The answer to this question is the change in neurotransmitter serotonin. A low level of serotonin can lead to a low mood, depression, and even anxiety. Serotonin is a chemical found in our body that gives / transmits impulses that is regulated to makes a person happy and maintains a mood balance.
<span>Large changes in allele frequencies can occur in a short time - any changes in frequency, occurring as a result of random chance, would have a proportionally larger effect in a small population. </span>
