When a certain young male baboon attached himself to a new troop, as male baboons of a certain age are wont to do, he became highly aggressive as he fought to establish himself in the hierarchy of his chosen society. The result was a steep increase in the cortisol concentration in his blood as well as that of his unwilling hosts. His immune system bore the brunt of his behavior. Such a fall is a classic precursor of furring up of the coronary arteries. Not only was the baboon, by his free-willed behavior, altering his hormones, and hence the expression of his genes, he was thereby increasing the risk of both infection and coronary artery disease.
People are like monkeys.
The discovery that monkeys low in the hierarchy get heart disease came soon after the far more startling discovery that British civil servants working in Whitehall also get heart disease in proportion to their lowliness in the bureaucratic pecking order. The status of a person's job was more able to predict their likelihood of a heart attack than obesity, smoking, or high blood pressure. Somebody in a low-grade job, such as a janitor, was nearly four times as likely to have a heart attack as a permanent secretary at the top of the heap. Exactly the same result emerged from a similar study of a million employees of the Bell Telephone Company in the 1960s. Think about this conclusion for a moment.