For the last 20 thousand years the human brain has decreased. But what does this mean?
You may not know this, but there are several 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 has led to a reduction of brain volume from 1,500 cubic centimeters to 1350 cubic centimeters. It is noteworthy that similar changes have been observed on all continents of our planet. According to some researchers, if our brains will continue to shrink at a pace over the next 20,000 years, it will begin to approach the size found in Homo erectus, a human ancestor that walked the Earth half a million years ago. The brain volume of Homo erectus does not exceed 1100 cubic centimeters. But does this mean that as a species we are becoming more stupid?
If we assume that people with large brains by nature smarter than everyone else, how to explain the difference in size? Today scientists believe that the human brain reaches its maximum size, when we turn from thirty to forty years. As the results of MRI scan, total brain volume is weakly associated with intelligence. As Scientific American, when certain areas of the brain of one person is greater or thicker than the other, for example, temporal, parietal and frontal area, it turned out to be associated with a small increase in intelligence.
On average, people with big brains do a little bit smarter than those who have the most difficult on the smaller size. However, does that make a person smarter, the mere presence of a larger brain has not been fixed. Perhaps, increased thinking can lead to a larger brain, but this problem is still not solved. Generally, when it comes to brains and intelligence, neuroscientists believe that people with higher intelligence tend to have more complex cellular and molecular organization of neural connections compared to other. This can be seen when looking at the brain under a microscope.
the Average size of the human brain is approximately equal to 1274 cubic centimeters
But what other factors influence brain size? Genes, as expected, remained on the sidelines. So, according to the results of the conducted research, variations in the gene HMGA2, was associated with higher IQ. This gene is responsible for encoding a protein that helps regulate transcription of DNA and the growth of brain cells.
One of the key components of examining the relationship – if any – between brain size and intelligence is how we define «intelligence». Typically, scientists measure it in accordance with the intelligence quotient, or IQ test. However, the question of whether IQ tests are a reliable criterion of mental abilities for many years is the cause of considerable debate in the academic community. One of the most common points of view is that, according to which instead of the size of the brain human intelligence could be associated with how effectively different parts of the brain work together and how each individual uses this power in life. How we were raised, the opportunities that we had can play an important role in the development of a complex network, which we call «intelligence».
the Question of whether intelligence is associated with the size of the human brain remains open for many decades.
Homo Sapiens with the biggest brains lived 20 000-30 000 years ago in Europe. They were called CRO-magnons and they had a massive, protruding jaw with large teeth. The results quoted showed that the ratio of brain volume to body mass, usually called the coefficient of encephalization, or EQ — was the same for CRO-magnons as it is for us. This may mean that our ancestors had the same cognitive abilities as we are.
Today, many anthropologists are reconsidering this view. Recent studies of human fossils show that the brain was declining faster than the body. Moreover, the analysis of the genome casts doubt on the notion that modern people are simply more graceful «version» our ancestors, down to our thoughts and feelings. During the period when the brain has become smaller, our DNA accumulated numerous adaptive mutations related to brain development and neurotransmitter systems — a sign that when the body becomes smaller, its inner work is changing. The impact of these mutations remains uncertain, but many researchers believe that as a result of evolutionary changes, has changed, and our temperament and ability to reason.
Actually the situation is that leading experts really don't know why the most complex organ of the human body, is directly linked with intelligence, it becomes less. However, after a long neglect of this issue, some researchers have acknowledged that this is a fairly important issue and research should continue. They even made some bold, albeit tentative conclusions.
In search of explanations for the gradual reduction of the brain some researchers point to a gradual change in the Earth's climate, which began 20,000 years ago. Because large bodies retain heat better, a large skull, probably a better cope with a colder climate. As the planet heated, natural selection probably favoured people of lower growth.As skeletons and skulls decreased with increasing temperature, the brain became smaller. Today, however, this is only one possible explanation. The fact that comparable warming periods occurred on our planet many times over the previous 2 million years, and the size of the body and brain regularly increased.
still from the film «Idiocracy»
Another popular theory attributes the changes to the appearance of agriculture, which, paradoxically, had initially led to a shortage of supply. The first farmers were not very successful to earn a living from the land, and their grain diet was devoid of protein and vitamins, which is critical to the growth of the body and brain. In the end, due to chronic malnutrition, our body and brain could become smaller. However, many anthropologists are skeptical of that explanation, which leads us to perhaps the most unpleasant conclusion: the best explanation for reducing the size of our brain is the theory of Idiocracy, could not be better described in the eponymous film of 2006.
The film tells the story of an ordinary guy who becomes involved in a hibernation experiment at the dawn of the 21st century. When he wakes up 500 years later, it is the smartest person on the planet. What would be insane not looked this theory, many researchers seriously believe that Idiocracy has already arrived. What do you think about this? Response
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