On an island in Southeast Asia, early humans coped with climate change by tailoring their technology

Image credit: Shutterstock/Andrew Kosyanenko. Retrieved from pnas.org

Over the course of some 44,000 years, humans occupying the island of Timor-Leste, just north of Australia, changed their methods of making stone tools in lockstep with climate change, according to a recent study in Quaternary Science Reviews.

During wet periods on the island, early peoples favored stone slicers and scrapers without much evidence of resharpening or re-use. But in dry times, the tools became more typical of mobile people. Stone slicers and scrapers became smaller and lighter weight, requiring less stone, which may have been a limited resource that required hiking long distances.

Dry-period tools also show evidence of resharpening and repurposing. For instance, a larger stone tool might be pounded with another rock in order to flake off smaller, sharp-edged pieces of stone. Those little flakes turn up much more frequently in dry periods, ostensibly conserving rock resources, says lead author Chris Clarkson, an archaeologist at the University of Queensland, Australia.

Clarkson and his coauthors have studied Timor-Leste for decades. They’ve found small stone tools scattered across many archaeological sites. For this work, they excavated a large pit near the front of the cave Matja Kuru 2. They “pulled out all the bits of shell, and fish bone, and so on,” Clarkson explains. Back in his Queensland lab, Clarkson identified each stone tool by material—whether obsidian, limestone, or chert—as well as by size and tool type. Some were blunt, while others had knife-like edges. Some hadn’t been used much, while others had been resharpened many times. Comparing these tools to pollen cores from Australia and other Southeast Asian islands, Clarkson observed how patterns of climatic change seemed to mirror the timing of changes in stone tool technology.