These two examples of sexually integrated combat forces--one in the Air Force, one in the Navy--demonstrate how the wisdom of sexual integration depends on the details. In the infantry, it sometimes happens that one soldier is asked to risk his life for the life of a comrade--hence the vital importance of solidarity. But Navy ships are another matter. The entire crew is literally in the same boat, so there is never a time when your comrade faces a menace you don't face, forcing you to decide whether to thwart it at some risk to yourself. Hate your comrade though you may, neglecting his welfare is not a live option. Rather, it is always in everyone's self-interest to perform his or her duties with maximal commitment. Of course, it's still possible that the presence of a few women on a ship erodes overall readiness in some oblique way. But I haven't heard of any evidence to this effect. (There is evidence that when you mix men and women on an aircraft carrier, some of them may get pregnant. But that's another issue, and you don't need a lot of Darwinian theorizing to ponder it.)

Squadrons of pilots lie somewhere between infantry platoons and ships in this analysis. A squadron is in some ways like an infantry platoon: There may be times when an airman is asked to risk his life for the sake of a comrade in another plane. But I doubt this happens much these days, now that technology puts would-be attackers at such a distance from the aircraft that it's hard to say which particular aircraft is menaced by a particular enemy plane. Still, to the extent that air warfare does provide opportunities to risk your life on behalf of a comrade, sexual integration becomes more dubious.