Gorillas divergence date from humans pushed back by 2 mln years

The last common ancestor of humans and gorillas might have lived at least 2 million years earlier than previously thought, according to a new study by a team of Japanese and Ethiopian researchers.

London, Aug 23 : The last common ancestor of humans and gorillas might have lived at least 2 million years earlier than previously thought, according to a new study by a team of Japanese and Ethiopian researchers.

The new species (Chororapithecus abyssinicus) from Ethiopia, appearing in the current issue of Nature, helps to fill in a huge gap in the fossil record, the scientists said.

The researchers based their conclusion on nine teeth from at least three individuals of the species, discovered in the desert scrubland of Afar about 170 kilometres east of Addis Ababa.

According to Gen Suwa of the University of Tokyo Museum, Japan, lead author of the study, the teeth, eight molars and a canine, "are collectively indistinguishable from modern gorilla subspecies" in size, proportion and scan-revealed internal structure.

The team says that the gorilla's divergence date from the human lineage is not about 8 million years ago as previously surmised but "greater than 10 to 11 million years ago" on the basis of the age of the new species.

Functionally, the teeth already seem to be evolving - they could shear through a plant diet, a gorilla trait - although other herbivore apes also exist in the fossil record, Suwa added.

"This finding could prompt discussions of how anthropologists and geneticists determine the hominin line's divergence from chimps, previously pegged at about 6 million years ago. Chororapithecus abyssinicus suggests, once again, that Africa was the place of origin of both humans and modern African apes" - not Eurasia as some researchers have argued," he said.

However, not all palaeoanthropologist seem to agree.

Jay Kelley from the University of Illinois at Chicago, who was not involved in the study said: "I'm not convinced it is a gorilla".

"More fossils, analysis and debate will be needed to determine whether the specimen is ancestral to hominids. For now, I would be "very cautious" about using the specimen to realign divergence dates between hominins and gorillas-chimps," he said.

ANI