Thursday, September 10, 2015
News media from around the world descended today on Johannesburg, South Africa, where scientists affiliated with the Rising Star Expedition announced the discovery of a new species of human ancestor, Homo naledi. In Erie, Mercyhurst University anthropologist Heather Garvin, Ph.D., who was a member of the international scientific team, shared her pivotal role in the discovery during a 10 a.m. press conference in the university’s Mercy Heritage Room.
The new species sheds light on the origins and diversity of our genus, Garvin said, adding that H. naledi looks much like one of our more primitive ancestors but with some surprisingly humanlike features, including feet nearly indistinguishable from those of modern humans. H. naledi also appears to have intentionally deposited bodies of its dead in a remote cave chamber, a ritualized behavior previously thought limited to humans.
Directed by National Geographic Explorer-in-Residence Lee Berger of the University of the Witwatersrand, researchers spent three weeks in 2013 bringing up an estimated 1,550 hominin fossils from an elaborate cave system in South Africa, in a region known as the Cradle of Humankind because of earlier fossil discoveries there. The fossils belong to 15 different individuals, including eight children, five adults and two adolescents.
The discovery, heralded by scientists around the world as groundbreaking, marks the single largest hominin fossil find on the continent. Speaking to its significance, Berger told CNN, "We have just encountered another species that perhaps thought about its own mortality, and went to great risk and effort to dispose of its dead in a deep, remote, chamber right behind us. It absolutely questions what makes us human."
During the spring and summer of 2014, Garvin and approximately 20 other early-career scientists from around the world – hand-picked by Berger – arrived in South Africa to analyze the fossils under the mentorship of expert senior scientists. In addition to Mercyhurst’s Garvin, scientists from the United States included those from Duke University, New York University and Dartmouth College, among others.
Today, the results of their work were made public for the first time by the University of the Witwatersrand, the National Geographic Society and the South African National Research Foundation. The finds are described in two papers published in the journal eLife, the cover story of the October issue of National Geographic and a NOVA/National Geographic Special.
“We have long known that forensic science at Mercyhurst University is a world-class program led by Pennsylvania’s only two board-certified forensic anthropologists, Dennis Dirkmaat and Steven Symes, who are experts in the archaeological recovery of human remains and trauma to bone, respectively,” said Mercyhurst University President Michael. T. Victor. “That we now add another expert of international acclaim in Heather Garvin makes Mercyhurst’s program second to none.”
As a young scientist with degrees in anthropology, zoology, biological and forensic anthropology, and functional anatomy and evolution, Garvin’s research in human skeletal variation and macro‐ and micro‐evolutionary events played an important part in her role as a member of the scientific team.
Working with the cranial team, Garvin was responsible for using 3D scanning methods to create a virtual reconstruction of the skull and, from that, estimate the brain size of the new species.
Garvin had come well prepared. Through her career research, she had amassed a collection of more than 700 3D surface scans of skulls and associated postcranial measurements from around the world, which were used to compare the newfound hominin fossils to modern forms. Their conclusions showed H. naledi’s brain was tiny: 500 cubic centimeters, or about the size of an average orange.
Garvin led the body-size team, which was charged with determining the height and weight of the species. Her group’s analysis showed that H. naledi stood about 5 feet tall and weighed approximately 100 pounds.
“What’s particularly interesting about H. naledi is that it has a relatively small brain despite its large body size,” Garvin said. “We used to think that body size and brain size increased together, but this proves that that’s not necessarily true – body and brain size must be under different selection forces. The small brain size is also surprising given the features of the hand, which suggest possible toolmaking as well as the possibility that this species was deliberately depositing their dead in this cave. Ultimately, these findings show that a larger brain is not necessarily a prerequisite for these humanlike behaviors.”
Scientists have yet to date the fossils, Garvin said.
“If the fossils turn out to be older than 2 million years, it will give us pertinent information about the beginning of our genus, Homo,” she said. “On the other hand, if they are less than a million years old, it would indicate that there were multiple forms of human ancestors living in South Africa at the same time, and that this small-brained species with climbing capabilities lived alongside larger-brained species, including Homo erectus, which was the first known hominin to leave Africa.”
The Rising Star Expedition is expected to continue as many more fossils remain to be unearthed and more questions are yet to be answered, Garvin said.
Garvin earned her master’s degree in biological and forensic anthropology from Mercyhurst, went on to earn her doctorate from Johns Hopkins University and returned to join her former professors – now colleagues – in the Mercyhurst University Department of Anthropology and Applied Forensic Sciences. She is in her fourth year of teaching at Mercyhurst.
The Rising Star expedition was led by National Geographic Explorer-in-Residence Lee Berger of the University of the Witwatersrand and involved an international team of scientists, including six “underground astronauts” who descended into the Dinaledi chamber to excavate and retrieve the fossils of Homo naledi. Support for the expedition and the May 2014 scientific workshop to analyze the fossils of H. naledi came from the South African National Research Foundation, Wits University and the National Geographic Society.