Lahn's own calculations acknowledge that the microcephalin variant could have arisen anywhere from 14,000 to 60,000 years ago, and that the uncertainty about the ASPM variant ranged from 500 to 14,000 years ago.
Those criticisms are particularly important, Collins said, because Lahn's testing did find geographic differences in populations harboring the gene variants today.
Other scientists urge great caution in interpreting the research.
We are free dating website, with most dating members from UK & US looking for speed dating.
To start dating its quite simple register, login, search profile, send messages, recieve messages and make new friends.
They were less common in sub-Saharan African populations, for example.
That does not mean one population is smarter than another, Lahn and other scientists stressed, noting that numerous other genes are key to brain development.
That the defining feature of humans — our large brains — continued to evolve as recently as 5,800 years ago, and may be doing so today, promises to surprise the average person, if not biologists.
"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.
The resulting tree matches many existing ideas about language development.
Spanish and Portuguese come out as sisters, for example - both are cousins to German, and Hindi is a more distant relation to all three.
The finding hints that farmers in what is now Turkey drove the language boom - and not later Siberian horsemen, as some linguists reckon.