The era known as the Late Stone Age saw a dramatic flowering of art and technology, including the first appearance of many of the things we consider make us truly human. A newly studied cave in Kenya reveals the oldest known examples of many of these developments, providing records of progress very different from the sudden revolutions seen elsewhere. It's even possible this is the site where some of our most important advances were made.
Panga y a Saidi Cave was first occupied by humans 78,000 years ago, when Homo sapiens were spreading across the globe, but still using technology not all that different from other human species. Some 11,000 years later, items that would become crucial to humanity's future appear in the cave record for the first time.
“You start to see things like decorated bones, beads made from marine shell or ostrich eggs, miniaturized stone tools, and bones carved into things like arrow points. This is the oldest date we have for when this behavior is first observed,” said Dr Ceri Shipton of the Australian National University in a statement.
Early stone tools tended to be large, Shipton explained to IFLScience. and the miniaturization was particularly important. These new, smaller tools were made from more fine-grained stones with sharper edges. “We're not quite sure how they were using them,” Shipton added, as the wood these stones were probably attached to has long since rotted away. “Perhaps they were combining several pieces as barbs on something like a harpoon.”
Shipton and his fellow anthropologists report in Nature Communications finding an astonishing 30,000 items in Panga y a Saidi, revealing occupation until 500 years ago. The stable microclimate protected items that would have degraded elsewhere, while the cave's limestone leached calcium carbonate into bones, preserving them as other sorts of rock would not.
Other sites from the same era were abandoned for long periods during hostile climates. While Shipton says there were presumably periods when the cave was uninhabited, we have evidence of occupation through “every environmental phase”.
The site's location explains its longevity. At a time when humanity usually hunted for big game on open grasslands, Panga y a Saidi was located in tropical rainforest. However, both grasslands and the coast were within a day's walk, offering diverse hunting grounds when circumstances changed.
Although the forest expanded and contracted over that time, the mix of ecosystems remained unusually stable, which Shipton attributes to the nearby ocean. Other coastal ice age locations have been inundated since, but the continental shelf drops off so sharply off Africa's east coast the shoreline here has barely moved.
Shipton told IFLScience there was a long period where the cave apparently supported a much smaller population, based on the number of artifacts and charcoal there. Then, just as numbers were recovering, we see the flowering of art and technology that marked the Late Stone Age. The authors think this may have come in response to the need for more sophisticated tools required to hunt small rainforest prey, rather than the occasional big kill from the plains.
Given the record-breaking age of many of the developments, Shipton said it is possible Kenyan rainforests, and maybe even Panga y a Saidi itself, was the original site of many of these innovations – a sort of Stone Age Silicon Valley – that subsequently spread around the world.
Intriguingly, however, new tools did not suddenly displace the old, as appears to have happened elsewhere. Instead, old technologies sometimes temporarily returned to dominance as the environment shifted again.