The Way We Eat Now -- Harvard Magazine June 2004-

[Guest guest]

Since we're on the subject and in case you haven't seen it, I

thought I'd mention an Excellent article on origins of Western diet

from Harvard Uniersity. For a somewhat mainstream magazine, I found

the article meaty and succinct. Lots of good stuff here...

http://www.harvard-magazine.com/on-line/050465.html

Here's a couple excerpts:

" Wrangham takes an extreme position: he postulates that cooking food

over fires began by about 1.6 million years ago, and was an

innovation so important that it allowed the evolution of Homo

erectus, the earliest hominid to resemble modern humans (see " Primal

Kitchens, " November-December 2000, page 13). " Cooking enabled these

animals—the very earliest erectus—to acquire their food more

efficiently and to get more of it, " he says. " A principal reason was

that it made food softer.

Softer food has many implications. Imagine what a nonhuman, raw-food-

eating primate like a chimpanzee consumes in one day. " It's a great

big pile of leaves, seeds, and roots, " Wrangham explains, gesturing

with his hands to suggest a mound the size of a small shrub. Humans,

with generally larger bodies, nonetheless fuel themselves with a far

smaller volume of food. " Compared with other primates, we are

evolved to eat foods of high caloric density—meats, roots, seeds, "

he says. Cooking makes this possible by changing the brittleness of

collagen fiber, softening it and making meat far easier to

chew. " People who think that meat dominated the diet of early Homo

may well be right, " he says, " but they would have to have spent five

hours a day just chewing. Raw meat is very hard to chew, and

presumably raw wild meat is even harder. "

Consider again the chimpanzees, who spend as much time eating as one

would expect for primates of their size and weight (100 to 120

pounds). " In primates, there's a nice relation between body weight

and the amount of time spent eating, " Wrangham explains. Chimps

spend about six hours a day chewing. Humans, who typically weigh

more than chimpanzees, should theoretically eat more and spend even

more time at it. Instead, data from 15 cross-cultural studies

indicate that on average, human beings spend about one hour a day

chewing food.

Chimps' jaws and teeth are bigger than ours, and they like to eat

meat—they will work hard to get it— " but they can't chew meat at all

fast, " Wrangham says. " The rate at which they chew and swallow meat

is equivalent to the way they eat fruits: 300 to 400 calories per

hour. " In contrast, humans eating cooked, softened food of high

caloric density can take in 2,000 calories during their daily hour

of chewing and swallowing. "

And then this excerpt appears a bit later...

" Since humans can take in large amounts of food in a short time, " we

are adapted to receiving much higher glycemic loads than other

primates, " says Wrangham, speculating that nonhuman primates

may be poor models for research on human diabetes because they have

a different insulin system. The only component of the hunter-

gatherer diet likely to cause extreme insulin spikes is honey, which

Wrangham feels " is likely to have been very important, at least

seasonally, for our ancestors. Chimpanzees love honey and modern

hunter-gatherers take in tremendous amounts of it. People have been

seen eating as much as four pounds at a sitting. "

We don't know how often such honey binges occurred in the distant

past; Ludwig opines that finding a beehive was " a very infrequent

event " for early humans. What is certain is that hunter-gatherers

never experienced anything like the routine daily glucose-insulin

cycles that characterize a modern diet loaded with refined sugars

and starches. Constantly buffeted by these insulin surges, over time

the body's cells develop insulin resistance, a decreased response to

insulin's signal to take in glucose. When the cells slam their doors

shut, high levels of glucose keep circulating in the bloodstream,

prompting the pancreas to secrete even more insulin. This syndrome

can turn into an endocrine disorder called hyperinsulinemia that

sets the stage for Type II, or adult-onset, diabetes, which has

become epidemic in recent years. "

~Robin