Meg Crofoot: UC Davis

Animals living in stable social groups may often disagree about where to go, but must reconcile their
differences to maintain cohesion and thus the benefits of group living. Although theory predicts that
shared (democratic) decision-making should be widespread in nature, in species that form long-term
social bonds, considerable asymmetries in dominance and social power often exist, and some have
proposed that these differences give high-ranking individuals increased influence over group decisions.
Determining how consensus is achieved in stratified societies remains a core challenge for
understanding the evolution of social complexity. To investigate how differentiated social relationships
shape the collective decision-making process, we captured simultaneous high-resolution GPS tracks
from 26 members of a wild olive baboon troop (Papio anubis; ~ 80% of adult and subadult members,
sampled at 1hz). We then used these data to explore the relative importance of individual relationships
vs. majority rule in driving group movement decisions in this highly structured society.