"What came first?" Churches. "Changes in speech or changes in the brain?"
Ray Jackendoff, a linguist at Tufts University who was not involved in the study, said the group was finding that the ease of saying some sounds may vary with diet "is interesting but not shocking." cultures may have uttered certain sounds more often than others "does not say much about the profound history of language."
Other cultural and social factors, such as the adoption of sounds by neighbors, may also have contributed to changes in language, the authors of the study said. For example, when groups of hunter-gatherers and groups of farmers mingled, so did their sounds .
Other linguists also point out that the study is based on untested hypotheses, just as how little these bite changes could affect the sounds, the types of errors they could produce, the age at which hunters' teeth wear out and notion of agriculture is a useful proxy for the diet. The role of cognitive factors, including neural control of speech organs, is also not addressed.
The authors reply that they are not minimizing the roles played by culture, society or cognition in language development. But they say that the physical differences between people deserve as much attention in the study of the development of human language as they do in research on animal communication systems.
Some linguists fear that if not treated with extreme care, subsequent studies of the physical or biological differences of language could reinvigorate the ethnocentric beliefs that have plagued linguistics in the past, especially if the research is interpreted publicly as a judgment of the value of languages of the different groups.
"The risk here is a bias to focus on positive benefits or what is gained by individuals in agrarian societies, rather than also considering the benefits that individuals can have in hunter-gatherer societies," said Adam Albright, a linguist at MIT