Saturday, September 16, 2006

A Tall Story

by Edward Hugh


This article from AP caught my eye:

Most of us are taller than our parents, who probably are taller than their parents. But in the Netherlands, the generational progression has reached new heights. In the last 150 years, the Dutch have become the tallest people on Earth — and experts say they're still getting bigger. It is a tale of a nation's health and wealth. With their protein-rich diet and a national health service that pampers infants, the Dutch are standing taller than ever. The average Dutchman stands just over 6 feet, while women average nearly 5-foot-7.

The Dutch were not noted for their height until recently. It was only in the 1950s that they passed the Americans, who stood tallest for most of the last 200 years, said John Komlos, a leading expert on the subject who is professor of economic history at the University of Munich in Germany. He said the United States has now fallen behind Denmark.

Many Dutch are much taller than average. So many, in fact, that four years ago the government adjusted building codes to raise the standards for door frames and ceilings. Doors must now be 7-feet, 6 1/2-inches high.


Now this is very much Robert Fogel territory (and here). Fogel famously argued, it will be remembered, that population heights correlate with economic growth, and that the prime mover in all of this was improved nutrition. This is an issue which is also dear to my very own heart, and I have a draft paper which I am working on (ouch, PDF) which has a lot of 'synnergy' with the Fogel view.

Basically it now appears that the situation is more complex than Fogel initially imagined, since height is not only a measure of health (it can, for example, imply increased cancer risk in some cases) but on the other hand we now (thanks to molecular biology) understand better some of the nutritional pathways which are at work here. The pre-birth environment is, as David Barker has long been arguing, now known to be very important.

"Prosperity propelled the collective growth spurt that began in the mid-1800s and was only interrupted during the harsh years of the Nazi occupation in the 1940s — when average heights actually declined."

Indeed, and the Dutch famine winter (1943/44) is one of the classic cases of a changed nutritional environment producing lifelong changes in the health of those born at the time. Really there is a lot more to say about this, and as we move forward I will undoubtedly say some of it, but I thought it was worthwhile bringing this phenomenon to everyone's attention, to start the ball rolling as it were.

8 comments:

S.M. Stirling said...

A population's height is a product of nutrition _and_ of genetics.

Any population will grow taller with a high-protein, high-calorie diet, but some will grow taller than others on the same diet.

Edward said...

"A population's height is a product of nutrition _and_ of genetics"

The interesting thing Stirling is that these two may well be much more interconnected than any of us have previously imagined. Basically proteins are fuel, fuel produces amino acids, and the amino acids regulate the protein structure. Essentially it is the availability of the nine key amino acids (plus a small number of micro nutrients and vitamins for enzyme formation) which influences the proteonome. The genome is simply a coding structure which facilitates/or regulates the proteins.

This is why more than the genes themselves (at the end of the day they are simply strings of code) it is the expressed phenotypes which are the important thing, and this we can now see very clearly in the arrival of the metabolic syndrome.

All the evidence in calorie restriction and knock-outs on model organisms lead towards this conclusion, ie that we have a common set of shared (and very ancient in evolutionary terms) regulatory mechanisms.

I could go on at great length on all of this, but I won't spoil the fun. Plenty of posts are coming, this is what I've been banging my head against all summer.

Movement in menarche age is a very important indicator here.

dutchmarbel said...

But menarche is coming sooner these days - and also indicates the end of growth for girls (I think you grow for approximately two years after the onset of menarche). Wouldn't that make women smaller?

Shouldn't you include something like the Masai? Also very tall and also lots of dairy products?

Edward said...

"But menarche is coming sooner these days - and also indicates the end of growth for girls"

Oh yes, definitely, the thing is we don't know which is the optimum age or the optimum diet here. It is almost certainly a non-linear process. That is some more nutrition is definietly beneficial, especially protein and micro-nutrients. But after a point there is 'ex-cess' nutrition relative to our needs, and this becomes negative.

So some lowering of menarché ages is probably a sign of health, and some is beyond what we need. The menarché ages in southern Europe and among the poorer communities in the US (which come from too-rapid a nutritional change, following the Barket hypothesis, these people were 'set' in foetus for another environment).

"But menarche is coming sooner these days"

Yes, and obesity and diabetes are becoming more common. These things seem to be connected. There are a variety of 'pathway's which keep turning up in the literature, but the one which is almost invariably mentioned is the insulin-like IGF1 signalling pathway. IGF1 is a growth factor, and related to both insulin sensitivity and Growth Hormone, so I guess, even if you don't get the biology you can see there is some connection with your point.

Basically, the menarche comes very early, and the growth is excessive. This does not make these people 'smaller'. But they may not live as long since the whole process may be accelerated.

On another front it is important here to realise that we may have a trade off between ageing (senesence) and cellular replication (growth). If your system is set for too much of the former you get the illnesses of ageing (coronary disease, Altzheimer etc) and if the lever points too much towards cellular renewal, then you get cancers. (This is basically why they had to stop giving Growth Hormone to pre-menopausal women, the GH was slowing down cellular senesence, and hence good for things like osteo-porosis and Altzheimer, but it was achieving this by pumping up IGF1 and hence increasing cellular growth and replication and indirectly producing cancer.

As I say, over a series of posts I will address some of this in detail with links.

"Shouldn't you include something like the Masai?"

This would be just the point, in the foraging society they normal ate well (unlike in the agricultural one). It is very important to understand what hapens in the agricultural society, particularly with the arrival of carbohydrates on the one hand, and of a fertility trap (the Malthusian world) on the other. Again, this is for more posts.

You could try this link:

http://www.thepaleodiet.com/

Loren Cordain was one of the anthropologists who started this whole debate off. This one is to the point too:

http://www.paleodiet.com/

There is a lot here that we still don't know or understand.

S.M. Stirling said...

As far as height is concerned, even the Dutch are still not as tall on average as the Cro-Magnon hunter-gatherers, whose males averaged over 6ft.

The adoption of agriculture led to a sharp drop in average heights, which has only recently been made good.

S.M. Stirling said...

There are two "genetic" aspects to height.

First, nutritional stress in one generation can restrict the height of the next, irrespective of the offsprings' intake. (And vice versa).

Then there's the upper limit even given multigenerational optimum nutrition, which varies between populations much as say coloration or the cranial index does.

Edward Hugh said...

"There are two "genetic" aspects to height."

Yup, we are definitely in the same ballpark (one more time) here. I will be posting more on all this.

Anonymous said...

The Dutch are taller because the short ones drowned