sexual reproduction and is ejaculated out of the body during sexual intercourse. Semen contains sperm, the male reproductive gametes, along with a number of chemicals suspended in a liquid medium. The chemical composition of semen gives it a thick, sticky consistency and a slightly alkaline pH. These traits help semen to support reproduction by helping sperm to remain within the vagina after intercourse and to neutralize the acidic environment of the vagina. In healthy adult males, semen contains around 100 million sperm cells per milliliter. These sperm cells fertilize oocytes inside the female fallopian tubes.

Physiology of the Male Reproductive System

Spermatogenesis

Spermatogenesis is the process of producing sperm and takes place in the testes and epididymis of adult males. Prior to puberty, there is no spermatogenesis due to the lack of hormonal triggers. At puberty, spermatogenesis begins when luteinizing hormone (LH) and follicle stimulating hormone (FSH) are produced. LH triggers the production of testosterone by the testes while FSH triggers the maturation of germ cells. Testosterone stimulates stem cells in the testes known as spermatogonium to undergo the process of developing into spermatocytes. Each diploid spermatocyte goes through the process of meiosis I and splits into 2 haploid secondary spermatocytes. The secondary spermatocytes go through meiosis II to form 4 haploid spermatid cells. The spermatid cells then go through a process known as spermiogenesis where they grow a flagellum and develop the structures of the sperm head. After spermiogenesis, the cell is finally a sperm cell, or spermatozoa. The spermatozoa are released into the epididymis where they complete their maturation and become able to move on their own.

Fertilization

Fertilization is the process by which a sperm combines with an oocyte, or egg cell, to produce a fertilized zygote. The sperm released during ejaculation must first swim through the vagina and uterus and into the fallopian tubes where they may find an oocyte. After encountering the oocyte, sperm next have to penetrate the outer corona radiata and zona pellucida layers of the oocyte. Sperm contain enzymes in the acrosome region of the head that allow them to penetrate these layers. After penetrating the interior of the oocyte, the nuclei of these haploid cells fuse to form a diploid cell known as a zygote. The zygote cell begins cell division to form an embryo.

human body | Organs, Systems, Structure, Diagram, & Facts

Human body, the physical substance of the human organism, composed of living cells and extracellular materials and organized into tissues, organs, and systems.

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Vintage anatomy charts of the human body showing the skeletal and muscle systems.

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Your Body: Fact or Fiction?

Does insulin regulate the level of sugar in the body? Do humans have only five senses? Take an X-ray of your knowledge in this human anatomy quiz.

Human anatomy and physiology are treated in many different articles. For detailed discussions of specific tissues, organs, and systems, see human blood; cardiovascular system; digestive system, human; endocrine system, human; renal system; skin; human muscle system; nervous system; reproductive system, human; respiration, human; sensory reception, human; skeletal system, human. For a description of how the body develops, from conception through old age, see aging; growth; prenatal development; human development.

For detailed coverage of the body’s biochemical constituents, see protein; carbohydrate; lipid; nucleic acid; vitamin; and hormone. For information on the structure and function of the cells that constitute the body, see cell.

Many entries describe the body’s major structures. For example, see abdominal cavity; adrenal gland; aorta; bone; brain; ear; eye; heart; kidney; large intestine; lung; nose; ovary; pancreas; pituitary gland; small intestine; spinal cord; spleen; stomach; testis; thymus; thyroid gland; tooth; uterus; vertebral column.

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Humans are, of course, animals—more particularly, members of the order Primates in the subphylum Vertebrata of the phylum Chordata. Like all chordates, the human animal has a bilaterally symmetrical body that is characterized at some point during its development by a dorsal supporting rod (the notochord), gill slits in the region of the pharynx, and a hollow dorsal nerve cord. Of these features, the first two are present only during the embryonic stage in the human; the notochord is replaced by the vertebral column, and the pharyngeal gill slits are lost completely. The dorsal nerve cord is the spinal cord in humans; it remains throughout life.

Characteristic of the vertebrate form, the human body has an internal skeleton that includes a backbone of vertebrae. Typical of mammalian structure, the human body shows such characteristics as hair, mammary glands, and highly developed sense organs.

Beyond these similarities, however, lie some profound differences. Among the mammals, only humans have a predominantly two-legged (bipedal) posture, a fact that has greatly modified the general mammalian body plan. (Even the kangaroo, which hops on two legs when moving rapidly, walks on four legs and uses its tail as a “third leg” when standing.) Moreover, the human brain, particularly the neocortex, is far and away the most highly developed in the animal kingdom. As intelligent as are many other mammals—such as chimpanzees and dolphins—none have achieved the intellectual status of the human species.

Chemical composition of the body

Chemically, the human body consists mainly of water and of organic compounds—i.e., lipids, proteins, carbohydrates, and nucleic acids. Water is found in the extracellular fluids of the body (the blood plasma, the lymph, and the interstitial fluid) and within the cells themselves. It serves as a solvent without which the chemistry of life could not take place. The human body is about 60 percent water by weight.

Lipids—chiefly fats, phospholipids, and steroids—are major structural components of the human body. Fats provide an energy reserve for the body, and fat pads also serve as insulation and shock absorbers. Phospholipids and the steroid compound cholesterol are major components of the membrane that surrounds each cell.

Proteins also serve as a major structural component of the body. Like lipids, proteins are an important constituent of the cell membrane. In addition, such extracellular materials as hair and nails are composed of protein. So also is collagen, the fibrous, elastic material that makes up much of the body’s skin, bones, tendons, and ligaments. Proteins also perform numerous functional roles in the body. Particularly important are cellular proteins called enzymes, which catalyze the chemical reactions necessary for life.

Carbohydrates are present in the human body largely as fuels, either as simple sugars circulating through the bloodstream or as glycogen, a storage compound found in the liver and the muscles. Small amounts of carbohydrates also occur in cell membranes, but, in contrast to plants and many invertebrate animals, humans have little structural carbohydrate in their bodies.

Nucleic acids make up the genetic materials of the body. Deoxyribonucleic acid (DNA) carries the body’s hereditary master code, the instructions according to which each cell operates. It is DNA, passed from parents to offspring, that dictates the inherited characteristics of each individual human. Ribonucleic acid (RNA), of which there are several types, helps carry out the instructions encoded in the DNA.

Along with water and organic compounds, the body’s constituents include various inorganic minerals. Chief among these are calcium, phosphorus, sodium, magnesium, and iron. Calcium and phosphorus, combined as calcium-phosphate crystals, form a large part of the body’s bones. Calcium is also present as ions in the blood and interstitial fluid, as is sodium. Ions of phosphorus, potassium, and magnesium, on the other hand, are abundant within the intercellular fluid. All of these ions play vital roles in the body’s metabolic processes. Iron is present mainly as part of hemoglobin, the oxygen-carrying pigment of the red blood cells. Other mineral constituents of the body, found in minute but necessary concentrations, include cobalt, copper, iodine, manganese, and zinc.

Organization of the body

The cell is the basic living unit of the human body—indeed, of all organisms. The human body consists of trillions of cells, each capable of growth, metabolism, response to stimuli, and, with some exceptions, reproduction. Although there are some 200 different types of cells in the body, these can be grouped into four basic classes. These four basic cell types, together with their extracellular materials, form the fundamental tissues of the human body: (1) epithelial tissues, which cover the body’s surface and line the internal organs, body cavities, and passageways; (2) muscle tissues, which are capable of contraction and form the body’s musculature; (3) nerve tissues, which conduct electrical impulses and make up the nervous system; and (4) connective tissues, which are composed of widely spaced cells and large amounts of intercellular matrix and which bind together various body structures. (Bone and blood are considered specialized connective tissues, in which the intercellular matrix is, respectively, hard and liquid.)

multicelluar organism: organization

The diagram shows five levels of organization in a multicellular organism. The most basic unit is the cell; groups of similar cells form tissues; groups of different tissues make up organs; groups of organs form organ systems; cells, tissues, organs, and organ systems combine to form a multicellular organism.

Encyclopædia Britannica, Inc.

The next level of organization in the body is that of the organ. An organ is a group of tissues that constitutes a distinct structural and functional unit. Thus, the heart is an organ composed of all four tissues, whose function is to pump blood throughout the body. Of course, the heart does not function in isolation; it is part of a system composed of blood and blood vessels as well. The highest level of body organization, then, is that of the organ system.

Learn how a failure in the endocrine system may affect digestive, circulatory, and excretory systems

A discussion of the organ systems of the human body and their influence on one another.

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The body includes nine major organ systems, each composed of various organs and tissues that work together as a functional unit. The chief constituents and prime functions of each system are summarized below. (1) The integumentary system, composed of the skin and associated structures, protects the body from invasion by harmful microorganisms and chemicals; it also prevents water loss from the body. (2) The musculoskeletal system (also referred to separately as the muscle system and the skeletal system), composed of the skeletal muscles and bones (with about 206 of the latter in adults), moves the body and protectively houses its internal organs. (3) The respiratory system, composed of the breathing passages, lungs, and muscles of respiration, obtains from the air the oxygen necessary for cellular metabolism; it also returns to the air the carbon dioxide that forms as a waste product of such metabolism. (4) The circulatory system, composed of the heart, blood, and blood vessels, circulates a transport fluid throughout the body, providing the cells with a steady supply of oxygen and nutrients and carrying away waste products such as carbon dioxide and toxic nitrogen compounds. (5) The digestive system, composed of the mouth, esophagus, stomach, and intestines, breaks down food into usable substances (nutrients), which are then absorbed from the blood or lymph; this system also eliminates the unusable or excess portion of the food as fecal matter. (6) The excretory system, composed of the kidneys, ureters, urinary bladder, and urethra, removes toxic nitrogen compounds and other wastes from the blood. (7) The nervous system, composed of the sensory organs, brain, spinal cord, and nerves, transmits, integrates, and analyzes sensory information and carries impulses to effect the appropriate muscular or glandular responses. (8) The endocrine system, composed of the hormone-secreting glands and tissues, provides a chemical communications network for coordinating various body processes. (9) The reproductive system, composed of the male or female sex organs, enables reproduction and thereby ensures the continuation of the species.

Penis size interacts with body shape and height to influence male attractiveness

Abstract

Compelling evidence from many animal taxa indicates that male genitalia are often under postcopulatory sexual selection for characteristics that increase a male’s relative fertilization success. There could, however, also be direct precopulatory female mate choice based on male genital traits. Before clothing, the nonretractable human penis would have been conspicuous to potential mates. This observation has generated suggestions that human penis size partly evolved because of female choice. Here we show, based upon female assessment of digitally projected life-size, computer-generated images, that penis size interacts with body shape and height to determine male sexual attractiveness. Positive linear selection was detected for penis size, but the marginal increase in attractiveness eventually declined with greater penis size (i.e., quadratic selection). Penis size had a stronger effect on attractiveness in taller men than in shorter men. There was a similar increase in the positive effect of penis size on attractiveness with a more masculine body shape (i.e., greater shoulder-to-hip ratio). Surprisingly, larger penis size and greater height had almost equivalent positive effects on male attractiveness. Our results support the hypothesis that female mate choice could have driven the evolution of larger penises in humans. More broadly, our results show that precopulatory sexual selection can play a role in the evolution of genital traits.

Male genitalia show great variation among closely related species (1). This variation is typically attributed to copulatory and postcopulatory sexual selection to increase male fertilization success under sperm competition (2) or cryptic female choice (3). There might, however, also be premating sexual selection on male genitalia. Precopulatory processes can influence genital morphology (4, 5), but it is unknown whether these results are due to direct female choice or sexual conflict. In species where genitalia are externally visible, sexual selection might also act if females prefer males with specific genital morphology. Despite this potential effect, relatively little research has tested whether primary sexual characters influence male attractiveness (6⇓–8).

How female choice acts on any given male trait, and hence the strength and direction of selection, can be influenced by several, nonmutually exclusive factors. First, females use multiple cues during the mate choice process (9). Overall male attractiveness is unlikely to be determined by individual traits (e.g., refs. 10 and 11), so manipulating traits in isolation can lead to faulty conclusions about net male attractiveness (but see also ref. 12). Second, traits within individuals are phenotypically and genetically correlated. These relationships can influence evolution via correlational selection (13). Third, there might be a size contrast effect such that female assessment of attractiveness varies if the trait of interest is viewed differently in relation to other traits, analogous to the Ebbinghaus–Titchener effect (14). For example, the same sized penis might be perceived differently on short and tall men. Finally, a female’s own phenotype might influence her mate choice decisions. Humans mate assortatively based on numerous traits, including height (15), facial symmetry (16), and body shape (17, 18). Hence, it is likely that how a female rates a male’s attractiveness will partly depend upon her own phenotype.

The upright body posture and protruding, nonretractable genitalia of male humans make the penis particularly conspicuous, even when flaccid. This observation has generated suggestions by evolutionary biologists that the comparatively large human penis evolved under premating sexual selection (19, 20). Furthermore, novels, magazines, and popular articles often allude to the existence of a relationship between penis size and sexual attractiveness or masculinity (21, 22). Many cultures have fashion items, like penis sheaths and codpieces, that draw attention toward male genitalia (20), highlighting the potential for female choice to influence the evolution of male genitalia. There are numerous psychological studies directly asking females for their preference regarding male penis size. The results are mixed, with studies finding that females prefer longer penises (23), wider penises (24, 25), or that penis size is unimportant (26). These studies, however, all use self-reported, direct questioning and are therefore susceptible to biases of self-censorship and pressure to conform to socially desirable responses to sensitive issues (e.g., refs. 27⇓–29).

The only scientific studies to attempt to test experimentally whether flaccid penis length affects male attractiveness asked women to rate five images created by modifying a single drawing of a male figure so that the test figures differed only in penis length (30⇓–32). These important studies were not designed to quantify directly the relative effect of penis length on attractiveness compared with other sexually selected male traits, such as height and body shape (30⇓–32). Therefore, it is still unknown whether penis size affects attractiveness when there is substantive variation in other, arguably more important, body traits, or whether interactions between these traits and penis size determine net attractiveness. For example, does a given increase in penis length have an equivalent effect on the attractiveness of a short and tall man? In addition, the use of small photographs to quantify size-based preferences might lead to different estimates than those obtained when viewing fully life-sized male bodies.

To address these issues, we presented a sample of heterosexual Australian women with projected life-size, computer-generated male figures (Fig. 1). Each figure was an animated 4-s video in which the figure rotated 30° to each side to allow participants to more easily evaluate the figure. We tested for the effects of flaccid penis size, body shape (shoulder-to-hip ratio), and height on male sexual attractiveness. The latter two traits have regularly been investigated and are known to influence male attractiveness or reproductive success [height (15, 33⇓–35), shape (18, 36, 37)]. Each trait had seven possible values that were within the natural range (±2 SD) based on survey data (36, 39). We generated figures for all 343 (= 7³) possible trait combinations by varying each trait independently. This process eliminated any correlation between the three traits across the set of figures. Penis width did, however, covary positively with length in the program used to generate the figures, so we refer to overall “penis size” (but see also Materials and Methods). The women (n =105), who were not told which traits varied, were then asked to sequentially view a random subset of 53 figures, including 4 of the same control figure, and to rate their attractiveness as sexual partners (Likert scale: 1–7). Figure rating was conducted in the absence of an interviewer and was completely anonymous. We then used a standard evolutionary selection analyses to estimate multivariate linear, nonlinear, and correlational (interactive) selection (using the attractiveness score as a measure of “fitness”) arising from female sexual preferences (e.g., ref. 38).

Fig. 1.

Figures representing the most extreme height, shoulder-to-hip ratio, and penis size (±2 SD) (Right and Left) in comparison with the average (Center figure) trait values.

Results

Selection Analysis.

There were highly significant positive linear effects of height, penis size, and shoulder-to-hip ratio on male attractiveness (Table 1). Linear selection was very strong on the shoulder-to-hip ratio, with weaker selection on height and penis size (Table 1). There were diminishing returns to increased height, penis size, and shoulder-to-hip ratio (quadratic selection: P = 0.010, 0.006 and < 0.0001) [“B” in Table 1] and, given the good fit of the linear and quadratic models, the optimum values appear to lie outside the tested range (i.e., maxima are >2 SD from the population mean for each trait) (Fig. 2). A model using only linear and quadratic selection on the shoulder-to-hip ratio accounted for 79.6% of variation in relative attractiveness scores (centered to remove differences among women in their average attractiveness scores). The explanatory power of height and penis size when added separately to this model was almost identical. Both traits significantly improved the fit of the model (log-likelihood ratio tests: height: χ² = 106.5, df = 3, P < 0.0001; penis: χ² = 83.7, df = 3, P < 0.0001). Each trait, respectively, explained an extra 6.1% and 5.1% of the total variation in relative attractiveness.

Table 1.

Linear selection gradients and the matrix of quadratic and correlational selection gradients based on average rating for each of the 343 figures and means of gradients generated separately for each participant

Fig. 2.

Relationship between attractiveness and penis size controlling for height and shoulder-to-hip ratio (95% confidence intervals) indicating quadratic selection acting on penis size.

The effects of the three traits on relative attractiveness were not independent because of correlational selection (all P < 0.013) [“B” in Table 1]. Controlling for height, there was a small but significant difference in the rate of increase in relative attractiveness with penis size for a given shoulder-to-hip ratio (Fig. 3A). More compellingly, after controlling for shoulder-to-hip ratio, greater penis size elevated relative attractiveness far more strongly for taller men (Fig. 3B).

Fig. 3.

Contour map of the fitness surface (red: more attractive) for (A) penis length and shoulder-to-hip ratio (height controlled) and (B) penis length and height (shoulder-to-hip ratio controlled) (1 = mean attractiveness).

Participant and Response Time Analysis.

The average age of female participants was 26.2 ± 6.8 SD y old. The participants were 71.8% European, 20.9% Asian, and 7.3% from elsewhere with respect to ethnic origins. Female height was positively correlated with the linear effect that male height had on her rating of his relative attractiveness (i.e., the linear selection gradient for height calculated separately for each female) (Pearson’s r = 0.292, P < 0.0001) (Table 2). Females that were heavier than expected for their height (i.e., high relative weight/body mass index) showed a stronger linear effect of penis size on their rating of a male’s relative attractiveness (Pearson’s r = 0.227, P < 0.021) (Table 2). Female age was not correlated with the linear effect that any of the three male traits had on her rating of a male’s relative attractiveness (all P > 0.164) (Table 2). There was no effect of either the use of hormonal contraception or menstrual state on the linear effect of any of the three male traits on how a female rated relative attractiveness (all P > 0.166) (Table S1). We note, however, that these tests have limited power to detect a cycle effect, as women were not repeatedly surveyed during both the high and low fertility phases.

Table 2.

Correlations between female traits and the strength of linear selection on male traits

The average latency to respond and rank a figure when pooled across all trials was 3.08 ± 0.028 s (mean ± SD) (n = 5,142). Controlling for baseline variation in response time among women, the response time was significantly greater for figures with a larger penis (F_1,5034 = 15.099, P < 0.001), greater height (F_1,5034 = 23.819, P < 0.001), and a greater shoulder-to-hip ratio (F_1,5034 = 316.878, P < 0.001). Given that all three male traits were positively correlated with relative attractiveness, it is not surprising that, on average, there was also a significant positive correlation between a female’s attractiveness rating for a figure and her response time (mean correlation: r = 0.219, t₁₀₄ = 8.734, P < 0.001, n = 105 females). Controlling for differences among women in their average attractiveness scores (i.e., using relative attractiveness), we found significant repeatability of the ratings given to the 343 figures (n = 14–16 ratings per figure) (F_342,4799 = 6.859, P < 0.001; intraclass correlation: r = 0.281). For example, the absolute difference in the rating score for the first and last (fourth) presentation of the control figure to the same female was 1.21 ± 0.10 (mean ± SE) (n = 105) on a seven-point scale. This is a high level of repeatability, as most figures had six adjacent figures that were identical except that they differed for one trait by 0.66 of a SD.

Discussion

We found that flaccid penis size had a significant influence on male attractiveness. Males with a larger penis were rated as being relatively more attractive. This relationship is nonlinear, however, indicating that the proportional increase in attractiveness begins to decrease after a size of ∼7.6 cm (Fig. 2), which is an under-average penis size based on a large-scale survey of Italian men (39). Although we detected quadratic selection on penis size, any potential peak (i.e., the most attractive penis size) appears to fall outside the range used in our study. A preference for a larger-than-average penis is qualitatively consistent with some previous studies (30⇓–32), but our results differ in showing that the most attractive size appears to lie more than 2 SDs from the mean (i.e., no evidence for stabilizing sexual selection, in contrast to refs. 30⇓–32). Our results are further supported by the analysis of response time. We found a significantly positive, albeit small, correlation between penis size and response time. This finding is consistent with a pattern in adults whereby attractive stimuli are viewed for a longer periods (40). A tendency to view attractive stimuli for longer is a generalized phenomenon that starts in infancy (41, 42).

Height and shoulder-to-hip ratio also influenced a male’s relative attractiveness with taller men and those with a greater shoulder-to-hip ratio being rated as more attractive by women. As with penis size, the proportional increase in attractiveness declined as both male height and their shoulder-to-hip ratio increased. These results are consistent with previous findings of sexual selection on male height based on evidence from attractiveness rankings and patterns of actual mate choice (15, 37; but see also refs. 43 and 44). Our results corroborate previously reported quadratic relationships between male height and reproductive success (34, 45; but see also refs. 33 and 35). Our results for shoulder-to-hip ratio are also broadly consistent with previous attractiveness studies on body shape (36, 46⇓–48). Again, the correlations between response time and height and shoulder-to-hip ratio, respectively, were both significantly positive, indicating the females made quicker decisions when viewing less attractive figures (40).

Our study found no significant difference in the proportion of variance accounted for in our model by penis size and height (6.1% vs. 5.1%), indicating that both traits had equivalent effects on relative attractiveness. This finding is intriguing given that height is one of the most widely investigated and well-documented traits known to affect male reproductive success (15, 33⇓–35, 37, 43, 44). The finding suggests that selection on penis size is potentially as strong as selection on stature. The shoulder-to-hip ratio, however, accounted for a much larger proportion of variance in attractiveness in our model (79.6%). This result might be because of our figures extending too far into the feminine range of body shapes (36), as those with a low shoulder-to-hip ratio were highly unattractive. However, given increasing waistlines (49), the values we used are well within the range now seen in many Western countries.

We detected correlational selection between all three traits, so the effects of each trait on attractiveness were not independent of one another. The effect of penis size on attractiveness varied with both height and body shape (Fig. 3B). After controlling for the shoulder-to-hip ratio, larger penis size had a greater effect on attractiveness for taller men. This result could be because perceived penis size was smaller when assessed relative to the height of a taller man; or because of general discrimination against short men irrespective of the value of other traits, so that even a larger penis did little to increase their net attractiveness. A similar relationship between penis size and shoulder-to-hip ratio was also detected (Fig. 3A).

Attractiveness scores were not independent of the female participant’s phenotype. Most importantly, a female’s height was significantly positively correlated with the strength of her tendency to rate taller men as being relatively more attractive. This result is consistent with evidence that humans mate assortatively based on height (15). There was also a weak, albeit significant (P = 0.021), positive relationship between a female’s relative weight (comparable to body mass index) and the effect that penis size had on her assessment of male attractiveness. This relationship was far stronger if we included two outliers (>4 SD from mean; r = 0.333, P = 0.001, n = 105). The relationship was also stronger if we used a more stringent criterion to exclude four outliers (>2 SD from mean; r = 0.296, P < 0.01, n = 101). This result is intriguing but should be viewed with caution given that we conducted multiple tests.

In sum, we show that flaccid penis size alongside its interaction with shoulder-to-hip ratio and height significantly influenced a male’s relative attractiveness. Our results directly contradict claims that penis size is unimportant to most females (22, 26, 50). Some studies indicate that preference for a larger penis might arise because penis size is associated with higher rates of vaginal orgasm (23, 51). In turn, vaginal orgasms are associated with higher levels of associated sexual satisfaction (52). The proximate basis of the decisions leading to the reported attractiveness scores is unknown. General preexisting aesthetic preferences, either innate or acquired through cultural norms, might account for the observed patterns. Another possibility is that females use previous sexual experiences to infer a link between penis size and desirable male properties [e.g., the likelihood of (vaginal) orgasm]. Arguing against this theory is the lack of a correlation between a woman’s age and the magnitude of the effect of penis size on her rating of male attractiveness. Regardless of the exact mechanism, however, our results show that female mate choice could have played a role in the evolution of the relatively large human male penis. More broadly, our study adds to growing evidence from several species that precopulatory sexual selection can influence the evolution of primary sexual traits in animals (4⇓⇓⇓–8).

Materials and Methods

MakeHuman (v0.9.1RC1) was used to generate anatomically correct wire-frame figures. Body shape, height, and flaccid penis size were manipulated on each frame. We aimed to generate figures that encompassed the typical range of variation in these three traits in populations of Caucasian males. The penis and height values used stem from a large-scale study of an Italian male population, but these values fit within the standard range for Caucasians (reviewed in ref. 39). These values should capture ∼95% of the variation that females are likely to encounter, although they do not encompass the full range of variation, and the mean values are known to vary among different human populations. For height and penis length, seven values were evenly spaced between ±2 SD of the population mean (range: height: 1.63–1.87 m; flaccid penis: 5–13 cm) (39). Using this program we could not generate penises that only increased in length, so we refer to penis “size,” as there was a slight increase in width of 1.2 cm between the shortest and longest penis, whereas there was an 8-cm change in length. Body shapes were generated as seven evenly spaced values along the “masculinity” function of MakeHuman. We then summarized these figures using the shoulder-to-hip ratio in our analysis (range: 1.13–1.45; i.e., pear to V-shaped). These values fell within the natural range (36). Figures were imported into LightWave 3D (v9.6), colored gray, modified to reduce pixilation, and standardized for testicle size. We then generated videos where a forward facing figure took 4 s to rotate 30° to each side. Rotation increased the ability of participants to gauge penis size. Full details are available upon request.

Female participants were recruited at Monash University and the Australian National University (students, staff, and nonuniversity). The experiment was briefly described to participants as a study of male attractiveness, but they were not told which male traits varied. Females were instructed to stand 6.5 m directly in front of a wall where figures were projected at full (life) size. Before data collection and after the interviewer left the room, participants filled out a questionnaire and were asked about their height, weight, and age (SI Text). A scale and tape measure (for height) were provided in the room. The participants were also asked whether they were using chemical/hormonal contraception and what stage of their menstrual cycle they were in. After the questionnaire, and before data collection began, all participants viewed the same set of 13 videos that spanned the range in male trait values to gain familiarity with the figures. Before testing, participants were then asked: “Please rate each figure based on how sexually attractive they are to you” (Likert scale: 1–7). During the test, each participant was shown a unique, randomly ordered set of 53 videos: 49 test videos and 4 control (all traits at mean) videos. After the participant entered a rating score (by pressing a keyboard button) the next figure in the sequence appeared. The system automatically recorded the time between the figure first appearing and a score for it being entered. We obtained data from 105 participants who self-identified as (i) heterosexual or (ii) exclusively attracted to men in a pretest questionnaire (data from other participants were excluded: n = 13). Hence, all 343 figures were each viewed by approximately 15 women (n = 5,145 ratings). Stimuli were displayed at life size using a digital projector in a private viewing room. Data were collected using SuperLab (v4.5). Data collection was anonymous so that no answers could be traced back to participants. Ethics approval was granted through Monash University (MUHREC Approval CF11/1378–2011000764).

Data Analysis.

Data on attractiveness were analyzed using standard multivariate selection procedures (13, 53). Our analyses clearly showed strong nonlinear and correlational selection, so we did not conduct canonical rotations of the data to generate eigenvectors (e.g., refs. 53⇓–55). We conducted two analyses. First, we used a standard analysis based on a multiple regression of “relative attractiveness” on standardized trait values (mean = 0, SD = 1). We centered the rating scores from each participant (i.e., the mean rating for each participant was then zero). This process generated participant-corrected scores to control for variation among participants in their tendency to give higher or lower than average scores. For relative attractiveness we then calculated the mean participant-corrected attractiveness score for each of the 343 figures (an average of 15 participants viewed each figure). The mean score of the 343 figures is 0, so we added 1 to each figure’s score to generate the final relative attractiveness score. This addition was done purely for presentation reasons, as the convention in selection analyses is that the average individual has a value of 1. Adding 1 does not change estimates of selection gradients (i.e., regression coefficients). The relative attractiveness score is the dependent variable that we used as a surrogate measure of “fitness.” We estimated selection gradients (13, 54) and associated P values from standard tests for regression coefficients (13) [see “A” in Table 1]. Because we present the results as a selection analysis, the regression coefficient for the squared product of individual traits are doubled (54). The selection gradients in Table 1 can therefore be read as the increase in attractive score (on the original 1–7 scale) with a one SD increase in the focal trait.

Second, we used the same multiple-regression approach to calculate a unique fitness surface for relative attractiveness for each participant. We did this to control for the fact that our first analysis did not account for participant identity. The dependent variable was simply the centered attractiveness for each participant. The three traits were each standardized for the set of figures that the participants viewed. We then calculated the mean value for each selection gradient (i.e., each mean was based on 105 independent estimates) and used one-sample t tests to determine whether means differed from zero (all distributions were normal, Kolomogorov–Smirnov tests, P = 0.23–0.94) [see “B” in Table 1]. Both methods yielded very similar estimates of selection gradients [compare “A” and “B” in Table 1]. In Figs. 2 and 3 we present data based on the relative attractiveness of the 343 figures. We generated attractiveness contour maps (Fig. 3) with thin-plate splines in the fields package of R (56).

To investigate the relationship between female traits and attractiveness scores, we used Pearson’s correlations to measure the relationship between the linear selection gradients (calculated using the second method) for each male trait (penis size, height, and shoulder-to-hip ratio) and each of three female traits (age, height, and weight). Weight and height are correlated (r = 0.322, P = 0.001), so to control for height, we used the residuals from a regression of weight on height. These parameters can be considered broadly equivalent to a measure of body mass index. We identified two females that showed a strong deviation from the regression line (residuals >4 SD). We excluded these participants from all of the results presented in Table 2. Finally, we used two-sample t-tests to compare selection gradients between females assigned to one of two categories for contraception (using or not using chemical/hormonal contraception) and stage in the menstrual cycle [peak of cycle (1–7 d after the start of menstrual cycle) or not peak cycle (8–28 d after the start of the menstrual cycle)], respectively (Table S1).

Response Time and Repeatability Analysis.

We analyzed the effect of penis size on female latency to rate a figure in two ways. First, we ran a general linear mixed model with response time as the dependent variable and the three standardized male traits as fixed covariates. We included female participant identity as a random effect to control for multiple trials per female. To improve the model fit, we log-transformed response time (analyses on untransformed data yielded the same conclusions). We also ran the model excluding all cases (n = 246 of 5,142) where the response time was less than 0.1 s (this was a natural break in the data, as the log-transformed response time then showed a very close fit to a normal distribution). Again, the model yielded the same conclusions. Second, to determine how figure attractiveness influenced response time, we calculated the Pearson’s correlation between the 53 attractiveness scores and log response time for each female. These 105 correlations were then compiled and a one-sample t test conducted to test whether the mean correlation was significantly different from zero. Use of Spearman ranked-order correlations yielded the same conclusion. Data on response time were missing for 3 of the 5,145 trials.

To determine the repeatability of ratings of a figure’s attractiveness across females, a repeatability analysis was performed for the 343 figures. We used participant-corrected attractiveness scores as the dependent variable in a one-way ANOVA (with figure identity as the categorical factor) to estimate the intraclass correlation. This correlation is measure of the agreement among females in how they rate a figure’s attractiveness.

See Dataset S1 for the original data (n = 5,145 ratings from 105 participants), Dataset S2 for the relative attractiveness scores and trait values for the 343 figures, and Dataset S3 for selection gradients and questionnaire responses for the 105 participants.

Acknowledgments

We thank J. Burchell, J. Irons, H. Kokko, E. McKone, and R. Reynolds for technical support; P. Backwell, I. Booksmythe, R. Catullo, and R. Lanfear for comments on previous drafts of the manuscript; and Geoff Miller and one anonymous referee for their thoughtful and constructive comments on our manuscript. This project was funded by the Australian Research Council; ethics approval was granted through Monash University (MUHREC Approval CF11/1378 – 2011000764).

Footnotes

• Author contributions: B.S.M., B.B.M.W., R.A.P., and M.D.J. designed research; B.S.M., B.B.M.W., R.A.P., and M.D.J. performed research; B.S.M. and M.D.J. analyzed data; and B.S.M., B.B.M.W., R.A.P., and M.D.J. wrote the paper.

• The authors declare no conflict of interest.

• This article is a PNAS Direct Submission.

• This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1219361110/-/DCSupplemental.

Macho Man: 10 Wild Facts About His Body

His Body

(Image credit: Yuri Arcurs, Shutterstock)

Looking under the hood of the male body reveals more than a simple sex-driven, sperm-carrying system. In fact, scientists are still trying to decipher some of the mysteries of the male physique. Here are some wild facts, and unknowns, about a guy’s body, from his other brain and the male G-spot to lactating man-breasts and more.

More to Semen Than Just Sperm

(Image credit: stockxpert)

The sticky concoction called semen holds more than just sperm(those DNA-carrying swimmers that make a mad dash for the nearest egg). In fact, semen is a combination of sperm and fluids produced by accessory glands surrounding the penis. Its non-sperm ingredients include a mix of fructose, molecules made from fatty acids called prostaglandins, and proteins that nourish sperm and help them swim, according to the National Institutes of Health.

Additional fluids from the prostate and bulbourethral glands are slightly alkaline, or basic, reducing the acidity of any urine residue in the urethra, neutralizing the acidic environment of the vagina, and lubricating the tip of the penis for intercourse.

And turns out, what a man eats affects the quality of this semen, with a study published in 2012 in the journal Human Reproduction finding that guys who consumed more of the fat often found in fish (called omega-3s) had better-formed sperm than those who ate less of the fishy fat.

And while semen carries those critical egg fertilizers, some women are allergic to it, reacting to it with genital itching, burning and swelling. In severe cases, women may experience hives or swelling elsewhere on the body, and even difficulty breathing. A study described in 2011 at the annual meeting of the American College of Allergy, Asthma and Immunology in Philadelphia suggested a possible cure: frequent sex.

Bulging Groins

(Image credit: Piotr Marcinski, Shutterstock)

Hernias are weak areas in the outer layer of the abdominal cavity that bulge out like little balloons. There are several kinds of hernias, according to the U.S. National Library of Medicine, depending on where they form in the abdomen. But inguinal hernias, those that extend into either side of the groin, are more common in men than in women. Weak spots in the inguinal ring, the entrance to a canal housing arteries and nerves that run to the testes, allow fat or parts of the small intestine to slip through, creating a bulge in the groin (and not the good kind).

Though women also have an inguinal ring and canals, they aren’t as large as those in men. Some men are born with weak spots in the inguinal ring, which can cause hernias; they can also occur because of lifting a heavy object or straining on the toilet.

The Other Male Brain

(Image credit: Andresr, Shutterstock)

Some reflexes, or involuntary muscle movements, are well known. Hit the area below your kneecap and your lower leg jerks up. But you may be surprised to find out muscles wrapped around a man’s testes, called cremaster muscles, also display reflexes; though if you hit the surrounding area you probably won’t get the response you’re looking for.

According to the National Cancer Institute, cremaster muscles are normally responsible for pulling the testes closer to the body when it gets cold or when a man is sexually aroused. And rather than responding to the knee-jerk hammer, the cremaster reflex activates when the inner part of a man’s upper thigh is stroked. The cremaster muscle contracts on the same side as the stroking, momentarily pulling the testes up toward the body.

Foreskin – What Is it Good For?

(Image credit: Vanessa Van Rensburg | Dreamstime)

The foreskin, which is removed during circumcision, is a double layer of skin and mucous membrane that covers the penis when the organ is flaccid. Although there is still some debate about all of the functions of foreskin, the World Health Organization (WHO) states that uncircumcised men have a greater risk of contracting HIV. Cells called Langerhans cells found in the mucous membrane of the foreskin are susceptible to HIV infection and can serve as a point of entry to the body for the virus. WHO studies have shown that circumcision reduces the risk of heterosexually acquired HIV in men by 60 percent.

A History of Circumcision

(Image credit: Public Domain)

One of the earliest depictions of male circumcision comes from artwork in Egyptian tombs dated to about 2300 B.C. During the Ottoman and Moorish Empires, as well as in Nazi Germany, it was seen as a mark of higher social standing. In addition to its importance in Jewish and Muslin religions, circumcision is viewed as a right of passage to manhood in some African and Oceanic societies, writes Peter Aggleton of the University of London in England in a 2007 paper published in Reproductive Health Matters. It wasn’t until the late 1800s that circumcision acquired public-health interest. It was touted as a cure for anti-social behavior and paralysis and blamed for decreased sexual pleasure. More recently, circumcision has been shown to reduce the risk of contracting HIV in men.

Male Lactation

Men don’t typically produce milk from their breasts. But under certain circumstances, they can. For instance, extreme starvation, hormone treatments for various health problems, and mechanical stimulation, can lead to lactating lads. This phenomenon is different from gynecomastia, male breast enlargement due to imbalances in testosterone and estrogen. Noted scientist and author Jared Diamond wrote in a 1995 Discover magazine article that male and female cancer patients being treated with estrogen started to lactate when injected with prolactin (a hormone known to stimulate breast development and milk production in women). Studies have also shown male lactation can also occur when tranquilizers disrupt the function of the hypothalamus — a region of the brain that controls the pituitary gland, the source of prolactin. [5 Myths About the Male Body]

Growers vs. Show-ers

Despite locker-room talk, a 1996 study in the Journal of Urology found that you can’t predict the length of an erect penis by looking at the flaccid version. Some get larger when erect, otherwise known as “growers,” while others stay about the same length, sometimes known as “show-ers.” However, a stretched penis is a good predictor of its length when erect, according to a 2000 study published in the International Journal of Impotence Research.

The Male G-Spot

(Image credit: Dreamstime)

A man’s prostate gland is perhaps best known for its role in reproduction — it releases fluids that both help sperm swim and protect them once they leave the penis. But it is also sometimes known as the male G-spot. Surrounding the neck of the bladder and urethra, this walnut-size gland can be felt, and stimulated, through the anal canal. The question and answer resource Go Ask Alice! at Columbia University in New York says that men can experience orgasms through prostrate stimulation alone, or in conjunction with other means. [10 Odd Facts About the Female Body]

The Scent of Love

(Image credit: Yaruta Igor | Shutterstock.com)

Men’s bodies stink. Reason? Compared with women, guys have more of the hormone androstenone in their sweat and urine. The hormone acts like a pheromone by mammals like boars to signal sexual and social information to other animals. Though humans can smell androstenone, it’s unclear whether it plays a similar role for humans. Depending on your genes, however, androstenone can smell like either urine, or vanilla, according to a 2007 study in the journal Nature. Some people can’t smell it all.

Why He Should Brush His Teeth

(Image credit: Dreamstime)

There are varying levels of gum disease, according to the National Institutes of Health, ranging from gingivitis to chronic periodontitis. And they can affect more than just your mouth. The American Academy of Periodontology states that the inflammation from gum disease has been linked to heart disease, diabetes and rheumatoid arthritis. Other studies have found a potential connection between chronic gum disease and erectile dysfunction. And although there isn’t a clear cause-and-effect relationship between the two, a nationwide study in Taiwan found that men with erectile dysfunction were more likely to have been diagnosed with chronic periodontitis than a randomly selected control group. [7 Surprising Reasons for Erectile Dysfunction]

Explainer: Sometimes the body mixes up male and female

(for more about Power Words, click here)

adolescent     Having to do with the transitional stage of physical and psychological development that begins at the onset of puberty, typically between the ages of 11 and 13, and ends with adulthood.

adrenal gland  Hormone-producing glands that sit at the top of the kidneys.

androgen  A family of powerful male sex hormones.

congenital  A term that refers to conditions that are present from birth, either because they were inherited or occurred as a fetus developed in the womb.

congenital adrenal hyperplasia   A genetic disorder that causes the adrenal glands to make too much testosterone. This could create developmental changes in the womb that cause baby girls to be born with features that made them appear partly or totally male.

development  (in biology) The growth of an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape.

dihydrotestosterone (DHT) A male sex hormone, or androgen, that plays an important role in the development of male physical characteristics and reproductive anatomy.

enzymes   Molecules made by living things to speed up chemical reactions.

feminize    (in biology) For a male person or animal to take on physical, behavioral or physiological traits considered typical of females.

fetus  (Adj. fetal) The term for a mammal during its later-stages of development in the womb. For humans, this term is usually applied after the eighth week of development.

gene   (adj. genetic) A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

genitals or genitalia    The visible sex organs.

gonads  The reproductive organs that make eggs (in females) and sperm (in males).

hormone    (in zoology and medicine)  A chemical produced in a gland and then carried in the bloodstream to another part of the body. Hormones control many important body activities, such as growth. Hormones act by triggering or regulating chemical reactions in the body.

intersex    Animals or humans that display characteristics of both male and female reproductive anatomy.

masculinize  (in biology) For a female person or animal to take on physical, behavioral or physiological traits considered typical of males.

mutation  Some change that occurs to a gene in an organism’s DNA. Some mutations occur naturally. Others can be triggered by outside factors, such as pollution, radiation, medicines or something in the diet. A gene with this change is referred to as a mutant.

ovary  (plural: ovaries) The organ in the females of many species that produce eggs.

pediatrics  A field of medicine that has to do with children and especially child health.

psychiatry    A field of medicine where doctors study and treat diseases of the human mind. Treatments may consist of talking therapies, prescription drugs or both. People who work in this field are known as psychiatrists.

sex   A person’s biological status, typically male or female. There are a number of indicators of biological sex, including sex chromosomes, gonads, internal reproductive organs, and external genitals.

testis   (plural: testes) The organ in the males of many species that makes sperm, the reproductive cells that fertilize eggs. This organ also is the primary site that makes testosterone, the primary male sex hormone.

testosterone  Although known as male sex hormone, females make this reproductive hormone as well (generally in smaller quantities). It gets its name from a combination of testis (the primary organ that makes it in males) and sterol, a term for some hormones. High concentrations of this hormone contribute to the greater size, musculature and aggressiveness typical of the males in many species (including humans).

transgender  Someone who has a gender identity that does not match the sex they were assigned at birth.

urology     The medical field that deals with diseases of the male and female urinary tract and conditions affecting male reproductive organs. Doctors who specialize in this area are known as urologists.

womb   Another name for the uterus, the organ in which a fetus grows and matures in preparation for birth.

90,000 “Male gaze” and the beauty of the human body :: Private Correspondent

Opinions

Edition of the “Private Correspondent”

Why “Chascor” turned green?

We have been trying for a long time to write this editorial statement. We wanted to fit into it 12 years of work, 45 thousand articles (and even a little more), several editions and infinity of work and effort.And also – try to explain the ongoing changes to our readers.

Vitaly Kurennoy

Traditional values ​​and dialectics of criticism in a society of singularity

Nikolai Patrushev’s article on Russian values ​​is interesting in itself, but also evoked a vivid response from Grigory Yudin, who exposes the paradigm of “values”, apparently interpreting it as something purely Russian-original, and the very concept of “value” characterizes as “rotten”. I will try to express here my attitude to this interesting remark, and at the same time comment on the nature of the statement about which it appeared.

Ivan Zasursky

It’s time to start publishing all diplomas and dissertations!

An open letter from the President of the Association of Internet Publishers, a member of the Council under the President of the Russian Federation for the Development of Civil Society and Human Rights, Ivan Ivanovich Zasursky, to the Minister of Science and Higher Education of the Russian Federation Valery Nikolaevich Falkov.

Sergey Vasiliev, facebook.com

What kind of money do we need?

Do you need investments in small business now and what really requires investments?

Over the past decades, our market has been saturated with many modern spaces for trade, entertainment and services.If you look at our figures for the saturation of retail space for grocery, clothing, furniture, construction retail, we will see that we have already outstripped the leading countries of the world. Moreover, among our cities in terms of this indicator, it is not Moscow that is leading at all, as it might seem, but Samara, Yekaterinburg, Kazan. Moscow is only on the 3-4th place.

Ivan Zassoursky

Post-Trump, or California in the era of the early Noosphere

A long and confusing story of one trip from the words of a traveler

Sitting in my office at the journalism department, Lawrence Lessig listened to the story of reform attempts for a long time and with interest copyright – from Dmitry Medvedev’s beautiful attempt to enter through the G20, ruined by the Eurozone crisis over Greece, to the not-so-beautiful second attempt by Medvedev to enter through the G7 (they even refused to speak).Now, I assured him, we can definitely – through BRICS – the main thing is to make the right proposals! Lawrence, oddly enough, agreed. “Come to the Grand Re-Opening of Public Domain,” he said, “everyone will be there, so we’ll discuss.”

Nikolay Podosokorsky

Virtual friendship

Communication tendencies in Facebook

Friendship on Facebook is a relative thing. Yesterday a person wrote to you that he admires you and your “network activity” (do not ask me what it is), and today he writes that you are a quilted jacket, a bastard, “uncovered” and in general “everything is clear with you” (should you write that what do you really think about Crimea, Ukraine, the USA or the West).

Marat Gelman

Manual on materialism

“What am I thinking? I’m trying to cultivate a materialist in myself. But it doesn’t work. ”

Many people poured onto the beach today. From the point of view of a materialistic researcher, it was a certain number of two-legged bodies, let’s say thirty men and thirty women. There were more highs than lows. There are more thin people than fat ones. There are few blondes. Half – after fifty, one eighth of the elderly and children.A quarter are young people. An inquisitive scientist, perhaps, could find out the volume of the brain of each of us, the color of the eyes, he would take forty blood tests and somehow divide everyone according to some criteria. And I would even do a genetic analysis for a thousand bucks each.

Dmitry Voloshin, facebook.com/DAVoloshin

The theory of self-disbelief

About why we are afraid of real actions

We live in interesting times. A time of open discussion, fast travel and slow action.It seems that everything is there for making decisions. Information, a lot of structured information, mass, and means of its analysis. Wednesday, open polemic environment, the acquired skill of expressing one’s opinion. People, a lot of intelligent people, honest and active, dreaming of changing at least something, thinking in categories of goals that go beyond life.

facebook.com/ivan.usachev

Silent love

“We met after the concert. I finished work late, after midnight, I was collecting the equipment, I went out, I looked, sitting on the street, such a lonely one.I recognized her – I saw her on stage. I went up to her, began to talk, and she told me “yyy”. Then she took out a notebook, wrote down her name, and added that she had nowhere to go, she had a falling out with a guy, and her parents were in another city. Well, I invited her to my place. At that time, the wife had already moved out. So we live together for six months. ”

Mikhail Epstein

Simpsychosis. Soul – mistress and slave

Nature knows such a phenomenon as symbiosis – the coexistence of organisms of different species, their biological interdependence.This phenomenon remains largely a mystery to science, although it was discovered by the Swiss scientist S. Schwendener back in 1877 when studying lichens, which, as it turned out, are complex organisms consisting of algae and fungi. The same power of indissolubility can act between people – on a psychic, not a biological level.

Lev Simkin

A person from the award list

On the “People’s feat” website there are award lists for Simkin Isaakovich.My father. He himself saw them not so long ago for the first time. All four. The latter, 1985, does not count, then Chernenko awarded all veterans with the Orders of the Patriotic War. And the rest, those dated to the forty-third, forty-fourth and forty-fifth years, he listened with great interest. I listened, because it is difficult for him to read, the font is too small. Still ninety.

Calendar

Oleg Davydov

Catherine’s Wheel

The current of suffering flowing through time

On December 7, the Orthodox Church celebrates the day of memory of the Great Martyr Catherine of Alexandria.This saint was considered in Russia the patroness of weddings and pregnant women. On her day, the girls wondered about their betrothed, and the guys arranged sled races (and therefore Catherine was called Sannitsa). All in all, it was one of the happiest holidays of the year. However, there is nothing funny about Catherine’s story.

Eve Fairbanks

Nelson Mandela, 1918-2013

On December 5, 2013, Nelson Mandela died at the age of 95 in Johannesburg. When he was sick, Eve Fairbanks wrote this article about his life and legacy

The achievements of Nelson Rolilahla Mandela, the first democratically elected President of South Africa, put him on a par with the likes of George Washington and Abraham Lincoln, and a pantheon of rare individuals who, with their deep insight and clear vision of the future, have transformed entire countries.Thrown into jail for 27 years by the white minority of South Africa, Mandela emerged from captivity in 1990, ready to forgive his oppressors and use his power not for revenge, but to create a new country based on racial reconciliation.

Hammer of witches. Does witchcraft exist?

On December 5, 1484, the witch hunt began

On December 5, 1484, Pope Innocent VIII’s famous “Vedic bull” – Summis desiderantes was published. From that day on, the Holy Inquisition, which until now enthusiastically monitored the purity of the Christian faith and the observance of dogmas, took up the task of destroying all witches and generally strangling witchcraft.And in 1486 the book “The Hammer of the Witches” was published. And soon it overtook even the Bible in circulation.

Alexander Golovkov

Reign of unfulfilled hopes

190 years ago, on December 1, 1825, Emperor Alexander I died, who ruled Russia from 1801 to 1825

Alexander I became the first and last ruler of Russia who did without organs, guarding state security by secret search methods. We lived like this for a quarter of a century, and the state did not perish.In addition, he came close to the line beyond which the country could get rid of slavery. And also, having won a victory over Napoleon, he led a coalition of European monarchs.

Interview

“Music of the Earth” of our

Pianist Boris Berezovsky never ceases to amaze his fans: either Prokofieva will play like Chopin – tenderly and lyrically, then she will appear at the piano as a delicate and refined accompanist – this is he who is accustomed to being a soloist.Now he acted as the artistic director of the festival-competition “Music of the Earth”, where he combined folklore and classics. Boris Berezovsky himself told the private correspondent about the concept of the festival and its participants.

Andrei Yakhimovich: “Play with the spinal cord, develop anti-money”

Conversation with Andrei Jakhimovich (Cement group), one of those who created not only Latvian, but also Soviet rock, the founder of the Riga Rock Club, a wise counterculturalist and a real Riga citizen – like good coffee with black balsam with an interesting companion in the Old Town of Riga.Suddenly, doomedly funny and paradoxical.

“Every dog ​​is a personality”

Interview with a specialist in dog behavior

Antoine Najaryan is a well-known specialist in dog behavior throughout Russia. When compared to dog handlers, he claims that his work is something completely different, and asks not to be confused. It is not for nothing that dog owners turn to Najaryan from all over the country: what they do with animals is amazing and seems impossible.

Yuri Arabov: “As soon as I find God, I will die, but for me it will be happiness”

Yuri Arabov is one of the most successful and famous Russian screenwriters.He works with directors of very different outlook and style. Arabov’s latest works are “Faust” by Alexander Sokurov, “St. George’s Day” by Kirill Serebrennikov, “Room and a half” by Andrey Khrzhanovsky, “Miracle” by Alexander Proshkin, “Horde” by Andrey Proshkin. All these films were met by critics and audiences with great interest, they all became events. It’s hard to believe that these plots were invented and written by one person. Our correspondent spoke with Yuri Arabov about his childhood and Moscow in the 60s, about the heroes of his scripts and his religious search.

90,000 Muscles of the human body | NORTHWAY Vilnius

The human body is made up of various muscle groups. We should be grateful to our muscles for the ability to breathe, move, chew, see, talk, laugh, cry, and many other things. Let’s talk in more detail on this topic with the family doctor, MD Asta Mastavichyute from the Northway Medical Center.

What is muscle?
Movement is the main property of living organisms, and the muscles of the body play the most important role.Movement, regardless of its amplitude, is a characteristic function of the body, which is carried out with the help of muscle contraction and relaxation. Muscles make up about 40% of the body weight of men and about 23% of the body weight of women. If the muscles are evaluated from the point of view of a single whole, then they are the largest formation of all the internal organs of the human body. Without muscles, it would be difficult to do anything. Absolutely everything that we are aware of with the mind is expressed in the movement of muscles. Any movement occurs due to the transmission of nerve impulses to the muscle fiber.Together with the nervous system, muscles consume the most energy in the body, as they perform mechanical work. Muscle mass consists of 70-80% water, 17-21% of proteins and 3-4% of other substances.

The largest muscle is the broad muscle of the back, the strongest is the chewing or jaw muscle, and the most active muscle is the eye muscle.

What types of muscles are there?

There are about 850 muscles in the body of every healthy person, but most people, when talking about muscles, think only of those that can be seen.For example, many of us know we have biceps in our hands.

Muscles are divided into three types: striated muscle, smooth muscle and cardiac striated muscle. Muscles of different types perform different functions: striated muscles are associated with the active movement of a person and depend on the will of a person. These are the muscles that we see and feel. Bodybuilders looking to build muscle mass train these very muscles. All muscles in the body work in pairs. Muscles that, when contracted, move in one direction are called synergists, and those that move in the opposite direction are called antagonists.Muscle work depends on the coordinated work of synergistic and antagonistic muscles, which is regulated by the nervous system. The striated muscles move at the will of the person, sending a conscious signal to the brain. These signals are transmitted along the somatic nerves. The striated muscles are anchored by joints and ligaments so that the person can move. Through contractions, smooth muscles help to carry out such “internal” functions of a person as digestion, breathing, elimination, etc. Smooth muscles perform various movements of internal organs, and are located, as a rule, in the walls of such organs, including the walls of blood vessels.Smooth muscles move involuntarily, obeying automatic impulses emanating from the central nervous system and sent through the autonomic nervous system, without consciously thinking about it. Smooth muscles are present in the walls of internal organs: blood vessels, intestines, bronchi, skin, eyes, etc. The function of the heart muscle practically does not depend on the will of a person. Heart muscle is found only in the heart, and its main properties are endurance and consistency. It is one of the strongest muscles in humans, tirelessly pumping blood and providing the entire body with vital oxygen and nutrients.

What functions do muscles perform? Muscles, like cars, are made up of many small components – parts that work together and depend on each other and do not provide any benefit in isolation. The main structural unit of muscles is a muscle cell, or in other words, a muscle fiber. Muscle fibers form muscle tissue to form an entire muscle, and their number depends on the size of the muscle and the function performed. Muscles perform the following functions: they support the body and internal organs, enable the body to move, its individual parts and organs, and protect the internal organs.Muscles tense around the damaged (overloaded) part of the body, thus protecting it from even greater stress. About 70% of body pain comes from muscles and ligaments. Muscles take part in the blood flow. By contracting, the muscles push the blood up through the veins, towards the heart. Working muscles generate heat, which helps maintain body temperature.

What causes muscle cramps?

As a rule, muscle spasms are caused by overuse, stretching, bruising or tearing of muscles resulting from various injuries.The pain covers specific muscles in one area. It begins during exercise or immediately after it. It is usually clear which activity is causing muscle pain. Muscle pain is also a sign of a disease of the whole body, for example, with various viral diseases (including influenza), malnutrition that affects the connective tissues of the whole body. The most common causes of muscle pain include:

• tension or stress;
• excessive tension: too intense, frequent or inappropriate use of the muscles;
• contusion or trauma;
• Incorrect posture;
• use of drugs;
• infection or inflammation;
• Autoimmune or rheumatoid diseases.

What kind of muscle pain should you worry about and see a doctor?

The degree of muscle pain can vary from mild to unbearable, even regardless of the disease. If muscle pain is not associated with another disease and lasts more than 2-3 days, then you need to see a doctor. This is also very important if there is swelling, redness around the muscle, it causes pain when touched, you feel warmth or even heat in it. The general rule is that if your muscles hurt and the temperature lasts for more than two to three days, you should consult your doctor.

What is the prevention of muscle pain?

To prevent the occurrence of muscle pain or injury, it is necessary to exercise more often, to warm up before training, and after training to let the muscles cool down. Stretching exercises are recommended before and after your workout. After warm-up, physical activity should be increased gradually, step by step. When doing physical work or exercising, you should not make sudden and quick movements. For those who spend most of the day in one position (for example, sitting at the computer), it is recommended to take breaks and stretching exercises.In addition, sudden changes in temperature and drafts must be avoided.

90,000 TV and radio: Internet and media: Lenta.ru

Completely naked adults stand in front of children and answer their questions about physiology. The picture is broadcast in all anatomical details: operators take close-ups of the scrotum and nipples. Children carefully examine the labia of an adult woman, try to guess the length of an adult man’s penis, study pubic hair and ask about acne.The host of the Danish program Ultra smider tojet claims that he is engaged in education, but on the network the creators of the show are accused of corrupting minors. This frank show was especially disgusted by Russian television propagandists, who discussed the Danish show on domestic TV, called it harmful and once again confirms the decay of the West. What actually happens in the children’s program – in the material “Lenta.ru”.

In 2019, a children’s program Ultra smider tøjet appeared on Danish television.In terms of emancipation, she left her predecessors far behind: in her, the heroes are removed completely naked.

On the one hand, children and adolescents of school age become the guests of the Danish show, on the other – several adults. The show is hosted by Jannik Schow, 29. It helps children to ask questions and arranges various interactions: for example, schoolchildren need to guess the average length of the penis in a non-erect state, count how many holes are in the human body, or imagine how much money an almost completely tattooed man spent on body modification.

So far, only two seasons of the program aired: the first was shown in 2019, it consisted of five episodes, and the second in 2020. Each Ultra smider tojet episode is just over ten minutes long and has a very straightforward plot. First, a humorous disclaimer is shown on the screen: “You need to know that breasts will appear on your screen soon” or “A lot of naked bodies will appear on the screen soon enough” – the text depends on the theme of the episode.

Then several adults in bathrobes enter the studio and undress almost immediately.The host says what the issue will be about. Sometimes the degree of nakedness of the guests depends on this: in the episode about the breasts, the women were in shorts, and in the episode about the penises, the men were in T-shirts. In almost all the show, children ask adults questions. As a rule, schoolchildren are most interested in how people relate to their body and how it works. At the end, Yannick Skow arranges some kind of interactive activity for the children.

According to the creators of the show, naked adults are not actors, but volunteers who agreed to pose for educational purposes.The guests of the show, as a rule, are very diverse in appearance. For example, both a very tall man and a man suffering from dwarfism (dwarfism) were invited to the issue about the forms of the human body. In the episode about breasts – a woman who had one breast amputated.

In the series entitled “The Sign of Life” (Mærket af livet), a man with a prosthetic leg, a man with a colostomy bag on his stomach, a woman with “irregularities” on his stomach, and a blind man answered the children’s questions. The children were interested in what it was like for them to take a bath, whether they were told unpleasant things to these people because of their appearance, how much the prosthesis looked like a real leg and whether it could be bent (at the end of the show, the man took off the prosthesis and let the children touch it).At the same time, when answering questions, adults remain completely naked – this is the concept of transmission.

Over the course of two years, Skow had time to talk with children about penises and vaginas, body hair, skin, the size and shape of the human body, and various decorations, including Botox, tattoos, silicone implants and intimate piercings.

Many children’s questions related to the problems that almost everyone faces in puberty: the transformation of the body often makes adolescents doubt their own normality and feel ashamed of themselves.Schoolchildren asked naked adults if they had acne, if shaving their hair hurt, wondered if they had “bad thoughts” about their own body, if they were embarrassed by their own size, and if they would have chosen a different body if they could. They asked if the adults regretted the body modifications they had done, and asked how their loved ones reacted to such changes.

Many children also wanted to know the details of human physiology. “Why do we go to the toilet? Why does menstruation happen? How do you feel when you put on a bra? What is it like to breastfeed? How does it feel to write when other men are around? ” – these and many other similar questions were asked by children.

Adult responses were usually reassuring. Many admitted that they used to worry about their appearance and certain physical parameters, but over time they learned to accept what they cannot change. Some said that they never had complexes because of their appearance.

Ultra smider tojet episodes are filmed uncensored and broadcast without blur, which looks very unusual for viewers from a different cultural environment. Especially considering the fact that operators often take close-ups of the genitals of the guests of the show.

The first season of the project in 2019 was recognized as the best children’s show at the Danish TV festival. However, even at home, the program faces criticism. Danish right-wing politician Peter Skaarup accused the broadcast of corrupting minors. According to him, it is too early for children to look at male and female genitals, and they should receive information about the body at school and at home, and not on TV.

Following the publication of an article about the show in The New York Times, the Danish program began to receive criticism on social media.“We complain about Cuties (Netflix’s Cuties about 11-year-old girls doing twerking; many have condemned him for sexualizing children – 90,038 approx. Lenta.ru ), but it’s okay when a 35-year-old man showing a penis to 11-year-olds, ”@ cy12 was indignant. “The TV company is well aware that the show will shock the audience. This is the only reason why they implemented this idea: to increase the audience through provocation, while using children. What is this if not child exploitation? ” – added the user.Many have written that they find the broadcast disgusting and corrupting.

However, the creators of the show do not agree with such estimates. In their opinion, Ultra smider tojet is an educational program that helps children overcome dissatisfaction with their own bodies and shame, teaches schoolchildren to accept themselves and others, regardless of appearance. Some boys and girls, having participated in the program, admitted that after filming they became less dissatisfied with their bodies.

The creators of the program draw attention to the fact that in the modern media environment children are haunted by the image of an ideal body.On social media and in advertisements, they look at perfect-looking people, when in reality the human body is not like that. “We have excess weight, unwanted hair or acne. We want children to understand from an early age that this is normal, ”the program host explained.

In addition, the show pays a lot of attention to child safety. First, producers do not invite young members without parental consent. Secondly, during filming, children are constantly asked if everything is in order.If one of the students feels uncomfortable, he can leave the studio and go to the room where the teacher is waiting for him. It is noteworthy that not a single child has ever used this opportunity, although more than 250 people have starred in the program over two seasons. Another condition of the show is never to show a child and a naked adult in the same scene.

“Some say:” Oh my God, they united nudity and children! ” But that has nothing to do with sex. Our program is about seeing the human body as it is – this is how children understand it, ”Yannick Skou responded to reproaches of corruption.

In Russia, the issue of sexual education of children is still a problem. The results of a recent poll showed that the introduction of such lessons in schools was supported by 74.7 percent of the country’s residents (only 7.3 percent were strongly opposed). Despite this, topics related to the body are often taboo, and adolescents most often have to deal with sex on their own.

74.7

percent of Russians

supported the introduction of sex education lessons in schools

The modern culture of publicly suppressing such issues is sometimes called neo-puritanism.For our society, it was not always characteristic. According to the Byzantine culture specialist, Professor Sergei Ivanov, “the everyday relaxedness adopted by the Muscovites amazed foreign travelers.” For example, baths were common in Russia until the middle of the 16th century.

Today, however, Muscovites are surprised at someone else’s “everyday relaxedness.” In 2013, in the Russian-language segment of the Internet, the Swedish children’s program Biss och Kajs was discussed with surprise, the presenters of which worked in costumes of jets of urine and feces, and funny songs about how the human body works were performed on the show to the backing vocals of pop singers.

TV presenter Dmitry Kiselev devoted an indignant plot to this Swedish program. “It looks wild in Russia,” said the presenter. Having linked the program on how the body functions with the issues of sexual education and the corruption of children, he concluded: “Here they are, European values ​​in all their glory!”.

Danish Ultra smider tojet was not spared by Russian television either. The plot of the program was aired on the Vremya Pokazhet program on Channel One. “Tolyan, I have to run away quickly after this story.Forgive me, do it yourself somehow ”, – Artem Sheinin, who is known for shouting about“ dead fagots ”on the air, turned after him to his co-host Anatoly Kuzichev. At the same time, he held his hand to his throat – it was understood that Sheinin was sick of what he saw.

The Danish show caused a heated discussion on Channel One, and among the cries of the guests and hosts of the program, one could make out that they see a direct connection between the content of the show and the involvement of children in incest, the lowering of the age of consent and the legalization of exhibitionism.At the same time, the studio heard the words that Denmark is the “most progressive” and “liberal” country in Europe.

Deputy Alexei Zhuravlev, on the air of the 60 Minutes program on Rossiya 1, having familiarized himself with the fragments of the Danish program, started shouting and said that such shows impose certain values, rape the psyche of children and are punishable by imprisonment in our country (though for which article, Zhuravlev could not say). “Their first porno booth was opened for zoophiles. Can you imagine, it officially works for zoophiles in Denmark! You can come and rape the turtle, ”the deputy shared the fake news on the federal air and completely refused to follow the Danish path and be enlightened.

15 features that make the human body unique

One of the greatest wonders of nature is man himself. Despite the fact that physicians and other scientists have been studying the human body for centuries, they continue to make new discoveries in this area.

Bright Side has collected 15 interesting facts about the human body for you that we usually don’t think about.

Scientists estimate the memory of the brain at 1 petabyte (or 1,000 terabytes)

Scientists from the University of Texas at Austin found that one synapse (the point of contact between two neurons) has a memory capacity of 4.7 bits.Given the known number of synapses in the brain, the approximate amount of memory is one petabyte – 10 times more than previously thought. If this amount of memory is presented in the form of a graphic file, then its printout 20 cm wide will have a length of more than 77 thousand km.

The likelihood of a heart attack on Monday is higher than on any other day of the week

Studies by Swedish scientists have shown that the risk of heart attack is highest on Monday, as well as during Christmas and New Years, and the lowest – on Saturday and mid-summer, namely in July.

Human bones are several times stronger than concrete

This is explained by the fact that our bones are a composite material, hard but elastic at the same time. Bones contain calcium hydroxyapatite (about 60%) and collagen, due to which their structure is resistant to cracking.

To burn 1 kg of fat, you need to spend 7,700 kcal

When we are actively losing weight, excess fat breaks down into carbon dioxide and water, thereby releasing energy.To lose 1 kg of excess fat, you need to spend approximately 7,700 kcal, which is equivalent to running for 10 hours, 16 hours of swimming or 24 hours of dancing marathon.

The area of ​​human lungs is approximately equal to the area of ​​a tennis court

The structure of this paired organ includes alveoli – vesicle formations that are involved in gas exchange. If we add up the area of ​​all the pulmonary alveoli, then we get an area commensurate with a tennis court.

Hiccups can last for years

Moreover, men suffer from this scourge more often than women. American Charles Osborne even got into the Guinness Book of Records, because he hiccupped, without ceasing, for 68 years, from 1922 to 1990, after which his unresponsive hiccups suddenly disappeared. Despite this nuisance, Charles lived a normal life: he worked, raised a family and lived for 96 years.

A person has not 5 senses, but much more

Sight, hearing, smell, touch and taste are far from all that we feel.Scientists count, according to various estimates, from 9 to 20 senses. For example, a sense of time, thermal perception (feeling of warmth), equibrioception (a sense of balance), as well as proprioception – awareness of one’s own body. Thanks to her, we can easily touch our nose with our eyes closed – we feel where it is without seeing it.

The cornea of ​​the eye is the only tissue in which there are no blood vessels

Due to the absence of blood vessels, the cornea of ​​the eye is transparent, and this is very handy – the vessels would certainly interfere with vision.Nutrition and supply of oxygen to this tissue occurs due to the diffusion of necessary substances from the structures surrounding the cornea.

Most babies are born with blue eyes

Many babies are born with blue eyes, but not everyone is born with this color in the future. This is due to the fact that the pigment melanin is responsible for the color of the iris. The more melanin the iris contains, the darker its shade will be. In fair-skinned babies, this pigment is still too low, but as it is produced, the color of their eyes can change.

The embryo treats its mother

Scientists have noticed that in 50% of women with cardiomyopathy, this ailment disappeared during pregnancy without any treatment. This is explained by the fact that the stem cells of the unborn child are able to repair the damaged tissues of the mother.

Women blink twice as often as men

It is believed that this is due to differences in the hormonal system: women have higher estrogen levels. This hormone, among other things, stimulates the production of natural lubricants that moisturize the mucous membranes, including the eyes.

The eyes are closed when sneezing to prevent bacteria from entering them

Many people believe that it is impossible to sneeze with open eyes, otherwise the eyes will “fly out” of their orbits. In fact, this is not so – it is difficult to sneeze with open eyes, but it is possible, and the eyes will not go anywhere. But nevertheless, a sneezing person does not close his eyes at all in vain – this is how the body protects our organ of vision from the possible ingress of bacteria.

In the morning, a person is about 1 cm taller than in the evening

During the day, while a person is in an upright position, his intervertebral discs become thinner and denser from the effect of weight pressing on them.During sleep, they return to their usual size, and due to this, the person becomes slightly taller in the morning.

The human ear can “hear” molecules

To verify this, do a simple experiment: close your eyes and ask someone to pour cold water into one glass and boiling water into the other. You heard the difference in the sounds of pouring water, right? And in fact, and in another case, this is the most ordinary water, and the difference lies only in the speed of movement of its molecules.

Exercises on the abs do not guarantee muscle cubes on the abdomen

It is not uncommon for people to persistently train their abs for months, but the cherished cubes still do not appear. Their visibility, among other things, also depends on how many percent of fat is contained in the body. The percentage of body fat at which the body looks prominent differs depending on gender: for men it is 3-6%, and for women – 8-12%.

90,000 Men and women

Steinach’s experiments were impressive, but left the question of what happens before birth: in the womb, males become males, and females become females due to the same mysterious substances, or is there another reason? Steinach assumed that embryos remain asexual until they develop gonads.True, then it was unclear why some individuals have female glands, while others have male glands.

The first mystery was soon clarified by the zoologist Frank Lilly. In 1914, he came across twin bovine embryos in accrete amniotic bladders. One was a male, and the second was something strange: it looked like a heifer, but inside it was more like a bull. Such individuals are called freemartins. They are quite common among cattle and annoy livestock breeders, because they are only suitable for meat.

In a couple of years, Lilly found another fifty pairs of twins in the vicinity.He thought that after fertilization the freemartins were females, reasoning as follows: calving cows matured two eggs, that is, twins could be of both sexes, but since one is definitely a bull, then the second is most likely a heifer, because otherwise a disproportionate number of males would be conceived …

Further, Lilly showed that the internal organs of the female acquire masculine features only when the twins have a common circulatory system. Something enters the embryo through the vessels and directs sexual development before birth.Although Lilly did not isolate these substances, he was sure that these were hormones from the male glands. Lilly even gave a plausible explanation of why there are no freemartin bulls: male hormones are produced earlier than female hormones, so the sisters simply do not have time to influence the brothers.

By the mid-1920s, Lilly’s experiments fueled interest in mysterious substances. Some tried to get them in their pure form, which was not so easy because of the negligible amounts of hormones in the tissues. Biologist Alan Parks, with the assistance of the British Museum, even agreed that huge blue whale gonads would be delivered to him, but the valuable material deteriorated on the way from the Southern Hemisphere.

Pharmacologists hoped to create hormonal agents for the treatment of infertility, frigidity, impotence, homosexuality and to prevent pregnancy. Eugen Steinach promoted testicular transplantation to gays and the elderly and performed partial ligation of the vas deferens to increase the production of hormones, and in France, the Russian emigrant Sergei Voronov, to the delight of some and the horror of others, transplanted monkey tissues to people in order to add masculinity to them.

In the common view, hormones looked like a clue to the mystery about sex differences.But hormonal theory didn’t explain everything. Firstly, hormones are produced by the sex glands, which means they do not affect whether the male or female glands will be in the embryo. Secondly, student Frank Lilly repeated Steinach’s experiments, and it turned out that rodents with transplanted gonads of the opposite sex never completely transform. A female or a male depends on something other than hormones.

Lilly, who studied Freemartins, was aware of these difficulties, but admitted that they would be solved by another theory, criticized for years – the chromosomal one.

5 life hacks to improve metabolism – Rossiyskaya Gazeta

The human body is a complex machine. Like all cars, the body needs fuel – everyone knows that without gas, a car will not go anywhere, and bad fuel will start to junk, if not stop at all. It is due to it that energy is generated, thanks to which the motor comes to life. All living organisms, including humans, work approximately the same way. “Gasoline”, that is, the food we eat, is included in the chain of chemical transformations.As a result, energy and compounds necessary for life are formed, and by-products are removed outside. Proteins, fats, carbohydrates, vitamins, water … All of them enter the body with food and enter into metabolism, or metabolism (literally translated as “transformation”). But what will happen to the person if this process goes wrong and fails? Can metabolic disorders be prevented and how to do it? And most importantly, why is it so important for everyone to know about metabolism? Let’s figure it out in order.

“Metabolism is a metabolism, a broad concept that characterizes all processes in the human body.The most often talked about metabolic disorders when it comes to the violation of fats and carbohydrates “, – told” RG “Professor, Doctor of Medical Sciences Antonina Starodubova, Deputy Director of the Federal State Budgetary Scientific Institution” Federal Research Center for Nutrition and Biotechnology “.

Today, most people associate metabolism with how quickly they burn calories and lose weight. This approach is too simplistic. Metabolism is the use of energy for life itself.

There are three main ways the body spends energy from food: rest, movement and food intake.

Surprised that the body can burn energy while resting? Even the fact that you just live requires serious costs: energy (60-70 percent of daily consumption) is spent on regulating body temperature, cell formation, heartbeat, blood circulation, breathing, etc. By the way, the brain also needs energy (that’s why strict diets and restrictions often cause a decrease in concentration).

With regard to food intake, the energy that the body uses to digest food is 5-10 percent of the total daily intake.It has been proven that if you eat often, little and healthy food, then the metabolic rate and calorie burning will increase. The formula is simple.

Physical activity accounts for up to 30 percent of total daily energy expenditure. It is important to understand that movement cannot be “stocked”.

Nevertheless, there are situations when the body begins to “save” the calories entering it. Many are familiar with the state when there is no strength even for the most ordinary daily activities or when you find yourself in a supply of new kilograms.So the balance is broken somewhere.

“Sooner or later, any disturbances in the body lead to the appearance of complaints: weakness, fatigue, the appearance of pain. The cause of these symptoms in the early stages can be identified by the results of a biochemical blood test. As a rule, the level of” bad “lipids, glucose, and some others But in order to identify these changes, it is necessary to undergo medical examination in a timely manner, and if complaints appear, immediately consult a doctor, “explained Antonina Starodubova.

To feel good, to be active and attractive, it is important to know about the prevention of metabolic disorders.

“The main secret of prevention is a healthy lifestyle. Movement is life, which means that every day a person must walk 10,000 steps or actively move for 40 minutes. And be sure to be attentive to what he eats. Eating should be regular, no less three times a day, preferably at the same time.In each meal, the diet must include two food groups: cereals – cereals, wholemeal bread, as well as vegetables, fruits, at least 400 g per day.Nuts, legumes, fish are also useful … But salt and sugar should not be abused. They are often the reason for the imbalance of metabolism, “- explained the professor.

Photo: depositphotos.com

Recently “RG” talked about the regional program, which has begun to operate in the Penza region, aimed at changing the stereotypes of nutrition. As part of the initiative, food outlets in the region not only placed banners about healthy food, but also found an opportunity to provide visitors with greens and vegetables for free.Officials from medicine came to such actions not from a good life. According to the Rospotrebnadzor report “On the state of sanitary and epidemiological well-being of the population in Russia,” the Penza region was included in the number of regions where most people are obese. According to statistics, the incidence of obesity in the region amounted to 678 per hundred thousand of the population and has almost doubled over the past three years. In other regions, the figures are also pessimistic.

Every month, there is new research from scientists around the world about which foods and drinks affect the metabolic function.Among the latest discoveries, tea contributes to weight loss, as it changes the intestinal microflora. As it turned out, regular consumption of tea led to a decrease in the bacteria that cause obesity. There is a lot of scientific work devoted to the effect of spices on improving metabolism: for example, chili, ginger and garlic help to spend additional calories in converting heat processes. Cinnamon, cardamom, and many others are also known for their ability to “awaken” the body. But it is important not to forget about the sense of proportion when adding seasonings and remember that many of them whet the appetite.

5 life hacks to improve metabolism

1

Regular meals – at least 3 times a day at the same time . And in any case, do not overeat at night – metabolic processes slow down at night. And also do not overuse diets , sugar and salt. Speaking of the latter, the WHO recommends to consume no more than 5 grams of salt per day . As for sugar, according to the conclusion of nutritionists, it is possible to significantly facilitate the withdrawal process by including in the diet, for example, high-quality dark chocolate, carrot sticks, and nuts.A handful of almonds a day is enough.

2

Forcing ourselves to move. Nothing prevents you from becoming active right now . Move while brushing your teeth, while waiting for the kettle to boil, while waiting for the elevator (or better, go up the stairs), remember the morning exercises and evening walk … Remember the importance of working on all muscle groups.

3

We say “no” bad habits . This applies not only to alcohol and nicotine, but much more.Watching TV shows or hanging on social media are also bad habits.

4

Let’s get enough sleep. People who sleep an average of about six hours a night are more likely to suffer from metabolic problems and are three centimeters wider at the waist than those who sleep more. Scientists from the University of Leeds came to this conclusion after studying the lifestyle of more than 1.6 thousand people. The optimal amount of sleep is individual for everyone, but for most people it is seven to nine hours .

5

For the thousandth time – do not forget to drink enough water. She is the most important participant in all chemical reactions (our body is 70 percent water).

It is human desire to stay always healthy. And the only thing that has been proven over the centuries is that the more correct you eat, the more you move, the more active and correct lifestyle you lead, the healthier you stay. Each of us has a huge stock of hidden reserves and opportunities.It is our responsibility to discover them in ourselves and learn to use them.

Human Anatomy Fundamentals: Advanced Knowledge of Body Proportion

This article assumes that you already have an idea of ​​the basic proportions and arrangement of compounds in the human body, and you, since you probably did not disdain to practice in this matter, should already be ready to move on. The most obvious differences can be seen between a man and a woman, however the artist should also be familiar with how the body changes depending on age (while it is still growing) and size.

Male and female proportions

Male and female proportions are so different that even the skeleton (more precisely, some of its parts) can give out the gender of the wearer. Keep in mind, however, that the vertical axis placement does not change: the joints in the body do not move higher or lower. Their location almost completely varies on the horizontal axis, in other words, along the width of certain parts of the body. How can we make the original image more feminine or masculine? At the structural level at which we work, there is only one big difference to learn, and the rest is small supporting details.

Shoulder / Hip Ratio

The main difference is the ratio of the width of the shoulders to the hips. Women have a much wider pelvic bone, if a man, they need to somehow bear children and give birth. This fact has implications for the whole body. This means that the hip line in women is the widest part of the body, with which a narrower waist is compared, while in men the shoulder line is the widest part, and the waist is hardly different ( by width) from the hips.In general, the female silhouette is an hourglass, as opposed to the male trapezoid, as shown below.

To make the idea of ​​measurements clear (approach it with skepticism, because the impression of the silhouette as a whole always surpasses the exact calculations), on our basic figure below (in the middle) I dropped the index lines on both sides of the head, and after another, at a distance between the central axis and the width of one head. These lines define the two yellow areas where the person’s shoulders and the pelvic bone are located.

To make a woman out of a neutral figure, you need to expand her pelvis so that the hip joints are closer to the outer sides of the yellow areas. The position of the shoulders varies, but does not go beyond this area. (Note that this comes from the legs: the thighs take a more tapered position to connect the pelvis and knees, which have not changed their location. The man’s legs appear more vertical relative to the woman’s).

In order for a neutral figure to turn into a man, the pelvis must remain narrow, while the shoulder joints will be outside the yellow zone.Again, this factor can change, but they will always tend to the outside of the yellow area. This again translates into the way both genders hold their hands, as you can catch a glimpse of in the previous image and in everyday life: women keep their elbows mostly closer to the body, and their hands at rest usually follow the contours of the body. A woman needs to deliberately remove her hands from her body. Meanwhile, due to the fact that the shoulders of the man “stick out” more, the arms at rest hang freely away from the body and naturally are not located close to it.

Smaller differences

Waist and elbows

The female waistline is level with the navel, but the male waistline is much lower. This makes the man’s torso look longer. This is worth remembering as in my early years, I drew torsos of the same length and a line of trousers of the same level for both genders, and for a long time wondered why men looked wrong. Also, make sure that your elbows are not below the waist! The navel is the indicator of the position of the elbow joint, so unlike a woman’s figure, if a man’s waist is at the level where his trousers begin, his elbows will be much higher.

Rounded or angular?

In anticipation of the detailed body we will be drawing shortly, it may be helpful to sketch women with rounded shapes and men with more angular trapezoidal shapes, as this reflects the overall impression of each physique.

Generally speaking, a woman’s body is made of flexible, rounded shapes — breasts and buttocks, for example — and also, if not modified, contains more fat under the skin.Male bodies are more angular and have sharper lines when muscular. The fact in question, of course, can undergo various changes, and is extremely amenable to them – you can easily use angular forms for a thin woman, for example, or flexible ones for a well-fed man. However, note that with a naturally slender body, a woman’s belly is slightly curved and her buttocks are rounded. The man, however, tends to be flat in both the buttocks and abdomen.

Hip joints

Small detail but important: Draw the female hip joints outside the hip bone.They are clearly protruding, which makes this feature noticeable. Conversely, leave the male hip joints inside.

Other parts

• Both sexes have palms and soles about half the width of the face. But they are longer, relative to the face, in a man than in a woman.
• The female spine tends to be more flexible and noticeably more curved than the male.
• And finally, on average, men are taller than women!

How important is ?

To make it clear, this is what happens if you draw a man with female proportions, and vice versa.

Even taking into account gender stereotypes about hair and breasts, the proportions and shoulder / hip ratios make the body look abnormal.

Male and female bodies can vary from the ones we just saw, to androgynous (“bisexual”), that is, those who do not position themselves on the wrong side. But only a nasty artist draws exclusively androgynous bodies and relies only on superficial details for gender differences.

In a future article, we will take a closer look at the main body types (somatotypes), which are the result of the combination of structure and musculature.

Proportions and age

This section shows how the proportions change from birth to the end of physical growth, which marks the end of adolescence and the beginning of adulthood. In fact, here almost everything is at your discretion, since people do not grow at the same rate even within the same family, let alone the whole world.However, the model is very useful for anyone who has trouble specifying a specific age for a character, and we will come back to it for other body and face details in due course.

Newborn (0 to 1 month)

Notice how short the legs are at this age: in this position, an adult would reach his shoulders with his knees, but here the legs and arms are almost the same length, and the knee and elbow are just touching. Babies at this age are still in fetal position most of the time, so I’m not counting the legs when I say the total length is about 2.5 heads.Indeed, a newborn’s head looks disproportionately large compared to everything else in their body.

Infant (1 month to 1 year)

After three months, the proportions may not change much, but the body becomes noticeably more plump, and as the legs slowly assume a more erect posture, a feeling of rapid growth appears. Raised at 10 months old (he may be too small to stand on his own), he will look quite similar to a child who can already walk, but with certain characteristics.Such as the absence of a neck, for example.

Toddler (1-4 yrs)

Apparently, someone’s future growth can be roughly predicted by multiplying the height at age two by two. In any case, babies at this age are the smallest people who can stand upright like the rest. The head is still very large for the body (close in size to what it will be when a child becomes an adult), the legs are short (just over a third of the total height, as opposed to half for an adult), and the beginning of the neck is present.

Child (5-11 years old)

Growth is continuous during childhood, and this image only illustrates what someone can be between 7 and 9 years old. Children of this age may look thin because the fat that was previously disappeared (even in cases where puberty later contributes to weight gain). Note that the thin neck grows out of the nearly horizontal line of the shoulder because the trapezius and neck muscles are not developed.I mention this detail because drawing a child with a fully developed shoulder line can look very strange!

Teen (12-17)

Until this stage, we did not mention the difference between boys and girls, because sexual dimorphism has not really been particularly evident until now. If you think about it, we know the gender of younger children only because we dress them appropriately and cut their hair, but at this age it is very easy to circle the observer.Puberty, by definition, is the time of life when hormones speak their own way and mature the body. Women reach puberty earlier, between 8 and 13 years of age. Men are between 9.5 and 14 years old. Structural level:

• The difference between waist and hip size increases. Fat can enlarge the belly, buttocks and legs, and this can be a sign that a woman has fully matured.
• The man’s shoulders become wider.

In both sexes, the head is still larger than in adulthood, and the limbs (palms, feet, even arms and legs) can grow faster than the rest of the body, resulting in a slightly awkward appearance.The same thing happens with animals, by the way!

The next stage of growth is the beginning of adulthood, where the final proportions are established, which are explained in the section on men and women. There is no need to consider other age categories at this time, because the human structure is no longer changing. I’ll just mention that in old age, bones begin to lose mass, so growth can become smaller, and the body – “sag”, as a result of which the neck will look shorter and the arms will sit lower.

Again, how important is all this?

Here’s a sketch of four people …

The first two people have proportions just for their age. The third illustrates what happens if you draw a child using “adult” proportions: tiny adult! This is what you need if you are drawing a fairy or ant-man, but it definitely does not represent a child.

The reverse is also true: the fourth figure shows what an adult would look like using “childish” proportions.An adult will look weird even if the skull could grow that way in reality.

Despite the inevitability of using a variety of styles, there is a certain minimum height below which the “adult” proportions will not be normal. Short women are only reduced to a certain extent; some childish characteristics will appear only if the considered, well, very low. The converse is also true: very tall people appear elongated, not just enlarged.

Despite the roughness of this sketch, we can make out a tall, robust man, a small adult woman, and a teenager (or possibly a girl). How do we determine this if there are no external features and the teenager is about as tall as the woman? Proportions provide a lot of information.

An interested artist who has probably studied all the diagrams above and realized them may have perceived it as hard work, but unconsciously, we all pay attention to the mass of proportional “clues” and their meanings.In this image, you cannot miss the clues in the form of the woman’s wide hips (a sign that she is an adult) and the undeveloped body of a teenager (neither shoulders nor hips are wide). This does not mean that you cannot draw adults with deliberately weak characteristics (such as narrow shoulders), but if they are incorrectly depicted, the whole drawing can be ruined. You, in principle, can notice that something is wrong with your drawing, but it will be rather difficult to realize what exactly.

Ethnic origin

The proportional “cues” I mentioned earlier are culturally dependent in part.There are more of them if we travel or otherwise study ethnic diversity, but until we do this, their number does not increase. That is why there is a perception in the western lands that Japanese women look younger than they are: in most of the descriptions that you may have heard, there is a mention that their hips remain narrow even in adulthood, unlike European women, thus , we are being misled visually. If we draw a Japanese woman with the same physique as the average European woman (including wider hips), we wonder why she looks more European than Asian.

There are dozens of ethnotypes and each has its own characteristics, but even at the most basic level of the skeleton, we can see a general difference between the three largest ethnic groups of humanity. Since this subject area is beyond the scope of these articles, I am writing this just for information: you need to be aware of the extreme diversity in the depiction of the human figure, and, paradoxically, you need to start drawing already having a complete idea of ​​the general features of the human body in order not to lose it structural characteristics.

Time to practice

Until next article, try to catch theory in practice. Here are some things you can do to be ready for the next lesson:

• Watch, watch, watch! Look at the people around you, men and women, this time, noting what is structurally different. Look at children of different ages, people of different nationalities, online or in real life.

• Dig up your baby photos (or photos of your children) at different times and sketch on them.Just don’t try to circle – use a combination of impression and knowledge about the proportion model that we have considered. This can be especially interesting if you can find pictures with the same poses, but at a different age, because you can see how the proportions have changed.

• Draw a crowd of people yourself, without using any references or sources. Does anything look wrong? If so, can you determine what the problem is?

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