What do you think this "sort out" means? "distinguish themselves"?
st100)One fascinating thing about Ardent Amazons is that as more and more women take up careers that require physical force, women's average strength is likely to increase.Since the late 1960s, men have improved their record marathon times by three minutes- but women have improved theirs by thirty-one minutes...But more women are taking physical training and are becoming stronger. For some time, men have been able to sort themselves out on the basis of physical strength...
In this context, I think it means that men have been able to rank themselves in order of physical strength; to demonstrate who is the strongest, who is the next strongest, and so on, down to the weakest.
In other contexts, to "sort oneself out" means to become better organised, or to stop doing something bad and start doing good.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....