To study how humans evolved large brains compared to other primates, scientists experimented with marmosets, a small primate with a small brain that is still genetically similar to humans. At the heart of the study is one of a few genes that appear in no other species besides humans.
ARHGAP11B, a gene found only in humans, is known for its role in expanding neocortex, the part of the brain responsible for higher cognitive functions such as language and planning. In experiments detailed in a new study published today in the journal Science, researchers inserted the gene into the fetuses of marmosets, who, like humans, are primates, but don’t carry the gene. The team found that after 101 days, the neocortices of the monkeys’ developing brains were larger and had more folds in the tissue than normal monkey fetuses without the gene.
If this experiment sets off your cringe response, you aren't alone. How man human brain genes can be transferred to another species before that species becomes human? More than one, apparently. Read about the experiment and what it could mean for the study of "humanness" at Smithsonian.
(Image credit: Leszek Leszczynski)