Human ancestors’ eating patterns discovered
USING laser techniques, palaeoscientists have discovered what our early human ancestors were eating.
Diet is an important factor in the development of hominids, because it not only indicates the environment they lived in — whether it was forest or savannah — but it also has a bearing on their later development.
The international paper, Evidence for Diet But Not Landscape Use in South African early Hominins published in scientific journal Nature, is co-authored by Francis Thackeray, director of the Institute for Human Evolution at the University of Witwatersrand.
The nearly 2-million-year-old Austrapithecus sediba fossils found in South Africa by Wits professor Lee Berger in 2008 have turned the country into a strategic geographic location for the study of human origins, attracting international researchers to the continent and forcing the government to review its funding of this type of research.
The fossils offered palaeoscientists a glimpse of our evolutionary past and have also ensured the discipline’s future.
This recent research sheds more light on the diet and home ranges of early hominids discovered in South Africa, mainly Australopithecus, Paranthropus and Homo, which were discovered at sites such as Sterkfontein, Swartkrands and Kromdraai in the Cradle of Humankind.
"This work has been done with laser beams," Prof Thackeray said on Wednesday, adding that the researchers at Lyon, in France, where the analysis was undertaken, were analysing the hominids’ teeth for barium, strontium and calcium.
Isotopes of strontium are unstable and allow scientists to date the object, similar to carbon dating.
"The strontium isotope ratios in tooth enamel are a means to decipher intra-individual diet and habitat changes," the authors write.
Other authors include Vincent Balter from the Ecole Normale Supérieure in Lyon, France; Jose´ Braga from the Université de Toulouse Paul Sabatier in Toulouse in France; and Philippe Te´louk from the Ecole Normale Supérieure in Lyon.
Strontium and barium levels in organic tissues, including teeth, decrease in animals higher in the food chain.
Paranthropus, which existed at the same time as the Homo genus about 1.5- to 2-million years ago, "was mostly a vegetarian — it ate roots, tubers, fruit", whereas Homo hominids ate a greater proportion of meat.
"It was probably scavenging from kills of other leopards and carnivores," Prof Thackeray said. "(There is evidence) of stone tool technology, but they didn’t have spear and arrow technology. Spears and arrows only came much later with later forms of Homo."
Australopithecus hominids, although they preceded both Paranthropus and Homo, "had a more varied diet".
This research was conducted on specimens of Australopithecus africanus.
However, there has been research conducted into the latest hominid species to be discovered in South Africa.
According to research published in Nature in June this year, Australopithecus sediba, a possible human ancestor and a species of Australopithecus, probably survived on a diet that included bark, leaves, and fruit, according to analysis of its fossilised teeth.
The food Au. sediba put in its mouth was similar to that eaten by modern-day chimpanzees, and suggests they lived in forests — rather than the open savannah favoured by many other hominid species, said Amanda Henry, lead author of a letter, describing an analysis of the fossilised Au. sediba’s teeth.
An important difference between Australopithus and Homo hominids is brain size.
"There is clear evidence that the size of the brain of humans increased exponentially within the last 3-million years … the consumption of protein would have contributed to the increase in the brain," Prof Thackeray said.
However, he added that there was more to brain development than size; brain organisation also played an important role.
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