Yes I agree. They are not very " advanced" but this is where we come from. Every one of us. So we still have these behaviors today.Yeah and such tribes still exist. Living in mud huts.
If you ever grew up in a very small town it's the same as a tribal unit. By the time you are in your 30s every one has basically smashed everyone. Or at the very least the women have been ejaculated into by multiple men within this town. Some of the more sexually adventurous women have had gang bangs etc.
All this book is saying is that this is natural. We don't see this dynamic so much today because of online dating. Women can fukk outside of their tribe now.
The reason men rage against this idea is because it bursts their bubble of female sexual purity. No, women are little *****s within a protected tribe. Period.