Homo erectus Dating the fossilshominin (Latin: “upright man”)

To reconstruct the position of H. erectus in hominin evolution, it is essential to define the place of this species in time, and modern paleoanthropologists have at their disposal a variety of techniques that permit them to do so with great precision. Potassium-argon dating, for instance, can provide the age of a specimen by clocking the rate at which radioactive isotopes of these elements have decayed. When radiometric methods cannot be applied, investigators may still ascribe a relative age to a fossil by relating it to the other contents of the deposit in which it was found.

Such lines of evidence have led to the tentative conclusion that H. erectus flourished over a long interval of Pleistocene time. The fossils recovered at Koobi Fora are from about 1.7 mya, and OH 9 from Olduvai is probably 1.2 million years old. The specimens from Sangiran and Mojokerto in Java may approach the age of the Koobi Fora skeletons, and one from the Lantian localities in China is roughly contemporary with OH 9. The youngest hominins generally accepted as H. erectus are from Tighenif in Algeria (800–600 kya), Zhoukoudian in China (500–250 kya), and Sambungmacan and Ngandong (Solo) in Java (perhaps less than 250 kya).

For the most part, fossils older than 1.7 million years are the remains of H. habilis and H. rudolfensis. These species are also known from Olduvai Gorge and Koobi Fora in Africa, the oldest specimens being about 2.0 to 1.8 million years in age. On the other hand, there is a group of later specimens that show some features of H. erectus but are commonly regarded either as “archaic” representatives of Homo sapiens or as belonging to H. heidelbergensis; these include specimens from Europe (Mauer, Arago, Bilzingsleben, and Petralona), northwestern Africa (Rabat and perhaps Salé and Sīdī ʿAbd al-Raḥmān), eastern and southern Africa (Kabwe, Elandsfontein, Ndutu, Omo, and Bodo), and Asia (the Dali find of 1978).