Scientists have found out why the brain of a modern person has decreased

American scientists analyzed 985 fossil and modern human skulls and found that the human brain increased sharply twice in size – 2.1 and 1.5 million years ago, and then, relatively recently, three thousand years ago, decreased again. Drawing parallels with ants, the authors hypothesized that the brain shrinkage occurred in parallel with the transfer of a number of functions to the area of ​​the collective mind. The results are published in the journal Frontiers in Ecology and Evolution.

It is well known that the human brain grew in size during the Pleistocene and then unexpectedly shrank in the Holocene. The exact time and reasons for this reverse transition were still unknown.

“The surprising fact is that our brains are smaller compared to the brains of our Pleistocene ancestors. Why our brains have shrunk has been a big mystery to anthropologists,” one of the authors of the article, Dr. Jeremy De Silva, quoted in a press release. Jeremy DeSilva) from Dartmouth College.

In the process of studying the size and structure of colonies of various ant species, as well as the physiology and energy use at the level of individual insects, the authors found that the brains of ants in highly organized colonies are smaller in relation to body size than in low-organized communities.

The brain is the most complex and energy-intensive organ. The authors believe that in social groups of ants, where there is a clear division of responsibilities, and decision-making is transferred to the level of the collective intelligence, the insect brain has shrunk in size to become more energy efficient.

Although ant and human communities differ in many ways, researchers believe they share common social traits, such as group decision making, division of labor, and co-production of food. But these features were not always characteristic of humans, but arose approximately at the turn of the Pleistocene and Holocene, when our ancestors passed from the clan to the tribal social structure. At the same time, there was a change in the size of the brain.

The authors believe that the success of the study is due to the fact that it involved experts from different fields.

“A biological anthropologist, behavioral ecologist, and evolutionary neuroscientist began to share their thoughts on the evolution of the brain and found that collaborative research in humans and ants had answered the question,” said co-author Dr. James Traniello of Boston University. We assume that the decrease in the brain in modern humans is due to the growing dependence on collective intelligence, since a group of people is always smarter than the smartest person in the group. ”

Scientists suggest that in the future, the increasing externalization of knowledge, requiring less and less energy to store large amounts of information individually, may lead to a further decrease in brain size.

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