[eli5] If genetics passed down from generation carry the anatomy of the creature, how does genetics pass down behaviors/instincts?
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This is getting into one of those questions that nobody really 100% understands yet. Presumably, these things are somehow encoded into the brain’s structure, which of course is encoded by genes, but the specifics are, to my knowledge, poorly understood
Core behaviour, instincts and reflexes are to do with your nervous system. Like the rest of your body, this is coded by your genes. Your brain is different to a dolphin’s because your DNA makes it grow and develop differently.
Of course a behaviour is hard to distill into a gene. Say, finding vermin disgusting. This will help you survive and pass on your genes to your offspring. But rats, roaches, flies etc. all look different and there isn’t a gene that codes all of these animals into your brain for automatic recognition. But you could have a gene that means you find the smell of rotting food disgusting. This would mean that your smell receptors tell your brain to be disgusted when they detect the chemical compounds found in rotten food.
That means you avoid rotting food, and thus avoid vermin, and thus survive longer, and so are more likely to pass on your genes so that the human race will evolve to find rotten food repulsive.
If Sally in the next hut lacks this gene, and leaves rotten food out and attracts vermin and disease, she will likely die before she can have offspring. But your children will have the rotten-smell aversion gene, and so will their children etc. And thus over time the human population will only consist of descendants of people who have the rotten-smell aversion gene. That is evolution.
maybe you have more of an comparative advantage to use your long arms? Like picking tall fruit (would that be a behavior, or you effectively and efficiently using the tools in your tool box?)
It’s not that they learn the behaviors and pass them down through genes, it’s the genes that enable the learned behaviors.
The learned behaviors that lead to survival and reproduction therefore are more likely to be passed down.
Do that a couple thousand times and you got something that no longer seems like a learned behavior.
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