Palaeontologists have found an 18-million- year-old tooth in Namaqualand, writes Lesley Cowling. Is this proof that Eden extended as far as South Africa?
FEW people taking a stroll along a beach would notice this small, white, pebble-like object. A dentist should recognise it as a tooth, says French palaeontologist Dr Brigitte Senut. “And if he didn’t, I wouldn’t want to go to him!”
But it takes experts in palaeontology like Senut and her research partner Dr Martin Pickford to identify it as a fossil and understand its significance. For this small, irregular tooth is a new piece in the jigsaw puzzle of evolution, an exciting discovery for two people who scour the world for new information about how humans and other species developed into their present-day forms.
It’s a little like detective work – reconstructing a scene from some leftover details. This detail, our palaeontologists can tell us, is the 18-million-year-old tooth of a hominoid, ape-like creatures from which both apes and humans evolved; and it shows that this group, from the prehistory of man, was not confined to East Africa, as some have theorised.
#The finding of the tooth was a “a bit of serendipity”, says Pickford. Pickford, from the College de France, and Senut, from France’s National Natural History Museum, are part of the Palaeontology Expedition to South Africa, a co-operative French-South African project that has been carrying out research in Namaqualand.
A year ago, they met Dudley Wessels, manager of Redaurum diamond mine near Hondeklip Bay, and an amateur fossil collector. They encouraged him to look out for fossils and hold on to them, and on this most recent visit, he showed them what he had found. Among the things he had spotted in the gravel turned up by the mining operations was the hominoid tooth, as well as the teeth of pigs and of a carnivore now extinct, called the bear-dog.
Then the detective work started. The tooth’s age could not be determined from the usual methods of carbon dating (carbon dating only measures up to 100 000 years ago) and potassium argon dating (because it relies on volcanic layers around a fossil).
But the tooth resembles that of a Kenyapithecus, the hominoids found so liberally in Kenya and Uganda, and the other teeth seem to confirm this diagnosis – they are found wherever Kenyapithecus occurs and plenty of specimens have come from East Africa.
The next step was to figure out how this find fitted or changed the current notions of how humans evolved.
Says Pickford: “Darwin predicted Africa would be the birthplace of mankind. The question was which part of Africa and what kind of animal (would we have evolved from).”
Senut and Pickford say the Rift Valley of East Africa was generally accepted as this place, mostly because so many hominoid fossils have been found there.
But in the past 10 years, some finds have begun to cast doubt on this hypothesis. Senut and Pickford say that part of the jaw of a hominoid was found in Saudi Arabia about a decade or more ago, but for some reason, not much attention was paid to the discovery.
#But in 1990, a researcher found an arm bone in Egypt that turned out to belong to a hominoid. Add their discovery, and the evolutionary picture begins to change.
But what about the million-dollar question: is this one of our ancestors?
Senut and Pickford can’t say, and are not impressed with the whole concept of “the missing link” – the idea we can find one fossil that will definitively show us what animal we are descended from.
“Evolution isn’t like that,” they both say. Because evolving is a process of slow change by degrees, there’s no one particular ancestor. The creature whose tooth has turned up on our shores can only be described as part of the group from which we and the apes have grown. But where it and its counterparts turn up can show us where in the world we originated from.