The Breeding Farm ran out of studs to seed their fertile women. So they sent their three female scientists back in time to caveman times to return with two high testosterone cavemen.
They would soon find that the cavemen didn't want to go with them, they wanted the women to stay.
"Could Sarah, Ellen, and Martha ever return to their era after having sex with cavemen alpha males? These men wouldn't stop until their girls were fat and pregnant with warrior babies growing inside them."
CONTENT WARNING: Breeding Farm, Pt. 8: Prehistoric is a hardcore erotica story meant for adult readers only.