SFU researcher examines fossils of early human ancestor

Photo courtesy of Wikimedia Commons

Humankind can welcome a new member to their evolutionary family, thanks in part to the work of SFU researcher Mana Dembo.

Dembo is a PhD student in the Department of Archaeology and was among the first select group of scientists who examined specimens of Homo naledi in South Africa.

Said Dembo, “What’s really significant about these fossils is [. . .] the sheer number — over 1500 specimens, representing at least 15 individuals. And we have fossils from infants, to adolescents, to adults, and even older adults.” She continued, “We’re lucky if we have a handful of [hominin] fossils from a site.”

SFU has been involved with this project from the beginning. In October of 2013, Marina Elliott, who recently completed her PhD in the Department of Archaeology, was one of 6 scientists chosen to excavate the fossils from a cave within the Cradle of Humankind, a UNESCO World Heritage Site outside of Johannesburg.

Dembo was among over 40 scientists who responded to a call in January of 2014 to travel to Johannesburg to study the fossils at the University of Witwatersrand. She thought her PhD work, using fossils to reconstruct evolutionary relationships, would prove useful.

The international team of scientists, who hailed from the US, Canada, and the UK, among other countries, were divided into teams, each given a different section of the body. Dembo worked on the cranial material.

Said Dembo, “We described [the fossils], we analyzed them, we compared them to other known species of hominins, and eventually came to the conclusion that we had a new species which was distinct from all other species that we know of.”

One challenge facing scientists is the inability to date the fossils, “which makes it difficult to sort of slot them into our understanding of human evolution,” explained Dembo. She remarked that since carbon dating requires destruction of parts of the sample it had not been attempted yet.

She added that “our understanding would change if it [we’re] 3 million years old or 30,000 years old.” Still, Dembo estimates that since Homo naledi is unlikely to be among the first members of the genus, it is most probably younger than 2.8 million years.

“It’s really a mosaic,” said Dembo of the entire body of the specimens. She described the cranial features of Homo naledi as “sort of a mish mash of primitive and derived features.” There are some features that liken it to Homo erectus while the upper and lower jaw look more primitive; these features are similar to Homo rudolfensis and australopithecus.

However, she added that “their foot looks quite modern. It looks like a modern human foot.” Dembo and her team of researchers believe that the species, which stood at a paltry 145 cm, is of the genus Homo, the same genus that human beings belong to.

She hopes that papers from the cranial researchers will be approved for publication “imminently,” however the naming of Homo naledi as a new species has been met with controversy in the scientific community. Tim White of The University of California told Reuters, “New species should not be created willy-nilly.”

White continued, “When you look across those [anatomical features] where it’s claimed to differ from [Homo erectus], you find that the portrayal of [Homo erectus] is often inaccurate. And only 13 of the 83 characters are even alleged to be different.”

Renowned paleontologist and project lead Lee Berger has responded to such criticisms. Berger told the same outlet that critics should not “shoot from the hip based on their pre-conceived ideas but look at these papers and give a thoughtful critique in the peer-reviewed literature.”