How do they know how to have sex? Plothole?

Nia was a writer and Silas was an illustrator. In one of their meetings, he mentioned his research about people and anxiety. It is possible that in doing research of the past, sex is mentioned. It could also just be natural instinct, just like in Blue Lagoon.

Instinct. Duh...

How did the cavemen knew how to have sex? How do animals know to have sex? It's an instinct. No one needs to teach you.

Nothing was said in the movie, about people not knowing about sex. Why wouldn't they know the facts of life. It would not be something they were curious about, because they had no emotions. They could know about it, but with out emotions, feelings or any real interpersonal interaction... it would never happen.

Instinct. How? Erogenous zones.
Kissing is natural because the tongue is the most sensitive organ, where we learn the most from. What to eat? How to survive? The tongue determines what we can safely eat. Fingers and hands are pretty sensitive, but the tongue adds the sense of taste in addition. Natural then that when we are exploring another person, we would put the tongues together and that will of course feel incredible.
Check. Now the kissing puts us face to face, which is the right position for sex, at least missionary. Ears and necks being super sensitive when explored by the tongue puts us even closer together. We hold each other closer, and that shared warmth feels great, but skin to skin feels even better, wayyyyy better. so that leads to taking the clothes off.
Check. Now we're rubbing

Because sex is a biological urge. An organic feeling. It's embedded in the core of our DNA.

Sex as a breeding mechanism is instinctual. Take a human being and raise it in a complete isolation with no other human, they will, when reaching puberty, begin to masturbate all on their own.




However, the sex that is instinctual is indeed different than what people do today. For example, if you go and look at some exotic lost people who are hidden from the modern world, you'll find that their sexual act are not the same as the ones you see in those you see with modern people.



Kissing for example, as someone mentioned above, was actually not used as often in the past. A big reason why kissing is a lot more common today than it was in the past is because in the days where Holywood was heavily censored, kissing was one of the few things that could escape censorship. So you saw it a lot more in movies and as a result, people did it a lot more in real life.

Chickens, spiders and chipmunks all manage to figure it out. No reason to imagine that humans couldn't.