Chital deer are from India, where their natural predator is the tiger. When attacked, the animal has the choice to either stay and fight or run. Naturally the deer choose to run. But transport the Chital deer into a captive situation like a fenced-in farmyard, and because they can't flee from what they see as a danger, they stand still in a group in a corner of the yard. They appear calm, yet if the threat remains for 15 minutes, one or two of the deer in the group will simply lie down and die.
Autopsy shows diffuse internal bleeding.
Blood tests show that their muscles have released enormous amounts of enzymes normally used to facilitate running away. After 20 years of studying baboons in the wild, Robert Sapolsky, a Stanford neuroscientist, has found that in a stable social circumstance, those lowest on the social hierarchy totem pole, whether in getting food or sex, had the highest levels of stress hormones and the highest rates of stress-related disease such as hypertension. In a separate monkey study, the situation was reversed. Animals were fed diets that predisposed them to atherosclerosis. Under these circumstances, the most dominant males had the highest incidence of coronary artery disease.