When we look at sexually reproducing species around the world, we see that lifelong monogamy is not a mating strategy that is commonly employed. Rather, the one-night stand is the norm, with mom left to raise the kiddies from that union. Pair-bonding for the purposes of raising offspring is the standard approach among songbirds and penguins, but the observed rate of extra-pair copulation is also quite high. Among the two species most closely related to humans – chimpanzees and bonobos – hippie-style free-love is the norm, with males and females mating for both reproductive and recreational purposes.