The ape man cometh - after two million years

After decades of compiling human evolutionary history from fragments of apeman skeletons, South African scientists have finally found the most complete apeman skull ever excavated.

The find - described as "phenomenal" by Francis Thackeray of Transvaal Museum's - consists of a complete skull of a female apeman, Paranthropus robustus, and the lower jaw of a male of the same species.

Christened "Orpheus and Eurydice", after the lovers of Greek mythology, by the team which made the find, the two fossils - believed to be up to 2 million years old - were discovered at Drimolen near Sterkfontein, 200km northeast of Johannesburg.

The find has been hailed as a major breakthrough because it is the first significant discovery of a female P robustus, a line which became extinct over 1 million years ago. Until now, available information centred mainly on the male.

The female's skull shows that, not only was she smaller than her male counterpart (1.2 metres to his 1.5m), but that she had an underbite, with her lower jaw protruding further than her top row of teeth.

While the male P robustus had a ridge on the top of his skull where powerful jaw muscles attached, this is absent in the female - a distinction echoed among modern male and female gorillas. The differences could help scientists shed further light on human evolution.

Andre Keyser, the man in charge of the team which discovered the fossil,recently retired after searching his entire life for such an exciting find. "I was looking for a retirement hobby, but now this hobby has really exploded on me, much to my delight," he said.

One of his volunteers, Rosalind Smith, an amateur palaeontologist, was the first person to stumble across the fossil. After realising the enormity of the discovery, she and Dr Keyser took three days to dislodge the fossilised bone by gently removing the hardened soil with toothpicks and soft brushes.

The fossil pieces were so fragile that they had to be treated with a special glue as they were being exposed. That was not the only problem. "It was full of plant roots and an ant colony," Geyser said of the skull.

Lee Berger, the director of Wits's Palaeoanthropological Unit for Research and Exploration, said yesterday that there had "never been a better discovery of this little-known branch of the human family tree. They are not direct ancestors of modern humans but are more like 'kissing cousins' of our ancestors," he said.

While there is still much debate as to where P robustus fits into the human lineage, the latest find once again confirms that humankind originated in Africa.

But it does not solve one of the central questions perplexing scientists: why some hominids became extinct. Modern man may have eliminated potential rivals at an early stage, according to some research.

The ancestors of modern man were omnivores and may as a result have been stronger, or at least more competitive, than the specialist P robustus who was probably a vegetarian, like today's great apes.

The pair of hominids found by Dr Keyser's team may have wintered in the cave where they were eventually entombed. The dolomite caves at Sterkfontein, which are a world heritage site, have given scientists fresh hope that they will eventually be able to answer why and when the humans and apes parted company on the evolutionary path.

The first fossil of an adult P robustus ever discovered was found at Sterkfontein in 1936.

Dr Keyser's find was made in 1994 but was not revealed until yesterday.