This chapter was primarily dedicated to briefly explaining the endocrine system, factors that cause stress and the result from too much stress. This text piqued my interest because I’m in a prime environment to feel the effects of stress being a pre-med college student, which I fear is already taking a toll on my body. I have had high blood pressure due to stress before, and had to do a complete 180 on my lifestyle to help lower it. With all the seemingly negative effects of stress in humans, made me raise the question whether or not there is some evolutionary advantage to stress. There was a passage which explained how that when a zebra is chased by a lion, its “fight or flight” response is engaged and it begins to produce hormones, but once the zebra is safe, its parasympathetic nervous system kicks in and calms down the body. I don’t think we have this luxury as humans. The zebras have the ability to turn the stress-response off almost immediately, while humans tend to dwell on experiences which keep us stressed out and producing hormones. If heart disease is one of the major causes of death, and stress causes heart disease, is the stress-response system really evolutionarily advantageous to humans?