Miniaturization is not just a modern fad. New research shows that hunter-gatherers in the Sri Lankan rainforests used this approach to ensure successful hunts over the past 45,000 years.

Making tech small and portable is something that engineers are putting a lot of thought and effort into. It’s what brought us from the building-sized computers of the 1940s to devices infinitely more capable that fit in the palm of your hand, or on your wrist.

Such miniaturization allows us to more readily apply our tools to various needs, making life easier, more comfortable, and more prosperous for all. The same, says new research, was true for stone-age communities.

Tiny rainforest tools

“Tropical rainforests have been seen as ecological barriers to human migrations, but our interdisciplinary archaeological research now convincingly shows that this was not the case at all,” says Dr. Oshan Wedage, of the University of Sri Jayewardenepura, corresponding author of the paper.

Rainforests are the richest natural ecosystems on Earth in regards to both biodiversity and total biomass contained. As such, it wouldn’t be too far-fetched to imagine that primitive, hunter-gatherer groups would find them to be ideal homes. After all, there still are isolated groups living at a stone-age development level in the world’s deepest rainforests.

But this isn’t the full picture. Because of how rich and biodiverse they are, rainforests are the site of intense intra-species competition. This often manifests itself in food sources that are hard to access, highly competed for, or protected with barb, fang, or poison. The current paper shows that groups of foragers could however understand how to access even such sources of nourishment and how to process them to remove any dangerous elements.

Miniature stone tools and bone projectiles were key in their ability to utilize these resources, allowing them to hunt a wide range of animals living in the Sri Lankan rainforests over the past 45 millennia and retrieve fruit from high above the ground.

The artifacts used for this study were recovered from the Kitulgala Beli-lena, a cave that is one of Sri Lanka’s most famous archeological sites, known for its wealth of stone tools, bone artifacts, as well as human and animal remains. Based on the evidence described in this paper, alongside data from other caves in the region, researchers have been able to establish that humans repeatedly and consistently inhabited the rainforested area between 45,000 and 8,000 years ago.

What all these people ate, the research shows, was the meat of tree- and ground-dwelling species, alongside helpings of wild fruit and freshwater mollusks. What they left behind gives us precious insight into how ancient groups adapted to life in the world’s rainforests.

Among one of their ingenious adaptation techniques was the manufacturing of miniaturized stone tools.

According to the team, such groups would forage appropriate pebbles or stones from local streams for processing. These would be placed on a rock anvil and struck with a hammerstone in a process known as ‘knapping’. These rainforest craftsmen would collect the small, slender, and very sharp flakes and mount them into wooden shafts to create projectiles. Bone fragments found at the site, which were sharpened to a point, were also used to craft arrows.

“The cave excavations in Sri Lanka have provided new insights into human behavior over the long term, showing that foragers were able to adapt and survive without adversely impacting their ecosystems,” explains Professor Michael Petraglia from the University of Queensland, Principal Investigator of the project and corresponding author of the paper. “The hunting of prey high in the trees and in dense forests required special subsistence strategies, planning, and sophisticated toolkits.”

“Though these hunter-gatherers became quite proficient in obtaining their dietary needs from the forest, our research shows that they did so without adversely impacting their ecosystems. In order not to over-exploit their local environments and food resources, foragers repeatedly moved from cave to cave, consistently shifting their residences without harming the long-term sustainability of their subsistence base.”

The paper “Homo sapiens lithic technology and microlithization in the South Asian rainforest at Kitulgala Beli-lena (c. 45–8,000 years ago),” has been published in the journal PLOS ONE.