Indeed. Painted exactly the picture I had in my head - hey look at that I can rhyme!
Rhyme? Where? If you mean "indeed" and "head," those are two different vowels. "Indeed" rhymes with "seed" and "feed." "Head" rhymes with "said" and "fed."
But stuff like fear - of heights and predators is instinctive, which is what I wonder about - how are instincts and behaviours genetically determined?
We're wandering off into material more appropriate for the Biology or Psychology subforums... But instincts are programmed into our brain cells by evolution. Any animal that doesn't have the instinct to flee from a large animal with both eyes in front of its face--without stopping to think about it--won't live long enough to reach sexual maturity and reproduce. A newborn giraffe will clumsily scamper away from a hyena, but will calmly stand and graze next to a much larger rhinoceros.
The same is true of any animal that will nonchalantly walk off a cliff.
All animal behavior is complicated, but for vertebrates, insects, molluscs and other phyla of animals with a centralized brain, it has taken hundreds of millions of years for the programming to evolve to its current level of complexity. Each new neuron configuration was the result of natural selection--or in the case of recently domesticated animals like dogs, very
unnatural selection. (We have bred dogs to be much more gregarious than wolves, to prefer scavenging to hunting, to have smaller brains which can survive on the lower-protein diet of a scavenger, and to accept a human as the alpha in the pack.)
Configurations which induce behavior that enhances survivability were passed down to the next generation; those which induce behavior that makes survival difficult or impossible were an evolutionary dead-end.
The psychology of our own species is much more complex because our forebrain is about ten times as large as that of our closest relative, the chimpanzee, and vastly larger than those of other animals. There's just so much more room for thinking in our brains.
We can identify many instincts in our own species that are not clearly related to survival. These are not all behaviors, just ideas and beliefs that occur in nearly all societies in nearly all eras. Legends, rituals, visual images in our art, Carl Jung calls these
archetypes. Perhaps they were once survival traits in an era whose dangers we can't imagine. Or they could be random mutations passed down through a genetic bottleneck.