What is it ? Where is it stored ? Where does it come from ? How is it passed on from parent to sibling ?
In: Biology
Instincts are complex innate behaviours, reflexes are simple innate behaviours. For instance, when a human baby is dipped underwater, it immediately holds its breath. That’s a reflex.
When a sea turtle hatches from its egg, it heads straight for the ocean. That’s far more complex than just holding your breath so we consider it instinctual behaviour.
The behaviour of complex living organisms is largely governed by brain chemistry and hormones in particular. When you find yourself in a surprising situation, it’s a hormonal response that causes you to feel afraid, aggressive, overjoyed or any other emotion. And your behaviour will result from that.
I’m sure you’ve heard of the fight or flight response in the face of something scary for instance. Something surprises the organism and the brain immediately gives a response that causes the organism to respond with aggression or fear.
So now that we understand that brain chemistry can determine how an organism behaves. We’re also closer to understanding how instinctual behaviour is “stored” or passed on from parent to sibling.
Take those hatching sea turtles for instance. Sea turtles immediately head for the ocean by heading towards the brightest patch of the horizon in their field of vision. If they keep doing that, they’ll find the quickest route to the water.
There are many possible reactions a baby turtle could take after hatching:
* It could lie still and rest after the exertion of hatching
* It could start looking for food to replenish its energy after hatching
* It could set off in a random direction
* It could follow the scent of water (and risk ending up in the wrong body of water rather than the ocean)
But lots of animals are hanging around for the express purpose of feasting on the hatching baby turtles.
So natural selection means that the lazy turtles, the lost turtles, the wandering turtles are the first to die. And the turtles whose brain chemistry urges them to get moving, to head towards the light on the horizon and to get into the water are the ones that survive the most.
The turtles who survive the most pass on their genes the most. Evolution simply means that for baby turtles, those whose brain chemistry urges them to rush for the ocean fastest are the best young survivors. And over time that means that every single turtle that hatches has the overwhelming desire to race to the water.
That’s instinct. And that’s how instinct is stored and passed on. They are chemical balances in the brain that produce behaviour that is so beneficial to survival that pretty much every member of a species has it. Because all others die.
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