Some of the earliest known Homo sapiens in Sri Lanka specialized in hunting semi-arboreal and arboreal monkey and squirrel populations, according to a study in Nature Communications. The findings suggest that the capture of small, elusive mammals was part of the plastic behaviour of H. sapiens that allowed them to rapidly colonize a series of extreme environments apparently untouched by their hominin relatives.

From the Late Pleistocene (126,000-11,700 years ago) onwards, humans inhabited a number of diverse environments as they dispersed beyond Africa. Tropical rainforests were thought to be a barrier to this because of the lack of mammalian megafauna in these settings. However, in Sri Lanka, south-east Asia and Melanesia, the earliest evidence for human occupation is often associated with rainforest environments. Owing to a lack of detailed faunal analyses, it has been unclear which foodstuffs sustained these populations, as well as the hunting strategies used.

Patrick Roberts and colleagues applied a number of techniques to analyse the earliest dated archaeological site in Sri Lanka: the Fa-Hien Lena cave (previously dated to 38,000 years ago). The authors found that H. sapiens here specialized in hunting primates and giant squirrels from around 45,000 to 3,000 years ago, using complex bone and microlithic (small stone tool) technologies. They suggest that the human populations able to exploit these species, which were considered among those most vulnerable to overhunting, had a close knowledge of their life cycles and territories and used sustainable hunting strategies.