Rewriting our evolutionary history

Prehistoric secrets from the early hominin ancestors of humans that lived 3.4 million years ago are being revealed by an international team of researchers.

University of Queensland School of Social Science researcher Dr Benjamin Schoville is part of the research group, led by University of Cape Town’s Dr Robyn Pickering, dating fossils in caves at the Cradle of Humankind in South Africa.

“We sampled and dated calcium carbonate flowstone rocks that form in caves, and discovered that the caves only accumulated fossils when the environment was dry,” Dr Schoville said.

“We know this because the caves were closed off when it was wetter. During these times the flowstones, such as stalagmites and stalactites, were able to grow and do not include fossils.”

The research suggests that the fossil record of early hominins in South Africa is biased towards drier periods, when the caves were open and bones from the landscape could accumulate.

Dr Schoville said gaps in the fossil record could be obscuring evolutionary patterns and affecting understanding of the habitats and dietary behaviours of early hominins in the region.

“Because the accumulation of fossils was constrained to certain periods, the evolution of these early hominins looks like it happened in rapid bursts, but it may have actually been much more gradual process,” Dr Schoville said.

“We see now that they are short glimpses of how they were behaving and adapting to periods with less available water.”

The research provides a new understanding for the evolutionary context of the hominin ancestors of humans.

“It changes how we understand the evolutionary history and behaviour of the hominins that lived in the Cradle of Humankind,” Dr Schoville said.

The research follows in the steps of renowned anatomist and UQ graduate, Raymond Dart, who found the early hominid remains of Australopithecus africanus at the same site in the 1930s.

The research is published in Nature (doi: 10.1038/s41586-018-0711-0).

MEDIA: Dr Benjamin Schoville, [email protected],

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