Where did Homo erectus first appear? The answer seems fairly simple: Most likely, this species initially evolved in Africa. Two important pieces of evidence help confirm this hypothesis.
- First, all of the earlier hominins prior to the appearance of H. erectus come from Africa.
- Secondly, What’s more, by 1.7 mya, there are well-dated fossils of this species at East Turkana, in Kenya.
But there’s a small wrinkle in this neat view. We now know that at about 1.8 mya, similar populations were already living far away in southeastern Europe, and by 1.6 mya, in Indonesia. So, adding these pieces to our puzzle, it seems likely that H. erectus first arose in East Africa and then very quickly migrated to other continents; nevertheless, as we’ll see shortly, the dating of sites from Africa and elsewhere does not yet clearly confirm this hypothesis. Let’s first review the African H. erectus specimens dated at 1.7–1 mya, and then we’ll discuss those populations that emigrated to Europe and Asia.
The earliest of the East African H. erectus fossils come from East Turkana, from the same area where earlier australopith and early Homo fossils have been found. Indeed, it seems likely that in East Africa around 2–1.8 mya, some form of early Homo evolved into H. erectus.
The most significant H. erectus fossil from East Turkana is a nearly complete skull (Homo ergaster). Recently redated at 1.7 mya, this fossil is about the same age (or even a little younger) as some other fossils outside of Africa; nevertheless, for now, it certainly is the oldest known member of this species from Africa . The cranial capacity is estimated at 848 cm3 .
Another remarkable discovery was made west side of Lake Turkana at a site known as Nariokotome. Excavations produced the most complete H. erectus skeleton ever found . Known properly as Nariokotome Boy(Homo ergaster), dated to about 1.6 mya. The skeleton is that of an adolescent about 8 years of age with an estimated height of about 5 feet 3 inches. Some estimates have hypothesized that the adult height of this individual could have been about 6 feet. Nevertheless, the postcranial bones look very similar, though not quite identical, to those of modern humans. The cranial capacity of Nariokotome Boy is estimated at 880 cm3 ; brain growth was nearly complete, and the adult cranial capacity would have been approximately 909 cm3 (Begun and Walker, 1993).
Other important H. erectus finds have come from Olduvai Gorge, in Tanzania, and they include a very robust skull discovered there by Louis Leakey back in 1960. The skull is dated at 1.4 mya and has a well-preserved cranial vault with just a small part of the upper face. Estimated at 1,067 cm3 , the cranial capacity is the largest of all the African H. erectus specimens. The browridge is huge, the largest known for any hominin, but the walls of the braincase are thin. This latter characteristic is seen in most East African H. erectus specimens; in this respect, they differ from Asian H. erectus, in which cranial bones are thick.
A recently discovered nearly complete female H. erectus pelvis comes from the Gona area in Ethiopia and is dated to approximately 1.3 mya (Simpson et al., 2008). The pelvis has a very wide birth canal, indicating that quite large-brained infants could have developed in utero (before birth); in fact, it’s possible that a newborn H. erectus could have had a brain that was almost as large as what’s typical for modern human babies.
Another recent discovery from the Middle Awash of Ethiopia of a mostly complete cranium from Daka is also important because this individual (dated at approximately 1 mya) is more like Asian H. erectus than are most of the earlier East African remains we’ve discussed (Asfaw et al., 2002). Consequently, the suggestion by several researchers that East African fossils are a different species from (Asian) H. erectus isn’t supported by the morphology of the Daka cranium.