NEW YORK: An early ancestor of human beings, who lived 1.8 million years ago, were able to make use of their teeth to eat, may be as effectively as a modern day man, according to a new study, which also questions an existing theory of how they were wiped out.
The ancestors, the bipedal hominid Paranthropus robustus, lived in an area roughly what is South Africa now, along with the direct ancestors of modern humans and animals like hyenas and cats.
Scientists have believed that the species became extinct because they could feed only on very limited diet, while our direct ancestors could bank on a diverse menu.
However, a team of scientists have found four teeth from the Swartkrans excavation site in South Africa, which has given clear indication that these species too had a more varied diet that earlier thought. This leads the scientists to speculate that Paranthropus robustus was wiped out by man's direct ancestors in a battle for supremacy in the African land.
The scientists have penned their thoughts in an article in the journal Science.
Until now, research on the shape of the teeth has indicated that the horminid became extinct because it was unable to adapt to environmental changes as its diet was rather specialized. But the four teeth show that Paranthropus could eat fruits and nuts, sedges, grasses, herbs, seeds, tree leaves, tubers and roots. They could have consumed meat too, may be not hunted.
The Anglo-American team, which carried out the study wrote in Science that the teeth showed evidence of seasonal variety in diet. There were also variations that may reflect annual rainfall.
The team, led by University of Colorado anthropologist Matt Sponheimer, used a laser to extract small samples from enamel of the 1.8-million-year-old molars, then focused on the ratio of two isotopes, or forms of carbon, that indicated the types of food consumed by the little hominids.
Because of the teeth build up over time, the scientists could establish that the individual's diet had changed. Ruling out an inability to adapt to new environments and new foods as a reason for their extinction, the team now wants to have a rethink on the causes.
A co-author of the study and University of Utah geochemist Thure Cerling said the result shows the variability in human diet has been in the family over a long time. He said the researchers would like to do similar studies on other species in humankind's family tree.
Paranthropus came from a line of close human relatives called australopithecines that includes the renowned fossil Lucy from Ethiopia dating back 3 million years. Australopithecines are known to have split about 2.5 million years ago into the genus Homo, which has led to modern humans Homo sapiens, and the genus Paranthropus, which mysteriously went extinct between 1.3 and 1 million years ago. Paranthropus never made any tools.
Sponheimer said some possible explanations for the extinction included direct competition with tool-wielding Homo species or greater vulnerability to predators.
