Serão arenques?

...Now, suddenly, there is a new and powerful reason to be nice: to persuade people to play with you. The reward of cooperation, and the temptation of defection, are forbidden to those who do not demonstrate trustworthiness and build a reputation for it. Cooperators can seek out cooperators.

Of course, for such a system to work, individuals must learn to recognize each other, which is not an easy feat. I have no idea whether a herring in a shoal of 10,000 fish or an ant in a colony of 10,000 insects, ever says to intself: 'There´s old Fred again.' But I feel quite safe in assuming that it does not. On the other hand I feel equally secure in asserting that a vervet monkey probably knows by sound and sight every other member of its troop, because the primatologists Dorothy Cheney and Robert Seyfarth have proved as much. Therefore, a monkey has the necessary attributes for reciprocating cooperation, but a herring does not....

in The Origins of Virtue, Matt Ridley