Read Online Catching Fire: How Cooking Made Us Human by Richard Wrangham - Free Book Online Page A

digested, which puts extra and unnecessary labor upon those over-worked organs.” This kind of argument persuaded generations of bodybuilders. The first muscleman with wide popular appeal was Steve Reeves, Hollywood’s movie Hercules of the 1950s, who famously ate raw eggs every day for breakfast. Celebrated strongmen like Charles Atlas and Arnold Schwarzenegger touted their merits too—as Mr. Universe, Schwarzenegger swallowed his eggs mixed with thick cream. Raw egg-eating by muscular athletes has even entered popular culture. In 1976 Sylvester Stallone’s boxing hero Rocky Balboa swallowed them as part of his training regimen in the movie Rocky . Thirty years later, in Rocky Balboa , he was still downing raw eggs. The quantity eaten by these legendary figures could be daunting: “Iron Guru” Vince Gironda, a popular teacher of bodybuilders, recommended up to thirty-six raw eggs a day.

    Raw eggs would seem to provide an excellent food supply not only because their protein needs no chewing but also because their chemical composition is ideal. The amino acids of chicken eggs come in about forty proteins in almost exactly the proportions humans require. The match gives eggs a higher biological value—a measure of the rate at which the protein in food supports growth—than the protein of any other known food, even milk, meat, or soybeans. Raw eggs have other natural advantages. Their shells make them safer from bacterial contamination than cuts of meat. When aborigines on the beaches of Australia’s tropical north coast are thirsty, they look for turtle nests and readily drink raw egg whites. Eggs are the only unprocessed animal food that can safely be stored at room temperature for several weeks.

    But even though eggs appear to be both high-quality and relatively safe when eaten raw, hunter-gatherers prefer to cook them. Unlike Australians, the Yahgan hunter-gatherers of Tierra del Fuego “would never eat half-cooked, much less raw eggs.” The Yahgan bored holes in eggshells to prevent them from bursting, buried the eggs on the edge of the fire, and turned them until they were quite hard inside. When not drinking eggs to slake their thirst, Australian aborigines would take similar pains, throwing emu eggs in the air to scramble them while still intact. They would then put them into hot sand or ashes and turn them regularly to cook them evenly, taking about twenty minutes. Such care suggests that the hunter-gatherers knew better than the musclemen.

     
     
     
    In the late 1990s a Belgian team of gastroenterologists tested the effects of cooking for the first time, using a new research tool that allowed the investigators to follow the fate of egg proteins after they had been swallowed. The researchers fed hens a diet rich in stable isotopes of carbon, nitrogen, and hydrogen. The labeled atoms found their way into the eggs, allowing the experimenters to monitor the fate of protein molecules when the eggs were eaten. To determine how much of an egg meal was digested and absorbed in the body, they adopted the same method that had been used for studies of starch digestibility: they collected the food remains from the end of people’s small intestine, the ileum. Any protein that was undigested by the time it reached the ileum was metabolically useless to the person who ate it, because in the large intestine bacteria and protozoa digest the food proteins entirely for their own benefit.

    At first the experimenters worked only with ileostomy patients, but later they were able to check their results with healthy subjects as well. The ileostomy patients and healthy volunteers each ate about four raw or cooked eggs, containing a total of 25 grams (0.9 ounces) of protein. Results were similar for the two groups. When the eggs were cooked, the proportion of protein digested averaged 91 percent to 94 percent. This high figure was much as expected given that egg protein is known to be an excellent food. However, in the