How far apart are human and chimpanzee genomes really different? Scientists have been solving the riddle of "simultaneous" minimum and maximum difference for several years
How far apart are human and chimpanzee genomes really different? The answer is far from clear.
In 1975, Mary-Claire King and Allan Wilson published an article in Science on the genetic similarity of chimpanzees and humans. But this material was more often cited to confirm the "near-complete identity" of chimpanzees and humans, although scientists have tried to explain that no one really understands how macroevolution took place.
King and Wilson compared the amino acid sequences of several chimpanzee and human proteins (such as hemoglobin and myoglobin) and found that the sequences are either identical or nearly identical. "… The sequences of chimpanzee and human polypeptides studied at the moment are, on average, more than 99% identical," the experts concluded.
Through the fault of the readers who were too lazy to read the article to the end, the "Myth of 1%" of the genetic difference between Homo sapiens and Pan troglodytes, as it was later called by Jon Cohen in his 2007 article in Science, was born.
Other studies were carried out, which confirmed the similarity of 98.5%. But this was a relative figure, since the comparison was carried out only in the coding parts of DNA and only among similar genes with "substitution of single bases". They did not take into account the "insertions-deletions" and "repeats" in DNA, since then it was not possible to compare them. Subsequent comparative analyzes using new technologies made it possible to refine the data.
In 2002, Roy Britten, comparing insertions and deletions, found that they increased the genetic difference by another 4%. Since then, the apparent "identity" has been less than 95%.
Four years later, another scientist, Matthew Hann and colleagues, found that insertion-deletion added even more difference than Britten had identified - 6.4% (that is, 1,418 genes). The total estimated coincidence has decreased to 92-93%.
And finally, in 2008, an attempt was made to carry out a comparative analysis of huge sections of "repeats" (the function of which is not yet fully clear), as a result of which it turned out that the absolute similarity between human and chimpanzee DNA could be less than 90%.
It may seem that the difference between 98% and 95% is quite insignificant, but if we consider that human DNA consists of 3 billion base pairs, then the difference of 3% will be 90 million base pairs. Add, a few years ago, American scientists found that great apes use the same gestures as humans. In their opinion, this supports the assumption that gesticulation was an important part of the language in which human ancestors communicated.
Scientists at Emory University in Atlanta observed two groups of 34 common and 13 pygmy chimpanzees. In these groups of monkeys, scientists have identified one gesture that will seem familiar to many people - an outstretched hand, palm up. Most often, chimpanzees in this way asked each other for food. But scientists noticed that the same gesture in a different context could acquire a different meaning: a male chimpanzee could offer sex to a female in the same way, or offer another male to make up after a fight.
This ability to change meaning makes the gestures of monkeys related to human language, in which each expression can take on a wide variety of meanings depending on the context.
Monkeys, as scientists have noticed, gesture with their right hand, which is controlled by the left hemisphere of the brain. In the same hemisphere, people have the center of the language.