Ancestral hominid

Five to six million years ago:
The ape/hominid line splits. At that point we have an ultraprimitive ape-man. This first bipedal primate has slightly curved hands and toes, relatively long arms and short legs, and, compared to an ape, smaller canine teeth and thicker dental enamel.

Around 4.5 million years ago:
We don’t know a lot about Ardipithecus ramidus, because the findings haven’t been published yet. But we do know it has smaller canines and slightly thicker enamel.

Around 4.1 million years ago:
We see Australopithecus anamensis, which Meave Leakey discovered near Kenya’s Lake Turkana. An anamensis knee joint indicates the animal is walking upright. It has relatively reduced canines and thicker enamel but a very small brain and a very primitive, protruding jaw not unlike a chimpanzee’s.

Photograph at left by Kenneth Garrett