Aristotle and Cool Old Age

Science does not have to look to ancient Greece for ideas. Even so, some of the assumptions that we have about aging are ancient. Ask anyone what they think about getting older and you will notice that we have not progressed very much recently—the central theme that emerges about aging involves attrition and running out of juice.

The idea of attrition started with Aristotle (384-322 BC) and was later adopted by the Romans, Muslim and Western European medical establishments.  It became the basis for our early understanding of how the human body works.  Essentially, Aristotle held that the human body was filled with four humors: black bile, yellow bile, phlegm, and blood. Any imbalance in these four humors resulted in diseases and disabilities. Aging is caused by the drying out and cooling of these humors. This idea had a wide following, and involved numerous hot baths and saunas in order to maintian our wetness and innate heat. 

Surprisingly, older adults do have slightly lower temperatures. The 98.6° F benchmark for body temperature comes from Carl Wunderlich—a 19th-century German physician.  In 2005,  Irving Gomolin from Winthrop University Hospital in New York, found that older people have lower temperatures than this average. In a study of 150 older people with an average age of 80-plus, they found the average temperature to be 97.7°. What is fascinating is that the older you are, the lower your body temperature.

This finding does not by itself dispute Aristotle’s. Since older people are more likely to die, then a decline in temperature would seem to indicate that their “innate heat” is ebbing.  But recent 2006 research, led by Italian researcher Bruno Conti at the Scripps Research Institute, has shown that a decline in body temperature is beneficial. The study found that mice who had lower core body temperatures lived 12% (male) to 20% (female) longer than mice with higher core body temperatures. The difference in temperatures between "cold" and "normal" mice was 0.5-0.9 F (0.3-0.5 C), which is the same difference between the average person and older adults.

The science behind this anomaly is just now becoming clear to us. One of the known ways to increase longevity is to restrict our calories. Caloric restriction increases life- and healthspan in all sorts of animals.  Several studies have reported that animals on reduced calorie diets also had a lowering of core body temperature.

It could be that lowering of the body core temperature is one way of slowing the aging process. Thus the reason older adults may have lower body temperature is not because they are dying, but because it is nature’s strategy for keeping them alive longer. In the Baltimore Longitudinal Study of Aging, men with a core body temperature below the average (median) lived significantly longer than men with body temperature above the average. Being cool is, well, cool.