By Alison George
Homo erectus skull fragments found in Ethiopia
Michael J. Rogers, Southern Connecticut State University
The discovery of skull fragments alongside different types of stone tools in Ethiopia sheds new light on the lifestyle of the ancient hominin Homo erectus. It dispels the idea that one species used just one type of tool technology, indicating that this human ancestor was more behaviourally flexible than we thought.
Sileshi Semaw at the National Centre for Research on Human Evolution in Spain and his colleagues identified two H. erectus skulls at a site in Gona, Ethiopia. One was 1.26 million years old and the other dated back at least 1.5 million years. Unusually, the skulls were found directly alongside various stone tools.
This is good evidence that these hominins were the creators of those artefacts, says Michael Rogers at Southern Connecticut State University, who was part of team that made the discovery. That means you can get a better handle on what kind of tools they were really using.
H. erectus evolved around 2 million years ago in Africa and was one of the first species in our genus, Homo. Compared with earlier hominins, members of this species had relatively large brains and were adept tool-makers. They invented the so-called Acheulian tools, such as teardrop-shaped hand axes, which superseded the older and simpler Oldowan tools.
Hand axes are a multipurpose tool, a kind of Stone Age Swiss army knife. It was thought that once these sophisticated implements had been invented, H. erectus stopped using the more primitive Oldowan tools, which are sharp-edged stone flakes.
The discoveries at Gona dispel this notion, showing that both types of tool were used at the same time. They were using both technologies as they saw fit, says Semaw.
The skeletal remains also revealed other information about these hominins. The older skull was much smaller than the more recent one. It has the smallest cranial capacity ever found for H. erectus, and was probably female, says Semaw. The other skull was larger and sturdier with big brow ridges, and probably male, implying large physical differences between the sexes.
Other clues about the lifestyle of the Gona H. erectus population come from analysing isotopes in teeth, which show they had a varied diet, possibly consisting of eggs, insects, woodland plants and grazing animals.
Not only were they physically quite variable, but their tool use behaviour was also quite variable, says Rogers. This emphasises that they were incredibly adaptable to their local settings. On all fronts biological, ecological and behavioural our evidence suggests more variability and more flexibility.
Journal reference: Science Advances, DOI: 10.1126/sciadv.aaw4694
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By Alison George