Chimpanzees are humans nearest genetic relatives, but gorillas come in at a close second, according to a recent study.
For the first time, scientists have successfully sequenced the genome of a gorilla. The research team, led by the Wellcome Trust Sanger Institute, a nonprofit British genome research center, found that 30 percent of the gorilla's genome is closer to that of chimps and humans than the latter are to each other.
The results, published online in the science journal Nature, are surprising because humans diverged from chimps more recently than they did from gorillas. Humans and chimps separated from gorillas 10 million years ago; chimps and humans diverged just 4 million years after that.
To explain the remarkable number genes that humans share with gorillas, scientists suggest that the members of the two lineages continued to mate even as they diverged into separate species.
The gorilla genome, which was taken from Kamilah, an Western lowland gorilla at the San Diego Zoo and compared with partial sequences from three other gorillas, contained a few surprises. The gene LOXHD1, which expresses itself in hair cells in the inner ear, has long been thought to have been associated with speech. But LOXHD1 was found to have evolved just as quickly in gorillas as it did in humans, a discovery that weakens the connection between the gene and language.
"We know gorillas don’t talk to each other," Aylwyn Scally the lead author of the study, told Nature. "If they do they’re managing to keep it secret.”