2013 was a banner year for early-childhood education in America. The president announced support of universal pre-K in last year's State of the Union address. Bill de Blasio, the new mayor of New York, ran on a platform of universal pre-K within the city. Hillary Clinton, the presumptive Democratic nominee in 2016, began an childhood-development initiative, Too Small to Fail.

But the issue of raising cognitive skills and test scores isn't just an educational issue; it's also public health issue. Or, rather, there's significant overlap between the two, and some of the most facinating new research on the subject suggests that early-childhood-education proponents should consider the significance of health—in this instance, nutrition—in early childhood, going back even to the womb.

Two leaders in this research are Diane Whitmore Schanzenbach at Northwestern and Hilary Hoynes of Berkeley, who collaborated on a paper last year on the "Long Run Impacts of Childhood Access to the Safety Net." The authors' focus is on food stamps, or SNAP, the 800-pound gorilla of the social-welfare safety net and the crux of the farm bill that's likely to pass with substantial cuts to the program.

Hoynes and Schanzenbach cleverly used a natural experiment to investigate the effects of food stamps: the slow, decade-plus-long rollout of the food-stamp program in the 1960s and 1970s, the main variable being "the share of time between conception and age 5 that a food stamp program was available in the individual's county of birth."

The strongest correlations the authors found were between food stamps and health outcomes: obesity, high blood pressure, heart disease, and diabetes. That is to say, pre- and post-natal access to food stamps (and thus more, and more nutritional food) lowers the prevalence of later-life health problems, at least those in particular. And the theory of causation is interesting:

There is an emerging scientific consensus that describes critical periods of development during early life that “program” the body’s long-term survival outcomes (Barker, 1992; Gluckman and Hanson 2004). During development, the fetus (and post-natally the child) may take cues from the current environment to predict the type of environment it is expected to face in the long run and in some cases adapts its formation to better thrive in the expected environment (Gluckman and Hanson 2004). A problem arises, however, when the predicted later environment and the actual later environment are substantially different. For example, if nutrients are scarce during the pre-natal (or early post-natal) period, the developing body therefore predicts that the future will also be nutritionally deprived. The body may then invoke (difficult-to-reverse) biological mechanisms to adapt to the predicted future environment. For example, the metabolic system may adapt in a manner that will allow the individual to survive in an environment with chronic food shortages.

It's a powerful explanatory hypothesis. Ohio State's Richard Steckel argues that going from extreme poverty (i.e. slavery, sharecropping, pre-industrialization) to comparative abundance—even in the still-impoverished South, wage gains far outpaced the rest of the country in relative terms—in the late 20th century leads to bodies that are poorly adapted to their future environment:

“The fetus builds inadequate organs because of the forecast on the part of the mother received from earlier generations that there is going to be a lean world. When the child then becomes obese and stresses these organs, this leads to metabolic syndrome among adults, and then diabetes,” he said.

So the theory is that food stamps, by providing a healthier prenatal environment, better prepare infants for a more abundant future. When that transition is a shock, as it is from famine, the body can suffer, which is why it's believed that the widespread starvation in Cambodia in the 1970s has increased rates of diabetes today.

But the authors found other, perhaps more unexpected correlations:

The results in column 5 suggest that food stamp exposure in both early and later childhood is beneficial to adult economic outcomes. This is consistent with a story whereby children with better nutrition gain more from school, which in turn translates into higher economic self-sufficiency.

The results are much stronger for girls, and not always statistically significant for boys—not the only recent study of food stamps and educational outcomes to come to this conclusion—but food stamps are a small piece of infant welfare; other recent research has connected infant-health intervention and educational attainment, though the causation is still unclear.

It's unclear because it's complex, as Brandon Keim writes. Periodic food insecurity, an ongoing problem with the SNAP program (recipients have a tendency to exhaust benefits before the month is up, which causes huge timing problems), can have an impact; lack of specific nutrients can inhibit brain development; the cause could be in part indirect, as food insecurity increases stress, which in turn has direct effects on the brain and indirect effects through worse health outcomes.

A lot of attention is given to SNAP as an economic program, such as its use as a multiplier, in comparison to things like unemployment, infrastructure and military spending, and so forth. But it's a public health program—and, it seems, an educational one as well.