As scientists continue to explore our evolutionary history, new facts emerge to explain how the past shapes modern humans, from the size of our brains to the length of our lives. Even more intriguing is the role that randomness has played in shaping the brain and body that modern humans have.
1. Human faces are shaped to withstand impact
Until recently, it was widely believed that tough human faces formed about four to five million years ago to help our Australopithecus ancestors chew on solid foods such as nuts. But now this opinion has been destroyed by a direct blow to the face.
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According to a study by the University of Utah, our distant past was not as peaceful as we once thought. Violence has probably played a much larger role in the development of human physiology than we previously suspected. Researchers believe that men's faces are shaped to minimize impact injuries during fights for women, food, and territory.
The bones of the face have become stronger so as not to break during hand-to-hand combat. These same bones represent the difference between a male and a female skull. Obviously, male faces needed to evolve in this way, because the bones that break in battle are larger in men.
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If this theory is correct, humans were not noble savages who became aggressive because of civilization. Instead, our physical abilities have evolved to enhance our fighting strength.
2. Human hands have evolved to strike
While human faces were shaped to withstand the blow, our hands were shaped to deliver it. In an earlier study by the same University of Utah, scientists found that human hands are formed in a paradoxical way.
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Compared to monkeys, the same features that allow us to clench our fists - short four fingers and a palm with a longer, stronger and more flexible thumb - also give us the dexterity to make and use delicate tools. But while chimpanzees can make tools, they cannot make fists.
It's also possible that our hands evolved from the same genes that gave us short toes and an elongated thumb when we started walking and running upright.
Scientists believe that our aggressive and violent nature has caused our bodies to turn into war machines. A person striking with a clenched fist can hit harder without harming themselves. Fists can also be used to intimidate. Ultimately, our hands - with their ability to both kill and create - can separate good and evil in human nature.
3. We had herpes before we became human
Some of our physical characteristics didn't just evolve over time. Some diseases, such as herpes, have come down to us from chimpanzees.
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About 67% of modern people have at least one herpes simplex virus (HSV). In fact, humans are the only primates to have two HSVs, usually presenting as herpes on the lips or blisters on the genitals.
Herpes of the first type affected humans before they separated from chimpanzees about six million years ago. HSV of the second type was passed to us from chimpanzees about 1.6 million years ago. Scientists at the University of California believe that studying the origin of these viruses will help prevent other diseases from spreading to humans.
Another group of scientists from Oxford and Plymouth Universities has discovered ancient Neanderthal viruses in modern human DNA. These viruses originate from the HML2 family and may be associated with modern human cancer and HIV. This information may be useful in the future for the development of therapy.
4. Man is the only primate whose tooth size decreases with increasing brain size
Over the past 2.5 million years, two trends in human development have been linked - the size of the human brain has increased and the size of the teeth has decreased. We are the only primates who can boast of this.
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Usually, when the brain grows, teeth grow too, because the body needs more energy from food. Therefore, scientists call what happened to people an evolutionary paradox. They believe that it happened due to the fact that people began to eat more meat, which feeds our brain.
Also, humans are the only primates that have developed thick tooth enamel. In herbivorous primates, the tooth enamel is thin, in higher primates and monkeys, which feed on both plants and animals, the enamel is of medium thickness. In humans, the enamel is even thicker, probably to crush tough foods. Human enamel also allows scientists to determine the age and diet of ancient people from human fossils.
And Neanderthals are the earliest hominids who used toothpicks to relieve pain from dental ailments such as sore gums.
5. Our common male and female ancestors lived at about the same time
Researchers often use the name "Y-chromosome Adam" for our closest common ancestor. Males usually have one X chromosome and one Y chromosome, while females have two X chromosomes.
According to a study published in the European Journal of Human Genetics, "Adam" probably lived about 209,000 years ago.
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This model contradicts previous research by the University of Arizona, which suggested that the Y chromosome existed before humanity. Scientists from Arizona believed that the Y chromosomes of modern men were created by crossing species more than 500 thousand years ago.
But the authors of the new study argue that the Arizona study, when interpreted correctly, creates a "time-space paradox that the oldest individual, Homo Sapiens, has not yet been born."
The new study also places the Y-chromosome "Adam" in the time of "Eve," the closest female common ancestor of modern humans. However, scholars argue that there was not one "Adam" and one "Eve" - instead there were groups of "Adams" and "Eves" roaming the world.
6. Grandmothers help us live longer
Grandmothers made us who we are. This conclusion was made by scientists from the University of Utah, who ran computer simulations to test the famous "grandmother hypothesis."
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According to this evolutionary theory, humans have a longer lifespan than apes because grandmothers helped feed their grandchildren. Other primates seek their own food after weaning.
When human grandmothers began to help feed their grandchildren, mothers were able to bear more children. Simulations have shown that it took 60,000 years to evolve from women who die shortly after childbearing to those living decades after menopause.
Many anthropologists believe that the increase in the size of our brains has contributed to the increase in the length of our lives. However, Utah researchers controlled brain size, hunting, and pairing in computer simulations. When they introduced the minimal effect of grandmother's presence, human life expectancy increased dramatically. Scientists concluded that grandmothers contributed - or even caused - important changes in human evolution, such as the development of larger brains, social dependency, and our tendency to work together.
7. Protein may have contributed to the development of a larger brain
Researchers at the University of Colorado have another theory about why the human brain evolved so quickly to such a size and complex system. These scientists found that a protein domain, which is a specific unit of protein structure, is found in more abundance in humans than in animals.
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This is the domain of the DUF1220 protein, and the more there is, the bigger your brain. Humans have 270 copies of their genome, followed by chimpanzees with 125 and gorillas with 99 copies. Mice only have one copy. This means that brain size can be highly dependent on the amount of protein domain.
Difficulties in finding rare insects to eat, which required developing problem-solving skills and using tools, also contributed to the development of large brains. But larger brain size was not the only factor in the evolution of humans from primates - humans also have more complex genetic activities to aid in learning.
8. Throwing made us human
The throwing skills of modern baseball players evolved from our extinct human ancestors. Early humans learned to throw stones and sharpened wooden spears while hunting nearly two million years ago.
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According to scientists at George Washington University and Harvard University, even chimpanzees cannot match humans in these skills. Chimpanzees, at best, can only throw a third as fast as a 12-year-old Minor League pitcher.
The researchers wanted to find out why people quit so well. While watching the footage of a baseball game, scientists realized that the human shoulder works like a slingshot, storing and releasing energy during the throw. Certain features of the human torso, shoulder, and arm have been specially developed to help us store this energy.
Throwing skills allowed our ancestors to kill and eat big game. Eating meat stimulated the development of the human body and brain to a large size. So the unique ability of our ancestors to throw helped us to become human.
9. Life expectancy of a person can be associated with extremely slow metabolism
Humans and other primates burn 50% fewer calories than other mammals. This means that in order to burn as many calories as other mammals of the same size burn in a day, a person will have to run a marathon.
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According to a new study, our slow metabolism may explain why we grow up so slowly, so rarely give birth to children and live so long. He can also explain why we have so many different weight loss programs.
But if you're exercising and you're having trouble losing weight, research can also point you to the cause. It was also found that primates in zoo cages spent as much energy as their counterparts in the wild, which in turn means that physical activity is likely to contribute less to calories burned per day than we thought.
In comparison, most mammals, such as our domestic dogs or hamsters, go through all life stages quickly and die early - often after ten years or less. Scientists believe that environmental conditions have influenced the development of the slow metabolism, which gives us long life.
10. The irony of fate that influenced human evolution
Scientists at the University of Chicago are doing molecular time travel to see how human evolution could have gone differently. They started with an important protein in the human body since it existed hundreds of millions of years ago. This protein eventually became a cellular receptor for the stress hormone cortisol.
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Biologists wanted to know how this ancient protein became sensitive to cortisol. After studying thousands of alternative versions, they found only one answer - it came out by accident. Two extremely rare mutations had to occur for the protein to develop sensitivity to cortisol. In other words, the modern form of protein came about by chance in our distant past.
The researchers believe a series of unlikely random events - an irony of fate - influenced the proteins that made us who we are. If proteins develop new functions, the diversity and genetic diversity of life can be explained. This also means that under a slightly different set of circumstances, people could turn into something completely different.