A study published in the journal Current Biology this week, investigated the behaviour of modern-day chimpanzees as they competed for food resources, in an effort to understand why our "hominin", or "human-like" ancestors became bipedal.
Its findings suggest that chimpanzees switch to moving on two limbs instead of four in situations where they need to monopolize a resource, usually because it may not occur in plentiful supply in their habitat, making it hard for them to predict when they will see it again. Standing on two legs allows them to carry much more in one go because it frees up their hands.
MORE: http://www.physorg.com/news/2012-03-reveals-ancestors-bipedal-power.html
