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Thrifty gene is bankrupt science? Or, why you should always be suspicious when you hear …


As Globe & Mail medical reporter Carolyn Abraham tells it (February 25, 2011):

Since James Van Gundia Neel proposed it almost 50 years ago, the thrifty-gene hypothesis has reigned as the dominant explanation for soaring rates of obesity and diabetes among many aboriginal groups. Native communities where diabetes didn’t exist in the first half of the 20th century had, by the end of it, the world’s highest prevalence, with Arizona’s Pima Indians in first place, followed by the Nauru islanders of Micronesia and the Oji-Cree at Sandy Lake.Dr. Neel, an influential geneticist at the University of Michigan, felt that genes were partly to blame. He speculated that genetic traits among the world’s prehistoric hunter-gatherers enabled them to store calories during times of feast in order to survive in times of famine.

But with “the blessings of civilization,” he wrote, these thrifty genes had become hazardous baggage in a sedentary world of all feast and no famine, predisposing carriers to obesity and the diseases it brings.

His idea spread like an epidemic, embraced by everyone from public-health officials and policy-makers to the media and many aboriginal people themselves. Although never billed as more than a hypothesis, it came to be seen as fact – “a scientific axiom,” Dr. Hegele says, “dogma almost.”

But now, with obesity and diabetes shaping up to be a global pandemic, the theory appears to be dying – raising the prospect that prejudice more than proof gave it such a long life.

Why you should always be suspicious when you hear … what? Here’s what: When you hear any medical thesis whatever that is based on what “prehistoric hunter-gatherers” supposedly did.

You need to monitor three simple devices to track the growth of diabetes:

Cupboard/cold storage: For research subjects, observe and rate contents, against published food guides.

Weigh scales: Weigh research subjects at regular intervals; record results against body mass index measures.

Couch/TV combo: Clock use by subjects.

In some households, the research team itself is at risk for diabetes just from making observations. And this is indeed a worldwide, multicultural problem.

As one commenter pointed out, it isn’t fair to assume that the spread of the thrifty gene idea was prejudice. Chances are, it was motivated in large part by a wish to blame something other than lifestyle, lest one seem to criticize.

No fear, anyone can increase their personal risk of diabetes by following a diabetes-prone lifestyle. Lifestyle diseases are equal opportunity predators.

By the way, if the “thrifty gene” is one of the triumphs of “evolutionary medicine” (EM), I am glad if EM is not in the health care budget.

One wise doctor says, diabetes happens when people outgrow their pancreases. There, you heard it, and it is not evolutionary medicine.

Note: Thanks to commenter SCheesman for putting me on to this. Read the Globe, do ya, Cheesman?

Every day, Denyse. Here are the parts of the article I found most interesting:
Dr. Hegele, now director of cardiovascular research at UWO's Robarts Research Institute, says he once had “an unquestioning acceptance” of Dr. Neel's theory, and liked the way it invoked Charles Darwin and the pressures of evolution and adaptation.
... and a sidebar (which I couldn't find in the on-line version) had the following:
"The Seafaring Ape": The thrify-gene hypothesis caught on as well as it did, says University of Aberdeen zoologist John Speakman, in part because "adaptive story-telling was very popular in the 1960s and 1970s. "Everything you saw, ... every trait, must have had some adaptive advantage. In some cases, this led to faulty assumptions about the past." As an example, Prof. Speakman cites the "aquatic-ape hypothesis," which gained popularity in the 1960s, suggesting that the ancestors of modern humans, unlike our monkey cousins, once lived in water. That would explain why, among other things, we are hairless, carry subcutaneous fat as insulation and have both a descended larynx and hood noses that prevent water from seeping in. But, he adds, "there is no fossil record of our ever being aquatic."
My letter to editor (which I sent today) notes that adaptive story telling is very much alive and well today.SCheesman
February 28, 2011
07:26 PM

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