Ancient ape gives clue to family origins
Fossil from 13 million years ago sheds light on human split from apes.
Fossil hunters in Spain have unearthed what seems to be the most recent common ancestor of gorillas, chimpanzees, orang utans and humans. The ape lived almost 13 million years ago, about the time that our different lineages are thought to have diverged.
The species has been christened Pierolapithecus catalaunicus, in reference to the Catalan village of Els Hostalets de Pierola, where the fossil was found. The specimen consists of 83 bones from an adult male, including parts of the skull, teeth, ribs and fingers.
Miguel Crusafont Institute of Palaeontology, Barcelona
The scarcity of the fossil record makes it difficult to say whether P. catalaunicus is actually the most recent common ancestor of all great apes living today, Moyá-Solá says. But it is likely to resemble it closely: analyses of the rates at which differences arise between our DNA and that of other apes show that our family must have begun diverging at about the time when P. catalaunicus was alive.
Intriguingly, the fossil shows a mixture of typical 'apelike' features alongside more primitive 'monkey' characteristics, the team reports. The creature would have been able to lift itself into a standing position as modern apes can, but its short fingers mean that it would not have been able to grip branches with enough strength to swing from them.
This means that tree-swinging might have evolved several times in different apes, rather than being a habit from the start, the researchers suggest. The earliest great apes might have scuttled around on top of branches, much as today's monkeys do.
This fits with the idea that apelike characteristics evolved very gradually, rather than all appearing together in a single ancestor, comments Todd Rae, who studies primates at the University of Durham, UK. "It's a stepwise process," he explains. "One bit changes and then another bit changes."
P. catalaunicus also has a very flat face, Moyá-Solá's team reports, with nostrils that are in almost the same plane as its eye sockets. Its face would have looked a lot like a gorilla's does today, but very different from a chimp's, in which the jaw is thrust forwards in a pattern called prognathism. The chimp pattern therefore probably evolved later in the great apes' family history.
Although the species was discovered in Spain, it is unlikely to have lived only there, Moyá-Solá says. "The problem is that our finding is the only one we know. However, we can speculate and suggest that the probable origin of this animal is Africa."
Africa is widely agreed to have been the birthplace of modern humans around 160,000 years ago. But palaeontologists also think that Africa's climate, and the number of different species that lived there, would have made it a hotbed of ape evolution for millions of years before that.
But the apes could just as easily have been found mainly in Europe, as its climate was certainly different back then, Rae argues. "At that time Europe had lots of different apes - you don't necessarily have to invoke Africa as the place where all these things evolved."
Of course, we will not know where else P. catalaunicus lived until other fossils are found. "We always need more and better fossils," says Moyá-Solá.
- Moyá-Solá S., et al. Science, 306. 1339 - 1344 (2004).