The Erectus Set Out on a Journey

License Creative Commons

David Rabadà

Shortly after two million years ago, and for the first time in the evolution of our kin, a human group dispersed beyond the African continent. This marked the moment when Homo erectus reached Europe, Asia, and Oceania. This expansion was accomplished while still employing their earliest stone tool tradition—Mode I technology. Evidence of this diaspora can be found in archaeological sites such as Barranco León in Spain (1.3 million years old), Sangiran in Indonesia (around 1.7 million), Dmanisi in Georgia (also 1.7 million), Longgupo in China (1.8 million), Mojokerto in Java (also 1.8 million), and Shangchen in China (dating to 2 million years). These and other sites attest to the early advance of the erectus across Eurasia from their African beginnings prior to two million years ago. The question arises: what factors spurred such a remarkable feat, given that their ancestors and relatives had largely remained within Africa?

The first reason is climatic. Around 1.8 million years ago, a major glacial maximum occurred, which opened up the Eurasian steppes, decimated forested regions, and expanded the African savannah. Within this context, erectus encountered the possibility of moving beyond their southern homelands. In fact, the Asian steppe was then connected to the African savannah, presenting erectus with an open gateway for dispersal. Yet this alone cannot explain their success, as previous glaciations had also created such corridors without prompting earlier bipeds such as Australopithecus to leave the continent.

The second reason is ecological. Carnivores tend to occupy vast territories to meet their protein needs, which often leads them to disperse more rapidly than most herbivores. The fact that other carnivores also spread throughout Eurasia during the same period lends support to this hypothesis. Large predators such as Machairodus, Panthera, and Smilodon expanded their ranges alongside Homo beyond the 1.8-million-year threshold.

The third reason has already been addressed in previous chapters: with their low sexual dimorphism, year-round sexual activity, and absence of overt female oestrus, erectus likely achieved higher reproductive rates than their antecedents.

But a fourth and final reason for the erectus diaspora was their encephalisation. Their relatively large brains rendered them more versatile, flexible, and adaptable to new environments. Their dispersal was inevitable—and not a singular event, but at least twofold. If the first expansion occurred between two and 1.8 million years ago, another was recorded some half a million years later. On this second occasion—once again departing from Africa—erectus improved their way of life around 1.6 million years ago. With a new and widely used stone tool tradition—Mode II technology—as well as the establishment of stable hearth-centred campsites and possibly even a form of protolanguage, erectus appears to have embarked once more from Africa towards Europe and Eurasia. This is evidenced by the presence of Mode II (bifacial tools) across Europe and Asia. Examples include the Bose Basin sites in southern China (c. 800,000 years old) and Tell Ubeidiya in Israel (c. 1.4 million years). Thus, the second diaspora began over a million years ago, associated with Mode II technology, the mastery of fire, and possibly early language. Mastery of fire conferred erectus with significant advantages: improved defence against predators, reduction of parasites in raw meat, an additional source of warmth, illumination of darkness, and the capacity to cook food. The latter made their meals softer, easier to chew and digest. In this sense, fire enhanced their adaptability, bolstered their reproductive success, and underpinned the second major dispersal over a million years ago.

Sites bearing evidence of controlled fire use that mark the start of this phase include Wonderwerk Cave in South Africa and Swartkrans (1.1 million years), as well as Chesowanja in Kenya (1.4 million years), where up to 40 circular patches of ash—central hearths around which individuals likely gathered—have been excavated. Other fire-related sites, such as Koobi Fora, Awash, and Gadeb (around 1.5 million years old), also exist, although in these cases the evidence suggests sporadic fires with no clear indication that erectus had yet mastered or managed them.

In sum, we may say that erectus began to master fire during the first third of their existence—an innovation that proved essential to their second wave of global dispersal. Within a few millennia, these populations would give rise to Homo sapiens and Homo naledi in Africa, Homo floresiensis and others in Indonesia, and Homo heidelbergensis and Neanderthals in Europe and the Near East. As we can see, the erectus dispersal constituted a prelude to ourselves—sapiens—and to something even more significant: the expansion of culture beyond the boundaries of species. From this point onwards, changes in lithic technology occurred within the same species, not between different ones, as was the case when erectus transitioned from Mode I to Mode II technology without substantial taxonomic change. The same would later occur with Neanderthals, who evolved from using Mode II bifaces to Mode III (Mousterian), and with sapiens, who moved from Mode III to IV—each shift occurring at an increasingly rapid pace.

From then on, cultural evolution became partially detached from biological evolution, with technological progress advancing ever more swiftly. The explanation for all this lies in the gradual increase in erectus’ encephalisation index. The brain would enable the cultural revolution of human evolution, and with it, the emergence of new successes—one of which was the arrival of erectus in Western Europe.

Source: educational EVIDENCE

Rights: Creative Commons