When it comes to fishing tasty termites out of their mounds, wild chimpanzees don't have the right stuff. Most, in fact, are southpaws.
A three-year study of 17 wild chimps in Gombe National Park, Tanzania, found that 12 of them used their left hands when using sticks to probe for termites.
Four were right-handed and one was listed as ambiguously handed, reported the research team led by William D. Hopkins of the Yerkes National Primate Research Center at Emory University in Atlanta.
The paper, published Tuesday in the Proceedings of the National Academy of Sciences, also looked at previous studies of chimpanzees. It found that other studies had noted a left-handed preference in chimps using sticks to fish for termites, but there had been reports of a right-handed preference when they were cracking nuts.
Scientists have long debated whether nonhuman primates exhibit handedness.
Because the hands are controlled by opposite sides of the brain, the finding could indicate that this brain division began as long as 5 million years ago, before the split between humans and chimpanzees.
Richard W. Byrne of the University of St. Andrews in Scotland, who was not involved in the research, said: "It now looks as if whatever gives a population skew to manually skilled behavior has its roots deep in the shared ancestry of humans and ... African great apes."
About 90% of humans are right-handed.
A larger question concerns the evolution of language, Hopkins said. Most people, right- and left-handed, use the left hemisphere of the brain to process language, he explained.
Some have argued that if humans developed language after the split from apes, and if language is related to handedness, then there shouldn't be handedness in apes.
"This reinforces the view that the whole historical link between language and handedness is probably not a correct one and people need to rethink those ideas," Hopkins said.