"The new theory is that it's 700,000 years ago and you just emigrated from Africa, it's a Saturday night and there's nothing on cable. So you go out and suddenly see this hot chick that looks exotic. She gives you the eye, you give her the eye, next thing you know you got three kids and the in laws living in your cave.
Nature being nature the second one sounds the most plausible. It still goes on today."
Yes, the new theory sounds a LOT more probable.
Really we know this from medieval history, if we think about it.
Are the Irish "Celts", the English "Anglo-Saxons", the French "Latins", and the Normans "Vikings"? You'd think so if you read the history books and took the replacement of one people or language by another completely seriously.
But if you think about it only a little bit harder, you realize it was Viking MEN getting on longboats and going here and there. Olaf may have stormed ashore at Caen, but Helga didn't come with him. Olaf's kid was with Madeline, and was neither wholly Viking nor wholly French.
And the Anglo-Saxons? Yep, they came ashore and conquered England. Does that mean that every red-headed Celtic lass in England perished under the sword? Ummmm...gee...do male warriors EVER behave like that? No. It means that the English are as Celtic as they are Germanic.
Etc.
Because a conquering warrior might kill as many menfolk as he can git his hands on, but what's the POINT of conquest if you don't get to keep the women? And it's the women wot makes the the babies...who then end up being not Vikings or Saxons, but half Irish and half Saxon. Etc.
Really, we ought to be able to look at Northwestern Europe and the Caribbean within historical memory and know that human invaders don't wipe out the natives when they conquer them, because wiping them out means killing the women, and 20-year old warriors have better things to do with women than killing them. Obviously.
Even more dramatic is the Norse(ish) conquest of China(ish), the descendants of whom looked wholly Asian when they came back west.
A precept apparently held since early Biblical times:
Numbers 31:13-18
13 Moses, Eleazar the priest and all the leaders of the community went to meet them outside the camp.
14 Moses was angry with the officers of the army—the commanders of thousands and commanders of hundreds—who returned from the battle.
15 "Have you allowed all the women to live?" he asked them.
16 "They were the ones who followed Balaam's advice and were the means of turning the Israelites away from the LORD in what happened at Peor, so that a plague struck the LORD's people.
17 Now kill all the boys. And kill every woman who has slept with a man,
18 but save for yourselves every girl who has never slept with a man.