Beginning around 1.8 mya, a new hominin appeared. And we couldn’t find evidence of Archaic Humans back beyond this period. These new hominids, called Homo erectus, shows a continuity with the missing archaic humans but with distinctive differences in anatomical features. During this fascinating and dynamic period of human evolution, hominins first left Africa, colonized vast areas of Asia and Europe, and underwent fundamental changes in culture and adaptation that shaped human biological variation. They became extinct from all parts of the world at least by around 100000 Ya.
Features
- Discovery Date: Eugène Dubois, a Dutch surgeon, found the first Homo erectus individual (Trinil 2) in Indonesia in 1891.
- Where Lived: Northern, Eastern, and Southern Africa; Western Asia (Dmanisi, Republic of Georgia); East Asia (China and Indonesia)
- When Lived: Between about 1.89 million and 110,000 years ago
- Image of reconstruction of Homo erectus based on ER 3733 by John Gurche
- Height: Ranges from 4 ft 9 in – 6 ft 1 in (145 – 185 cm)
- Weight: Ranges from 88 – 150 lbs (40 – 68 kg)
One of the most striking characteristics is the combination of relatively short arms and long legs. That is, the H. erectus body plan is much more like that of a living human in its ratio of arm length to leg length. If some Homo erectus has walked along the street of our town, we could not be able to distinguish from the Modern Homo sapiens. This change in limb proportions in H. erectus signals the beginning of a major alteration in the pattern of bipedal locomotion: H. erectus became completely committed to terrestrial life by adopting a fully modern stride. Life in the trees as that was the case with tits earlier ancestors became a thing of the past.
H erectus showed significant increase in body size from its ancestors. Comparisons suggest that it occurred rapidly, perhaps in less than a few hundred thousand years. It is estimated that the size of the H. erectus was increased by around 30% from the H. Habilis, its immediate ancestor.
In addition to the increase in body size, a key difference between its ancestors and H. erectus is the latter’s much larger brain. From H. habilis to H. erectus, brain volume increased by 33% (from 650 cc to 950 cc). The increase in sophistication of tool technology and other cultural changes seen after 2 mya or so strongly suggests that this increase in brain size reflects an increase in intelligence and cognitive abilities generally.
One of the fundamental reasons for both increase in body size and brain size was likely increased access to animal food sources—protein— acquired from hunting.
Two things had to happen for early hominins to routinely acquire meat. First, to kill game, hominins had to become able to manufacture the right tools, especially stone tools that could be thrown or thrust accurately, such as spears. Second, hominins had to develop the social structure whereby a group of individuals could efficiently track and kill game. Both developments were part of the increase in hominin intelligence at this time, as recorded by brain size expansion and more complex technology. Cutmarks made with stone tools have been found on bones of animal prey in Kenya and Ethiopia, at the Olduvai Gorge and Bouri sites. Once hominins had developed the technological and social means of accessing animal food sources daily, they likely had increased access to high-quality protein. This increased access to protein would in turn have produced H. erectus’s bump in height and providing nutrition and energy for the bigger brain.
Soon after we see evidence in the fossil record of the earliest Homo erectus fossils (by about 1.9 million years ago), we see evidence in the archeological record for the first major innovation in stone tool technology (by about 1.76 million years ago). Known as the Acheulean stone tool industry, it consisted of the creation of large cutting tools like handaxes and cleavers. Increased reliance on a broader set of tools may have helped Homo erectus survive during changing climates.
The earliest evidence of hearths (campfires) occur during the time range of Homo erectus. While we have evidence that hearths were used for cooking (and probably sharing) food, they are likely to have been places for social interaction, and also used for warmth and to keep away large predators.
Fossil evidences
The earliest record of H. erectus comes from Africa, less than 2 mya. At that time, ancestors of H erectus were still around in East Africa and South Africa, and comparing the fossils of each reveal great differences in anatomy and adaptation between H. erectus and the last ancestors. Among the earliest and the most spectacular of the H. erectus fossils is an 80% complete juvenile skeleton from Nariokotome, on the western side of Lake Turkana. This remarkably complete skeleton dates to about 1.6 mya.
Nariokotome Fossil
Features of the pelvic bones and overall size indicate that the Nariokotome individual was likely a young adolescent male. He was quite tall, about 166 cm (66 in). Had he survived to adulthood, he would have grown to nearly 180 cm (71 in) in height with cranial capacity about 900 cc
Multiple sets of footprints on an Ileret landscape dating to around 1.5 mya. These footprints provide a kind of fossilized picture of behaviour: evidence of how early human ancestors walked. They reveal that the Ileret H. erectus walked just like a modern human. The footprints have all the fundamentals that we see in our feet, namely, the double arch (the long one extending from your heel to the base of your toes and the side-to-side one) and an adducted big toe (the big toe is close to the second toe).
Other key H. erectus fossils from Africa include a partial cranium found in Olduvai Gorge and dating to about 1.2 mya, a partial cranium and postcrania found at Daka and dating to 1 mya , a partial cranium found at Buia and dating to about 1 mya, a pelvis found at Gona and dating to 1.2 mya, and a cranium found at Bodo and dating to about 600,000 yBP
H. erectus in Asia consists of five skulls, other bones, and many stone tools found by the Georgian paleontologist David Lordkipanidze and his colleagues in Dmanisi, Republic of Georgia. The date for this important site, 1.8 mya, indicates that H. erectus colonized western Asia very soon after it began to evolve in Africa. The earliest presence and subsequent evolution of H. erectus were somewhat later in Europe than in Africa and Asia. The earliest fossil evidence of H. erectus in western Europe is from the Sierra de Atapuerca, northern Spain—at the cave sites of Sima del. The earlier site is represented by a partial mandible and some teeth, along with animal bones showing cutmarks from butchering.