3 Answers

  1. There is a loss of brains. If we take as an example not only natural selection, then some dog species have lost a large brain volume, along with body size.

  2. Evolution didn't have the task of creating big brains as such. All changes, including changes in the size and structure of the brain, were a response to external changes and an attempt to adapt to them. Therefore, if it is more profitable, the brain may decrease in the course of evolution.

    For example, imagine a situation in which there were, say, some of our ancestors who lived for themselves, hunted mammoths and ran from tigers. They need a fairly large brain to outwit both creatures. And now they have moved to an area (for example, an island) where there are no predators that are too dangerous for them, and the food is not very fast and completely stupid. They no longer need a huge organ that consumes a huge amount of energy, but is idle at the same time. In this case, they will begin to degrade in terms of brain size and intelligence.�

    And the most important thing is that the situation is not hypothetical at all — a species that is now called the Flores man sailed from Java to the island of Flores about a million years ago. So their brains in the process of evolution lost more than half of their weight — about 600 grams (originally it was about a kilogram). Of course, there were also predators (giant storks and monitor lizards), but they were much more stupid than their previous natural enemies, and you don't need much intelligence to escape from them. They mostly hunted rats.

    The second example is a person. Over the past 25 thousand years, we have lost an average of about a hundred grams of brains. And indeed, having learned to write down information instead of keeping everything in mind, to divide work (to specialize in one thing), and to stop fighting for survival in an aggressive environment, we no longer need to be so smart. After all, the same Cro-Magnons had to learn how to hunt, hide from predators, make their own shelters, cut up and cook food, and know which plants and animals are poisonous, which ones can be eaten, and which ones can't. There was no room for error, and it was necessary to remember and think quickly and forever. Over time, people no longer need it. Yes, now there is a lot of information again, but universal education in schools first appeared about two hundred years ago, at most, or even hundreds at all. Such time intervals are too small for evolution and how this will affect human intelligence and the size of his brain, we will find out very soon.

    It is interesting that the greatest decrease in brains is observed in developed countries — where NT progress is gaining momentum and there is no point in storing a lot of information and knowledge in your head. In countries that are developing slowly, on the contrary, the improvement of technology does not keep up with the growth of the amount of information, and as a result, the brain increases. The Mongols, Buryats and Kazakhs have the biggest brains now, and they've probably even increased over the past 25,000 years.

    The loss of brain quantity can also be due to an increase in its quality, but at the moment this is unprovable, since it is not possible to compare our brain with the brain of our ancestors.

  3. I remember the inimitable Yevgenia Timonova. In one of the programs she talked about bats, the mass of the sexual organ of which reaches 8.5% of the body weight (if such a member was a man weighing 80 kg, the weight of the member would be about 7 kg).�

    So, it turned out that the tissues from which the testicles are formed are the same ones from which the brain is formed. And the males who managed to grow large perks did not differ in large brain size. �

    And that's where natural selection comes in. Since females like bigger eggs, males with bigger brains will produce fewer offspring. And at the same time, the brain size of bats of this species will decrease.�

    And in general, as far as I know, everything in the universe tends to conserve energy. And the brain spends hoo-hoo much energy. Therefore, as soon as the development and preservation of the species reaches some stable stage, where the presence of intelligence is not so important, then the most energy-consuming parts of the body will first go under the roller of natural selection. But in relation to a person, this is unlikely to happen, because we are already very dependent on intelligence.

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