Tuesday, October 20, 2015
Just weeks after Mercyhurst University anthropologist Heather Garvin gained international attention for being on the team of scientists to discover a new species of human ancestor in South Africa, Homo naledi, Mercyhurst forensic anthropologist Steven Symes has made yet another significant discovery in South Africa’s Cradle of Humankind.
Symes was able to reconstruct for the first time from the fossil record the manner of death of two ancient hominins of the Australopithecus sediba species and attribute their deaths to accidental causes rather than predation.
“This is the first time that modern, biomechanical forensic trauma analysis has been applied to human paleontology to reconstruct the manner of death with such confidence and detail; and the first time in which the manner of death of an australopith can be confidently attributed to accidental causes,” said Luis Cabo, anthropology lab director at Mercyhurst and a member of the team assisting Symes. (Symes is currently in South Africa on sabbatical working on a book on bone trauma interpretations.)
Au. sediba is characterized by a combination of ape- and human-like characteristics. It was a biped with an upper body clearly displaying all hominin characteristics, but its feet were more ape-like than in other hominins, indicating climbing adaptations.
Symes, a professor of applied forensic sciences at Mercyhurst for the past 12 years and a world-class expert in trauma to bone, was part of a team to analyze the skeletal trauma of two hominins at Malapa, where the Au.sediba species was first discovered. Malapa is situated in the fossil-rich Cradle of Humankind; not far from the Rising Star Cave, where Homo naledi was discovered.
The skeletal remains of Malapa hominins 1 and 2, an adolescent male and an adult female dating back two million years, were recovered from a deep pit in 2008 by paleoanthropologist Lee Berger, who also headed the Rising Star excavation. Malapa was part of a limestone cave formation with natural sinkholes, into which creatures lured by the water source would often fall and be unable to escape.
Hominin paleoanthropologists rarely work with well articulated fossils that can be confidently attributed to the same individual, which hinders their ability to make supportable determinations of manner of death. However, because the skeletons of Malapa hominin 1 and 2 were so well preserved, with large areas of their bodies in anatomical position, Symes and his colleagues were able to identify bone trauma patterns and actually reconstruct the way in which they died. The fracture patterns they cite are consistent with blunt force trauma from a fall and indicate active bracing against it.
“Our findings are that the injuries suffered by the two Malapa individuals are consistent with an accidental fall,” Cabo said. “In particular, the injuries in the arm of the female can only be explained if she was not only alive, but conscious at the time of the fall. The pattern of fractures indicates that she actively used her arm in an attempt to cushion the impact. In other words, her arm was extended at the time of impact in a manner that is only possible if her muscles were actively extending it, loading the arm parallel to its axis and causing simultaneous injuries in the hand, wrist and elbow.”
The findings were published Oct. 13 in Scientific Reports, the open-source journal of Nature, by Ericka L’Abbé, Steven Symes, James Pokines, Luis Cabo, Mercyhurst alumnae Kyra Stull and Sharon Kuo, David Raymond, Patrick Randolph-Quinney and Lee Berger.
(Symes File Photo)