If I remember correctly from researching this topic a few years ago, humans and dolphin are the only two species of animals on earth that have sex for recreation. I wasn't sure what that meant since ALL animals reproduce from a strong instinctual desire and/or for pleasure (isn't that considered recreational?). Also, the human penis' design was theorized to have been shaped with the bulbous head to ream out and through the excesses of other males' "deposits" to have a better chance at fathering an offspring. As far as the contrast with the primates, I find it interesting that the larger of the primates have the smaller schlongs. Anyway, my $0.02.
GERMPARROT (Former Miss America) 13:25:43 11/11/2007 (14)
GERMPARROT (Former Miss America) 23:37:32 11/11/2007
GERMPARROT (Former Miss America) 16:53:44 11/11/2007