You can think of it this way:
- Presumably, some mammals would have been born that did not enjoy sex. Those would not procreate and their gene would die out.
- Other mammals would enjoy sex. They would procreate, and their genes would spread.
It's the sex and enjoyment thereof that is the driving force behind procreation. When you hear people saying "the ultimate drive is to spread one's genes," that's just a hand-wavy explanation used for simplification (which, unfortunately, many people have come to interpret too literally - as is often the case when simplification is involved).
It's the same type of simplification as when a nature documentary says "Nature found a way to do X". As if nature is some conscious entity with a will that is working towards achieving some goal.
Suppose we take two human children - a boy and a girl. We separate them from their parents at age 1 and we isolate them from society. A professional caretaker visits them a few times a day, giving them food and helping them with their necessities. They are taught to communicate in one manner or another, perhaps given access to some form of entertainment.
Now, I'm going to be brutal - for science: the hypothetical boy has been sterilized. He doesn't know it, of course.
At no point do the children learn how humans are born. Nothing in their surroundings is an indication, and the caretaker never tells them.
Also, they never learn that it is "normal" for regular people to have children of their own.
As far as the kids are concerned, no other humans except them and the caretaker exist.
Do you think that:
1) Those children will experience an innate need to have children of their own?
2) What activities will the children undertake to satisfy that need?
Thanks
- Additionally, consider that you could perhaps fool a duckling to imprint upon someone/something else as his/her mother. This one example is not useful if one were to attempt to disprove that this imprinting behaviour evolved to help the ducklings stay with their mother in a vulnerable period.
To me, this appears clear. However, I am not sure if I've articulated it in a way where you are able to also see where I am going with this.
Cheers