From 3.8 million years ago, the ancestral species is the oldest known member of Australopithecus, the grouping of creatures that preceded our own branch of the family tree, called Homo.

Australopithecus possessed ape-like face proportions and a brain about a third the size of our species, as well as relatively long arms with curved fingers, good for tree-climbing.

A 2007 image shows a three-dimensional model of the early human ancestor, Australopithecus afarensis, known as Lucy, on display at the Houston Museum of Natural Science.

The study determined the diet of seven Australopithecus individuals from South Africa dating to between 3.7 and 3.3 million years ago based on the chemistry of their tooth enamel.

For Australopithecus africanus, on the other hand, Raymond Dart assumed a height of 1.25 meters and a weight of 25 to 30 kilograms. Early man was small and weak.