Olive baboon troops decide where to move democratically, despite their hierarchical social order, a new study has found.
At the Mpala Research Centre in Kenya, researchers conducted the first-ever group-level GPS tracking study of primates, finding that any individual baboon can contribute to a troop's collective movement.
"Despite their social status, it's not necessarily the biggest alpha males that influence where groups go," said Margaret Crofoot, research associate at Smithsonian Tropical Research Institute (STRI) and assistant professor of anthropology at University of California, Davis (UC Davis).
"Our observations suggest that many or all group members can have a voice, even in highly stratified societies," she said.
Wild olive baboons (Papio anubis) live in strongly hierarchical troops. Dominant individuals displace subordinates when feeding or mating.
However, analysing the second-by-second GPS trajectories of individuals in a troop showed that neither a baboon's rank nor their sex conferred leadership ability, researchers said.
Much to the scientists' surprise, what emerged was almost identical to patterns previously predicted by theoretical models based on the movements of fish schools, bird flocks and insect swarms.
Decision making in baboons is largely a shared process: individuals vote with their feet by choosing to lead or follow their troop-mates.
In the study, researchers trapped and fitted 25 members of a wild baboon troop with custom-designed GPS collars to record each individual's location every second for 14 days.
The resulting 20 million GPS data points - representing the continuous movements of more than 80 per cent of the group's individuals relative to each other - included not just collective movement decisions but also eating, hanging out and playtime.
Researchers then wrote a programme to calculate the relative movements of the baboons in pairs.
