Leading paleoanthropologists to assume that the hominins who migrated to Asia and Europe descended from earlier African ancestors. Also, these travelers look like Homo, with longer limbs and bigger brains. Since H. erectus originated in East Africa, they were close to land links to Eurasia (through the Middle East) and thus were probably the first to leave the continent.
What we do know is that we’re seeing a greater range of physical variation in the specimens outside of Africa and that the emigration out of Africa happened earlier than we had previously thought. Current evidence shows H. erectus in East Africa about 1.7 mya, while similar hominins were living in the Caucasus region of southeastern Europe even a little earlier, about 1.8 mya. Eventually, hominins made it all the way to the island of Java, Indonesia, by 1.6 mya. It took H. erectus less than 200,000 years to travel from East Africa to Southeast Asia. Let’s look at this fascinating evidence. The site of Dmanisi, in the Republic of Georgia, has produced several individuals and an associated assemblage of Oldowan stone tools, giving us a unique look at these first possible travelers. The age of this crucial site has recently been radiometrically redated to 1.81 mya (Garcia et al., 2010).
The Dmanisi crania are similar to those of H. erectus . However, other characteristics of the Dmanisi individuals are different from what is seen in other hominins outside Africa. In particular, the most complete fossil has a less robust and thinner browridge, a projecting lower face, and a relatively large upper canine. At least when viewed from the front, this skull is more reminiscent of the smaller early Homo specimens from East Africa than it is of H. erectus . Also, specimen cranial capacity is very small— estimated at only 600 cm3 , well within the range of early Homo. They weren’t especially tall, having an estimated height ranging from about 4 feet 9 inches to 5 feet 5 inches.
Certainly, based on this evidence, they seem smaller than the full H. erectus specimens from East Africa or Asia. Yet, although short in stature, they still show body proportions (such as leg length) like that of H. erectus (and H. sapiens) and quite different from that seen in earlier hominins. Based on the evidence from Dmanisi, we can assume that Homo erectus was the first hominin to leave Africa. While the Dmanisi specimens are small in both stature and cranial capacity, they have specific characteristics that identify them as H. erectus (for example, a sagittal keel and low braincase). So, for now, the Dmanisi hominins are thought to be H. erectus, although an early and quite different variety from that found almost anywhere else.
While new and thus tentative, the recent evidence raises important and exciting possibilities. The Dmanisi findings suggest that the first hominins to leave Africa were quite possibly a small bodied very early form of H. erectus, possessing smaller brains than later H. erectus and carrying with them a typical African Oldowan stone tool culture. Also, the Dmanisi hominins had none of the adaptations hypothesized to be essential to hominin migration— that is, being tall and having relatively large brains. Another explanation may be that there were two migrations out of Africa at this time: one consisting of the small-brained, short-statured Dmanisi hominins and an almost immediate second migration that founded the well recognized H. erectus populations of Java and China.
Archaeology of Early Hominin Dispersal
The first hominins to leave Africa were tool-assisted scavenger-gatherers who carried with them the basic concepts and technological capabilities of the Oldowan tool industry (e.g., see Mgeladze et al., 2011). As such, they differed greatly from modern humans. They began their extraordinary journey without the benefit of language, the controlled use of fire, or projectile weapons and other killing tools. Nevertheless, they demonstrates that they were equally capable of successfully invading new habitats across the Old World, from the Atlantic to the Pacific.
Evidence of butchering is widespread in early H. erectus sites, and in the past, such evidence was cited in arguments for consistent hunting. Researchers formerly interpreted any association of bones and tools as evidence of hunting, but many studies now suggest that cut marks on bones from this period often overlay carnivore tooth marks. This means that hominins were gaining access to the carcasses after the carnivores and were therefore scavenging the meat, not hunting the animals. Wild plants, tubers, and fruits were also important foods, but these hominins, who were not fire using, had limited ability to deal with common plant toxins that cooking inactivates.
The stone tool assemblages of early sites such as Dmanisi in Georgia and Atapuerca in Spain resemble those of Oldowan sites in East Africa, which implies not only a similar grasp of technology but also the technological requirements for its use. By contrast, the assemblages of early East Asian sites in the Nihewan Basin in northern China exhibit patterned differences (for example, smaller artifacts and more artifacts that show evidence of pounding) that may reflect technological requirements and tool kits unlike African Oldowan assemblages (Braun et al., 2010; Potts and Teague, 2010). Equally interesting is the absence of unequivocal Oldowan archaeological evidence in South Asia, where Acheulian sites are known from most of the subcontinent after about 1.5–1.2 mya (Gaillard et al., 2010; Pappu et al., 2011).
By 1.7–1.6 mya, a new stone tool industry called Acheulian is found in Africa and, soon after, at sites in the Near East, the Indian subcontinent, and parts of East Asia (Semaw et al., 2009). The Acheulian tool kit was both more diverse and more complex than the Oldowan. It represented several new concepts about making stone tools.
- First, Acheulian toolmakers invented the idea of a bifacial stone tool—one that has been worked to create two opposing faces. A notable example of an Acheulian bifacial tool is the hand axe , thousands of which have been found at Lower Paleolithic sites from Africa to Europe and eastward to India.
- Second, Acheulian toolmakers developed a new way to knock flakes from stone cores, which gave more predictable results than the “hard hammer” percussion method used by their Oldowan predecessors. “Soft hammer” percussion employs a hammer made of a somewhat flexible material, such as wood, bone, or antler. When struck against a core, the soft hammer absorbs some of the striking force, giving an experienced stone toolmaker greater control over the length, width, and thickness of the resulting flakes . While this may sound like a small change, it was an era during which such small technological changes could make big differences in how stone tools were made and how they looked when finished.
- Finally, some kinds of Acheulian tools tend to reflect shared notions of form, or what they should look like. In other words, not only did Acheulian toolmakers create new stone tools and ways to make them; they were also capable of developing and communicating to each other ideas of form and design. For example, pretty much everything was a “Swiss Army knife” to an Oldowan toolmaker; but when an Acheulian toolmaker sat down to make, say, a hand axe, he or she clearly expected to end up with a stone tool that was bifacially worked, often about 6 to 8 inches long, and possessing a pear or teardrop shape with a point at one end and a rounded base at the other . Conceptualizing tools in this way was something new.
The most distinctive Acheulian artifacts are hand axes and cleavers, which are much like hand axes except that they end in a broad straight edge rather than a point. While we still don’t have a clear idea what cleavers were used for, hand axes show wear patterns and other evidence of having been used for many different kinds of tasks, especially cutting and chopping.
The Acheulian tool kit was not just hand axes and cleavers. It also included many kinds of flake tools , which were used for cutting, abrading, scraping, piercing, and other tasks, as well as hammer stones, cores, and other artifacts, many of which would also have been familiar to an Oldowan toolmaker.