8 facts about your body that may surprise you

1. Humans have the same density of body hair as chimpanzees and gorillas

Compared to apes, even the hairiest people appear bald. But in fact, the density of follicles per centimeter of skin we have is the same as that of great apes, in particular, gorillas and chimpanzees. Both humans and monkeys aboutWhy Humans Lost Their Hair and Became Naked and Sweaty / Discover Magazine 5 million hair follicles.

This indicator was measured by scientists from the University of Sheffield in the UK.

Human hair follicles are very similar to those of monkeys, but ours hair not dark, but thin and colorless, like fluff. People got rid of thick wool in order to have more plentiful sweatWhy Humans Lost Their Hair and Became Naked and Sweaty / Discover Magazine: They run faster than primates, therefore, more effective protection against overheating is needed.

Scientists considerThe not-so-naked ape / The Economistthat fluff on the skin came to us from ape-like ancestors for a reason. This is a kind protectionThe semi‑naked ape, or why peach fuzz makes it harder for parasites / National Geographic from parasites - to fleas and lice biting less.

Now, of course, this is not very relevant, but in some Middle Ages it was not superfluous at all. Fluff allows you to quickly feel the parasite on the skin and get rid of it. And besides, it covers the body from the stings of insects.

2. You can't taste food without saliva.

Do an experiment - take a clean towel and wipe your tongue. Then put some dry foods in your mouth, like cookies or chocolate. They become completely tastelessR. Matsuo. Role of saliva in the maintenance of taste sensitivity / Critical Reviews in Oral Biology & Medicine.

The fact is that our saliva is necessary to transport fragments of flavoring substances from food to receptors on the tongue.

Remember how unappetizing food becomes when you have a cold. Due to infectious diseases, the body often begins Problems with salivation - this symptom is called "xerostomiaE. A. Field, L. Longman, W. R. Tyldesley. Tyldesley's Oral Medicine». In addition, people with a stuffy nose breathe through their mouths, which leads to additional dehydration of the mucous membrane.

3. Men's faces are different from women's because they get hit more often

In many animals on our planet, sexual dimorphism is extremely weak, that is, males are very similar to females in appearance. Try to determine the sex of individual crocodiles or wolves from a photograph. But in humans, the differences between men and women, as they say, there is.

Anthropologists believe that male jaws and cheekbones are stronger than female ones for a reason. Initially researchers assumedMale faces ‘buttressed against punches’ by evolution / BBC News: such strong facial muscles of primitive people became because they ate very hard food. But this did not explain the strong difference between the sexes - it is unlikely that our distant ancestors were such gentlemen that they chewed food for their ladies.

As a result, scientists from the University of Utah found that reasonProtective buttressing of the human fist and the evolution of hominin hands / Journal of Experimental Biology. Men's faces do not look like women's, because men were more often punched in the face - so historically happened. Therefore, their jaws, cheekbones and brow ridges stand outD. R. carrier. Protective buttressing of the hominin face - Carrier / Biological Reviews noticeably stronger - it is in these places that most often flew inMaking a fist of it / The Economist punches in a fight.

Fisticuffs are a purely human way of dealing with issues. Monkeys are not capable of squeezing the brush like that.

Australopithecus four million years ago have learnedThe human face developed over 5m years of fisticuffs, scientists claim / The Guardian to do so, and their faces had to develop an appropriate defense.

Why are men's faces now still not as rude as those of primitive of people? Well, with the advent of civilization, mankind began to rely more and more on firearms than on melee, so the brow ridges and jaws were slightly reduced.

4. Man is the only primate with the whites of his eyes

Fortunately people evolve not only through violence and fisticuffs. Some features of our bodies are due to the desire to live in peace with others and jointly solve common problems.

For example, the whites of the eyes of people appeared because it is easier to determine the direction of a person’s gaze from them. In other primates and in general the vast majority of animals, the sclera are colored, so it is very problematic to understand where their owner is looking.

This theory confirmedWhy Eyes Are So Alluring / Live Science experimentally by specialists of the Max Planck Institute for Evolutionary Anthropology in Germany. They found that the monkey is able to determine where a person is looking only when he turns his head in the appropriate direction.

It just doesn’t fit in her mind that the direction of the gaze of the creature standing in front of you can be tracked by the eyes. But among people, even babies can easily guess where others are looking, and at the same time direct their gaze there.

Why is it useful for people to observe the eyes of their comrades? Obviously for socialization.

So we quickly determineWhy we show the whites of our eyes / The University of Melbourne emotions of others. And we can easily communicate viewsDo any mammals other than humans have ‘whites of the eyes’? / BBC Science Focus Magazine, even without words, which probably came in handy for our ancestors on the hunt.

And finally, the ability to quickly understand that your interlocutor is looking not at your face, but at the hatchet lying nearby, allows you to stop his bad intentions in time. And this generally reduces the level aggression in society, which is important for social creatures like us.

5. Your internal organs detect toxins by taste and smell

You've probably heard the term "taste buds". These are sensitive receptors located on the tongue that capture flavors. We also have very similar olfactory receptors in the nose.

So, not only your tongue and nose can taste and smell, but also your bladder, intestines, kidneys, pancreas and brain.

And also receptorsThe startling sense of smell found all over your body / BBC Futurealmost similar to taste buds language, is found in the respiratory tract, muscle tissue, spine and many other organs and systems. Olfactory - in the blood vessels and in the heart.

In fact, our entire body is one huge tongue-bearing tongue that senses tastes and smells. Yes, bladder. reactsThe startling sense of smell found all over your body / BBC Future for sweetness, the brain and pancreas perceive bitterness, and the spine is equipped with sour taste receptors.

At first, scientists believed that this was a kind of atavism, but then they realized: the organs are literally findThe startling sense of smell found all over your body / BBC Future thus there are poisons and toxins in the body. For example, it is by taste that the kidneys feel which substances to leave in the blood, and which ones to filter out and excrete with urine.

If a person has earned poisoning, all organs, feeling unpleasant for them, the smell and taste will try to get rid of the harmful compound.

And even spermatozoa determine where to move with the help of bitter taste receptors.

6. There are many unexplored life forms in your navel

We already toldthat a lot of all sorts of bacteria, viruses, fungi and archaea live in people. In fact, there are three times more such living cells in our bodies than our own. This is approximately 3 kilograms of biomass.

And the navel is especially popular with various guests of the human body. By calculationsJ. Hulcr. A Jungle in There: Bacteria in Belly Buttons are Highly Diverse, but Predictable / PLOS ONE researchers from the University of North Carolina, about 2,368 species of bacteria live there.

At the same time, 1,458 of them have not really been studied. It is not clear what they are doing there and whether they are needed at all for the normal functioning of the body.

The reason for this diversity is that the navel of even the cleanest people rarely gets under the shower.

In one subject, for example, scientists discoveredWhat Lives in Your Belly Button? Study Finds Rain Forest of Species / National Geographic there is a unique type of bacteria that was previously found only in the soil of certain regions of Japan. Moreover, this comrade has never been to Japan. In smears from another, two types of extremophiles were found, which usually live in the ice caps of mountains and thermal springs.

From this we can conclude: do not poke around in the navel, otherwise you will find some rare pathogen there and provoke a new pandemic. You never know.

7. Intestinal gases can be absorbed into the blood and exit through the mouth

It's time to learn a new terrifying, but scientifically confirmed fact, after which you want to erase your memory.

All people periodically release intestinal gases - usually this going onFlatulence causes & treatments — Illnesses & conditions / NHS inform from 5 to 15 times a day. We constantly absorb air while eating food and swallowing saliva, it is sent through the digestive tract and must somehow go out.

Naturally, in the presence of others, it is not good to blow the winds, so we restrain ourselves. And this leads to unpleasant consequences.

A significant part of the mixture of methane, carbon dioxide and hydrogen sulfide produced in the digestive system, if not released in time, will be absorbedA. b. Sahakian. Methane and the gastrointestinal tract / Digestive Diseases and Sciences into the blood through the walls intestines. Through the blood vessels, these elements will pass throughout the body and enter the lungs, where they will be brought out by the body during breathing. Live with it now.

Luckily, it doesn't smell because intestinal gases break down into their constituent elements as they travel through the blood vessels and not reabsorbedCan a Fart Escape In Your Mouth? Another Reason to Not Hold It In / Healthline.com. Prolonged containment mayK. R. price. Flatulence - causes, relation to diet and remedies / Nahrung lead to indigestion and bloating, but is unlikely to cause serious health problems.

8. There used to be spikes on human penises

One last interesting fact. Some people nowadays strive decorate your intimate organs with various inserts. But long before this, nature had provided the genitals of our ancestors with adaptations of a similar nature.

Scientists establishedHow the penis lost its spikes / Naturethat about 700,000 years ago, human penises were covered with hard fragments of keratin. Such "thorns" now there is1. How man lost his penile spines / BBC News,
2. Wombat reproduction (Marsupialia; Vombatidae): an update and future directions for the development of artificial breeding technology / Reproduction Volume 145 Issue 6 (2013),
3. Sexual selection and genital anatomy of male primates / Proceedings of the Royal Society of London. Series B: Biological Sciences in cats, hyenas, many species of rodents, wombats and other mammals. They are also present in our closest relatives - chimpanzees.

Animals use their spiny organs to perform sexual acts as quickly as possible, as this provides additional stimulation. And in some species, such as domestic cats, males leave a sticky secret in females during mating, generativeEvolution of sexual size monomorphism: the influence of passive mate guarding / Journal of Evolutionary Biology — Wiley Online Library the so-called copulatory plug. She does not allow other gentlemen to court the lady. Genital spikes help to overcome this barrier.

Why did people get rid of such keratin growths? Apparently, because they switched to monogamy and the creation of families: sexual intercourse became longer, and the spikes began to interfere.

Some men, by the way, still have their remains. These tiny growths calledThe real "junk" DNA / John Hawks Weblog pearlescent papules.

Especially curiousShedding our penis spines helped us become human, DNA study hints / The Guardianthat the genes responsible for pimples on the penis are simultaneously associated with suppressionHow Men Lost Their Penis Spines / Live Science protein reproduction and cell growth brain. Why this is so is not particularly clear. But perhaps it was the rejection of spikes that led to the fact that modern people have such a large brain.