Comments on life, the universe and everything from an aging Sixties survivor.

Location: Massachusetts, United States

Ummm, isn't "about me" part of the point of the blog?

Thursday, April 12, 2007

Beware of the Simple Answer

Mass Marrier /Harrumpher drops in here sometimes, about as often as I write these days, so he may be able to provide a link to comments of his that started this train of thought.

He was on about the average height in the Netherlands having exceeded that in the United States. It couldn’t be any reflection of racial diversity, he said. It must be because the Dutch were doing a better job raising and feeding both children and adults. I think that’s a fair executive summary?

For me, this sparked a rewind to the mid-1970s, when I worked at a Freedom Trail historic site with a brand-new MA in American Studies. Like “everybody” in public history, I believed that “everybody was short back then.”

One day, I was at lunch with a co-worker, who happened to be a graduate student in biological sciences at one of our august institutions. I mentioned the general belief in casual conversation; he cocked an eyebrow and asked what the arguments were in favour of the belief. I recited them, and he said that biologically, the belief made no sense.

That rather sparked my interest and a fair amount of research. Damned if he wasn’t right.

For Americans, the matter of stature is a deeply embedded cultural myth: a myth in the literal sense of a story that reflects a peoples’ sense of identity. The myth began with the offhand discovery that the “average height” of World War Two draftees was an inch taller than that of World War One. It was reinforced with some highly biased anthropological studies arguing for a deterministic connection between individual height and nutrition. The fact and the anthropology fit in neatly with an American desire to see this as a progressive culture, one in which everything is always better. One could argue that this was painfully important to adults who had been the children of the Great Depression. The draftee evidence also lent itself wonderfully to one of the great pitfalls of humanities research: the sine wave fallacy. For instance, using the draftee evidence as an example, if there was a one inch difference between these two generations, then it is allowable to posit a one inch increase in stature going back indefinitely. That is the sine wave fallacy. The absurdity of the logic is easily demonstrated: it would make Charlemagne one inch tall.

Alas, the biology is far more complex. The height of Homo Sapiens, barring a few widely scattered populations, falls on a bell curve ranging between 4 feet 9 inches and 6 feet 9 inches, and has done so as far back as we have evidence of Homo Sapiens. While there are medians that fall out along this curve in given populations, there is no "average height:" that is just a mathematical construct. Everything on that curve is normal. All other things being equal, the female median will be lower than the male median in a given population. Nutrition is just one of a host of factors influencing the median. One of those appears to be that changes in stature distribution can be entirely, and maddeningly, random.

Alas too for MM’s argument, genetics do play a powerful role in stature distribution. Let’s take the argument that Southeast Asians are shorter because they are malnourished. That is true is some, but not all, cases. For one thing, there is a good deal of food in Southeast Asia when people are not busy killing one another over politics. There is a hypothesis advanced that individuals from cultures using rice as a staple tend to be shorter than those in cultures using wheat as a staple. This has some merit. However, if you move a child from a rice culture to a wheat culture at an early age, she or he doesn't usually become an adult at or above median height for the new culture. Likewise, there is good evidence that individuals malnourished as children can, if they escape other diseases of malnutrition, make up some or all of their growth deficiency in young adulthood.

Other interesting arguments have been advanced that age at menarche is a better indicator of health in a population than stature. American ages at menarche have plummeted during the last two generations. What do we get if we factor that against the shift in stature between Dutch and Americans? Deadlock.

In the case we were studying, that of Colonial America, the nutritional determinist argument was blasted by hard evidence that even the very poorest inhabitants were eating a more complete and balanced diet than 20th century Americans. I know that the nutritional determinists have made a comeback in recent years. However, their branch of the tree of knowledge really doesn’t stand much strain.

It is important to look very carefully at nearly any such argument made either from "common knowledge" or from single causation. As in this case, you need to know all the empirical variables and account for them in your conclusions. You must also weigh the cultural baggage that you are bringing to the party, often unconsciously, before you draw a conclusion.

Damn, that was fun! I haven’t played with this toy for years!


Blogger Mass Marrier said...

Well, you can follow the links in my related post. Everything works there, except that the Financial Times link requires the $98 extra a year for access. Yet this is plenty of both research and analysis to back up the points.

What I find most fascinating is the conclusion in the Dutch research that they can easily see which factors took them from Europe's shortest to the industrialized West's tallest since WWII.

The genetic theory would have had them remaining pretty short. Instead what they found is that when nearly everyone got good nutrition and medical care from prenatal up, there was no longer the distinction between the tall, healthy rich and the short, puny or chubby middle-class and poor. It is the necessary physical resources that the wealthy hog here to the detriment of the poor that we can measure.

Now the Dutch also claim to be happier and more fulfilled. We do know that they live much longer on average.

Such fairness as providing equal care to pregnant moms and preschoolers may be Dutch. It may be UU. Yet, I can't see America rushing to try to prove this one way or another.

6:07 pm  
Blogger Uncle said...

As I said, 30 years on from my period of research, the nutritional determinists have regained the upper hand on this contentious bit of scholarship. It appears that the Dutch, much as we do, have many reasons to believe this is true. Therefore it is true, therefore all evidence that supports it is right and presented, and that which does not goes in the trash can. That way of thinking influences academics just as much as the person on the street...if not more.

You may have to stay tuned a while to see whether the other side chimes in. You may also have to watch the issue for much longer than either of us have left to see if the gains stick. Sixty years is bupkis in genetic time.

Likewise, plummeting age at menarche in the U.S., of itself, may not prove anything except the increased presence of HGH in milk.

None of this is to say that the Dutch haven't improved the lot of their poorer citizens: only that leaning so heavily on stature as a measurement is suspect in some eyes.

10:25 am  

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