IN BRIEF

摘要

A SIMPLE rule governs a seemingly random phenomenon: the sizes of the groups in which primates live. It seems our closest living relatives opt for social groupings that aren't as varied and flexible as you might think. Susanne Shultz at the University of Manchester, UK, and her colleagues compared group sizes in 215 primate species. The average number in a group varied between species but was always clustered around five distinct sizes (Biology Letters, DOI: 10.1098/rsbl.2017.0490).