'Lucy' had company, says new analysis of African fossils

'Lucy', one of the most complete skeletons found till date from the early hominids, wasn't alone after all!

Key fossil discoveries over the last few decades in Africa hint towards the existence of multiple early human ancestor species that lived at the same time as Lucy, more than three million years ago.

The perspective paper, 'The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?', based on the review of fossil evidence, identified four hominin species that co-existed between 3.3 and 3.8 million years ago during the middle Pliocene. A team of scientists compiled an overview that outlines a diverse evolutionary past and raises new questions about how ancient species shared the landscape.

Authors Dr. Yohannes Haile-Selassie and Dr. Denise Su of The Cleveland Museum of Natural History and Dr. Stephanie Melillo of the Max Planck Institute for Evolutionary Anthropology in Germany have provided an up-to-date review of middle Pliocene hominin fossils found in Ethiopia, Kenya and Chad.

The researchers trace the fossil record, which illustrates a timeline placing multiple species overlapping in time and geographic space. Their insights further raise questions about how these early human ancestors were related and shared resources.

"It is now obvious that more than one species of early hominin co-existed during Lucy's time," said lead author Dr. Yohannes Haile-Selassie.

Co-author Dr. Denise Su, curator, while reconstructing ancient ecosystems said, "These new fossil discoveries from Woranso-Mille are bringing forth avenues of research that we have not considered before."

He further said that these new discoveries expand the horizon of knowledge and, at the same time raise more questions about human origin and evaluation.

Paleoanthropologists face the challenges and debates which arise from small sample sizes, poorly preserved prehistoric specimens and lack of evidence for ecological diversity.

Questions remain about the relationships of middle Pliocene hominins and what adaptive strategies might have allowed for the coexistence of multiple, closely related species.

This study has been published in Proceedings of the National Academy of Sciences.