About one million years ago, Homo erectus populations began migrating out of East Africa. They soon spread into South and West Africa, Asia and Europe. This adaptive radiation was the result of several biological and cultural factors.
H. erectus was physically larger than earlier hominids. This probably allowed them to fun faster and further than their ancestors and could have given them an advantage in hunting and escaping. It may also have increased their food gathering abilities by expanding the amount of terrain they could cover daily.
The most important biological characteristic of H. erectus leading up to this adaptive radiation is its increase in cranial capacity. H. erectus cranial sizes range from 750 – 1250 cc with an average of about 1000 cc. Their increased brain-sizes allowed for all of their cultural adaptation. Additionally, latex moulds made from H. erectus skulls show a larger BrocaOs area, a part of the brain used for language, then in earlier hominids. Even if H. erectus did not possess language as we know it, they must have had a highly advanced vocabulary of calls or other complex communication system. This would allow for better cooperation between individuals in hunting, scavenging, gathering, escaping predators and tool making.
Tool use was an important cultural adaptation of H. erectus. Their tools were much more sophisticated and efficient than those made by H. habilis. Populations outside of China made flatter, sharper tools with straight blades known as bifaces. All H. erectus populations made a wide variety of stone tools. Central to their tool kit was the Ancheulian hand axe; a pear shaped tool used for a variety of purposes including cutting, scraping, digging and pounding. Other tools included smaller scrapers, pointed tools and large, chisel bladed cleavers used for butchering scavenged or hunted animals. Unlike H. habilis, H. erectus used wood and bone in addition to hammer stones to fasten their tools. A finer edge can be achieved this way than with stone alone.
H. erectus is also the first hominid known to use, and possibly control, fire. Fire has many uses; it provides warmth and light, cooks food, facilitates the flaking of stone and hardening of wood, and can be used as a defence against predators. There is, however, some dispute over whether or not H. erectus controlled or even used fire, but a great deal of evidence suggests that they did.
It is still unclear why H. erectus left Africa. It was suggested that a major climactic shift took place but there is no evidence to support this theory. Perhaps H. erectusO increased viability led to an increase in population densities which neccesitated migrations. Whatever the antecedent, adaptive radiation was facilitated by the biological and cultural innovations introduced by H. erectus