One Million Year Old Chance Event Sparked Human Brain Evolution.
A chance rearrangement of the human genome over a million years ago probably kick-started the evolution of modern humans from our primate ancestors. These stretches of human-specific DNA are called human accelerated regions (HARs). The physical structure of a section of DNA can be an important indicator of its function. The researchers analyzed 241 different mammalian genomes and found that HARs tend to arise in parts of the human genome that are structurally very different to their counterparts in other mammalian genomes. The team then used a machine-learning approach to compare human and chimpanzee DNA sequences, and concluded that almost 30 percent of HARs were in genomic regions that were folded differently in humans than in chimpanzees.