The earliest known member of the genus Homo, habilis evolved on the savannah of Africa between 2.5 and 2 million years ago. They are believed to have been the earliest part of our evolutionary chain to have been fully bipedal, to have lost (almost all of) the body hair that other primates have, and to have lived entirely on the ground – although possibly still gathering fruit from and seeking shelter in trees, much as we still do.
The reasons for this evolutionary move are many, but some of the more important ones include greater access to water, increased dietary variety and increased use of tools in hunting, which also made defence against predators easier than it had been for their australopithicene ancestors.
By John Hawks, Marina Elliott, Peter Schmid, Steven E. Churchill, Darryl J. de Ruiter, Eric M. Roberts, Hannah Hilbert-Wolf, Heather M. Garvin, Scott A. Williams, Lucas K. Delezene, Elen M. Feuerriegel, Patrick Randolph-Quinney, Tracy L. Kivell, Myra F. Laird, Gaokgatlhe Tawane, Jeremy M. DeSilva, Shara E. Bailey, Juliet K. Brophy, Marc R. Meyer, Matthew M. Skinner, Matthew W. Tocheri, Caroline VanSickle, Christopher S. Walker, Timothy L. Campbell, Brian Kuhn, Ashley Kruger, Steven Tucker, Alia Gurtov, Nompumelelo Hlophe, Rick Hunter, Hannah Morris, Becca Peixotto, Maropeng Ramalepa, Dirk van Rooyen, Mathabela Tsikoane, Pedro Boshoff, Paul H.G.M. Dirks, Lee R. Berger – Hawks et al. (9 May 2017). “New fossil remains of Homo naledi from the Lesedi Chamber, South Africa”. eLife 6. DOI:10.7554/eLife.24232>/a>., CC BY 4.0, Link
As mentioned in:
Cowtown — They Might Be Giants