Hasn't the human brain finished developing?

After examining 1,300 people (and one chimpanzee), the researchers determined: the evolution of the brain continues, and the human race has not reached its peak

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Scientists say they have found strong evidence that the human brain continues to evolve. By comparing modern humans with our ancestors from 37 years ago, a team from the University of Chicago discovered two genetic changes related to brain size. One of the new variants appeared 5,800 years ago and is found today in at least 30% of humans alive today.
"It's a very short time in evolutionary terms, and this shows enormous selective pressure." They told the journal Science.

Walla News adds that according to the research of researchers from the University of Chicago, for thousands of years it seemed that these two genes were producing new and improved versions of themselves - better mutations, which spread rapidly among the human population to change the capacity of the brain and strengthen it.

One of the researchers claims that "many people think that the human species is at the peak of its development, and that we have reached an advanced state as a species. But this is not the case. Our discovery shows that the human race continues to develop, if you look at the brain."

As part of two studies, the results of which were published last week in the scientific journal "Science", 90 men and women and one chimpanzee were tested, and then 1,200 women and men, from 59 different ethnic groups from around the world, were tested.

The researchers discovered the changes that occurred in the various genes and identified "natural selection" processes, in which the mutations had a developmental advantage over the original. "The prevalence of the gene is increasing because the people with these genes are stronger and have more children," said Bruce T. Lahn, the lead scientist in the study, "we know that the selection process favors these mutations."

Lahn and his research colleagues believe that over time human behavioral and cultural developments may occur in a similar way to this genetic selection. The researchers concluded that the general genetic history of these two mutations is evidence that the brain evolves in both size and complexity. "In 10,000 or 20 years, the human brain will probably be different from today," concludes Lahn.

Even in a million years we will not be smarter

Zvi Atzmon, Haaretz (Galileo's scientific editor)

Researchers have discovered that genes that affect brain size underwent a significant change only a few thousand years ago. What can and cannot be concluded from this?

"Our studies indicate that the trend that most characterizes the development of the human species - the increase in the size and complexity of the brain - will most likely continue," says Prof. Bruce Lahn, adding: "If the human species continues to exist for another million years, I imagine that the human brain will then be somewhat different Significantly more than the modern human brain".

Naturally such a statement, from the mouth of a renowned scientist, finds its way to the headlines. Indeed, Prof. Lahn received media exposure that scientists rarely receive. However, the same statement raised quite a few eyebrows among other scientists.

Prof. Lahn, from the Howard Hughes Institute for Biological Research and the Department of Human Heredity at the University of Chicago, headed a team of researchers who published two articles in the scientific journal "Science" at the end of last week. The two published studies are based on an analysis of two genes whose damage causes a rare genetic condition called Microcephaly Vera, in which the volume of the brain is only about 400 cc, less than a third of the normal volume in a person.

So far, six genes have been identified whose damage causes true microcephaly. One of them is called microcephalin and resides on chromosome 8; Another gene is called ASPM and resides on chromosome 1. However, the published studies do not, in fact, concern microcephaly: from the fact that damage to these genes causes the brain to shrink, the researchers conclude that in the normal state the genes have an effect on the size of the brain and possibly its function.

The largest brain in the animal world does not belong to man - the large whales have a brain whose volume exceeds six liters, the volume of an elephant's brain is about five liters, while humans "make do" with 1,300-1,400 cc. Humans also do not hold the record for the ratio between brain and body size: in humans, the brain makes up about 2% of the body weight, while the brains of the little squirrel monkeys are 3% of their body weight. However, man does hold the record: his brain coefficient (the ratio between the actual brain size and the average brain size for a mammal of similar size) is the largest in the animal world. In a chimpanzee they measured 2.3, while in a human they measured 7.6 - a world record.

But among the human population, the relationship between the size of the brain and its abilities is very elusive. On the one hand, there is a certain, albeit weak, correlation between the size of the brain (relative to the body) and the IQ, and on the other hand, Einstein had a normal sized brain, maybe even a little smaller than average.

Research conclusions: Both genes are relatively "fresh".

We will return to the two genes, Microcephalin and ASPM. From examining the differences in the structure of these genes in humans and other mammals - an accepted method for analyzing and reconstructing evolutionary processes - the researchers concluded that these genes underwent relatively rapid changes in the evolutionary path that led to humans.

In the current studies, Lahn and his colleagues examined the different versions of these two genes in different population groups.
The conclusions: one of the very common versions of microcephalin is very "recent" on an evolutionary scale - modern man appeared about 200 thousand years ago, while this version of microcephalin was created much later, only tens of thousands of years ago, and since then has become so widespread in the human population, that According to the researchers, the assumption that it gave the subjects the same evolutionary advantage is warranted. They point to an overlap in terms of times between the spread of this version of the gene and the development of human language and art.

The ASPM garden has an even more "fresh" common occurrence - a few thousand years old in total. The researchers end their article on this gene version with a sentence that seems to aim to hint at a thick hint and perhaps wink at the popular newspaper headlines, without provoking too harsh criticism among scientists: "Although the age of the gene version that spread in the human population and its geographical distribution in Eurasia more or less coincide For two central events in the development of culture in Eurasia - the appearance of domestication and its spread from the Middle East to other regions about ten thousand years ago, and rapid population growth together with the development of cities and the appearance of writing 5,000-6,000 years ago in the Middle East region - the importance of this correlation has not yet been clarified."

But is the brain really going to grow?

The British geneticist Chris Tyler-Smith commented on the pages of "Science" by saying: "The fact is that all (healthy) humans use language and are capable of symbolic expression." In his view, this suggests that these gene variants cannot have a dramatic effect. He adds and claims that the attempt to link the appearance of gene versions to major events in human history is "very speculative". It is perhaps also worth wondering if at the same time as the gene version appeared and its effect on brain abilities, a jump in the size of the human brain was not also expected a few thousand years ago. There is no archaeological-anthropological evidence for such a jump.

However, it seems that the claim that if there are evolutionarily "fresh" versions of genes that are widespread in the human population, then there is something in them as evidence of evolutionary processes that are actually taking place these days, and hence also the prediction of the evolutionary future ("If the human race continues to exist for another million years, I imagine that the human brain then will be significantly different"), she is even more speculative. Maybe to an unreasonable level.

An evolutionary process means a change in the gene versions prevalent in a population, and accordingly - a change in the characteristics characteristic of individuals in that population. This happens when new gene versions give the subjects an advantage in producing fertile offspring. These offspring carry the gene versions of the parents, so they also have an advantage in producing offspring. In this way these gene versions become common from generation to generation. And here a question arises: nowadays, is there an advantage in having offspring for those who are endowed with high cognitive qualities, such as have enabled the development of language, technology, and culture in human history?

The answer seems to be negative. Sharp-witted, curious people with innovative ideas often have fewer children than the average population. The obvious conclusion is that even if evolutionary processes of enlarging the brain and improving its skills were operating only a few generations ago, and even if they were indeed affected by the two genes studied, today, in a significant part of the human population, they have stopped. It seems that the affluent society and the welfare state, as well as effective means of preventing pregnancy, have changed evolutionary processes in man. And contrary to the headlines that appeared in some media, if we meet in another million years, the minds of our descendants will not be bigger or more sophisticated than ours.

Knowledge of human evolution
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