Sophisticated bladelet find suggests they passed on their technological skill through generations
A haul of stone blades from a cave in South Africa suggests that early humans were already masters of complex technology more than 70,000 years ago1.
The tiny blades – no more than about 3cm long on average – were probably used as tips for throwable spears, or as spiky additions to club-like weapons, says Curtis Marean, the archaeologist from Arizona State University who led the team that found them.
Twenty-seven blades, which archaeologists call microliths, were found in layers of sand and soil dating to as far back as 71,000 years ago and representing about an 11,000-year timespan, showing how long humans were manufacturing them.
The find could add weight to the idea that early humans were capable of passing on their clever ideas to the next generation of artisans, creating complex technologies that endured over time. John Shea, a paleoanthropologist at Stony Brook University in New York says it also suggests that “previous hypotheses that 'early' Homo sapiens differed from 'modern' ones in these respects are probably wrong”.
But because the evidence of human technology is patchy, this hypothesis has been disputed. Some archaeologists argue that humans could have repeatedly devised and then lost the ability to make such complex tools, as their population size fluctuated over time2. “It is still tricky to know whether this behaviour is continually there,” says Chris Stringer, who studies human evolution at the Natural History Museum in London. At this time, modern human groups were likely to be small, and those with expertise could easily have been wiped out. “If you haven’t got the population size, knowledge can get lost”, he says.
The recipe used to make these tools is a multistep process. First, people would have collected a rock called silcrete, and then heat-treated it to make it easier to flake into bits. Then, they would use a larger rock to flake off sharp slivers of rock, blunt them on one side and use them as blades on composite weapons.
Marean thinks they probably had to be able to talk to each other for it to work. “You have to have high-fidelity transmission of a process like that,” he says. “In order for it to be communicated across generations we think they almost certainly had complex language.”
But even this might not count as evidence for ‘complex thought’. Some scholars want to see evidence of symbolism – such as art or ornaments3 – in order to grant this.
Nonetheless, the weapons made them a force to be reckoned with. The flakes are “very small and light, and that suggests that they were components on a dart or spear that could be thrown a long distance.” There is even the possibility that modern humans used such spear-throwing technology to outsmart Neanderthals when they spread out of Africa and into Europe after 100,000 years ago. The spear points that Neanderthals used were too unwieldy and heavy to be thrown, says Marean. “If you come up against a competitor that has a spear thrower, you’re at a distinct disadvantage."
But Shea isn’t so sure that microliths were the clincher for humans’ success against other hominin populations. It’s not clear that they brought this technology into Europe. “Microliths seem to show up much later than first appearance dates for Homo sapiens fossils in most parts of Eurasia,” he says. And Stringer is keen that archaeologists don’t underestimate the Neanderthals themselves. Their archaeological record is also incomplete, and more data is needed to understand whether their cognitive skills were also getting more complex. “I’m trying to be fair to the Neanderthals,” he says.
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Curtis Marean tells Kerri Smith about the bladelets his team has discovered and what they imply about their makers' minds
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Smith, K. Early humans tooled up [back by 2.10pm pls]. Nature (2012). https://doi.org/10.1038/nature.2012.11765