Johannesburg – “Is it a tree? Is it a bush? Or is it a thicket?” Professor Francis Thackeray raised these questions on the form of humankind’s evolution when discussing new research about the hominid species' two-million-year-old Australopithecus sediba published in the journal Science.
Thackeray, director of the Institute for Human Evolution at the University of the Witwatersrand, says that while the discovery of Au. sediba provided almost two complete skeletons that researchers have been able to look at in more detail, it does raise questions about where the species fits into the hominid family tree.
“We recognise sediba as a valid species but how it relates to other taxonomoy is another question all together.”
He adds that in the past, when there were fewer specimens it was easier to separate the different species but now with an increase in fossil specimens the boundaries are disappearing.
“As the sample sizes increase, you find that boundaries between the taxonomy break down.”
Thackeray’s comments follow the new research, which shows that this possible human ancestor climbed trees but was not able to run fast.
A team of South African and international scientists from the Evolutionary Studies Institute at Wits and 15 other global institutions, contributed to the papers.
The six papers represent the culmination of more than four years of research into the anatomy of Au. sediba based on the holotype and paratype skeletons commonly referred to as MH1 and MH2, as well as the adult isolated tibia referred to as MH4. The fossil remains were discovered at the site of Malapa in August of 2008, and Professor Lee Berger and his colleagues named the species in 2010.