by Antonio Regalado
April 10, 2019
Human intelligence is one of evolution’s most consequential inventions. It is the result of a sprint that started millions of years ago, leading to ever bigger brains and new abilities. Eventually, humans stood upright, took up the plow, and created civilization, while our primate cousins stayed in the trees.
Now scientists in southern China report that they’ve tried to narrow the evolutionary gap, creating several transgenic macaque monkeys with extra copies of a human gene suspected of playing a role in shaping human intelligence.
“This was the first attempt to understand the evolution of human cognition using a transgenic monkey model,” says Bing Su, the geneticist at the Kunming Institute of Zoology who led the effort.
According to their findings, the modified monkeys did better on a memory test involving colors and block pictures, and their brains also took longer to develop—as those of human children do. There wasn’t a difference in brain size.
The experiments, described on March 27 in a Beijing journal, National Science Review, and first reported by Chinese media, remain far from pinpointing the secrets of the human mind or leading to an uprising of brainy primates.
Su was fascinated by a different gene: MCPH1, or microcephalin
. Not only did the gene’s sequence differ between humans and apes
, but babies with damage to microcephalin are born with tiny heads, providing a link to brain size. With his students, Su once used calipers and head spanners to the measure the heads of 867 Chinese men and women to see if the results could be explained by differences in the gene.
By 2010, though, Su saw a chance to carry out a potentially more definitive experiment—adding the human microcephalin gene to a monkey. China by then had begun pairing its sizable breeding facilities for monkeys (the country exports more than 30,000 a year) with the newest genetic tools, an effort that has turned it into a mecca for foreign scientists who need monkeys to experiment on.
To create the animals, Su and collaborators at the Yunnan Key Laboratory of Primate Biomedical Research exposed monkey embryos to a virus carrying the human version of microcephalin. They generated 11 monkeys, five of which survived to take part in a battery of brain measurements. Those monkeys each have between two and nine copies of the human gene in their bodies.............
A derived form of MCPH1 called haplogroup D appeared about 37,000 years ago (any time between 14,000 and 60,000 years ago) and has spread to become the most common form of microcephalin throughout the world except Sub-Saharan Africa;