Evrim Yazgin
Cosmos science journalist
Anthropologists have used enamel from 2-million-year-old teeth to determine the biological sex and genetic variability of ancient hominins in Africa.
The new method will deepen anthropologists’ understanding of our early human ancestors and how modern humans evolved.
Paranthropus robustus was a species of ape-like hominin that lived about 2.3 million to 870,000 years ago in southern Africa. The species grew to just 1.2m tall and had a robust build, including prominent cheek bones, teeth and chewing muscles.
Hominins from the Early Pleistocene like P. robustus are not very well understood because DNA doesn’t survive in fossils as old as theirs, especially in hot, dry climates like those of southern Africa. Current ancient DNA technologies struggle to give genetic sequences if the sample is more than 200,000 years old.
To get around this, the new study published in the journal Science uses ancient proteins, which survive much better than DNA, to understand the genetics of P. robustus.
The research follows an earlier study by the same team which announced that the Paranthropus tooth enamel was the oldest material from which archaeologists could glean ancient hominin genetic data.
They tested their new method on the remains of 4 P. robustus individuals between 2.2 and 1.8 million years old. These are some of the earliest members of the species studied.
All 4 individuals were found in Swartkrans cave, approximately 40km northwest of Johannesburg in South Africa’s Cradle of Humankind UNESCO World Heritage Site.
The researchers found that the individuals were 2 males and 2 females. They also found differences between the individuals, some of which were sex-based. This find challenges the idea that early hominins can be sexed by size.
One of the individuals is described as “genetically distinct”, suggesting that it may have been from another group or demonstrates a high degree of variation between P. robustus individuals.
Further use of enamel protein could help better understand other hominin species, they say.
“Successful protein extraction should be achievable for hominins recovered in other southern African cave sites of similar age and geology, making biological sex identification and intraspecies analysis possible,” the authors write.
