BATON ROUGE – The collection of teeth recovered from the Rising Star cave in South Africa showed the researchers that they had 15 individuals from young to old of the newly named early human ancestor, Homo naledi. LSU Assistant Professor Juliet Brophy is a paleoanthropologist who specializes in the study of teeth. Her expertise and experience from previous research at the fossil site, Malapa in South Africa, for which she has a paper in Science, earned her a coveted spot on the team that recently named the new early human ancestor.
Finding Homo naledi was unprecedented in many ways. More than 1,500 fossils including 190 teeth were excavated from the Rising Star cave. No other site has yielded such a high concentration of early human fossil samples.
“We were so excited because before we got to South Africa we just knew there were a lot of fossils, but we didn’t know much about them,” Brophy said.
The lead investigator issued a call for early career scientists to work on identifying and analyzing the fossils at the lab in the University of Witwatersrand in Johannesburg about an hour from the excavation site.
“The Rising Star Workshop was designed specifically to involve a new generation of researchers with specific expertise,” Brophy noted. Moreover, this form of collaboration is also unprecedented in paleoanthropology. As an early career scientist, she could not pass up this unique opportunity.
For six weeks in summer 2014, Brophy worked with a group of scientists from around the world in a room within the lab called the “tooth booth,” where she helped discover some unexpected findings. It has long been thought that early human ancestors had a small brain and large teeth that were used to eat a range of unrefined foraged foods. As hominins evolved to use tools and fire to prepare food, their teeth became smaller. However, Brophy and her colleagues found that the Homo naledi teeth are unexpectedly small for such a small brain size. This discovery begins to question when the shape and form of early human teeth change.
"One of the most fascinating things that my research has found is that the mandibular third premolars are unique in their outline morphology and do not appear to overlap with any other specimens in the fossil record. These results contributed to the identification of these specimens to a new species,” Brophy said. “My research also revealed that the intraspecific variation is low, which is interesting. This is shown by the very similar shape and size of the outlines of the teeth. There is so much to be learned from these specimens.”
While other fossil species typically have a large amount of variation among the teeth, the shape and form of the teeth were surprisingly similar among the individuals at the Rising Star cave.
Her research includes taking precise images of the surface of teeth, digitizing the outlines and quantitatively comparing them to other species. A next step in her research includes creating an open access database that can group these images of early hominid teeth based on their similarities and reveal potential linkages between where they were found and what species they were identified as. This may help paleoanthropologists, such as Brophy, to answer large-scale questions.
“Features on the body that we thought would be found together are not found together in Homo naledi,” she said. “It’s an exciting time in paleoanthropology because these new fossils force us to review our current models of the origins of early humans.”
Juliet Brophy is an assistant professor in the Department of Geography & Anthropology. She is available for interviews. LSU has a video uplink studio with live broadcast capabilities.
Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa: elifesciences.org/content/4/e09560
Contact Alison Satake
LSU Media Relations