If combat means living in a ditch, females have biological problems staying in a ditch for thirty days because they get infections and they don't have upper body strength. I mean, some do, but they're relatively rare. On the other hand, men are basically little piglets, you drop them in the ditch, they roll around in it, doesn't matter, you know. These things are very real. On the other hand, if combat means being on an Aegis-class cruiser managing the computer controls for twelve ships and their rockets, a female may be again dramatically better than a male who gets very, very frustrated sitting in a chair all the time because males are biologically driven to go out and hunt giraffes.