Imagine you're a cave woman living in a tribe of about 80 people. Food can be scarce - you can forage during the warmer months but are basically reliant on the protein available from large animals hunted - this is a process that takes days of tracking and hunting, so you maybe get that big animal to share once every couple of weeks, and you're programmed to eat as much as possible to keep you going over the leaner foraging days.
You're occasionally attacked by another tribe which lives about 20 miles away, and you're definitely constantly at risk of wolf attack.
Rape doesn't exist as a concept, and neither does paternity (yet) so you're pregnant a lot. Not always, because you don't menstruate during leaner periods, and lots of miscarriages, still births, or postpartum homicide when the tribe can't afford another mouth. BUT you are pregnant a lot, and there are lots of little kids about, which are important to the future of the tribe, and you're the one with the milk, so really you're confined to the cave a lot with the kids and the other women, except when you go out foraging, which you do daily, but the distance you can travel is fairly small because of the children.
So who has the speed, aggression and freedom to take days away to hunt and track, and who has the aggression to fight off marauders and wild animals? The dudes, that's who. So they're important, and they get the animal protein that keeps the tribe alive, so the tribe puts them on a pedastal.
At some point in the paleo era, someone finally makes the mental connection between I put MY willy in this woman, so that there is MY son. I prefer him to all the other children and I want to pass on MY basic tools and necklaces to him. So...that means I also have to control this lady. OK then.
Bam! Patriarchy.
And it felt so good, that men just wouldn't let it go.