Hyenas Inherit Power from Mothers, But It's A Privilege They Pay Dearly for
Published:18 Jul.2023 Source:Max-Planck-Gesellschaft
In some monarchies, inherited power offers a ladder that can be ascended to absolute authority -- be it through diplomacy, ruthlessness, or the passing of time. But in hyena monarchies, inherited power is a slippery downward slide. A study from the Max Planck Institute of Animal Behavior (MPI-AB) examined hyena societies over three decades. They found that the process by which hyenas inherit rank from their mothers -- known as maternal inheritance -- corrodes the social status of individuals. According to the study, every member of a hyena clan, except the highest-ranking queen, suffers downward mobility across their lifetime.
Strauss tapped a remarkable database from the Mara Hyena Project, which has been studying spotted hyenas in the Maasai Mara National Reserve in Kenya since the late 1980s. Analyzing three decades of data on hyena behavior from four social groups, Strauss discovered that hyenas could indeed move up and down in the hierarchy over time, but they slid down much more often than jumping up. But what was causing the persistent downward trajectory? By digging into the life histories of all individuals, Strauss found that hyenas descended in rank most often because another hyena had joined or left the group. In other words, through simple demographic turnover.
Drawing on methods used to study social mobility in human societies, Strauss then created computer simulated hyena societies, where he could turn off various aspects of their biology. This allowed him to pinpoint the specific societal rules that were driving the unusual pattern. The simulation pointed to two sources: the monarchy-like inheritance of hyena societies and the fact that higher-ranking females also give birth to more offspring. These combined traits mean that new group members are not being added randomly.The work demonstrates how societal features can have an outsize influence on individuals, sometimes usurping an animal's own agency in altering the course of its life.