I believe the answer is...a change in allele frequency over many generations!
Hope this helps!
Answer:
Autonomic nervous system
Explanation:
Autonomic nervous system controls body functions that do not require thought.
Typical types of neurotransmitters include small molecule neurotransmitter substances (acetylcholine, serotonin, dopamine, histamine, norepinephrine, and epinephrine), amino acids (GABA, glutamate), neuroactive peptides (insulin, glucagon) and soluble gases like nitric oxide and carbon monoxide
