The First Changes

The first major changes made by hominids to the present human condition are believed to be the adoption of an erect posture and bipedal locomotion.  It is inferred that the earliest australopithecines lived in forests. This inference is made based on the animal and plant remains associated with the fossils.  The old hypothesis that an erect posture was adopted to allow the hominids to peer over long grasses to watch for predators is deemed less likely than the possibility that it was the freeing of the arms which was the great benefit of bipedalism.
 Bipedalism enabled the hominid to carry food back to his or her family.  Chimpanzees share this behaviour.  They share food amongst a complex social structure.
Chimpanzees are also known to make and use an array of crude tools.  Such tools include stone and wooden hammers.  They make use of these tools for cracking nuts and twigs.

 Authorities believe that the advantages of using a greater variety of tools selected for greater intelligence and brain size in the hominid lineage.