Researchers working in Ethiopia have detailed what they believe to be a newly-discovered ancestor species of humans. It means as many as four such species, known as hominins, could have coexisted.

The results, published in Nature, are from analysis of 14 teeth and jaw bones discovered beween 2006 and 2013. The bones appear to come from four individuals and date to somewhere between 3.3 million and 3.5 million years ago. The biggest signs the bones are from a previously undiscovered species are that the jaws are particularly robust and the teeth, particularly the canines, much smaller than in other hominins. That may suggest a differing diet.

The researchers have dubbed the species Australopithecus deyiremeda, which translates as “close relative” in the local language of the Afar region where the discovery was made.

The BBC notes this follows on from discoveries of Australopithecus afarensis (the most famous example of which was known colloquially as Lucy) just 35 km away in the same Afar region, Kenyanthropus platyops in Kenya and Australopithecus bahrelghazali in Chad. The researchers say there’s now “incontrovertible evidence to show that multiple hominins existed contemporanously in eastern Africa”.

The discovery casts further doubt on previous theories that Australopithecus afarensis was a straightforward and sole “ancestor” of humans. It also raises questions about whether any of the four species may have encountered one another and, if so, whether they pooled their collective skills and physical advantages.