For an alternate view on why giraffes' necks are so long, click this:
After clicking on the link directly above these words, you should see a letter written by Dr. Sarah Blaffer Hrdy; in the second paragraph of that letter, you'll find:
"... In 1974, I (Sarah Blaffer Hrdy) was the first to propose that female primates may mate with multiple males so as to confuse information available to males about paternity and thereby enhance the survival of subsequent offspring, since former consorts might be more disposed to help, or at least not to harm, possibly related offspring...".
Perhaps realizing she was focusing on a time in our development when our ancestors DID NOT KNOW THAT SEX LED TO REPRODUCTION, Professor Blaffer Hrdy, a few years later, in the endnotes of her seminal work, "The Woman That Never Evolved," took it a step further, and wrote about Australian Aborigines and brothel workers who employ the evolutionarily-favorable selection strategies that are described in "DERP: The Origin of our Timing Disparity."
Blaffer Hrdy is a former student of Harvard's Edward O.Wilson, the man who coined the term "sociobiology." She is Professor Emeritus of Anthropology at Cal Davis, and is still involved with the Animal Behavior Graduate Group thereat.
The below is one of many links where one might buy her book; if somebody out there finds a link to a free pdf, please let me know.
A technical note: the word that my computer swallowed at the 6:24 mark is "...nature...". What I'm currently doing, in case you haven't noticed, to make up for my computer's short-comings, is exaggerating my hand signals. Normally or usually an "air quote" needs to be flashed for about a second for that message to be delivered; I found that too many of these signals disappeared completely! So that's why my "air quotes" seem to drag on and on and on and on. No, I wasn't inspired by the "air quotes" character that the late Chris Farley perfected. I'll get a new computer when some kind soul notices the perspicacity and mails me one, or the remunerative means to find one at Best Buy.