Neanderthals and homo sapiens have more in common than distinguishes them. This is increasingly the conclusion of many paleoanthropologists. But researchers are also tracking down crucial differences. A team led by Felipe Mora-Bermúdez from the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden and the Max Planck Institute for Evolutionary Anthropology in Leipzig found out that the division of stem cells in the brain occurs at different speeds in the two human forms went. at homo sapiens the process was about 50 percent slower than its cousins. As a result, homo sapiens Fewer errors crept in during cell division, the working group writes in the journal Science Advances.
In contrast to the Neanderthals, around 100 amino acids have changed in the evolution of modern humans. Mora-Bermúdez and his colleagues investigated the effects of these mutations in the protein building blocks using three proteins that control the arrangement of the chromosomes during stem cell division in the brain, more precisely in the neocortex. The neocortex played an important role in human evolution: this part of the brain expanded significantly, which helped develop improved cognitive abilities such as speech.
For their study, the researchers now produced mouse models with the amino acids of anatomically modern humans. Since unmodified mice would resemble Neanderthals in the case of these amino acids, the scientists used them as a control group. They then compared brain growth in the mouse embryos in both groups. “We found that three modern human amino acid changes in two of these three proteins, namely KIF18a and KNL1, cause a longer metaphase, a phase in which the chromosomes are prepared for cell division,” says Mora-Bermúdez, according to a press release. “This leads to fewer errors in the distribution of chromosomes to the daughter cells of the neural stem cells, just like in modern humans.”