These just in from the Animal Psychology Department; first up, rats are surprisingly good at the classic Prisoner’s Dilemma [via BoingBoing]:

It may not be entirely surprising that rats cooperated in the Prisoner’s Dilemma.  After all, animals often cooperate in nature to altruistically serve the group, whether that means hunting in packs to get more meat, or a surrogate mother animal adopting an abandoned baby to boost the pack’s numbers.  Still, there’s no direct evidence that shows rats grasp the concept of direct reciprocity.  Given that the rats in this study changed their strategy based on the game their opponent was playing, and cooperation rates were only high when the rats played against a tit-for-tat opponent, the authors showed, perhaps for the first time, that rats directly reciprocate. But an even more surprising finding was how well the rats played the game.  They plotted and schemed.  They manipulated their opponents by taking calculated strategic risks for the high payout reward. In essence, these rodents challenged our perception of animal intelligence and proved that they, too, can master both the game, and the psychological component of competition.

Furthermore, apes have been discovered to have the capacity to doubt their own decisions [via George Dvorsky].

Josep Call […] put food in one of two opaque plastic pipes and had watching bonobos, chimpanzees, gorillas and orangutans pick the one with the food. If they were made to wait, the apes sometimes forgot where the food was, but by and large they did well on the task.

To test if the apes doubted their own decisions, Call gave them the option to peek into the end of the pipes before they chose one. He found that the apes were more likely to check the pipes if they had to wait before picking one. Call says this suggests that the apes had begun to doubt their memory.

That consensus definition of “human” is starting to look a lot less exclusive than it used to, no?