Princetonians Team Up to Study China’s Demographics

For many Princeton graduates, the senior thesis guides career choices, ignites passions, and remains a source of pride years after graduation. But few can top Lex Rieffel ’63, whose senior thesis experience inspired a research project 60 years later.

Rieffel, a retired economist and policy researcher with expertise in East Asia, was advised for his thesis by Ansley J. Coale ’39 *47, then the director of Princeton’s Office of Population Research (OPR) and an internationally recognized demographer. Rieffel quickly developed an interest in demographics that grew as his career took him to India, Indonesia, Myanmar, and, on a few short occasions, China, an economy whose development particularly interested him ever since graduate school.

So, in January 2023, when the Chinese government announced that its population had begun to shrink for the first time since the 1960s, Rieffel took note — but didn’t share in everyone else’s panic.

“The announcement produced headlines in media around the world about China’s demographic crisis. And I said, ‘That’s ridiculous. This is not a crisis,’” Rieffel recalls. China’s declining birth rate might not automatically cause drastic labor shortages and stunted economic growth. On the contrary, it could lead to quality-of-life improvements for Chinese citizens without jeopardizing the country’s global superpower status.

Rieffel decided to publish an article pushing back against the crisis narrative, seeking to illustrate the projected changes to China’s population using population pyramids — graphs that show the distribution of a population by age and sex. Lacking the technical and computational skills needed to create them himself, Rieffel knew where to turn for help: Princeton’s Office of Population Research.

“To my incredible delight and good luck, the head of the Office of Population Research at the time (Professor Sanyu A. Mojola) circulated my email to the entire staff — which, by the way, is many times larger than it was in the 1960s, when I was there,” Rieffel says.

Xueqing Wang, a sixth year Ph.D. student in Princeton’s Population and Social Policy program who goes by Zoey, answered the call. Born and raised in China, Wang studies population aging and its consequences for both China and the U.S. ­— work that often incorporates population pyramids — making her expertise a great match for Rieffel’s interests. Rieffel and Wang, then aged 81 and 28, respectively, decided to collaborate.

“I study China, I know how to produce population pyramids, and I thought this [project] would be fun,” Wang says.

Not all populations take the classic pyramid shape, where a wide base and a narrow top represent a population constituted by a higher proportion of younger people. For countries where a demographic transition is producing higher death rates than birth rates, such as China, it creates a bulge in the population pyramid reflecting a greater number of older, working adults. As these individuals age, the younger working population will be tasked with supporting the elderly people, a burden that could slow the country’s economic growth. 

Rieffel and Wang concede that if China’s current total fertility rate, which is the average number of children a childbearing person has in their lifetime, persists throughout the 21^st century, China’s economy would undoubtedly suffer. Such forecasts, which are used by the United Nations, predict that China’s population will number 770 million people by the year 2100, down from its current 1.4 billion. But the two calculated that Chinese birth rates — actively encouraged by the Chinese government, which now permits families to have three children — could stabilize and slowly climb over the course of the century, culminating in a total population of around 1.2 billion in 2100.

In such a scenario, which Rieffel and Wang outline in a May 2024 Scientific American article alongside their population pyramids, China’s economic output and the well-being of its citizens might very well continue to grow. A smaller population could mean improved quality of education. Advances in artificial intelligence and robotics might compensate for the smaller workforce. And as the existential threat of climate change looms, smaller populations in China and beyond might become more sustainable due to resource constraints.

“The very low total fertility rate, well below replacement level, is not a bad thing. It’s a good thing in the context of climate change globally, and the particular resource endowment and economic moment that China finds itself in,” Rieffel says.

Additionally, China might pursue policies that incentivize childbearing and later retirements but also serve to boost quality of life, like expanding childcare facilities, granting longer maternity leave, and improving pension schemes.

“I particularly enjoyed how we formed and improved this argument and made it accessible to readers with very minimal academic knowledge,” Wang says. For her, the collaboration was not just professionally valuable (she plans to become a demographer specializing in China after completing her degree), but personally meaningful as well.

“I belong to the generation where my parents could only have one child,” Wang says. “As a demographer, I’m interested in studying my generation’s role in Chinese society in light of the population decline.”

Though it remains unclear how China’s different generations will adapt to the forthcoming demographic changes, Wang’s and Rieffel’s own generation gap was certainly no obstacle to an unconventional but successful collaboration.

“Zoey is terrific,” Rieffel says, “and I hope I can be helpful to her in her career.”

“Lex is knowledgeable, humble, and I learned a lot from him,” Wang adds. “Hopefully I’ll be as intellectually sharp when I reach the age of 82.”