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"The genetic evolution of humans in the very recent past might in some ways be linked to the cultural evolution," he said.
Other scientists urge great caution in interpreting the research.
Those criticisms are particularly important, Collins said, because Lahn's testing did find geographic differences in populations harboring the gene variants today.
They were less common in sub-Saharan African populations, for example.
Russell Gray and Quentin Atkinson, of the University of Auckland in New Zealand use the rate at which words change to gauge the age of the tree's roots - just as biologists estimate a species' age from the rate of gene mutations.
The differences between words, or DNA sequences, are a measure of how closely languages, or species, are related.
Spanish and Portuguese come out as sisters, for example - both are cousins to German, and Hindi is a more distant relation to all three.
Lahn and colleagues examined two genes, named microcephalin and ASPM, that are connected to brain size.
The work was funded by the Howard Hughes Medical Institute. A family tree of Indo-European languages suggests they began to spread and split about 9,000 years ago.
The finding hints that farmers in what is now Turkey drove the language boom - and not later Siberian horsemen, as some linguists reckon.
"We, including scientists, have considered ourselves as sort of the pinnacle of evolution," noted lead researcher Bruce Lahn, a University of Chicago geneticist whose studies appear in Friday's edition of the journal Science.
"There's a sense we as humans have kind of peaked," agreed Greg Wray, director of Duke University's Center for Evolutionary Genomics.