Our Minds May Not Be Made Up, Studies Say

The human brain may still be evolving.

So suggests new research that tracked changes in two genes thought to help regulate brain growth. The genes appeared well after the rise of modern humans 200,000 years ago, the researchers say.

The defining feature of humans -- our large brains -- continued to evolve as recently as 5,800 years ago and may be doing so today, noted lead researcher Bruce Lahn, a University of Chicago geneticist whose reports appear in Friday’s edition of the journal Science.

The findings are controversial because it’s unknown what effect the genetic changes had or if they arose when Lahn suggests -- about the same time as some cultural achievements, including written language and the development of cities.

Some scientists urged caution. The link between the genetic changes and brain size or intelligence “is totally unproven and potentially dangerous territory to get into with such sketchy data,” stressed Dr. Francis Collins, director of the National Human Genome Research Institute.

Lahn and his colleagues examined two genes, named microcephalin and ASPM, that are connected to brain size. If those genes don’t work, babies are born with small brains, called microcephaly.

Using DNA samples from ethnically diverse populations, Lahn’s team identified a collection of variations in each gene that occurred with unusually high frequency.

Researchers said the frequency of the variations probably was due to natural selection, where favorable genetic changes gain a foothold and begin to spread.

For the microcephalin gene, the variation arose about 37,000 years ago, about the time period when art, music and tool-making were emerging, Lahn said. For ASPM, the variation arose about 5,800 years ago, roughly correlating with the development of written language, the spread of agriculture and development of cities.

“The genetic evolution of humans in the very recent past might in some ways be linked to the cultural evolution,” Lahn said.