Winning streak

Conflict and social organization in the animal kingdom

source: Lee Dugatkin
New Scientist March 9 2002
starts p32, 4 pages long

Past experience can affect whether animals win or lose fights, and observing conflicts can also affect behaviour. This can affect levelsof aggression in animal societies, and the extent to which societies are meritocratic or autocratic.

Gordon Schuett has studied copperhead snakes, and he has found that male snakes that lose a fight are more likely to lose subsequent fights against males of a similar size that had not fought before. The first fight is likely to be won by the larger male, and the loser is then likely to be affected by the experience of losing. Winners, though, were not more likely to win their next fights against males of the their size. The 'winner effect' is, however, found in some other species such as rats, and so far it is found alongside a 'loser effect, rather than on its own.

Computer simulations have been used to study winner and loser effects. Players with high scores and high opinions of their ability relative to their opponents are more likely to fight. Where both have a low assessment of their ability, neither fights. Where one player has a high estimation and the other a low estimation, one attacks and the other cowers. Fights occur when both have a high estimation. Winner effects have been linked to linear hierarchies, and loser effects are linked to autocratic hierarchies, with one alpha and little interaction among the remainder of the group members.

Bystanders observing fights may be more likely to attack losers, and less likely to win fights against animals they have seen winning. Bystander winner effects can lead to attacks on omegas, while bystander loser effects can lead to aggressive encounters, with no observable hierarchy.

Animals may intervene and stop fights, perhaps to prevent an individual from becoming to powerful. The simulation suggests that intervention is more common where there are 'winner effects', but not where there are 'loser effects'.
GN,BT