Scientist hypothesises that using tools to make slings made us human.

Archaeologist and anthropologist Timothy Taylor claims that tools use came before Homo species, that Australopithecines used stone tools to create baby slings to carry their young.

Bipedalism requires baby to have a small brain at birth because of the mother’s small pelvis, but it makes it harder for baby to cling to mother.

“Upright female hominins walking the savannah had a real problem: their babies couldn’t cling to them the way a chimp baby could cling to its mother. Carrying an infant would have been the highest drain on energy for a hominin female – higher than lactation. So what did they do? I believe they figured out how to carry their newborns using a loop of animal tissue. Evidence of the slings hasn’t survived, but in the same way that we infer lungs and organs from the bones of fossils that survive, it is from the stone tools that we can infer the bits that don’t last: things made from sinew, wood, leather and grasses.”

So now the helpless babies can be carried, allowing Homo species to gve birth more prematurely and the baby to continue to develop extra-uterine. Duncan Caldwell also hypothesizes that the sling enabled humans to give birth to more immature babies and develop bigger brains post-natally and that the sling environment also led to loss of hair to combat parasites