A cache of fossils found in Ethiopia's Afar desert offers interesting insights into the evolution of human beings. The discovery, made by a team of experts led by University of California in Berkeley paleo-anthropologist Tim White, might provide the 'missing link' between Australopithecus, believed to be ancestors of humans, and an ape-type animal that roamed the area around 4.4 million years back.
“This new discovery closes the gap between the fully blown Australopithecines and earlier forms we call Ardipithecus. We now know where Australopithecus came from before 4 million years ago,” said Tim White, the leader of the expedition. The fossils are mainly of teeth and bones of around nine creatures, found near the villages of Aramis and Asa Issie close to Awash River, after efforts of five years. According to the researchers, the brains of the animals are similar in size to 'modern chimps'.
One of the biggest question marks about human evolution is that of the origin of Australopithecus. “For the first time, we found fossils that allow us to connect the first phase of human evolution and the second phase,” said Dr Berhane Asfaw, the co-director of the international Middle Awash research project.
Among fossils of the Australopithecus species, 'Lucy', a three and a half foot tall female dated over 3.18 million years, is the most famous. Lucy, scientifically called Australopithecus afarensis, was found by Donald Johanson in 1974, near the region of the latest discovery. “Here, in a single Ethiopian valley, we have nearly a mile-thick stack of superimposed sediments and 12 horizons yielding hominid fossils. These discoveries confirm the Middle Awash study area as the world's best window on human evolution,” White said.
According to the researchers, the creatures whose fossils have been found are Australopithecus anamensis, which existed much before Lucy. A reconstruction shows that they were short and thick set, had small brains and teeth that could easily chew hard roots.
Earlier in 1994, Ethiopian expert Alemayehu Asfaw had unearthed the first anamensis fossils in the Awash area. So the discovery wasn't new but for the first time, 'these three species have been shown to be time-successive in a single place', the researchers said in a report published in the journal
Nature.
But it is not yet clear if Australopithecus came as a direct descendant of the Ardipithecus, which is considered more chimpanzee than human. “It is fair to say some species of Ardipithecus gave rise to Australopithecus.
Australopithecus became a superior omnivore, able to eat tubers and roots with more fibre and grit, adapting it better to times of scarcity during periods of extended drought,” White added. One difference between the anamensis and the Ardipithecus was that the former had teeth that were more enamelled than those of the latter. This indicates that the Ardipithecus had a diet that was different from that of anamensis.
Other fossils, like those of pigs, monkeys, big cats, rodents, kudus and other animals were also found at the venue, suggesting that the anamensis lived in a forest-type habitat.
