Can chimpanzees learn new accents?
A widely-covered study published in February that suggested that primates can adapt their grunts to match those of new neighbors in new places is now being questioned by a group of primatologists.
The original study followed a group of Dutch chimps who, in 2010, moved to a zoo in Edinburgh, Scotland, with new Scottish chimp neighbors. By 2013, the Dutch chimps' call for apples changed from excited, high-pitched calls to less excited, lower-pitched grunts that matched those of their new Scottish chimp neighbors. Their calls changed even as their preference for apples appeared to remain the same, which led researchers to suggest that the Dutch group had learned a new word – or a new accent – from the Scottish group.
But in a letter to the journal Current Biology, a group of three researchers have said the results of that study are flawed.
"There are a number of problems with the original study," James Higham, an anthropologist from New York University, told the BBC. "Some of these relate to the methods used, while others are fundamentally a misrepresentation of what the data actually show."
For starters, Higham and his fellow critics said the two groups calls actually weren't so different in the first place.
"Closer inspection of the data reveals that both groups largely overlapped in the range of calls they were originally giving in response to the apples," Brandon Wheeler, an anthropologist from the University of Kent in Britain, said.
Both the original researchers and the critics replotted data on chimp calls to re-examine whether the calls overlapped. While the critics' findings emphasized the similarity in the two groups' calls, the original authors' findings confirmed their earlier conclusion: that the chimps had different calls that converged over time.
In fact, the original researchers even found that those chimps who had assimilated more to their new environment and neighbors also showed a bigger change in their calls.
"If you've integrated more over the three-year period, then your calls change more over time," Simon Townsend, a psychologist at Britain's Warwick University who co-wrote the original study, said.
The critics of the study also said the original study didn't account for the Dutch chimps' excitement, which may have settled down over time. The higher-pitched calls could have reflected excitement at being offered their favorite treat, apples, or it may have reflected excitement or anxiety about their new home and neighbors, either of which may have dissipated into the lower-pitched calls over time.
But the original researchers have countered that the Dutch chimps' preference for apples remained the same throughout the three-year period (in preference testing, they chose apples 70 percent of the time), suggesting their excitement for apples remained the same even as their calls changed.
What's more, they said the Dutch chimps' calls didn't change even a full year after moving in with the Scottish chimps, at which time their excitement or anxiety about a new environment should have settled. Instead, the changes came a full three years after moving, suggesting the Dutch chimps were assimilating by adapting their language.
The debate, which is ongoing, sheds new light on the popular primate "accent study," and, as the BBC pointed out, highlights an important point in scientific research: that different scientists can draw different conclusions from the same data.