Agence France Press reports that scientists taking a fresh look at a celebrated find of apeman remains in South Africa say they are convinced it is around four million years old, a discovery that will reshape our knowledge about the possible forerunners of human beings.

The researchers have applied new dating techniques to "Little Foot," a remarkably intact Australopithecus skeleton which is the star of the Sterkfontein caves - a treasure trove of fossils about 50km northwest of Johannesburg.

A two-footed creature with ape-like facial features, Australopithecus was a species of hominid that lived several million years ago and may have been the ancestor of our own genus, Homo, which appeared on the scene around 2.3 million years ago and later evolved into modern man, Homo sapiens.

The study, published in the April issue of US magazine Science, is by Tim Partridge and Ron Clarke of the University of Witwatersrand and Darryl Granger and Marc Caffee of Purdue University in the United States.

They employ a technique known as cosmogenic burial dating which is based on the decay of radioisotopes in the rocks through cosmic rays - energy particles from space that bombard the Earth. This estimate puts Little Foot at a mighty 4,17 million years old.

Clarke and Partridge had originally dated Little Foot at 3,3 million years old, a date that was questioned by Dr Lee Berger, head of the Palaeoanthropoligical Unit for Research and Exploration, who believes it may be less than 2 million years old. Berger has also questioned the latest findings saying that the technique is not flawless and there may be problems because of Sterkfontein's notoriously complicated stratigraphy

If Little Foot is 4,17 million years old, it will be not only the most ancient hominid discovered in South Africa but a contemporary of the Kenyan specimens which were previously believed to be the earliest species of Australopithecus. This contrasts with Dr Berger's belief that the South African australopithecines are generally younger than 2,5 million years old, which would make them unlikely candidates for giving rise to our genus Homo

"The newly-dated Sterkfontein fossils may well be contenders for a place in the lineage from which humankind arose," the South African members of the team declared in a press release.

"What they tell us is that the genus Australopithecus was widely dispersed across the African continent for a period of at least two million years. During that time, several different species of Australopithecus evolved."

Despite Little Foot's astonishing age, it is still not the earliest hominid found. That honour is disputed by fossils aged six to seven million years old that have been found in Kenya, Chad and Ethiopia, although all of this evidence is fragmented and their links to our genus are cloudy.