Because as humans grow bigger, so does there brain. So the smaller you are, the smaller your brain.
Hope this helped!
-Edge
The difference between a dominant trait and a recessive trait is that the dominant trait must have one copy of each from two different parent
Example: Brown Hair=H
Light hair=h
Hh is dominant because this is of a copy of each from two parents
A recessive trait must have two same copies coming from the same two parents
Example: HH
The ribosomes cause the outer surface of the rough endoplasmic reticulum to appear rough.