The oldest collection of mass-produced prehistoric bone tools reveal that human ancestors were likely capable of more advanced abstract reasoning one million years earlier than thought, finds a new study involving researchers at UCL and CSIC- Spanish National Research Council.
The paper, published in Nature, describes a collection of 27 now-fossilised bones that had been shaped into hand tools 1.5 million years ago by human ancestors.
It's the earliest substantial collection of tools made from bone ever found, revealing that they were being systematically produced one million years earlier than archaeologists once thought.
Early human ancestors known as hominins (human ancestors who could walk upright) had already been making tools out of stone in some capacity for at least a million years, but there's been scant evidence of widespread toolmaking out of bones before about 500,000 years ago.
The hominins who shaped the recently-discovered bone tools did so in a manner similar to how they made tools out of stone, by chipping away small flakes to create sharp edges - a process called 'knapping'.
This transfer of techniques from one medium to another shows that the hominins who made the bone tools had an advanced understanding of toolmaking, and that they could adapt their techniques to different materials, a significant intellectual leap. It could indicate that human ancestors at that time possessed a greater level of cognitive skills and brain development than scientists thought.
Co-author Dr Renata F. Peters (UCL Archaeology) said: "The tools show evidence that their creators carefully worked the bones, chipping off flakes to create useful shapes. We were excited to find these bone tools from such an early timeframe. It means that human ancestors were capable of transferring skills from stone to bone, a level of complex cognition that we haven't seen elsewhere for another million years."
Lead author Dr Ignacio de la Torre of the CSIC-Spanish National Research Council added: "This discovery leads us to assume that early humans significantly expanded their technological options, which until then were limited to the production of stone tools and now allowed new raw materials to be incorporated into the repertoire of potential artifacts.
"At the same time, this expansion of technological potential indicates advances in the cognitive abilities and mental structures of these hominins, who knew how to incorporate technical innovations by adapting their knowledge of stone work to the manipulation of bone remains."
The tools were discovered in Olduvai Gorge in Tanzania, a site renowned for its long history of important archaeological discoveries revealing the origins of humans.
The researchers found 27 bones that had been shaped into tools at the site. The bones mostly came from large mammals, mostly elephants and hippos. The tools are exclusively made from the animals' limb bones, as these are the most dense and strong.
The tools originate from a time in prehistory where early hominin cultures were undergoing one of the first ever technological transitions.
The very earliest stone tools come from the "Oldowan" age which stretched from about 2.7 million years ago to 1.5 million years ago. It employs a simple method for making stone tools, by chipping one or a few flakes off a stone core using a hammerstone.
The bone tools reported in this study were from the time that the ancient human ancestors were progressing into the "Acheulean" age which began as far back as about 1.7 million years ago. The Acheulean technology is best characterised by the use of more intricate handaxes that were carefully shaped by knapping - allowing the production of tools through more standardised means.
The bone tools show that these more advanced techniques were carried over and adopted for use on bones as well, something previously unseen in the fossil record for another million years, much later into the Acheulean age.
Prior to this find, bones shaped into tools had only been identified sporadically in rare, isolated instances in the fossil record and never in a manner that implied that human ancestors were systematically producing them.
Though it's unclear precisely what the tools were used for, because of their overall shape, size and sharp edges, it's likely that they may have been employed to process animal carcasses for food.
It's also unclear which species of human ancestor crafted the tools. No hominin remains were found alongside the collection of bone artefacts, though it's known that, at the time, our human ancestor Homo erectus and another hominin species known as Paranthropus boisei were inhabitants of the region.
Because these tools were such an unexpected discovery, the researchers hope that their findings will prompt archaeologists to re-examine bone discoveries around the world in case other evidence of bone tools has been missed.
This research was supported by the European Research Council (ERC).
