Discovery destroys myth of 'missing link' on the evolutionary ladder

The discovery of Toumai man – who lived about seven million years ago in what is now northern Chad – finally explodes the myth of there being a "missing link" in a ladder-like chain of direct descent from an ape ancestor to present-day Homo sapiens.

The discovery of Toumai man – who lived about seven million years ago in what is now northern Chad – finally explodes the myth of there being a "missing link" in a ladder-like chain of direct descent from an ape ancestor to present-day Homo sapiens.

Ever since Darwin first suggested that human beings had evolved from the apes, popular accounts of evolution have depicted man's journey as a series of smooth, linear transitions from a knuckle-walking hairy simian to upright "naked ape", complete with briefcase and rolled umbrella. But it is a notion that most modern Darwinists have long since consigned to the dustbin of evolutionary history. And Toumai man vindicates the view that human origins are a far more messy affair.

What we know is that chimps are our closest living relative, sharing as much as 98 per cent of our DNA. About 10 million years ago we also shared a common ancestor with chimps but what happened in the intervening years was not a straightforward divergence along two lines.

Instead of a simple "tree of life", there were many dead-ends and blind alleys with perhaps dozens or even hundreds of our ancestral cousins becoming extinct, including, perhaps, Toumai man himself.

As Bernard Wood, one of the world's leading anthropologists, writes today in Nature: "Here we have compelling evidence that our own origins are as complex and as difficult to trace as those of any other group of organisms."

The simple, linear model of human evolution with a step-wise change leading to new species with ever-more human characteristics has now been replaced by a more untidy or "bushy" model as successive ape-like creatures acquired different kinds of human-like attributes.

Professor Wood says: "This model predicts that because of the independent acquisition of similar shared characters, key hominid adaptations such as bipedalism, manual dexterity and a large brain are likely to have evolved more than once."

Toumai man illustrates the difficulties of tracing man's precise lineage. "Quite simply, a hominid of this age should only just be beginning to show signs of being a hominid. It should not have a face of a hominid less than one-third of its geological age," he says.

Further finds may show that the world was once home to ape-like creatures, some with remarkably human attributes. What may never be clear is why almost all of them became extinct, allowing one of their number to dominate the planet.