An interesting write-up over at The Economist on Richard Wrangham’s argument about the role of cooking in human evolution, which he reiterated at the 2009 AAAS Annual Meeting in Chicago. The orthodox view among the anthropology community seems to be that human brain size increased due to a shift in diet from vegetables to meat. Wrangham’s view is that it is the cooking of food rather than its origin which has influenced human brain size:
Cooking alters food in three important ways. It breaks starch molecules into more digestible fragments. It denatures protein molecules, so that their amino-acid chains unfold and digestive enzymes can attack them more easily. And heat physically softens food. That makes it easier to digest, so even though the stuff is no more calorific, the body uses fewer calories dealing with it.
On the face of it, it seems plausible. Cooked foods make more nutrients available, and would presumably require less chewing, reducing the size of the jaw and making more of the skull’s internal space available for the brain.
This is a more application-oriented twist:
Indeed, Dr Wrangham suspects the main cause of the modern epidemic of obesity is not overeating (which the evidence suggests—in America, at least—is a myth) but the rise of processed foods. These are softer, because that is what people prefer.
On a very unscientific level, I had suspected once that upma made with fine semolina was digested more quickly (and consequently felt less filling) than upma made with coarse cracked wheat. It is nice to learn that there is a scientific basis for that hypothesis.
Now: assuming that food habits are harder to change than foods themselves, would it be possible to make people gain less weight by making foods artificially rough? Could one make a taste-free coarse-particled edible powder (like a “magic food”) to sprinkle on (or mix with) soft creamy foods to make them digest more slowly? I’m not being facetious — if the food is grittier and rougher and takes longer to digest, the glycogen peak after a meal should be wider and shorter, and should presumably make a person less susceptible to diseases like Type II diabetes. One way to do this would be to eat naturally grittier and healthier foods (whole wheat flour instead of refined wheat flour for instance), but if one habitually eats foods that are too soft and easily digestible, could we add an antidigestive agent to the food to slow down the sugar rush?