Monkey or man? Toumai, hailed as our oldest ancestor, is stirring ancient scientific rivalries
Palaeontologists are going to war over whether bones discovered in African desert are of an ape or a proto-human
James Meek, science correspondent
Thursday October 10, 2002
As he awoke on his last day on earth, it is unlikely Toumai thought about much more than how he would survive the following hour - let alone that, 7m years later, a bunch of ape-like creatures would be furiously discussing how much they resembled him.
Today, three months after the sensational announcement in Britain's leading scientific journal, Nature, that the oldest member of the human family had been found, the same journal publishes a sustained attack by rival scientists on the contention that Toumai's skull is, in fact, that of a hominid.
Few regions of science provoke more passion than the nature of the evolutionary journey from early ape-like mammals to homo sapiens, and other palaeontologists began grumbling about the sapience of the skull's French discoverer, Michel Brunet, as soon as his press release, with the bold claim "Toumai the Human Ancestor", hit the news media.
Today's attack on Professor Brunet and his colleagues in Nature - accompanied by a harshly worded rebuttal from Prof Brunet himself - ups the ante, putting doubts about whether the skull is hominid, ape, both or neither into the orthodox scientific arena.
Much is at stake - science, individual reputations, careers, research grants. Beneath this clash, however, lies the deeper and more disturbing question about when humans end and non-humans begin.
The skull was found in the Djurab desert of northern Chad by a team led by Prof Brunet of the University of Poitiers, who said at the time that it had been the culmination of 25 years' searching.
Prof Brunet, backed by independent scientists, claimed that the skull and jaw fragments provided enough evidence to show that we were looking into the face of the earliest hominid ever discovered.
The excitement around the discovery - it was proclaimed "a turning point", "a small nuclear bomb", and "the most important fossil discovery in living memory" - came because the skull's age put it in the middle of a 5m-year gap in our knowledge, between the accepted ancient apes and the accepted ancient hominids.
Today, another group of scientists, two based in France, two in the US, present a point-by-point demolition of Prof Brunet's case, arguing that there is no evidence to suggest Toumai was a hominid. "We believe [Toumai] was an ape," they conclude.
Prof Brunet's defenders point out that two of the authors of the critique, Brigitte Senut of France's National Museum of Natural History and Martin Pickford of the College of France, are direct rivals, having discovered their own candidate for oldest hominid in Kenya two years ago.
But another member of the anti-Brunet camp, John Hawks of the University of Wisconsin in Madison, pointed out that he had no axe to grind.
"There are social benefits that come from having the earliest hominids," he admitted. "You get your grants renewed, and the world at your door. I don't have a lot invested in it myself. My co-authors do, but I am not out digging these things up. I just read something I didn't find convincing."
Mr Hawks and his colleagues do not dispute the age of the fossil, or even its importance, but argue there is not enough evidence to put it in on the human side of the primate family tree, and much to link it with gorillas or chimpanzees.
Toumai's teeth have at least as much in common with early apes as they do with hominids, they say. Features like the large brow ridge are indeed seen in relatively recent human ancestors, but not in earlier, known hominids - meaning the brow would have to have evolved one way, then back, then evolved again to get into the human family.
Even with only part of a head to go on, critics say, the balance of evidence suggests the creature could not walk upright.
"The evidence they present is not conclusive, but there's conclusive evidence that it's not a biped, and therefore we conclude it's not a hominid," said Milford Wolpoff, of the University of Michigan in Ann Arbor, the fourth member of the anti-Brunet group. "We think it's an ape. I suppose it could be a female gorilla. To be honest, I think it could be an ancestor of both chimps and humans before the species split, and probably this is an extinct branch."
Dr Wolpoff stressed he was not taking issue with the momentous nature of the find, only the conclusions Prof Brunet had drawn: "It's the only fossil ape we've got from between 10m years ago and today."
Prof Brunet could not be contacted for comment yesterday. In his rebuttal, he said his critics had misrepresented the dimensions of Toumai. "Wolpoff et al have described no derived ape feature of [Toumai], nor have they disproved any derived features that this species shares with later hominids."
Henry Gee, a senior editor at Nature, said that the journal had gone to enormous lengths to verify the original Brunet paper. He had visited Poitiers twice to see the skull, and the paper had been anonymously peer-reviewed by five independent scientists in the same field.
Both Prof Brunet and Dr Gee pointed out that in 1925, when Nature stunned the world with its publication of Raymond Dart's account of his discovery of a 3.3m-year-old hominid fossil in South Africa, critics said the skull was that of an ape.
Dr Gee said the critics made interesting points, but were, he felt, "barking up the wrong tree". "Whatever Toumai is, it shows a combination of features we haven't seen before in hominids or apes," he said.
Professor Chris Stringer, head of human origins at the Natural History Museum in London, was more cautious, pointing to growing evidence that human evolution was "bushy" rather than linear.
"It is premature to push the claims too far for any existing fossils to represent the earliest members of the human family in the present patchy state of our knowledge," he said.
Large, continuous brow ridge
· Supporters of the hominid theory say this suggests a link to more recent human ancestors. Critics point out that known early hominids, younger than Toumai, didn't have the ridge. The same is true of the creature's vertical face: could these features have evolved, de-evolved, then re-evolved?
· Some critics say the hole where the spine enters the skull is too far forward for Toumai to have walked upright. Supporters of the hominid theory say this cannot be known
Thickened enamel on molars
· Critics say this feature means Toumai was as likely to have been an ape ancestor - or an evolutionary dead end - as a hominid ancestor
· Critics say the ratio of the distance between Toumai's canine teeth and from the canines to the back of the mouth are as chimp-like as they are hominid-like, and prove nothing
from http://news.bbc.co.uk/2/hi/science/nature/2645183.stmFriday, 10 January, 2003, 11:20 GMT
Georgian skull's link to our past
The moment is indelibly burned into Dato Zhvania's memory.
It had been a day like any other - a day of back-breaking, painstakingly meticulous work. A day of throbbing, enervating heat.
But as he sifted gingerly through the baked patch of ground before him, his fingers touched something different.
His pulse quickened.
The archaeological site at the medieval town of Dmanisi, 80 kilometres (50 miles) south-west of the Georgian capital, Tbilisi, had already revealed some of its secrets.
Perhaps, just perhaps, this was his turn.
But what emerged as he brushed away the earth was to far exceed his expectations.
He did not know it yet, but in his hands he held the almost perfectly preserved skull of the most ancient human being ever found in Europe - 1.8 million years old.
More extraordinary still, it was about to throw into question all accepted theories about the migration of our ancestors out of Africa.
Dato could not contain his excitement.
A message was sent out to team leader, Davit Lortkipanidze, a paleoanthropologist at the Georgian State Museum in Tbilisi.
The media were alerted and Dato and his colleagues prepared to celebrate.
"The first thing we did was pool together all the money we had - around about $800. Then we drove around all the villages for miles around and bought every bottle of champagne we could find."
He shakes his head and smiles to himself at the memory.
We were standing at the spot where the skull had been found, deep beneath the foundations of the medieval town.
"And you know," he said, "this site is so big and so important that what we've found so far could be nothing compared with what still lies beneath the ground."
The remains of seven individuals have been found at Dmanisi - the most recent this summer - but what made this discovery so special was that it did not look like the skull of any human ever found outside Africa before.
Its brain cavity was far smaller - half the size of a modern human - and it had the huge canine teeth and thin brow of an ape.
This was not the tall, upright, big-brained Homo erectus we had assumed the first humans to leave Africa to have been.
This guy was short, long-armed and probably trailed his knuckles along the ground.
Not only that, the tools found around him were basic choppers and cutters, just like those found at the sites of early, primitive men in Africa.
Dato Lortkipanidze thought he recognised Homo habilis, a hominid with a close resemblance to an ape.
But what was he doing in Georgia? The theory had always been that the migration out of Africa had only happened with the evolution of big brains and the development of the tools and hunting skills to make the exodus possible.
The discovery has opened so many questions about our ancestry that one scientist quipped: "They ought to put it back into the ground."
Early humans Homo habilis: The first species in the genus Homo, dating back 1.9 million years, and found only in AfricaHomo erectus: The first species in the genus Homo to leave Africa
Another unusual aspect of the Dmanisi find is that it was discovered in the same layer of sediment as other hominids with substantially larger brains - Homo erectus.
Mr Lortkipanidze suggests the variation may force us to rethink the definition Homo.
Land of origins
The old town of Dmanisi sits atop a promontory formed by the confluence of the Mashavera and Pinezauri rivers.
Today, it is a picnic spot for visitors from Tbilisi who come to see the ruins of the early medieval church and castle.
Modern Dmanisi is a short drive away and just a small village, but this was once an important stopping point on the Silk Route - a trading centre between Byzantium and Persia.
When I stood on the battlements above the church, I could easily make out the road the camels used to take and the steam baths once used by the traders.
It is a place of steep slopes and whispering winds, of forests and basalt cliffs, but to the north a plateau of cultivated fields stretches away to the horizon.
This was once savannah - home to rhinoceros, game and sabre-tooth tigers. Perfect hunting ground for hungry hominids.
Gazing out across this scene 1.8 million years after our ancestors stumbled out of Africa, I spotted a group of Georgian villagers cheering on a wrestling match amidst the ruins - a reminder that strife has been the defining characteristic of our existence ever since.
But for Europeans, Dmanisi is a reminder of something else too.
This, it seems, is where our history began. Dmanisi recalls our common origins.
Robert Parsons reported from Dmanisi for Europe Direct, which can be seen on BBC News 24 on 11 January at 1130 GMT, and on 12 January at 0230 GMT and 1430 GMT. The programme can also be seen on BBC World on 15 January at 2230 GMT, on 16 January at 0230 GMT, 0930 GMT and 1730 GMT, on 18 January at 1630 GMT and 2330 GMT, and on 19 January at 0230 GMT and 1930 GMT.