Well funded NINE YEAR LONG study — Summary of Relevant Findings and Recommendations – Army Gender-Integrated Basic Training (GIBT) – 1993-2002:
Marine study of gender integrated units:
All-male squads and teams outperformed those that included women on 69 percent of the 134 ground combat tasks evaluated.
All-male teams were outperformed by mixed-gender teams on two tasks: accuracy in firing the 50-caliber machine gun in traditional rifleman units and the same skill in provisional units. Researchers did not know why gender-mixed teams did better on these skills, but said the advantage did not persist when the teams continued on to movement-under-load exercises.
All-male squads in every infantry job were faster than mixed-gender squads in each tactical movement evaluated. The differences between the teams were most pronounced in crew-served weapons teams. Those teams had to carry weapons and ammunition in addition to their individual combat loads.
Male-only rifleman squads were more accurate than gender-integrated counterparts on each individual weapons system, including the M4 carbine, the M27 infantry automatic rifle and the M203 grenade launcher.
Male Marines with no formal infantry training outperformed infantry-trained women on each weapons system, at levels ranging from 11 to 16 percentage points.