Two million years ago, the chimp-sized brains of the early australopithecines almost doubled in a growth spurt. Homo habilis is characterized by a progressive reduction of the dental and facial apparatus and by the development of cranial capacities that led to an increasingly preponderant social and material culture. Homo habilis has a bigger brain than A. afarensis but also has a different brain circumvolutions’ pattern. His Broca area, which controls human language in sapiens sapiens, has a pattern different from that of A. afarensis and monkeys and quite similar to that of modern man. Homo habilis must have been able to master the pronunciation of some sounds. He also made stone tools.
The earliest member of the “Homo” genus known is a cranium dated at about 2.2 to 3 million years ago (fig. 7.3).
Figure 7.3. The discovery of a 2.2 million years old skull that does not seem to belong to one of the four main hominid species suggests that we are still lacking much of the knowledge needed to ascertain with full confidence the phyletic line of the Hominids.
This skull presents many Australopithecine features. The oldest known cultural evidence, dating about 2.5 million years ago, suggests that some hominids had developed by that time behavioral patterns that were of fundamental importance for the evolutionary differentiation of modern Homo sapiens from other primates. These patterns included tool manufacturing and use, meat eating and operation out of a home base. These patterns were fully exploited two million years ago, when the humid wooded Savannah of northern Kenya changed suddenly to an open landscape with extensive grasslands, and lasted 1.5 million years.