Altruism in primates

Bonobos find it easier to share than chimps do, although young chimps do just as well as bonobos of all ages. It was speculated to be because bonobos don't have to worry about having more or less food like chimps do.

At the same time, chimps will adopt orphaned kiddos, according to a new study that found 18 cases of orphaned chimps being adopted in the wild.

Speaking of more and less, researchers based at the Institute of Neurobiology at the University of Tubingen in Germany set out to see whether rhesus monkeys could learn and flexibly apply the greater-than and less-than rule. They tested the monkeys with groups of both ordered and random dots, many of which were novel combinations to ensure that the subjects couldn't have simply memorized them. The monkeys were cued into applying either the greater-than or less-than rule by the amount of time that elapsed between being shown the first and second group of dots.

"The monkeys immediately generalized the greater than and less than rules to numerositiesthat had not been presented previously," the two researchers, Sylvia Bongard and Andreas Nieder, wrote. "This indicates that they understood this basic mathematical principle irrespective of the absolute numerical value of the sample displays." In other words: "They had learned an abstract mathematical principle."