In general, human beings tend to be quite generous. As such, it is not a big step to question whether the same is true for our close evolutionary cousins, the chimpanzees (Pan troglodytes). A new study indicates that it might.

When it comes to chimp sharing behavior, there has long been a discrepancy between studies in the field, and those in laboratory settings. In the field, chimpanzees have been known to share food, console each other and lend support during a fight. In lab experiments, however, chimps don’t really share, and are viewed as ‘reluctant altruists’, sharing only when prompted by solicitation and other forms of pressure.

Anisogamy (see figure 1), or sexual reproduction in which two different gametes fuse to produce a new individual, leads to an inequality between female and male organisms. After all, females produce a limited supply of costly egg cells, while males produce a virtually endless supply of cheap sperm cells (this is the case in the vast majority of animals, and is known as oogamy (see figure 1), in which a large, non-motile egg cell is fertilized by a small, motile sperm cell (see figure 2)) . So, females best carefully choose the male they mate with, while males best copulate as much as possible, with as many females as possible. Females are choosy, males are promiscuous. Of course, there are exceptions, but still, this holds true in many cases.