Now that there seems to be a little lull in the discussion, I thought I'd address this post.. I hope you won't mind this temporary digression.
This is by no means true. Let me tell you about a little fellow called the bonobo ape. ;)
http://primategallery.files.wordpres.../bonobo_eg.jpg
From
Wikipedia - "Sexual intercourse plays a major role in bonobo society, being used as what some scientists perceive as a greeting, a means of forming social bonds, a means of conflict resolution, and postconflict reconciliation. Bonobos are the only nonhuman animal to have been observed engaging in all of the following sexual activities: face-to-face genital sex, tongue kissing, and oral sex."
Might it not be more to do with the fact that all animals are hunted - not least by humans - except humans?