By Maina Kiarie
Chororapithecus abyssinicus was an ape that lived about 10 to 10.5 million years ago and is believed to be the earliest known species of gorilla. Its existence indicates that the last common ancestor between the human/chimpanzee lineage and gorillas may have lived greater than 10 to 11 million years ago, which is at least 2 million years earlier than the previously thought date of divergence of about 8 million years ago.
The only evidence found of this extinct ape is currently nine fossilized teeth of at least three individuals, recovered from the Chorora formation which runs along the southern Afar Depression of Ethiopia (the same place where the remains of the fossil nicknamed ‘Lucy’ were discovered in 1974). The analysis of eight molars and a canine tooth showed that their structure is partly similar to modern gorillas. Chororapithecus mostly ate high-fibre plants.
Berhane Asfaw, at the Rift Valley Research Service in Ethiopia and co-author of the groundbreaking Chororapithecus study reported that molecular evidence indicates that it is likely that the mutations arose five times slower than previously thought, hence other common ancestors of great apes arose longer ago that it was previously known. Not all scientists agree, however. Although Chororapithecus and gorilla teeth are similar, they could have been shaped by parallel evolution of a different species which consumed similar foods. The problem is made more difficult because there is scant evidence for the evolution of chimps and gorillas, according to Prof Peter Andrews at the Natural History Museum in London, UK.