Center for Archaeological Science, Sichuan University publishes new evidence of tropical rainforest adaptation in South Asia from the Late Pleistocene to the mid-Holocene

In recent years, the adaptation of modern humans to extreme environments during the dispersal process has attracted much attention. For example, when and how modern humans expanded to high-altitude, permafrost, desert, and tropical rainforest environments are at the forefront of archaeological debate. Archaeological evidence from Sri Lanka, located in the Indian Ocean, shows that evidence of modern human fossils, small stone tools, bone tools, and symbolic ornaments appeared around 40,000 years ago. This fully demonstrates that the tropical rainforests of Sri Lanka have special significance for early human foraging patterns.

In order to further understand the continuation and change of the tropical rainforest foraging tradition represented by small stone tools from the Late Pleistocene to the Early and Middle Holocene, the Center for Archaeological Science, Sichuan University collaborated with Sri Lankan archaeological colleagues to carry out joint excavations and research on the Kebella-lena rock shelter site deep in the tropical rainforest. Recently, the joint research team published a research paper titled Terminal Pleistocene to mid-Holocene Rainforest Foragers in Sri Lanka: Multidisciplinary Insights at Kebella-lena Rock shelter in the geosciences journal Quaternary Science Review, adding new evidence for the adaptation strategies of modern humans in tropical rainforest environments at the end of the Pleistocene.

The Kebella-lena site is located in the Runakanda area of the Sinharaja primary tropical rainforest in Sri Lanka, with geographic coordinates of 80掳19鈥�31.4鈥矱, 6掳30鈥�25.5鈥砃 and an altitude of approximately 322 meters. The site was first discovered in 2017 and systematically excavated from 2021 to 2022, yielding rich archaeological materials, including a large number of stone tools, microliths, bones, bone tools, pigments and ornaments, including shark tooth pendants, shell beads, etc. A paleo-floor, which may be a stone-paved ground, was also discovered. Through stone tool technology analysis, animal and plant remains analysis, and micro-trace analysis, technological innovation and cultural complexity from approximately 13,000 to 7,000 years ago were revealed.

The study found that the microliths technology of Kebella-lena started in the Late Pleistocene and continued into the Holocene, while similar technologies previously discovered in the same area mostly disappeared after the Late Pleistocene. Many small hammers were also found for processing small stone tools. Animal fossil remains are mainly arboreal mammals such as monkeys, as well as medium-sized mammals such as porcupines and squirrels, and a small number of large mammals (such as wild boars and deer). Some bones have obvious cut and burn marks, reflecting hunting, processing or cooking activities. Mollusk shells are mainly freshwater species, indicating that humans made full use of water resources in the rainforest. In addition, analysis of plant pollen revealed that they were good at collecting rainforest plants with high economic value, such as yams and jackfruit, demonstrating their mature adaptation to the rainforest ecology.

A total of 16 bone tools were newly excavated, all of which were pointed tools (single-pointed or double-pointed). Some handles have traces of repair and use, and it is speculated that they may be used for throwing or handle installation for hunting arboreal mammals such as monkeys. Ochre exists both in block form and in the form of traces on grinding stones and percussion tools, and it is speculated that it may be used for decoration or ritual activities. However, these pigments were not collected from nearby areas, and it is speculated that they were obtained through trade or long-distance exchange. In addition, shark tooth pendants, shell beads, and ornaments made of shark vertebrae were unearthed at the site, indicating that early humans not only had contact with coastal areas far from the rainforest, but also demonstrated important progress made by early Homo sapiens in technology, culture, and symbolic behavior.

This research not only challenges the past view that tropical rainforests are "green deserts" that are "unsuitable for human survival", but also proves that early Homo sapiens can successfully adapt to diverse environments, including tropical rainforests, through complex technological and cultural means. This research provides a new perspective for understanding human adaptability, technological innovation, and symbolic behavior of modern humans in South Asia, and also provides a comparison and supplement for the study of other early human sites worldwide.

The first author of this article is Pahiyangala Sumangala, a doctoral student at the Center for Archaeological Science. Professor Hongliang Lv and Associate Researcher Yue Hu of the Center for Archaeological Science are the co-corresponding authors. The cooperative units also include Bhiksu University of Sri Lanka, the Excavation Department of the National Archaeological Bureau of Sri Lanka, and the University of Kelaniya.

Original link: https://www.sciencedirect.com/science/article/pii/S0277379125000216