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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Why Mice Don’t Get Ulcers

In his 1994 book “Why Zebras Don’t Get Ulcers,” Robert Sapolsky described the difference between the types of stress that people often experience and the ones that other animal species do. In his titular example, if you were a zebra, you’d most likely face acute physical stress – the lion about to eat you – which requires immediate physiological adaptations (the fight-or-flight response). A second type of stress might be chronic and physical (drought, famine, parasites, etc.).

However, the third type of stress on Sapolsky’s list – the type most prominent in an industrialized human’s life – was social and psychological. While our species certainly benefited from expanding brain size over the last few million years, it too came with trade-offs, including the ability to overthink and worry about things to come down the road. This type of stress would not have featured too prominently into the mental lives of other species. As Sapolsky wrote:

“How many hippos worry about whether Social Security is going to last as long as they will, or what they are going to say on a first date? 

For the vast majority of beasts on this planet, stress is about a short-term crisis, after which it’s either over with or you’re over with. When we sit around and worry about stressful things, we turn on the same physiological responses – but they are potentially a disaster when provoked chronically. A large body of evidence suggests that stress-related disease emerges, predominantly, out of the fact that we so often activate a physiological system that has evolved for responding to acute physical emergencies, but we turn it on for months on end, worrying about mortgages, relationships and promotions” (p. 5 – 6).

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Syria, After the War

Conscience cannot stand much violence. Once thoroughly broken down, who is he that can repair the damage?” – Frederick Douglass, “My Bondage and My Freedom” (1855, Chapter XI)

The war in Syria has to end, eventually. However, the tragic reality is that the damage is likely to last for decades.


Woman and child in Douma, Syria in Dec 2014. (AFP Photo/ Abd Doumany)

Yesterday, The New York Times reported that in the past few days “tens of thousands of civilians” have fled the city of Aleppo as the Syrian military, aided by Russian jets, have tried to reclaim the area. This is only the latest wave of civilians being forcibly displaced by the war. Altogether, the UN estimates that more than half of Syrians have been displaced from their homes at least once. Some of these have crossed into other countries, while the rest remain internally displaced.

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Forgiveness in Boston

Boston-Magazine Shoes

Cover of ‘Boston Magazine,’ by Mitch Feinberg

Less than a week after the Boston Marathon bombings, which left 3 people dead and over 280 injured, Cardinal Sean O’Malley emphasized the importance of forgiveness during Mass at the Cathedral of the Holy Cross. According to the Boston Globe, Cardinal O’Malley gave the congregation  two reasons to consider forgiveness. The first was  to avoid the “eye for an eye, tooth for a tooth mentality.” In that way, forgiveness offered a potential means to avoid further hostilities between groups. In fact, local tensions seemed to be simmeringO’Malley was likely cognizant of this, hoping to help defuse things before they progressed any further.  

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Inequality, Health Disparities, & Obesity

An October poll of 1,000 likely voters found that Americans are increasingly concerned about income inequality. When asked: “How Big a Problem is Income Inequality in the US?,” the majority (74%) replied that it was either a big problem or somewhat of a problem. Predictably, there were differences in opinion by political ideology, but a majority of liberals (94%), moderates (81%), and conservatives (55%) answered that inequality was at least somewhat problematic. However, as is true of many polls, it was not specified exactly what people found unsettling about it. I suppose there are many reasons that people might find increasing inequality (and climbing rates of poverty) to be troubling, but I wanted to focus here on inequality and health, particularly on obesity.

First, what do we mean by poverty? I remember watching an interview on PBS with the economist Jeffrey Sachs years ago (transcript here – thank you, Google), where he distinguished between two types of poverty. The first was an extreme form, which he called the type of “poverty that kills.” The other type was more of a poverty of inconvenience or jealousy. I don’t want to over-interpret Sachs’ meaning. It was a passing phrase in an interview from ten years ago, and his primary focus was on alleviating the extreme poverty faced by more than a billion people in the world living on $1 per day (see Sachs 2005). Elsewhere, Sachs has lamented that the media have ignored poverty in the United States at a time when “the U.S. has the greatest income inequality, highest per capita prison population and worst health conditions of all high-income countries.” His credentials in fighting poverty are unassailable. But I cite the old interview here because I think his descriptions (‘poverty that kills’ vs. ‘poverty of jealousy’) might resonate with many people today, and not necessarily in a good way.

Extreme poverty: scavenging at a garbage dump in Phnom Penh (abcnews)

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A Human Biology of War: The Proximate and the Ultimate

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)

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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The Power of Love

Infant rhesus monkey with terrycloth ‘mother’

As social animals, we need to be around others. Virtually everything we do is social – trade, eating meals, watching sports in stadiums or movies in theaters, religious services, education, the internet, etc. Even war is a social activity. No human being on the planet is completely self-sufficient. Being social is more than utilitarian, however; it is also biologically and psychologically necessary. For example, one of the most severe forms of punishment in prisons is solitary confinement.

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