Tracking ancient hominids
Piecing together relationships between the diets of hominids several million years ago to that of early and modern humans is allowing scientists to see how diet relates to the evolution of cognitive abilities, social structures, locomotion and even disease, said University of Colorado at Boulder anthropology Professor Matt Sponheimer.
Sponheimer specializes in stable isotope analysis, comparing particular forms of the same chemical element, like carbon, present in fossil remains to help reconstruct past lives of hominids. Zapping hominid teeth with lasers, for example, frees telltale carbon gases from the enamel, allowing scientists to pinpoint the types of plants consumed by the hominids and the environments where they lived, said Sponheimer, who also relies on the microscopic wear of ancient hominid teeth for data on food consumption.
One hominid genus under study by Sponheimer is the 2 million-year-old Paranthropus, a short, upright member of the australopithecine family that includes the Ethiopian fossil, Lucy, discovered in 1974.
A 2006 study by Sponheimer of Paranthropus robustus documented its diverse diet, clouding the notion that it was driven to extinction by its picky eating habits. And a 1999 study led by Sponheimer indicated 3-million-year-old australopithecines may have even have been catching and eating small animals.
Roughly 2.5 million years ago, the australopithicenes are thought to have split into the genus Homo and the now-extinct genus Paranthropus, including South Africa's Paranthropus robustus and East Africa's Paranthropus boisei, said Sponheimer. Research presently under way at University of Colorador indicates that while Paranthropus robustus and Paranthropus boisei are almost indistinguishable anatomically, they may have had very different diets.
Other intriguing research under way by Sponheimer and his colleagues hints that some female australopithecines, including members of the Paranthropus genus, died in different geographic areas than where they were born. The researchers are comparing such data to social patterns of chimpanzees, in which females generally migrate away from their original ranges and move into new areas -- the opposite of behavior charted in most other primates, said Sponheimer.
"Textbooks treat these ancient hominids as static piles of fossil bones," said Sponheimer. "We treat them as biological organisms moving across the landscape. It's entirely possible that many things we thought we knew about them were wrong, and pages of textbooks will have to have to be re-written." ■