Senegal's spear-wielding savannah chimps offer clues to human evolution

The Fongoli community of about 35 savannah chimpanzees in southeast Senegal displays unusual behaviours — including spear use by females and soaking in pools — documented over 25 years by primatologist Jill Pruetz.

The Fongoli chimpanzees live in the dry savannah of southeast Senegal and show behaviours not typical of forest chimpanzees. Primatologist Jill Pruetz has studied this community since 2001 and now has 25 years of data. The group numbers about 35 individuals and occupies roughly 100 square kilometres. Observers report females make and use spears, the chimps soak in natural pools and use caves to rest and cool. Key observations: - The Fongoli community comprises about 35 chimpanzees with a home range near 100 square kilometres in southeast Senegal. - Female chimpanzees have been observed whittling sticks into spears and hunting bush babies in tree holes; researchers recorded this behaviour nearly 600 times. - The apes use natural pools to soak and caves to cool, and endure heat indices reported up to 49°C during the hot season. - Researchers follow adult males in rotation and avoid routine tracking of females to reduce the risk from poachers. - A recent local gold rush has increased artisanal and industrial mining nearby, bringing noise, fires at mine sites and risks such as water pollution and disease transmission. Summary: The Fongoli chimpanzees' behaviours give researchers comparative insight into how early hominins might have adapted to savannah conditions and to high heat. Researchers continue long-term monitoring led by Jill Pruetz and local teams, and local authorities have access to data relevant to conservation planning. The community faces ongoing pressures from mining and climate-related heat stress, and the longer-term outcomes are undetermined at this time.