Primate Adaptations to Predation Pressure: Modelling Hominin Behaviour and Transforming Wildlife Conservation

The dynamic evolutionary arms race of predator-prey interactions plays a significant role in shaping complex animal behaviours, due to its direct and severe impact on the inclusive fitness of both predators and prey1. Operating within equally-dynamic ecosystems, evolutionary history is smattered with events of faunal extinction and speciation. Recent paleontological advances afford us increasingly detailed snapshots of these events throughout our own evolutionary history; for example, a noticeable bout of carnivore extinctions occurred at 1.5 Ma2,3, followed by a dramatic climatic shift (1.2 Ma)4, both of which coincide with a very significant period of hominin evolution. The fossil record indicates that two East African hominin species, and one South African - Homo habilis, Paranthropus boisei, and Paranthropus robustus- went extinct between 1.5 and 1.2 Ma, leaving behind a single lineage, Homo ergaster/erectus, who first thrived in Africa, and then dispersed across Eurasia as ancestors to modern Homo sapiens5-8.
After the Mozambican civil war of 1977-1992, populations of large mammals, including carnivores, were greatly depleted in Gorongosa21. This lack of predators has meant that other animals have thrived, most noticeably the 225 troops of as yet unstudied baboons, living widespread across the mosaic habitats of the park18. However, restoration projects are making great efforts towards the recovery of carnivore numbers; the lion population which had dropped from 200 to below 10 after the war, rose to 80 individuals in 201618, and a newly-established project will soon re-introduce leopards into the park (Susana Carvalho, pers. commun.). The trajectory of these projects provides a unique window for monitoring baboons' behavioural adaptations to low and shifting predation pressures, research that will have far-reaching implications for our understanding of primate evolution, human origins, and effective wildlife management.
This research will also contribute to a larger body of work at the advent of Gorongosa's Paleo-Primate Project, initiated in 2015. The park constitutes the southern tip of the East African Rift Valley, an area famous for its abundance of fossils generating prolific research on human origins6-8. The Paleo-Primate Project aims to integrate evidence gathered from Gorongosa's fossil sites with studies of its extant primates in order to reconstruct the evolutionary history of the area. Early human evolution was pervaded by extensive ecological variability, likely shaping the incredible adaptability of Homo sapiens10,22. A complex ecosystem like Gorongosa is the perfect natural laboratory for thorough examination of the impact of particular ecological variables on primate behaviour, providing insights into the mechanisms that link variability with adaptability. Beyond an empirical investigation of behavioural flexibility and adaptations in modern primates and pre-historic humans, this project also has implications for wildlife management in areas like Gorongosa. An imbalance of predator prey dynamics within an ecosystem can have a serious impact on human-wildlife conflict and local economies.
Gorongosa's lack of predators has facilitated the growth of the park's baboon population and has emboldened the animals to engage in behaviours like crop-raiding and invasion of human settlements. The local population and economy suffers not only through loss of resources, but also as parents take their children out of school to guard crops and cattle from the baboons. Understanding the dynamics of such conflict under different ecological circumstances is essential for implementing effective and sustainable conservation and wildlife management strategies23.
In addition to its large population of baboons, current ecosystem, and Rift Valley fossil sites, Gorongosa is also home to various long-term and multidisciplinary research projects, providing an invaluable and ever-growing record of the park's ecology and history. R