"No matter how we [changed] the analysis or assumptions, we couldn't get a date of around 6,000 years," says Gray."This kind of study is exactly what linguistics needs," says April Mc Mahon, who studies the history of languages at the University of Sheffield, UK.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.
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.
That the genetic changes have anything to do with 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.
The conclusion will be controversial, as there is no consensus on where Indo-European languages came from.
Some linguists believe that Kurgan horsemen carried them out of central Asia 6,000 years ago.