As I understand it a lot of MBs early research was done with the spines and pelvice from cadavers (male) so that they could get the setting of the initial bang correct without killing the pilot. The seat limits were then set for the average (male) pilot.
When female FJ crew came along the earlier research had been forgotton until a 2 stick Harrier crashed with a girl (UAS Cadet) in the back. The doctors treating her were surprised by the lack of back injuries (she had two broken legs but they were from the landing). Looking for a reason it was realised that as women are 'designed' to bear children the lower spine and pelvice are different from the male and as such could take a greater g loading.
No doubt chauvanists will just use this as proof that women are designed to be kicked up the backside
