Professor garcia is teaching her class about the harmful effects of stress, citing that it leads to early death. professor garcia likely subscribes to the:

I believe the answer is: hormonal stress theory.

hormonal stress theory believed that stress could affect the hormones that control our organs and determine its function. So, prolonged to stress could cause our body to not functioning properly and would accelerate our aging process.

It is meant that like tapestry scientific theories often need to pull out since they are not relevant and often times the whole chain of theories may be pulled out.