Human growth

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How War Gets “Under the Skin”

Unbending rigor is the mate of death,
And wielding softness the company of life
Unbending soldiers get no victories;
The stiffest tree is readiest for the axe.
(Tao Te Ching: 76)

 

Early in life, our bodies are like unmolded clay, ready to be shaped by our experiences. For some of us, that matching process can create problems. If circumstances change, we could end up poorly adapted to our adult environment. A child born into harsh conditions, though, may have to take that risk in order to make it to adulthood at all.

The Hmong in French Guiana may be an example of this process. They are a fascinating population for many reasons, the most obvious being that they are there at all. A few dozen refugees from Laos first resettled in French Guiana in 1977, a few years after the Vietnam War, after they and the French government agreed that life in small, ethnically homogenous villages in a tropical environment was a better option than acculturating to the cities of Métropole France. The experiment paid off. Today, more than two thousand Hmong are farmers in the Amazonian jungle, producing most of the fruits and vegetables in the country. The result is a level of economic autonomy and cultural retention that is likely unique in the Southeast Asian refugee diaspora.

scenes in fg

Scenes from Hmong villages in French Guiana. (Clockwise from top left: fields of Cacao, young men going on a hunting trip in Javouhey, swidden agriculture of Cacao, a street lined with farmers’ trucks in Javouhey.

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Growth of Recently Arrived Refugee Children in the U.S.

A recent paper in the journal PLoS One examined growth patterns of 982 refugee children (age 0-10 yrs) from 35 countries who were resettled in the state of Washington (Dawson-Hahn et al 2016). Using height and weight measured at the time of their overseas health examination, the authors calculated rates of stunting (low height-for-age), wasting (low weight-for-height), and overweight/obesity as markers of a child’s nutritional status. These statistics were also compared to low-income children in Washington.

To me, the most important part of the results was that rates of substandard growth were quite high among refugees. Overall, refugee children aged 0-5 years old were more likely to be wasted and stunted, and less likely to be obese in comparison to low-income children in Washington.

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Figure 1 from Dawson-Hahn et al

 

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Did the Atomic Bombs in Hiroshima and Nagasaki Affect Child Growth?

In 1967, James Wood and colleagues published a study on the growth of Japanese adolescents whose pregnant mothers were exposed to the atomic bombs in Hiroshima and Nagasaki years earlier. Of course, many people were killed by the bombs, although estimates vary somewhere between one and two hundred thousand in all. By one estimate, the mortality rate of people within one kilometer of the bomb’s hypocenter in Hiroshima was 86%. This rate dropped to 27% for people who were between 1 and 2.5 km, and to 2% for those between 2.5 and 5km. Comparable numbers were reported for Nagasaki: 88%, 34%, and 11% respectively. This study was about some of the survivors.

Hiroshima blast and fire damage, U.S. Strategic Bombing Survey map. From wikicommons.

Hiroshima blast and fire damage, U.S. Strategic Bombing Survey map. From wikicommons.

In all, the Wood et al. study included 1,259 seventeen-year-olds, who had annual medical examinations since 1950. They were then compared for height, weight, and head circumference by their mother’s distance from the bombs’ hypocenters. They concluded that:

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The Biology of Forced Displacement

“Seeking asylum is not illegal under international law and people have a right to be treated humanely and with dignity.”  – UNHCR

“We crossed the Mekong to get to Thailand at night, so no one would see us. We had always lived in the mountains (of northern Laos), so we did not know how to swim. When we came to the river, we used anything to help us float – bamboo, bicycle tubes. But at night, it is easy to get lost. Someone in our group said: ‘Remember, if you get lost when you’re going down the river (with the current), don’t panic. Thailand is on your right.’ ”

 

 

Every refugee has a story. The one above was told to me by a Hmong man I met in French Guiana in 2001. I went to learn about the experiences of the people there and how they had adjusted to being resettled half a world away, from Southeast Asia to a French ‘overseas department’ in Amazonia. They were actually doing quite well at the time, living as independent farmers who had been given land by the government years earlier.

Hmong men in French Guiana going hunting by bike.

Hmong men in French Guiana going hunting by bike.

They also retained a good degree of cultural continuity. While most are fluent in French, the majority of the 2,000+ Hmong in the country lived in rural, semi-isolated, ethnically homogenous villages. This gave them a buffer of sorts, allowing them to acculturate on their own terms. As they often put it, they were “free to be their own boss,” free to be Hmong, and most said they were happy with life in French Guiana. This combination of traits – economically self-sufficient, culturally distinct, mostly content, living in a rural overseas department – is not the typical refugee story. In fact, because of that relative uniqueness, the French Guiana Hmong have drawn attention from media outlets such as the BBC and the NY Times.

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Developmental Plasticity and the “Hard-Wired” Problem

“Development is the missing link between genotype and phenotype, a place too often occupied by metaphors in the past … But a strong emphasis on the genome means that environmental influence is systematically ignored. If you begin with DNA and view development as “hard-wired,” you overlook the flexible phenotype and the causes of its variation that are the mainsprings of adaptive evolution.” (Mary Jane West-Eberhard, 2003: 89-90)

“Genes, unlike gods, are conditional. They are exquisitely good at simple if-then logic: if in a certain environment, then develop in a certain way… So here is the first moral of the tale: Don’t be frightened of genes. They are not gods; they are cogs. (Matt Ridley, 2003: 250)

 

Plasticity: actor Christian Bale at two points in time. Same genes, different phenotypes.

Plasticity: actor Christian Bale at two points in time. Same genes, different phenotypes.

In his book The Triple Helix, Richard Lewontin told the story of the molecular biologist and Nobel laureate Sydney Brenner, who – while speaking at a conference – predicted that one day we would be able to “compute” an organism (2002). All we would need are two things: the organism’s full genome and powerful enough computers that were up to the task.

The idea is seductive. Genes are sometimes seen as self-sufficient molecules, almost existing in a vacuum, that contain all the information necessary to code for proteins. From there, it’s not a very big logical leap to think that if you had the genome, you could enter the code in some database, hit “run,” and then watch some digitized version of the organism unfold.

In fact, scientists are doing something much like this for the tiny roundworm C. elegans with the project OpenWorm. Yet even for a relatively simple organism such as this, with only about a thousand cells in total, there are reasons to be cautious. As The Economist warned in its write-up of OpenWorm: “Attempting to simulate everything faithfully would bring even a supercomputer to its knees.” However, this isn’t due solely to the limits of computing power (what if we had a super-duper computer!?). Rather, it’s a matter of how the question is framed.

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How War Gets Under Our Skin

beinghuman.org front page

I wrote this piece on BeingHuman.org about how war (and the world in general) gets under our skin. It looks at the Hmong example, as well as examples from a few other wars around the world (the Dutch Hunger Winter, the Biafran famine, and the Khmer Rouge period), and how these experiences get into our bodies. 

 

http://www.beinghuman.org/article/how-world-gets-under-our-skin

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Unbending rigor is the mate of death,
And wielding softness the company of life:
Unbending soldiers get no victories;
The stiffest tree is readiest for the axe.
Tao Te Ching: 76

 

Early in life, our bodies are like unmolded clay, ready to be shaped by our experiences. For some of us, that matching process can create problems. If circumstances change, we could end up poorly adapted to our adult environment. A child born into harsh conditions, though, may have to take that risk in order to make it to adulthood at all.

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Growing Up in the Two Koreas

The Korean peninsula at night (google earth)

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The above image of east Asia at night is worth more than a thousand words. Below the 38th parallel is the birthplace of my mother-in-law in South Korea, which is luminescent at night as the result of its highly developed economy. My father-in-law was born above that line in North Korea, which today appears to be little more than a shadow of its southern neighbor. Even if one knew nothing about history or geography, they could infer from that single satellite image that there must be a chasm in living standards on either side of the border.

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A full history of the two Koreas and the war of 1950-53 is beyond the scope of this post. What is relevant is that the forces of history and politics took a once cohesive nation and cleaved it in two, having disparate effects not only on the ideologies on either side, but also on the physical bodies of the respective inhabitants. It’s almost as if someone collected a population of dandelions from a single field and then placed them in two different greenhouses for six decades, replete with different soil quality, sunlight, and temperatures, and then observed how they fared. By now, many people have heard something about how North Koreans are significantly shorter than their southern cousins, implying that, like our dandelion example, the conditions for physical growth are quite different in the two greenhouses. John McCain even mentioned this during the 2008 presidential debates to illustrate North Korea’s brutality toward its citizens. How true is this claim?

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The God of Growth (James M. Tanner, 1920-2010)

The journal Economics and Human Biology has an obituary (in press) describing the life of James M. Tanner, and his singular contributions to the development of the study of human growth.  In his memorial, Roderick Floud quotes David Barker as saying “Jim was the God” of growth studies.

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I had missed news of Tanner’s passing, which occurred in August, and was sad to learn of it. His work has been invaluable to many people, including my own teaching and research, from formulating growth charts to a comparative look at how people grow in different parts of the world. But it’s important to reflect not just on his contributions to science, but also the person behind them. One gets a sense of his compassion from the way he referred to childhood growth as a mirror for “the material and moral condition” of a society (1986: 3). Floud quotes an oft-cited passage by Tanner:

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A child’s growth rate reflects, better than any other single index, his state of health and nutrition, and often indeed his psychological situation also. Similarly, the average value of children’s heights and weights reflect accurately the state of a nation’s public health and the average nutritional status of its citizens. . . . Thus a well- designed growth study is a powerful tool with which to monitor the health of a population, or to pinpoint subgroups of a population whose share in economic or social benefits is less than it might be.”

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Select Works

Eveleth, Phyllis B. and Tanner, James M. 1990. Worldwide Variation in Human Growth (second edition). Cambridge: Cambridge University Press.

Tanner, James M. 1986. Growth as a mirror for the conditions of society: secular trends and class distinctions. In Human Growth: A Multidisciplinary Review. Arto Demirjian and Micheline Brault Dubuc, eds. Pp. 3-34. London: Taylor and Francis.

Tanner, James M. 1990. Fetus into Man: Physical Growth from Conception to Maturity. Cambridge, MA: Harvard University Press.

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A Human Biology of War: The Proximate and the Ultimate

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On the surface, it may not be so clear where war, health, and evolution intersect. From the perspective of biological anthropology, many have called for a holistic, transdisciplinary approach to human biology and health which considers the environment as the totality of its evolutionary, ecological, and social components, including social inequality (Little and Haas 1989; Thomas et al. 1989; Wiley 2004).

Girl in Darfur refugee camp (source: Colin Finlay)

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More than a decade ago, Leatherman and Goodman (1998) suggested that biological anthropologists put more effort toward better understanding what they termed the ‘biology of poverty.’ In this sense, poverty is an ‘environment’ that may induce consistent, but obviously varying, biological responses depending upon local circumstances. Similarly, war can be conceived as a biological environment. At least in the short term from an evolutionary point of view, wartime conditions may be as biologically challenging as some of the classic ecologically extreme environments faced by humans (circumpolar, tropical, high-altitude, desert, etc.) (Clarkin 2010).

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War and child growth: Iraq & WWII Germany

At the population level, childhood growth is often seen as a marker of health and the quality of the environment. When populations get taller in a few generations, this is likely due to some improvement in local conditions (better nutrition, less infection, cleaner water supply, etc.). Conversely, when linear growth declines, it is usually because local conditions (ecological, economic, political) have deteriorated. Two recent working papers illustrate how this pattern applies to war conditions.

Destruction of Dresden, 1945

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