As you're all aware (from monitoring my online activity yesterday and today), I'm searching through Dr. Ricardo Duchesne's tweets to find a specific meme (a depiction of a black male surrounded by numerous pregnant white females). If I find that meme I'm going to add it to this blog. I'm also sorting through my Yahoo account to determine which emails I can delete so that I can continue sending and receiving emails. As an aside, I'll leave this blog post up until tomorrow.
Ancestral Polynesians who were driven to explore the open ocean with their sophisticated navigation and large canoes (as we saw in chapter 2) may have created selection pressures on genes that better equipped their bodies to cope with periods of starvation or cold while at sea. Their journeys likely imposed selection for more efficient handling of the energy needs of the body via what are sometimes termed thrifty genes. Plus, living on islands - despite people's romantic fantasies - is extremely harsh because adverse weather (like hurricanes) can wipe out all of the available food for substantial periods, which imposes a set of constraints similar to long sea voyages. Adaptive though they were for the long journeys and isolated living centuries ago, these genetic changes are a prescription for diabetes and obesity today, now that the descendants of those Polynesians have built settlements on land and obtain sources of food that are more stable. (Blueprint: The Evolutionary Origins of a Good Society)
It is hypothetically possible that for example the Samoan population has not has such strong recent selection of these traits, and therefore would be more susceptible to obesity following introduction of modern high-calorie foods.
I'LL EXCERPT THE MOST PERTINENT PARAGRAPHS FROM THE BELOW ARTICLES THEN ADD THOSE PARAGRAPHS AND ARTICLES TO THE ABOVE LINK! I'LL DO THIS LATER THIS WEEK! IN THE MEANTIME, READ ABOUT THE THIRFTY GENE HYPOTHESIS AND HOW IT INFLUENCES POLYNESIAN PHYSIOLOGY (e.g. FAT STORAGE) IN TODAY'S FOOD ABUNDANT ENVIRONMENT.
"Island Raiders" ABC Four Corners 2004
In New Zealand, Ian Prior, a young cardiologist who would later become the nation's most renowned epidemiologist studied a population of five hundred Maoris living in an isolated valley of the North Island thirty-five miles from the nearest town. Despite a physically active life - certainly by the standards of modern-day Europe or the United States - the Maoris, as Prior reported in 1964, had a remarkably high incidence of diabetes, heart disease, obesity, and gout. Sixty percent of the middle-aged women were overweight; over a third were obese. Sixteen percent had heart disease, and 11 percent had diabetes. The staples of the Māori diet, Prior reported, were bread, flour, biscuits, breakfast cereals, sugar (over seventy pounds per person a year), and potatoes. There was also "beer, ice-cream, soft drinks, and sweets." Tea was the common beverage, "taken with large amounts of sugar by the majority."
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After the United States exploration expedition under Captain Charles Wilkes visited the Polynesian atolls of Tokelau in January 1841, the expedition's scientists reported finding no evidence of cultivation on the atolls and confessed their surprise that the islanders could thrive on a diet composed primarily of coconuts and fish. Tokelau came under the administration of New Zealand in the mid-1920s, but the atolls remained isolated, visited only by occasional trading ships from Samoa, three hundred miles to the north. As a result, Tokelau lingered on the fringes of Western influence. The staples of the diet remained coconuts, fish, and a starchy melon known as breadfruit (introduced in the late nineteenth century) well into the 1970s. More than 70 percent of the calories in the Tokelau diet came from coconut; more than 50 percent came from fat, and 90 percent of that was saturated.
By the mid-1960s, the population of Tokelau had grown to almost two thousand and the New Zealand government, concerned about the threat of overpopulation, initiated a voluntary migration program during which more than half the Tokelauans moved to the mainland. From 1968 to 1982, a team of New Zealand anthropologists, physicians, and epidemiologists led by Ian Prior took the opportunity to study the health and diet of the emigrants as they resettled, as well as those who remained behind on the islands as their diets were progressively Westernized. This Tokelau Island Migration Study (TMS) was a remarkably complete survey of the health and diet of all men, women, and children of Tokelauan ancestry. It was also quite likely the most comprehensive migration study ever carried out in the history of nutrition-and-chronic-disease research.
On Tokelau, the primary changes during the course of the study came in the mid-1970s, with the establishment of a cash economy and trading posts on the atolls. The year-round availability of imported foods led to a decrease in coconut consumption to roughly half of all calories. This was offset by a sevenfold increase in sugar consumption* and a nearly sixfold increase in flour consumed - from twelve pounds per person annually to seventy pounds. The islanders also began eating canned meats and frozen foods, which they stored in freezers donated by the United Nations; by 1980, six pounds of mutton per capita, three pounds of chicken backs, and five pounds of tinned corned beef had been consumed. (In comparison, 270 pounds of fish were caught per islander in 1981.) By then, the trading ships were also delivering annually some eighteen pounds per person of crackers, biscuits, and Twisties, a cheese-flavored corn snack. Smoking increased dramatically, as did alcohol consumption.
Through the 1960s, the only noteworthy health problems on the island had been skin diseases, asthma, and infectious diseases such as chicken pox, measles, and leprosy. (Modern medical services and a trained physician had been available in Tokelau since 1917.) In the decades that followed, diabetes, hypertension, heart disease, gout, and cancer appeared. This coincided with a decrease in cholesterol levels, consistent with the decrease in saturated-fat consumption. Average weights increased by twenty to thirty pounds in men and women. A similar, albeit smaller, trend was seen in Tokelauan Children. The only conspicuous departure from these trends was in 1979, when the chartered passenger-and-cargo ship Cenpac Rounder ran aground and the islanders went five months without a food or fuel delivery. "There was no sugar, flour, tobacco, and starch foods," reported the New Zealand Herald, and the atoll hospitals reported a shortage of business during the enforced isolation. It was reported that the Tokelauans had been very healthy during that time and had returned to the pre-European diet of coconut and fish. Many people lost weight and felt very much better including some of the diabetics.
As for the migrants to New Zealand, the move brought "immediate and extensive changes" in diet: bread and potatoes replaced breadfruit, meat replaced fish, and coconuts virtually vanished from the diet. Fat and saturated-fat consumption dropped, to be replaced once again by carbohydrates, "the difference being due to the big increase in sucrose consumption." This coincided with an almost immediate increase in weight and blood pressure, and a decrease in cholesterol levels - all more pronounced than the increases witnessed on Tokelau. Hypertension was twice as common among the migrants as among the Tokelauans who remained on the islands. The migrants also had an "exceptionally high incidence" of "diabetes, gout, and osteoarthritis, as well as hypertension." Electrocardiographic evidence suggested that the "migrants were at higher risk for coronary heart disease than were non-migrants."
A number of factors combined to make this higher disease incidence among the migrants difficult to explain. For one thing, the Tokelauans who emigrated smoked fewer cigarettes than those who remained on the atolls, so tobacco was unlikely to explain this pattern of disease. The migrants tended to be younger, too, which should have led to the appearance of less chronic disease on the mainland. And though the weights of the Tokelauan migrants were "substantially higher" than those of the atoll-dwellers and, "in fact, obesity became a problem for some," the migrant lifestyle was definitively the more rigorous of the two. The men worked in the forest service and casting shops of the railway; the women worked in electrical- assembly plants or clothing factories, or they cleaned the offices during the evening hours, and they walked "some distance to and from the shops with their purchases." Finally, the original Tokelauan diet had been remarkably high in fat and saturated fat, but the migrants consumed considerably less of both. If Key's hypothesis was correct, the migrants should have manifested less evidence of heart disease, not more.
In fact, the migrant experience had led to an increased incidence over the entire spectrum of chronic diseases. Prior and his colleagues acknowledged that their data made this difficult to explain in any simple manner. They suggested "that a different set of relevant variables might account for observed differences in incidence." Excess weight, whatever the cause, could explain at least part of the increased incidence of hypertension, diabetes, coronary heart disease, and gout among the migrants. They appeared to get more salt in their diets than the islanders did, so that might also explain the increased incidence of hypertension, as might the stress of assimilating to a new culture. The red meat consumed on the mainland might have contributed to the increased incidence of gout as well. The greater incidence of asthma could be explained by the presence of allergens in New Zealand that were absent in Tokelau.
*According To Records From The Local Trading Ships, This Increase Was Nearly Tenfold Between 1961 And 1980: From Seven Pounds Per Person Per Year To Sixty-Nine Pounds.
Good Calories, Bad Calories: Challenging The Conventional Wisdom On Diet, Weight Control, And Disease. Taubes, p. 108-109, 136-139.
