(This is Part 9 of a continuing series. Go back to Part 8.)
Have you ever wondered why animals in the wild are never fat? Out in nature, we never see an obese giraffe or cheetah. Why is that? Conversely, modern industrial societies are getting more and more obese. Why is that?
All animals, including us, have remarkeable systems for maintaining ideal weight. If the body of an 150-pound chimpanzee miscalculated caloric input vs caloric activity by even 1%, over the lifetime of that chimp it would gain or lose 100 pounds. Yet this never happens.
Our human bodies are by no means less sophisticated than that of other animals. Why then do our weight-regulation systems seem to be out of whack? The answer to that little question is a fascinating tale.
It turns out that our human weight-regulation system is functioning normally—just as in other animals—but it's being deceived.
Deceived by what? By the very nature of "foods" in our modern developed societies, and particularly in the U.S. where the obesity epidemic is most pronounced.
One of nature's cardinal principles is the conservation of energy. Scientists have established that all animals seek to be as efficient as possible in their pursuit of pleasure and avoidance of pain.
This being so, if an animal can achieve the same goal with less energy it will do so. As an example, this is why predators seek to predate first upon the young or injured —less energy is required to kill the prey.
In the area of food, this has an interesting consequence: It means that, within its natural diet, an animal will always seek to maximize the caloric density of its foods. If two foods are in its natural diet, are both equally available, an animal will prefer the one with the higher caloric-density. It's more efficient; it conserves energy.
Thus, when we lived in the trees for millions of years and were natural fruitarians—proved by electron microscopes and striations in fossilized teeth—we preferred fresh fruit (300 calories/pound) to tree leaves (100 calories/pound).
As another example, when the Agricultural Revolution occurred about 11,000 years ago we came to rely upon grains (500 calories/pound) as the mainstay of our diets.
But what about meat and dairy—don't they have an even higher caloric density? Indeed they do, but for most of human existence they were very difficult to come by. As a general rule, meat and dairy were available on a regular basis only to royalty.
But then, about 200 years ago, the Industrial Revolution changed this. As societies became more prosperous the consumer class gradually came into being and for the first time ordinary people could afford to have meat and dairy on a regular basis.
(This is the end of Part 9. Go to Part 10.)
—jim sloman, 9.24.04 for Jun 6
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