Human evolution followed the path of increasing and developing the brain, the rest of the changes in anatomy are nothing more than the result of the growing appetites of the nervous system, modern anthropologists are sure. There is no consensus as to why the stake was made on the brain, and not on steel muscles or sharp teeth. The adult brain consumes about a quarter of the body's total energy. In the wild, this is not only disadvantageous, but also dangerous.
All resources to the brain
In the spring of 2017, 62 students competed in strength and intelligence in one of the laboratories of the University of Cambridge (UK). First, they had to answer tricky questions that tested their intelligence and memory, then on the simulators they had to find out who was more enduring and faster. At the third stage, the competition participants simultaneously performed physical exercises and solved intellectual problems. All this time, scientists recorded how many calories were spent by students for muscle and brain activity.
According to researchers, this indicates the special importance of the brain in human evolution. It was more useful for our ancestors in critical and dangerous situations to provide food for the brain, rather than muscles. The need to keep him on constant alert affected metabolism. The human body has learned to consume energy faster and store it in fat deposits, which are absent in other primates.
Eat faster, think better
Maintaining a large brain is very difficult. The closest human relatives, chimpanzees, in which this organ is about three times smaller, spend eight to ten hours a day on food. Otherwise, there will simply not be enough energy. According to the work of an international team of paleontologists, our distant ancestors 3.5 million years ago did the same. And then there was a great food revolution - some of the hominids dramatically changed their taste preferences. Scientists from the remains of teeth and jaws studied the diet of ancient primates that lived in East Africa - Afar australopithecus, paranthropus, the ancestors of modern baboons, Kenyanthropus and Rudolfian people. It turned out that all hominids ate approximately the same - fruits and leaves of trees. But then the australopithecines switched to a mixed diet - fruits and leaves of herbaceous plants were added to woody foods,found mainly in savannas and near water bodies. They were easier to digest, and the excess energy was spent on maintaining the work of other organs, including the brain, which allowed it to increase in size. Research by Spanish, Australian and British specialists partially confirms this. But, according to these scientists, it was not the plants themselves that played the main role, but the fact that people learned how to cook them. Molecules of starch and other carbohydrates contained in the rhizomes of edible plants, fruits and nuts break into pieces during cooking, and carbohydrates are absorbed much more easily, which, again, could contribute to the complication and enlargement of the brain. This theory is supported by the fact that the human brain consumes up to sixty percent of the glucose contained in the body. Our body itself can synthesize it, decomposing fats and proteins,however, it is much easier to obtain this substance from starch and other plant sugars. In addition, human DNA contains as many as six copies of the gene encoding amylase, an enzyme in saliva that breaks down starch in food. It is assumed that these copies appeared in the genome about a million years ago - just after the ancestors of Homo sapiens learned to cook food.
A good father is the head of everything
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According to the hypothesis of scientists at the University of Rochester (USA), the intellectual development of a person was launched by the helplessness of his offspring. Caring for newborns required a certain amount of mental effort, which enlarged the brain. This, in turn, led to an earlier birth of young - in order not to get injured during childbirth, the child must be small enough. Caring for even more dependent offspring required greater intelligence, and therefore increased brain size. Anthropologists from the University of Zurich partly agree with this theory, but they believe that the main factor that triggered the evolution of the human brain is not the young themselves, but their attentive and loving fathers. Observations of 478 carnivorous mammals, rodents and primates have shown that if the male actively helps raise the young, the brain mass of this species tends to be higher. The same correlation exists between parental behavior (when offspring are looked after by relatives and group members) and the number of offspring. The researchers hypothesized that our ancestors had both behavioral traits - parental care and group help. Moreover, unlike other species of mammals, in humans, relatives practically did not shy away from participating in the upbringing of young. As a result, paternal care contributed to an increase in brain mass, a large brain helped to better negotiate with group members, which made Homo sapiens more fertile than all other primates. According to the calculations of British researchers, the ability of our ancestors to connect fathers to raising offspring, to agree with each other, to get food together and raise young is not the most important thing. The contribution of these factors to brain enlargement is thirty percent. Sixty percent gave a change in diet and the formation of culinary skills. Another ten percent is due to the competition between the tribes of ancient people. This explains why other primate species have never been able to grow their brains as large as ours. In their evolution, the stake was made exclusively on social connections and life in a society of their own kind.
Alfiya Enikeeva