About 100 thousand years ago, man as a species was on the verge of extinction (numbers decreased by about 10 thousand). However, thousands of years later, people became actively spread around the world. Based on the results of recent genetic research shows one - for all the above variations is a bacterial epidemic infection, writes New Scientist.
Bacteria, which are in a call, influenced 2 gene immune system, drawing their action against the person. At this time the body and decided to get rid of these genes. According to the range of Cooking from the University of California (USA), "guilty" may be genes Siglec-13 and Siglec-17.
The above genes involved in the control of immunity, being the chimpanzee active, but the man off. Siglec-13 from human genome has completely disappeared, and Siglec-17 does not operate, since they lost 1-well letter code.
The researcher carried out the reconstruction of the lost proteins and found that two very dangerous bacteria - Escherichia coli K1 and group b Streptococcus - to them can join. Especially dangerous these pathogens for newborns.
Experiments with transformed cells have proved that the cells had a reduced immune response to bacteria. In other words, bacteria inhibited the immune system, tied to the two ill-fated proteins. Most likely, 440000-270000 years ago in the human genome saving changes occurred.