pargentum

With such high stakes, it is likely that eavesdroppers have shaped the evolution of animal communication. Some behaviours seem adapted to avoid prying ears. In many songbirds, says Mennill, the longest, most evenly matched song duels are the quietest. Where both males are struggling to dominate, he suggests, "they might not want to broadcast what's going on".

The effect of an audience on animals' social interactions is harder to study than eavesdropping, and this work is at an early stage. Again working with fighting fish, McGregor's team has found that males display to each other differently when a female is watching9. They reduce their aggression, and switch to conspicuous displays incorporating some of the elements used in courting, such as tail waving. And in July, Michael Kidd of the University of New Hampshire in Durham told the Animal Behavior Society's annual meeting at Indiana University in Bloomington that defeated male fighting fish prefer to court females that didn't witness their humiliation. "They have a fairly strong preference for females that didn't see them lose," says Kidd.

Eavesdropping is thought to help animals to avoid fights they cannot win. But paradoxically, eavesdroppers might make contests more aggressive, according to evolutionary biologist Rufus Johnstone of the University of Cambridge, UK. He used game theory to analyse the costs and benefits of winning and losing fights, and of backing down quickly versus a prolonged tussle. Eavesdroppers, he found, increase the value of victory: an animal that wins its current contest will get the deterrent benefit of a tough-guy reputation, and so is more likely to escalate a fight10. "Eavesdropping can evolve to reduce the risk of fighting, but once it becomes established it promotes aggression," says Johnstone.

Replace acts of violence with ones of charity, and Johnstone's model becomes similar to those used to explain apparently selfless kindness. We often help people we are unlikely to meet again. One reason might be that good deeds get their perpetrator a glowing reputation that helps them in the future. Theoretical models suggest that altruism can survive in populations where individuals trust those they have seen cooperate with others, but give nothing to those they have seen behave selfishly.

Вообще, интересная статья, подтверждающая мысль, которую я некоторое время назад думал, но не помню, публиковал ли я ее в связном виде.

Смысл в том, что "неограниченный self-interest", вообще говоря, не приводит к войне каждого против всех по одной простой причине: воевать очень дорого и очень рискованно. Поэтому виды, которые находили те или иные способы разумным образом (не в смысле что эти виды были разумны, а в смысле, что им удавалось найти ограничение, который разумный наблюдатель счел бы таковым, то есть которое и не сильно ущемляло бы собственно interest, и предотвращало бы эскалацию как можно большего числа конфликтов до полномасштабной войны) ограничить свой self-interest, получали неслабое преимущество в межвидовой борьбе. Во всяком случае, ни одно позвоночное развитее ланцетника войны каждого против всех не ведет (а про социальную жизнь ланцетников просто не в курсе, они может быть и ведут) - не утверждая, впрочем, что жизнь большинства позвоночных легка и приятна и что они никогда не конфликтуют.