Study: High hierarchy, more aggression

The researchers from the University of Cambridge and University College London wanted to investigate the extent to which differences in aggressive behavior within a cooperative society can be explained by "inheritance rank" -- the likelihood an individual will get to mate successfully in that society based on its place in the social hierarchy.

"Certain group members inflict or receive many more acts of aggression than others," write the researchers. "In some cases, these acts (including bites, shoves, mounts and charges) appear to regulate cooperative activity in the group by activating lazy workers, for example, or punishing defectors."

The researchers developed two mathematical models that predicted if inheritance rank mattered in a cooperative society, the rates of aggression would be highest toward the front of the queue and aggression would increase as time available to inherit the ability to breed ran out in seasonal animals.

The predictions were proved correct.

The entire study is detailed in the June issue of American Naturalist.

Copyright 2006 by United Press International