On Monday, Angus Deaton, a longtime professor at Princeton, was awarded the 2015 Nobel Prize in Economics for his work on consumption, poverty, and welfare. Professor Deaton’s wide range of research touches on topics that are important to the lives of people all over the world: from what they consume and what they save to their health and happiness.

For the past 25 years, an important part of his research has focused on India. He has notably tackled the question of what happened to poverty and inequality in India after liberalisation, bringing painstaking analysis and careful thinking to an issue of great policy relevance. He has also made key contributions to the study of health and nutrition in India. As a graduate student of Professor Deaton at Princeton University, writing my dissertation about maternal and child nutrition, I paid special attention to his work on nutrition in India.

Sometimes, the best research doesn’t answer questions: it poses them. This is the case with much of Professor’s Deaton’s work on nutrition in India. Take, for instance, his research on the puzzle of declining calorie consumption. Working with Indian economist Jean Drèze, Professor Deaton used the National Sample Surveys to explore what happened to food consumption in India between 1983 and 2005. They found, as other researchers had before, that richer people eat more than poorer people. They also found that, on average, Indians were getting richer over time. Neither of these facts were a surprise. But many people would think that these facts, when conflated, imply that people in India consumed more calories in 2005 than they did in 1983.

To the contrary, what Professors Deaton and Drèze discovered was a calorie decline: the average household in India, in both rural and urban areas, was eating fewer calories in 2005 than it was in 1983. This was despite the fact that the average household were getting richer, and that many people would have been healthier if they consumed more. In fact, three quarters of Indians consumed less than what the government considered to be a healthy minimum requirement. Furthermore, high fractions of men, women and children were underweight.

The height paradox

Other researchers have proposed partial resolutions to the puzzle of the calorie decline, including some of my colleagues at r.i.c.e., a research institute for compassionate economics, but the paradox is far from settled.

Another paradox that Professor Deaton’s work has raised relates to the height of people in India. Many people think of how tall a person is as a genetic fluke, but though there is a genetic dimension to it, a person’s height is in large part determined by her health in early life. Health insults (a physical or mental injury) from conception until the age of two years can cause a person to grow much shorter than her genetic potential would have allowed in a healthier environment.

Considering that height is importantly shaped by early-life health, and that richer people tend to be healthier, we might expect a country’s economic performance to be a good predictor of the average height of its people. But, as Professor Deaton has demonstrated, per capita gross domestic product is a poor predictor of the average height of adult women in developing countries. In fact, women and children in sub-Saharan Africa are taller than women and children in India, despite the fact that Indians are on average richer.

More nutrition puzzles

I am personally grateful to Professor Deaton for calling my attention to the fact that Indians are among the shortest people in the world. Without his influence I would have been unlikely to begin on a path that led to my dissertation research, helping me document that maternal nutrition in India is so poor that the average woman in India ends pregnancy weighing less than the average woman in sub-Saharan Africa weighs at the beginning of pregnancy.

More Deatonian nutrition puzzles remain at best partially solved (when you when a Nobel prize, your name can become an adjective). He has shown that, cohort after cohort, year after year, younger generations of adult men in India are becoming taller than the older generations at a faster rate than Indian women are becoming taller. This strongly suggests some form of discrimination against the girl child in health or nutrition. Though many researchers, including Professor Deaton, have documented forms of gender bias in India, much remains to be learned about the growing height gap.

There is no doubt that nutritional outcomes in India are abysmal, and that these reflect poor early-life health, maternal nutrition, environmental conditions, and people’s choices. But why exactly, and can anything be done about it? Here, Professor Deaton teaches perhaps his two most important lessons. First, dogged commitment to finding out what the data say can help answer even big, seemingly intractable questions. Second, doing so require handling data with special care – and perhaps with Deatonian wisdom. May his Nobel Prize inspire a new generation of empirical economists to rise to the challenge.

Diane Coffey was Angus Deaton’s PhD student at Princeton. She is now a visiting economist at the Indian Statistical Institute, Delhi, and Princeton University. She also co-directs r.i.c.e., a research institute for compassionate economics.