A science mystery

Why Is Animal Size So Constant?

by Roger Bourke White Jr., copyright March 2018


This is a new science mystery that has come to mind: Why are plants and animals so consistent in their size?

Think about plants and animals growing in forests. Think about the wild animals you see in zoos. All these plants and animals are very consistent in both shape and size.

Why is this?

In particular why is size so consistent?

Form, fit, function

Shape being consistent makes a lot of sense because the organism is composed of a lot of parts that have to work together. As an example if teeth are too big they won't fit in the mouth. If they are too small they can't clamp down on what the animal is trying to eat. So having a consistent shape makes good sense because of what the various parts of an organism are trying to accomplish.

But size... why is size so consistent as well? As an example of an organism that isn't consistent in size, look at domesticated dogs. They vary enormously in size. This indicates that size variation is possible. But few species living in wild conditions, or farming conditions, engage in such variation. Why not?

It appears that when an organism is living in wilderness or farming living conditions size is just as constrained as shape is.

Fascinating. And why this is so remains a mystery to me.



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