According to the fossil records and the profusion of scientific data, the Australopiths flourished in Africa for nearly 3 million years but went extinct about 1.4 Mya (million years ago). One of the seven identified species was probably a direct ancestor of our new genus, Homo, which arose in Africa 2.4 Mya with the discovery of Homo habilis, the “handyman”. Homo habilis was a 4’ tall walking primate with a larger brain than the Australopiths and the ability to make stone flaked tools for butchering its scavenged meals. It lived on raw meat since there is no evidence that it knew how to make fire.
Homo erectus appeared about 1.9 Mya, which means it co-existed with Homo habilis for at least a half million years. It was much taller at 5’10” and more erect in posture with a flatter though still chinless face. Its brain was much larger than Homo habilis and it made more complex tools, such as stone axes. Remarkably, it had the unique ability to make fire. It was also, as previously noted, among the first of our ancestors to travel outside of Africa.
Homo ergaster lived between 1.9 and 1.4 Mya in eastern and southern Africa. A nearly complete skeleton of this species was discovered in Kenya in 1984 by Kamoya Kimeu. The specimen was an 8 to 10-year-old boy, christened “Turkana Boy”, with a tall, slender frame who may have grown to the size of a modern human. His brain was larger than the Australopiths, and burned bones and tools have been found at some of the discovery sites, indicating this species also knew how to make fire. Scientists also believe that he may have been relatively hairless, perhaps as an adaptation to the warming climate. Fossil remains have also been found in Eurasia.
Homo rudolfensis was discovered by Richard Leakey in 1972 near the shores of Lake Rudolf in Kenya. It had a braincase of 775 cc, which is larger than Homo habilis, a longer face, but also larger molar and premolar teeth similar to an Australopith. Some scientists think it may have been an Australopith with a much larger brain, while others put it squarely inside the Homo genus.
All of these species co-existed in time and some co-existed in space. Hominins were born from Australopiths but were moving strongly in new directions: larger brains, opposable thumbs, smaller teeth and jaws, relatively hairless bodies with more sweat glands to cool body and brain in the warming climate of the late Pliocene (3.6 to 1.8 Mya) and into the Pleistocene. (to be continued in next post)