Evolution of Human Diet Article in Sci. Am.

[Guest guest]

In the December 2002 issue of Scientific American, there is an interesting

article about the evolution of the human diet: " Food for Thought--Dietary

change was a driving force in human evolution, " By R. Leonard. It

can be found at:

http://www.sciam.com/article.cfm?chanID=sa006 & articleID=0007B7DC-6738-

1DC9-AF71809EC588EEDF

It may be particularly interesting to those who have thought about and/or

follow the " Paleolithic diet. "

Some quotes from the article:

" We now know that humans have evolved not to subsist on a single,

Paleolithic diet but to be flexible eaters, an insight that has important

implications for the current debate over what people today should eat in order

to be healthy. "

" From a nutritional perspective, what is extraordinary about our large brain is

how much energy it consumes-- roughly 16 times as much as muscle tissue

per unit weight. Yet although humans have much bigger brains relative to

body weight than do other primates (three times larger than expected), the

total resting energy requirements of the human body are no greater than

those of any other mammal of the same size. We therefore use a much

greater share of our daily energy budget to feed our voracious brains. In fact,

at rest brain metabolism accounts for a whopping 20 to 25 percent of an adult

human's energy needs-- far more than the 8 to 10 percent observed in

nonhuman primates, and more still than the 3 to 5 percent allotted to the brain

by other mammals. "

" Just as pressures to improve dietary quality influenced early human

evolution, so, too, have these factors played a crucial role in the more recent

increases in population size. Innovations such as cooking, agriculture and

even aspects of modern food technology can all be considered tactics for

boosting the quality of the human diet. Cooking, for one, augmented the

energy available in wild plant foods. With the advent of agriculture, humans

began to manipulate marginal plant species to increase their productivity,

digestibility and nutritional content-- essentially making plants more like

animal foods. "

" Thus, it is not just changes in diet that have created many of our pervasive

health problems but the interaction of shifting diets and changing lifestyles.

Too often modern health problems are portrayed as the result of eating " bad "

foods that are departures from the natural human diet--an oversimplification

embodied by the current debate over the relative merits of a high-protein,

high-fat Atkins-type diet or a low-fat one that emphasizes complex

carbohydrates. This is a fundamentally flawed approach to assessing human

nutritional needs. Our species was not designed to subsist on a single,

optimal diet. What is remarkable about human beings is the extraordinary

variety of what we eat. We have been able to thrive in almost every ecosystem

on the earth, consuming diets ranging from almost all animal foods among

populations of the Arctic to primarily tubers and cereal grains among

populations in the high Andes. Indeed, the hallmarks of human evolution

have been the diversity of strategies that we have developed to create diets

that meet our distinctive metabolic requirements and the ever increasing

efficiency with which we extract energy and nutrients from the environment.

The challenge our modern societies now face is balancing the calories we

consume with the calories we burn. "