They are called physiologists.
A scientist that studies muscles is called a myologist. They specialize in researching the structure, function, and diseases related to muscles in the human body.
An archaeologist studies the remains of human life, including artifacts and structures left behind by past societies.
An individual who studies eyes is called an ophthalmologist.
A virologist is someone who studies viruses, including their structure, classification, evolution, and interaction with host cells. They also study how viruses cause disease and how to prevent and treat viral infections.
florist
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'd call them a sociologist if they study society and group behavior or a psychologist when it involves just one subject.
A scientist that studies muscles is called a myologist. They specialize in researching the structure, function, and diseases related to muscles in the human body.
You call someone that studies metal a metallurgist.
A physicist.
a person who studies planets is a planetologist.
florist
Microbiologists
An Anthropologist.
malacologist
A Zoologist
Brocollogist