What are the melechanisms that cause his breathing rate to increase

I am not completely sure what the context of the question is, but here are some things that could make your breathing rate increase:

Anything including moving like running, jumping, exercise, etc.

An anxiety attack, panic attack, or any situation in which you intake more oxygen. Such as when you have high levels of stress or are in danger.

These things cause your heart rate to increase as well causing your body to pump blood to the muscles faster.

Have a nice day.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."