“What came first?” he asked. “The changes in the speech, or the changes in the brain?”
Ray Jackendoff, a linguist at Tufts University who was not involved in the study, said the group’s finding that the ease of saying some sounds may vary with diet “is interesting but not earthshaking.” That different cultures may have uttered certain sounds more often than others “doesn’t say much about the deep history of language.”
Other cultural and social factors, like adopting sounds from neighbors, also may have contributed to changes in language, the study’s authors said. For example, when hunter-gatherer groups and agrarian groups mixed, so did their sounds.
And others point out that labiodental sounds have even been found among hunter-gatherers with edge-to-edge bites, like some Yanomami people of South America, who live mostly as isolated hunter-gatherers, fishers and horticulturists.
Other linguists also point out that the study rests on untested assumptions, like just how much these small bite changes might influence sounds, the types of errors they could produce, the age at which hunter-gathers’ teeth wear down, and the notion that agriculture is a useful proxy for diet. The role of cognitive factors, including neural control of speech organs, also goes unaddressed.
The authors respond that they are not minimizing the roles played by culture, society or cognition in the development of language. But they say that physical differences between people deserve as much attention in the study of human language development as they do in research into the communication systems of animals.
Some linguists worry that if not handled with extreme care, subsequent studies of the physical or biological differences of language could invigorate ethnocentric beliefs that have plagued linguistics in the past, especially if research is publicly interpreted as making value judgments of different groups’ languages.
“The risk here is a bias to focus on positive benefits or what is gained by individuals in agrarian societies, rather than also considering whatever benefits individuals in hunter-gatherer societies might have,” said Adam Albright, a linguist at M.I.T.