Corvidae wrote:Personal genetic survival, maybe. It backfires when the population is small: monogamy is the best way to prevent incest. Which, moral arguments aside, is biologically inadvisable. Causes all kinds of nasty recessive traits and mutations to show up.Well, speaking from a natural world, evolution stand point, the biggest relationship taboo seems to be monogamy. Very few animals engage in it, which makes sense in a reproduction stand point. Spreading and mixing your genes as much as possible is the best way to insure your genetic survival.
Actually, a great many avian species are monogamous. To be fair, a lot of them are serially monogamous, especially if they're migratory: they have one mate for one breeding season, then a different mate for the next breeding season. In tropical areas, where fewer species migrate, birds can't afford to be polygamous--because females become fertile through short periods spaced throughout the year (as opposed to migratory songbirds, who all become fertile at the same time), the only way a male can be sure of siring chicks is to remain with his mate.
Also, a fair number of mammals practice either monoamory or polygamy (polyandry is rarer, but not unheard of)--that is, harem-style sexual behavior. Far fewer species are truly polyamorous, where both males and females have multiple mates, not necessarily the same ones. In polyandrous or -gamous settings, the dominant female or male will usually prevent her or his subordinates from mating, to the point of forcefully rejecting rivals from a social group (herd, pack, what-have-you).
linkWhile over 90% of bird species appear to be monogamous, genetic studies show that in most populations at least a few offspring in each generation result from matings with partners other than a pair member. In some species extrapair copulations produce over half of the offspring.
linkMonogamy is so rare in the animal world that only 3-5 % of the mammals are known to form lifelong pair bonds, like beavers, otters, jackals, foxes, some bats and a few dwarf deer and antelopes.
Polygamy does not equal monogamy, it is polygamy. I'm not sure why you brought it up in an argument over how monogamous or not animals are.