Is there a specific reason this feeling is evoked in men in relation to one another as opposed to in relation to women? Let's even drop sex from the equation - what if you have a man and a woman who have 0 sexual chemistry, or a homosexual man (or woman) who is friends with a woman (or man) - does the mere lack of a Y chromosome preclude this kind of buddy-buddying? Is there no room for personality? And perhaps most importantly, is this something biological, sociological, or something in between?

What of transexual/transgendered individuals? A great many people would agree that gender is not a binary but is, instead, a spectrum in which everyone's identity falls. What implications does this have? I'd be interested to know how this author might relate to a good buddy of a decade or two who comes out as identifying as a woman - would he be there for his mate? Or does she lose that 'mate' status for being a woman?

It's a nice feel-good piece for men looking for an explanation as to why they treat one another differently than women with some pop-psychology, but I don't think that having good female friends with whom you have that kind of bond is an edge case anymore. The existence of people who do not fit the clear gender binary also deeply complicates this issue of "men just be men, yo." I don't wholly disagree that there is a different kind of bond in the majority of situations. Where I disagree is to simply accept that it is a part of us on any fundamental level - I'd like to understand why we are how we are.