Dating a persian american men
"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.
Around this time, farming techniques began to spread out of Anatolia - now Turkey - across Europe and Asia, archaeological evidence shows.
The farmers themselves may have moved, or natives may have adopted words along with agricultural technology.
Those criticisms are particularly important, Collins said, because Lahn's testing did find geographic differences in populations harboring the gene variants today.
The differences between words, or DNA sequences, are a measure of how closely languages, or species, are related.
"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.