Fetal origins

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New Article: “The Embodiment of War”

Been looking forward to this. I just published an article in the Annual Review of Anthropology titled “The Embodiment of War: Growth, Development, and Armed Conflict.” In essence, the article conceives of war as an extreme “environment” that has many long-term effects on human biology, particularly for civilians in the earliest stages of life (children, infants, and prenatally).

Obviously, most people know that civilians are harmed during war, including through injuries (fatal and non) and psychological distress. I tried to go beyond this, reviewing the effects various wars have had on biological variables, including birth weight, child growth, maturation (ex. menarche), and the development of chronic diseases via the DOHaD hypothesis.

I’m hoping to build on this.

Figure 2. Some of the stressors faced by conflict-affected populations.

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Links Between War & Famine: From the Chevauchée to Yemen, S. Sudan, Ukraine, and Syria

“Armed conflicts lead to hunger and reduced food production and economic growth in developing and transition countries. Reciprocally, food and economic insecurity and natural resource scarcities–real and perceived–often precipitate violence.”

-Marc Cohen and Per Pinstrup-Andersen (1999)

Recent images coming out of war-torn Yemen are heartbreaking. After three years of fighting between Houthi rebels and a Saudi-led coalition (backed by the US, UK and France), an estimated eight million people are near starvation. The war has exacerbated the nutritional situation in what was already one of the poorest countries in the region, causing infrastructure to crumble and unemployment rates to skyrocket. A blockade of Yemen’s ports has also led to a rise in food prices and to a lack of medical supplies, leaving people dependent on insufficient amounts of food aid.

BBC

A malnourished infant in Yemen, with a low upper arm circumference (source: BBC).

This has been building for a while. Nearly two years ago, a BBC report cited statistics from the UN that 370,000 children in Yemen were starving. Even infants, who may be buffered from difficult economic conditions via breastfeeding, were not spared as many mothers were too malnourished to produce milk.

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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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Year in Review: Top Posts of 2017

Looking through the 5 most frequently read essays of 2017, I see few themes. They are mostly attempts to find reasons to be hopeful (even though that has been hard at times). Humans are adaptable and flexible, and we aren’t fated to any single behavioral way of being. That means we can always make a better world. Light up the darkness.

Cumulative learning. From
A variety of skin colors. From the Humanae Project, by Angelica Dass (source).
The Revolution of Giraffes by Matthieu Robert-Ortis
Who’d want to hurt Spiderman?
Plantain trees flattened by Hurricane Maria in Yabucoa, P.R. In a matter of hours, the storm destroyed about 80 percent of the crop value in Puerto Rico, the territory’s agriculture secretary said. Credit Victor J. Blue for The New York Times

 

1. The Conditions of the Game: It’s Not a “World of Eternal Struggle” (Sept 2)

This was by far the most read post on this site, which I wrote after the violent clashes in Charlottesville, Virginia. This was upon seeing a photo of a man with a t-shirt that quoted Hitler in which he wrote that ours is “a world of eternal struggle.” I found it disturbing, but also just wrong. In evolution, adaptations are context specific, and they depend on the conditions of the game. This is also true for cooperation and conflict.

“How we view the world matters. If we see it as zero-sum, as an eternal struggle against other people where only one party can win, then we will act accordingly. Norton and Sommers (2011) found that many white people see racial relations as a zero-sum game: that if other groups are making progress toward equality, that this progress comes at their expense. But remember that non-zero-sum relationships are widespread. With cooperation so prolific in nature (genes, cells, organisms, groups, human societies), it just seems odd to declare that life is solely a contest of struggle. Nor does it make sense to say that cooperation is impossible between groups. Or we can see it as a chance for coalitions, that the success and well-being of others around us does not require us to lose. We make a niche for the others around us, as they do for us, and we all decide whether the costs that come with building up our armor are worth it. They may be, depending on how we perceive the conditions of the game.

I don’t know about you, but I think my life would be better if I was surrounded by healthy, fulfilled, cooperative people over those who feel distrustful, held back, and resentful. Of course, some people may feel differently. There are many strategies one can use. But don’t argue that nature gave us only one hand to play.”

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The Future Health of Puerto Rico after Hurricane Maria

Darieliz Michelle Lopez, her 20-month-old son and three-year-old daughter sit on a sofa where her apartment stood in San Isidro on Sept. 28. (Andres Kudacki for TIME) 

 

In 2013, Orlando Sotomayor, a professor of economics at the University of Puerto Rico-Mayagüez, looked into whether two hurricanes in 1928 and 1932 impacted the long-term health of the people of the island. He specifically explored whether people exposed to the hurricanes prenatally had higher rates of various chronic diseases and lower education levels decades later.

He framed this within what used to be referred to as the fetal origins of disease hypothesis, but is now usually called the DOHaD (developmental origins of health and disease), acknowledging the importance of development beyond the fetal period. In a nutshell, the DOHaD is based on decades of evidence that various biological insults (malnutrition, maternal psychological stress, pollution) in the prenatal and early postnatal stages of life may predispose individuals to chronic diseases later in life. This has been linked to type 2 diabetes, coronary heart disease, and hypertension (Barker 1994), schizophrenia (Wahlbeck et al 2001), osteoporosis (Cooper et al 2009), and possibly cancer (Walker and Ho, 2012).

In one of the best-known examples, women who were pregnant during the Dutch “hunger winter” in World War 2 had offspring who had a higher risk of various conditions by the time they reached middle age, including a doubled rate of coronary heart disease, obesity, and diabetes in adulthood (Rooseboom et al 2011). They also had an increased chance of having schizophrenia and depression, and did worse on cognitive tasks. While famine conditions are not necessary to have such impacts (poverty and deprivation operate in a dose-like fashion), the well-defined period of the “hunger winter” provided a way to compare exposed and unexposed persons. 

 

The 1928 and 1932 Hurricanes

Professor Sotomayor viewed the decades-old hurricanes in Puerto Rico as akin to something like the Nazi-imposed famine in the Netherlands. There are differences, obviously. Disasters resulting from intentional, anthropogenic (human-generated) disasters like war usually end up leading to protracted humanitarian crises (Schultz et al 2014). While natural disasters are often devastating, they are usually short-lived and can be ameliorated by humanitarian aid, whereas unsafe conditions during war often makes such assistance logistically difficult. Of course, aid following natural disasters depends on the scale of destruction, a country’s pre-disaster wealth and access to resources, and the political willingness of neighboring countries to assist.

Hurricane San Felipe (1928) and hurricane San Ciprian (1932) both had devastating effects on the agrarian economy of Puerto Rico, with damages estimated to be about one-third and 20% of national income, respectively (Sotomayor, 2013: 282-3). Coffee, citrus, and sugar cane crops were particularly affected. Using data from the CDC Behavioral Risk Factor Surveillance System surveys, Sotomayor looked at people born between 1920 and 1940, and defined those individuals born in the years immediately following the hurricanes (1929 and 1933) as having been exposed to difficult early life conditions. Unfortunately, month of birth was not available in the dataset, so year of birth had to suffice.

Plantain trees flattened by Hurricane Maria in Yabucoa, P.R. In a matter of hours, the storm destroyed about 80 percent of the crop value in Puerto Rico, the territory’s agriculture secretary said. Credit Victor J. Blue for The New York Times

 

In all, the sample comprised 11,990 individuals, with 1,197 defined as being exposed to the effects of the hurricanes in early life. Overall, he found that exposed individuals were more likely to be diagnosed with hypertension, high cholesterol, and diabetes, as well as be more likely to have no formal schooling. This latter outcome variable was interpreted as possibly being a “cognition shock,” suggesting that exposed individuals may have had some decline in mental faculties resulting from poor early neurological development.

Incidence (and 95% confidence intervals) of chronic diseases and lack of schooling in Puerto Rico by year of birth. People born in 1929 and 1933 were viewed as being exposed to the effects of a hurricane in early life (Sotomayor 2013).

 

 

After Hurricane Maria

We can speculate whether something similar might result from hurricane Maria, which made landfall on Puerto Rico on September 20 of this year. As a Category 5 hurricane, it was among the most powerful ever recorded and its devastating effects likely won’t be resolved anytime soon. It has been estimated that more than 1,000 people died as a result of Maria, while a substantial proportion of the population still remains without electricity, months later.

Similarly to Hurricanes San Felipe and San Ciprian, Maria destroyed up to 80% of Puerto Rico’s agriculture, and rates of food insecurity have increased (rates were already high before the hurricane). Reports indicated that following the hurricane, many people on the island had to skip meals and waited in lines for hours waiting for emergency food supplies, as relief supplies were below standards that were available in other recent hurricanes that hit Texas and Florida (even though all are American citizens). According to CBS News, more than 215,000 people left Puerto Rico for Florida between October 3 and December 5, and it’s been projected that perhaps more than 470,000 people will leave in the next two years (and up to 750,000 people over the next four). Proportionally, this is a staggering loss of population on an island that had 3.4 million people in 2016.

A combination of NOAA satellite images taken at night shows Puerto Rico in July, top, and on Sept. 24, 2017, after Hurricane Maria knocked out the island’s power grid. NASA/NOAA/Handout/Reuters

 

All of this suggests that there is the potential that Maria could have long-term effects on health, growth, and development similar to San Felipe and San Ciprian. Early life is a particularly vulnerable period, and there are an estimated 175,000 children under the age of  to 4 years old on the island. Growth rates are fastest in this stage, and the potential for long-term effects on health should factored into Maria’s costs beyond the effects on mortality, damaged infrastructure, destroyed crops, economic losses, and displaced population. It also hints at the urgent need to summon the political will to respond rapidly and sufficiently to minimize the effects of natural disasters like this. Otherwise, the costs will have to be paid later in terms of loss of health, premature death, and possibly diminished cognitive capacity (and all of its concomitant costs to education and economic potential). As Professor Sotomayor wrote (2013: 291):

“Evidence therefore suggests that in absence of preventive measure, effects of events like Bay of Bengal cyclones, Caribbean Sea storms like hurricane Mitch, or the great Haitian earthquake may not be over for a long time.”

 

References

Barker DJP. Mothers, Babies, and Disease in Later Life. BMJ Publishing; 1994.

Caruso GD. The legacy of natural disasters: The intergenerational impact of 100 years of disasters in Latin America. Journal of Development Economics. 2017 Jul 31;127:209-33. Link

Cooper C, Harvey N, Cole Z, Hanson M, Dennison E. 2009. Developmental origins of osteoporosis: the role of maternal nutrition. Early Nutrition Programming and Health Outcomes in Later Life. 2009:31-9. Link

Shultz JM, Ceballos ÁM, Espinel Z, Oliveros SR, Fonseca MF, Florez LJ. 2014. Internal displacement in Colombia: fifteen distinguishing features. Disaster Health. 2(1):13-24. Link

Sotomayor O. Fetal and infant origins of diabetes and ill health: Evidence from Puerto Rico’s 1928 and 1932 hurricanes. Economics & Human Biology. 2013 Jul 31;11(3):281-93. Link

Wahlbeck K, Forsen T, Osmond C, Barker DJ, Eriksson JG. 2001. Association of schizophrenia with low maternal body mass index, small size at birth, and thinness during childhood. Arch Gen Psychiatry 58: 48-52. Link

Walker CL, Ho SM. Developmental reprogramming of cancer susceptibility. Nature Reviews Cancer. 2012 Jul 1;12(7):479-86. Link

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Prenatal “Shocks” and Birth Outcomes

Birth weight is often used as a rough gauge for the quality of the prenatal environment. A newborn who weighs 2500g or less (about 5.5 pounds) is considered to be “low birth weight” (LBW). At the individual level, weight alone is an imperfect measure because of confounders such as gestational length (it’s axiomatic that the less time spent in the womb, the less time there is to grow). However, at the population level, if average birth weight fluctuates, then it is an indication that something in the environment probably has changed.

Sometimes, stressful changes can be low-intensity and chronic; at other times, they can be abrupt and dramatic. Biologists, psychologists, and bioanthropologists might call these changes “stressors” or “insults.” Economists might use the term “shocks.” They’re both getting at the same idea: to what extent can harmful environmental factors affect growth and health outcomes? 

In the case of a natural disaster, the harm done can be substantial. Florencia Torche (2011) found that rates of LBW increased following the 2005 Tarapaca earthquake in northern Chile. Despite the magnitude of the earthquake (7.9 on the Richter scale), the amount of destruction was relatively limited: eleven people died, and 0.035% of the population had to temporarily relocate to shelters. This was attributed to the low population density of the region as well as Chilean preparedness and building codes to withstand earthquakes. Although the damage was not as severe as it could have been, Torche reasoned that the earthquake likely caused acute maternal stress, which in turn could affect prenatal development. 

Looking at over half a million births, Torche used maternal county of residence as an estimate of the earthquake’s intensity across different trimesters of exposure. She found that mothers who were lived in the most intensely affected regions during the first trimester were the most affected. The probability of LBW increased from 4.7% to 6.5%, while rates of pre-term births also increased from 5.2% to 8.0%. Later periods of gestation were not substantially affected, and for infants who were conceived after the earthquake, the probability of LBW returned to baseline.

Again, these outcomes seemed to result primarily from acute psychological stress stemming from the earthquake. Torche reasoned that – given the relatively low amount of damage to infrastructure – the increases in LBW and pre-term births were unlikely to have resulted from other factors such as malnutrition, infection, stress resulting from deprivation, strenuous workloads, or exposure to environmental toxins. In reality, it’s not possible to control for all of these variables entirely, but overall it seems plausible that maternal psychological stress played a substantial role in birth outcomes.

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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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Infant Mortality Rates, War & Laos

I finished my dissertation on how the war in Laos was correlated to the physical growth of Hmong refugees in 2004. The general idea was that early stressors, particularly prenatally and in infancy, can have long-term impacts on growth and health. The model I was working with came largely from David Barker’s (and others’) ‘fetal origins hypothesis,’ based on evidence that low birth-weight infants tended to grow up to have higher rates of things like type 2 diabates, coronary heart disease, hypertension, etc. A classmate in graduate school, Stephanie Rutledge, introduced me to Barker’s work and told me that I’d find it really enlightening. I did. Sadly, Barker passed away earlier this year, but his work helped spawn a new direction in research. 

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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.