Scientists have discovered a gene variation, perhaps involved in brain size, which showed up only 6,000 years ago a mere blink of the eye in evolutionary time.
This discovery, along with another brain gene that arrived about 37,000 years ago, is providing scientists with strong evidence that the human brain is still a work in process.
"It's very exciting stuff," said Henry Harpending, a professor of anthropology at the University of Utah who was not part of the research. "The brain is still evolving."
The new study was led by Bruce Lahn, a Howard Hughes Medical Institute investigator at the University of Chicago, and appears today in the journal Science.
Analyzing DNA samples from individuals throughout the world, they identified two genetic varieties that are unique to humans. One called abnormal spindle-like microcephaly, or ASPM, first appeared 6,000 years and is now found in 30 percent of the population. The other, called microcephalin, evolved about 37,000 years ago and has spread to more than 70 percent of the population.
"We don't know what these new variants do," Lahn said. "But they might confer a selective advantage by improving cognitive abilities. This needs to be confirmed," reports Newsday.
According to Forbes, the researchers initially focused on identifying all the variations or mutations of microcephalin and ASPM genes present among the participants. They then honed in on one particular class of each of the two genes that appeared more abundant and genetically younger than the rest.
This class of microcephalin mutations first emerged approximately 37,000 years ago, while the ASPM variant class was estimated to have arisen about 5,800 years ago.
These time frames are a blink of the eye in evolutionary terms, the researchers point out, noting that the type of Homo sapien existent in the world today emerged only about 200,000 years ago.
Both gene groupings appeared to be nearly identical among those participants in which it was identified. According to the researchers, that may be because new mutations have simply not yet had time to diversify in this relatively short time span.
Lahn and his team observed that each of the gene classes were present among a significant number of the scanned subjects 30 percent in the case of the ASPM mutation, and 70 percent in the case of the microcephalin mutation.
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