You probably didn’t know this, but there isseveral theories about why the human brain is getting smaller since the Stone Age. The changes that have occurred during the evolution of Homo Sapiens over the past 20,000 years have led to a decrease in brain volume from 1,500 cubic centimeters to 1,350 cubic centimeters. It is noteworthy that such changes were observed on all continents of our planet. According to some researchers, if our brain continues to contract at such a pace over the next 20,000 years, it will begin to approach the size found in Homo erectus, the ancestor of a man who walked the Earth half a million years ago. The brain volume of Homo erectus did not exceed 1100 cubic centimeters. But does this mean that as a species we become dumber?
Brain Size and Intelligence
Assuming that people with big brains fromnature is smarter than everyone else, then how to explain the difference in size? Today, scientists believe that the human brain reaches its largest size when we turn thirty to forty years old. As shown by the results of MRI scans, the total brain volume is weakly associated with intelligence. According to Scientific American, when certain brain regions in one person are larger or thicker than in another, for example, the temporal, parietal and frontal areas, this, as it turned out, is associated with a slight increase in intelligence.
On average, people with big brains reallya little smarter than those who have the most complex organ of a smaller size. However, whether the fact of having a larger brain makes a person smarter has not been determined. Perhaps enhanced thinking can lead to a larger brain, but this problem is still not resolved. In general, when it comes to brain and intelligence, neuroscientists believe that people with higher intelligence tend to have more complex cellular and molecular organization of neural connections compared to others. This can be seen when you look at the brain under a microscope.
Researchers also believe that a higher intelligence correlates with a larger volume of the frontal lobe and a larger body volume of nerve cells and synapses, and not with the size of the brain.
But what other factors influence brain size? Genes, as expected, did not stand aside. So, according to the results of studies, variations in the HMGA2 gene were associated with higher IQ. This gene is responsible for encoding a protein that helps regulate DNA transcription, as well as brain cell growth.
What is intelligence?
One of the key components of studying communication isif any, between brain size and intelligence is how we define "intelligence." As a rule, scientists measure it in accordance with the IQ, or IQ test. However, the question of whether IQ tests are really a reliable criterion for determining mental abilities for many years now has been the cause of heated debate in the academic community. One of the common points of view is that, instead of the size of the brain, human intelligence can be related to how effectively different parts of the brain work together and how each individual uses this power in life. The way we were brought up, the opportunities that we had could play an important role in the development of a complex network, which we call “intelligence”.
Homo sapiens with the largest brain lived 20,000-30000 years ago in Europe. They were called Cro-Magnons and they had massive, protruding jaws with large teeth. The results of a widely cited study showed that the ratio of brain volume to body mass - usually called the encephalization coefficient, or equalizer - was the same for Cro-Magnons as it was for us. This may mean that our ancestors possessed the same cognitive abilities as we did.
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Today, many anthropologists are redefining thispoint of view. Recent studies of human fossils show that the brain decreased faster than the body. Moreover, the analysis of the genome casts doubt on the idea that modern people are simply more elegant “versions” of our ancestors, right down to our thoughts and feelings. During the very period when the brain became smaller, our DNA accumulated numerous adaptive mutations associated with the development of the brain and neurotransmitter systems - a sign that when an organ becomes smaller, its internal work changes. The effect of these mutations remains uncertain, but many researchers believe that as a result of evolutionary changes, our temperament and ability to reason has changed.
In fact, the situation is such that leadingworld experts do not really know why the most complex organ of the human body, directly related to intelligence, is becoming smaller. However, after prolonged ignoring of this issue, some researchers admitted that this is a rather important issue, and research needs to be continued. They even made some bold, albeit preliminary conclusions.
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Climate Change and Idiocracy
Seeking an explanation for the gradual declinesome researchers point to a gradual change in the Earth’s climate that began 20,000 years ago. Because large bodies retain heat better, a large skull can handle a colder climate better. As the planet warmed up, natural selection probably favored people of lower stature. As skeletons and skulls decreased with increasing temperature, the brain became smaller. However, today this is only one of the possible explanations. The fact is that comparable periods of warming have occurred on our planet many times over the previous 2 million years, and the size of the body and brain has regularly increased.
Another popular theory ascribes what happenedchanges to the emergence of agriculture, which, paradoxically, initially led to a lack of nutrition. The first farmers did not really succeed in earning a living from the land, and their grain diet was devoid of protein and vitamins, which is critically important for the growth of the body and brain. As a result, our body and brain could become smaller due to chronic malnutrition. However, many anthropologists are skeptical of this explanation, which leads us to perhaps the most unpleasant conclusion: The best explanation for the reduction in the size of our brains is the theory of Idiocracy, which was perfectly described in the 2006 film of the same name.
The film tells the story of a simple guy,who becomes involved in a hibernation experiment at the dawn of the 21st century. When he wakes up 500 years later, he turns out to be the smartest person on the planet. No matter how crazy this theory looks, many researchers seriously believe that Idiocracy has already come. What do you think about this? We will wait for the answer here!