For example, inbreeding is something all animals take great pains to avoid. Inbreeding is taboo among most human cultures, including our own Western one. We know that both lethal mutations and the likelihood of a disease wiping out an entire population increase with the level of relatedness. Where we have social codes and laws, non-human animals have evolved social systems in which males leave their natal groups to mate and raise families elsewhere, away from sisters and daughters. This practice has been found in a diversity of animals, from lions to birds.
Lions are also a model for another human social no-no, homicide.
Adult male lions are known to commit infanticide after they take over a pride by killing the dominant male. The theory says this relieves the lion of having to defend and share resources with an unrelated cub. Infanticide has the added benefit of causing the mothers of the dead cubs to resume reproductive status. Human sociobiologists Daly and Wilson say this same logic explains the fact that step-parents commit twelve to fifteen percent more child abuse than do biological parents. The choosing of mates, sociobiologists might argue, is modeled by the bower bird.