Kind of a (very) late reply, but better late than never. Lots of things you posted are wrong.
1) Human beings are, in fact, pretty damn bisexual, your silly comments about the erastes-eromenos relationship aside (also, that has been recorded to have been enjoyed by many eromenos!). Many, many historical have had prolific expressions of male-male homosexuality, which is generally expressed as either mentor-student relationship or a relationship between two masculine warriors. There are major mythological examples of these: Gilgamesh and Enkidu, Achilles a...
The source he cites is A World on the Wane, or Tristes Tropiques in the original French.
It can be found here:
http://www.archive.org/details/tristestropiques000177mbp
The quote from the book itself (p. 307): "The Nambikwara have, however, another way of resolving the problem, and that is by homosexual relations or, as they call them, tamindige kihandige: 'the loving lie'. These relations, common among the younger men, are carried on with a publicity uncommon in the case of more normal relations. The partners do not go off into the bush, as they would wi... (read more)