The spectacular growth of human intelligence, that man differs so much from the rest of the animal kingdom, it could be due to a single gene, leading to an increased number of cells in a key region of the brain, scientists have discovered.
Cognitive abilities, which he distances himself than even the closest relatives in the animal kingdom its current - apes - might be due to a single gene, absolutely specific people, according to a recent study.
The gene was identified in modern humans (Homo sapiens), the Neanderthals and other extinct human species called Denisova man (or denisovan), but not in chimpanzees.
Gene allowed the development area called neocortex, which came to include in humans, many more neurons than in any other species, including apes.
The study was led by Marta Florio, cellular and molecular biologist at the Max Planck Institute for the study of molecular biology, cell and genetics in Dresden, Germany. This gene appears to be responsible for the development of the human brain to actual parameters and the evolution reached by the primitive apes to modern man, endowed with a complex language and culture - a process that took millions of years.
Now about. 3.8 million years ago, Australopithecus afarensis, a human ancestor primitive, have a brain volume of only 500 cc, approximately one third of the actual human brain.
1.8 million years ago, Homo erectus had a brain volume double that of Australopithecus and lived in more complex social groups, using tools and use fire.
Modern humans (in the anatomical sense) Homo sapiens and "summer" their missing Neanderthal and Denisova man, had a brain volume of about 1,400 cubic centimeters, the largest increase occurring in the area called the neocortex, which contains a number large neurons and is the seat of advanced features such as language and logical thinking.
The authors analyzed a type of neural progenitor cells, a type of stem cells that form during embryonic development, neurons.
In mice, for example, the cells divide only once and then be transformed into neurons. However, in humans, the same cells divide many times before their final transformation, resulting in a huge number of neurons.
Researchers have looked at genes were activated in mice and humans, the most intensive stage of development of the brain.
They found that a certain gene, called ARHGAP11B was strongly activated in human neural progenitor cells, but was not present in the mouse.
This DNA fragment was once part of a much larger gene, but somehow was duplicated (occurring copies of itself) and duplicate fragment was inserted into the human genome.
The researchers inserted and activated the DNA fragment in brains of mice. Although these animals normally a smooth neocortex (without convolutions) and underdeveloped mice in which the gene was inserted human neocortex more developed, containing a greater number of neurons and even showing a tendency to form convolutions ( "folds" or "wrinkles" brain characteristic of higher animals, like man - a configuration that allows the accumulation of several neurons in a small volume of space). The researchers did not test intelligence mice to see if increased, but this is a potential direction for future research, said Marta Florio.
Comparing the genomes of several species of mammals, scientists have confirmed that ARHGAP11B gene exists in modern man, was present and neaderthalieni and denisovan, but it does not exist in other mammals, such as mice and chimpanzees.
This finding suggests that the gene appeared soon after human evolutionary branch split from chimpanzees and it is this gene has paved the way for the rapid development of the human brain.
However, this genetic change is probably not fully explain the superior intelligence of modern man, say researchers. And other kinds of people - such as Neanderthals - they had big brains, but Homo sapiens remarkable intelligence could soon be linked to how brain cells and abolishes its neural connections formed in the course of time.
The research results were published in the journal Science.
Source: Fox News
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