Your question is a bit difficult to understand. Perhaps you mean to ask: Question: What do you call someone who studies the statistics related to human populations? Answer: A demographer. http://en.wikipedia.org/wiki/Demographics
You call someone that studies metal a metallurgist.
A physicist.
a person who studies planets is a planetologist.
There is no special name for someone who studies Hebrew.
florist
Microbiologists
An Anthropologist.
malacologist
A Zoologist
Brocollogist
A physicist.
Musician.