For a really good assessment of this situation, written by a female Marine, check this link: Jude Eden, USMC on women in combat and training.
In particular, about halfway down is her seminal piece: Women in Combat: The Question of Standards, by Jude Eden
Here, from that article, is the passage that says it all:
"...Meanwhile, the argument to maintain the combat exclusion makes itself easily in every aspect. Including women in combat units is bad for combat, bad for women, bad for men, bad for children, and bad for the country.
The argument for the combat exclusion is provable all the time, every time.
Political correctness has no chance against Nature. Her victories are staring us in the face at all times.
The men just keep being able to lift more and to run faster, harder, and longer with more weight on their backs while suffering fewer injuries. They just keep never getting pregnant.
The combat units have needs that women cannot meet. Women have needs that life in a combat unit cannot accommodate without accepting significant disadvantage and much greater expense. Where 99 percent of men can do the heavy-lifting tasks typical of gunners, but 85 percent of women cannot, there is no gap women need to fill..."
done - thanks !