Abstract
Cholesterol is an essential lipid molecule for plasma membranes of animal cells so that they can perform signal transduction functions and consequently an indispensable compound for life of multicellular organisms. A system to maintain strict homeostasis of cholesterol has therefore evolved. Our genetic machinery is designed to allow rigorous monitoring of its shortage and to prepare for self-supplementation. However, cholesterol requires a large amount of energy and labor for its synthesis, and many animals procure it by external supply to save the energy. Furthermore, the backbone structure of cholesterol is not readily degradable, so that we excrete it from the body only with modifications to facilitate break down by microorganisms in the environment. With this background, under normal circumstances oversupply of cholesterol would be beyond the scope of our physiology at the current stage of evolution. We may therefore consider ectopic cholesterol accumulation and atherosclerosis as a consequence of under-preparation of human crisis management at the psychosocial level.
