Those criticisms are particularly important, Collins said, because Lahn's testing did find geographic differences in populations harboring the gene variants today.
If those genes don't work, babies are born with severely small brains, called microcephaly.Using DNA samples from ethnically diverse populations, they identified a collection of variations in each gene that occurred with unusually high frequency.Gray and Atkinson analysed 87 languages from Irish to Afghan.Rather than compare entire dictionaries, they used a list of 200 words that are found in all cultures, such as 'I', 'hunt' and 'sky'.Words are better understood than grammar as a guide to language history; the same sentence structure can arise independently in different tongues.
The resulting tree matches many existing ideas about language development.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.In fact, the variations were so common they couldn't be accidental mutations but instead were probably due to natural selection, where genetic changes that are favorable to a species quickly gain a foothold and begin to spread, the researchers report.