Maybe the women gathered near the cave entrance after the men cleared the surroundings of bears and wildcats with spears and arrows.

And maybe the women gathered with a couple of men nearby with spears, on the lookout for intruders or enemy tribesmen.

As soon as there is a division of labour based on male identity versus female identity, whether it is with bears or with birds, different selection pressures automatically impact each group.

You are free to imagine that the selection pressures were exactly identical in type and magnitude among both groups. I find that idea to be laughably unlikely.