That's different. It's within the group, it's a social thing. Not consciously practiced for the protection of the bloodlines. Not to make sure they have good healthy offspring
How is it different? Because it's "within the group" it's now a social thing and not an instinctual thing to protect the life-givers of the group? How is that social instead of instinctually ensuring the group has viable offspring?
The instinct for any group to procreate and continue gives much weight to the protection of its females and its infants, regardless of whether the group is cognizant that intercourse = offspring.
If you start at the beginning of this thread and read through, you'll see we were puzzling over whether or not Neandertals interbred with Cro-Magnons. And if not, why not.
In that context, I was saying that a concern over bloodline purity could not have been a factor, around 30,000 years ago.
I was not talking about the physical protection of individual females from general dangers of everyday life.
I've been posting to this thread since nine this morning so I'm too tired to go over it all.