Thursday, March 07, 2013

VeggieDag Thursday: Why do we cook our food?

It's been twenty-two years and counting since I last consumed an animal. On 17 February 1991, I declared meat independence. No trumpet fanfares. Just did it. The words "vegetarian" and "vegan" are so fraught with connotations and clarifications, that I avoid them, and say, "I don't eat animals." Even that simple declaration seems to sow confusion. "So, do you eat fish?" To which, I want to sarcastically reply that the fish plants are growing well next to the tomato vines. But, I don't.

I am not a raw-foodist, however. I might juice; I might eat raw vegetables; but the majority of my calories comes from cooked food, as it does for most other humans. In my mind, this begs an elemental question: Why do humans cook food. And when did they start doing so, and are cooked foods less nutritious than raw foods?

Researchers at the Federal University of Rio de Janeiro have conducted research into the rapid evolutionary growth of the human brain. They have concluded that this evolutionary burst required a drastically higher higher caloric load than, say, that needed for the vegetarian gorilla's brain. They cite meat-eating and cooking (of meat AND vegetables) as having been essential to human development: meat because it was calorically more dense than vegetables and fruits.

And why cooking? Here's Dr. Richard Wrangham, of Harvard University, speaking to the American Association for the Advancement of Science, in 2009, as paraphrased in The Economist:

Wrangham believes that cooking and humanity arose simultaneously. He thinks that cooking and other forms of preparing food are humanity's “killer app”: the evolutionary change that underpins all of the other—and subsequent—changes that have made people such unusual animals.

Humans became human, as it were, with the emergence 1.8m years ago of a species called Homo erectus. This had a skeleton much like modern man's—a big, brain-filled skull and a narrow pelvis and rib cage, which imply a small abdomen and thus a small gut. Hitherto, the explanation for this shift from the smaller skulls and wider pelvises of man's apelike ancestors has been a shift from a vegetable-based diet to a meat-based one. Meat has more calories than plant matter, the theory went. A smaller gut could therefore support a larger brain.

Dr Wrangham disagrees. When you do the sums, he argues, raw meat [even though it has more calories than plant matter] is still insufficient to bridge the gap. He points out that even modern “raw foodists”, members of a town-dwelling, back-to-nature social movement, struggle to maintain their weight—and they have access to animals and plants that have been bred for the table. Pre-agricultural man confined to raw food would have starved.

Start cooking, however, and things change radically. 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.

In support of his thesis, Dr Wrangham, who is an anthropologist, has ransacked other fields and come up with an impressive array of material. Cooking increases the share of food digested in the stomach and small intestine, where it can be absorbed, from 50% to 95%.

As to cooking's deleterious effect upon food nutrients, here's a passage from Nutrition For Dummies:
There’s no denying that some nutrients are lost when foods are cooked. Simple strategies such as steaming food rather than boiling, or broiling rather than frying, can significantly reduce the loss of nutrients when you’re cooking food.

Virtually all minerals are unaffected by heat. Cooked or raw, food has the same amount of calcium, phosphorus, magnesium, iron, zinc, iodine, selenium, copper, manganese, chromium, and sodium. The single exception to this rule is potassium, which — although not affected by heat or air — escapes from foods into the cooking liquid.

With the exception of vitamin K and the B vitamin niacin, which are very stable in food, many vitamins are sensitive and are easily destroyed when exposed to heat, air, water, or fats (cooking oils).

[But] Some foods are less nutritious raw because they contain substances that destroy or disarm other nutrients. For example, raw dried beans contain enzyme inhibitors that interfere with the work of enzymes that enable your body to digest protein. Heating disarms the enzyme inhibitor. Some, foods (such as meat, poultry, and eggs) are positively dangerous when consumed raw (or undercooked).

When did humans 'discover' cooking? Again, from Wrangman:
The archaeological evidence for ancient cookery is equivocal. Digs show that both modern humans and Neanderthals controlled fire in a way that almost certainly means they could cook, and did so at least 200,000 years ago. Since the last common ancestor of the two species lived more than 400,000 years ago fire-control is probably at least as old as that, for they lived in different parts of the world, and so could not have copied each other.

So, maybe evolution isn’t a reason to 'go' vegetarian. But, there are significant environmental, economic, ethical, moral, and health reasons to go there. "With supermarkets and refrigeration, humans today can and increasingly do eat a vegetarian or vegan diet year-round. And given the amount of heart-stopping saturated fats in factory-produced animal products, a plant-based diet can be more healthful" (along with highly processed foods).

Finding calories is not difficult in the modern era. With good fortune  YFGF will be going for at least another 22 years of meat-free eating. As I said in a 2008 post celebrating this anniversary: "Now, beer: ahh! That IS a wonderful vegetarian foodstuff!"

  • I hope this post is not interpreted as an anti-raw-food screed. Far from it. From Dr. Douglas Graham, here's here's strategy for modern raw food eaters to avoid caloric deficiency.
  • Joe Yonan, the editor of the Food Section of the Washington Post, a major U.S. newspaper, has "come out" as a vegetarian: that is, he eats no animal flesh, but does eat dairy and eggs.

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