While I almost (edit: actually less, as I glanced over the whole homo=pedo thing, wtf) wholly agree, there is one issue that always bothered me without any good explanation for years - homosexual acts and tendencies amongst animals.

While I believe that humans and animals have more similarities and commonalities than differences, I never could find any satisfactory answer "why", with answer being at least partially correct for both cases

Until I rested my case on homosexual tendencies/deviancy in general being natures fail-safe to stop spread of other, possibly harmful, genes and characteristics. Won't pass it on if individual don't want to procreate

Don't know if that's the case, but it works as explanation for me and that's enough as far as I'm concerned - I'm not working in academics...