LEIPZIG, GERMANY—Cosmos Magazine reports that a team of researchers led by Felipe Mora-Bermúdez of the Max Planck Institute for Evolutionary Anthropology suggests that modern human brain evolution and function may be independent of brain size. The researchers tested six amino acids present in three proteins of modern human cells that are not found in the cells of Neanderthals and Denisovans, our closest human relatives. The modern human amino acids were introduced into mice, whose brains have identical amino acids to Neanderthals in particular positions. The researchers found that during the process of cell division, three of the modern human amino acids worked to lengthen the period in which chromosomes are prepared for cell division, resulting in fewer errors in the daughter cells. To check these results, the scientists then introduced ancestral amino acids into human brain organoids grown in a lab from modern human stem cells. Mora-Bermúdez explained that as these cells divided, more errors in the distribution of chromosomes occurred than is usually observed in modern human brain cells. Such errors in cell division can result in cancer and genetic disorders, he added. Team member Wieland Huttner concluded that some aspects of Neanderthal brain evolution and function, for example, may have been more affected by chromosome errors. Read the original scholarly article about this research in Science Advances. To read about a Neanderthal gene variant that makes some modern human populations who inherited it more susceptible to pain, go to "Painful Past."