(Clarissa Casper | The Salt Lake Tribune) Used baby onesies collected as part of erthaware's 10,000 Onesies Project in Logan.
Twenty years ago, Utah had the highest fertility rates in the country. But since 2007, the total fertility rate in Utah has dropped from 2.68 births per woman to 1.80 births. This trend isn't unique in Utah, or even the United States -- globally, total fertility is 2.30 births per woman, less than half the fertility rate 75 years ago.
Fertility has implications on issues like economic growth, climate change and retirement benefits, and as debates continue over whether or not this declining trend is adverse for humans, people want to understand why birth rates are dropping.
As an evolutionary anthropologist studying collective childrearing around the world, I'm familiar with what some contributing causes may be. As with many issues, it's tempting to look for simple answers to complex questions. Instead, the decline in fertility is likely being driven by many different causes. Because birth rates have fallen across the world, including in low- and middle-income countries, these explanations need to work across diverse cultural contexts.
Here are three possibilities that are all likely contributing to declining fertility -- to a degree -- but are also insufficient for explaining the decline all on their own.
First, one of the most popular theories is that as children and housing have become more expensive to raise, and as education has become increasingly important in the workplace, parents have decided to have fewer children that they invest more resources in. These same processes in turn lead parents to start families later in life -- and hence have fewer children -- while they build their careers and accrue the capital required to pay for children. But economic costs can't be the only explanation. Countries that have tried to increase birth rates by providing resources for parents haven't moved the needle on fertility, and the rapid increase in home prices that have affected places like Utah aren't universal.
A second possibility, one that's been under-discussed and is also close to my own research, is the rise of the nuclear family and the decline of cooperative childcare. Nuclear families as the dominant unit of familial organization are a recent phenomenon. For most of history, people have lived in extended kin groups, and there's strong evidence that humans evolved to raise children with the help of their extended families and support networks. As people have become less likely to live near or with their extended families, their access to childcare has also decreased, perhaps influencing decisions about family size. However, access to help with childcare is also unlikely to be the only explanation. For example, multigenerational households are becoming more common in the U.S., but fertility continues to decline.
Third, others have implicated changing cultural values as causing declining fertility, whether as the result of ideological changes such as feminism, pessimism about the future due to climate change or the decline in romantic partnerships that may be associated with the rise of the smartphone. Oftentimes, these explanations are ideologically motivated themselves, offering proponents the opportunity to blame declining fertility on some social trend they take issue with.
However, they are ultimately unsatisfactory explanations for wholly explaining the decline in fertility. For example, there's less evidence of a tradeoff between fertility and gender equality in work, and fertility has also declined both in countries with low gender equality, and in regions such as South Asia where marriage rates have not much decreased.
A more convincing possibility is that instead of changing values influencing fertility rates, people's ability to set their own fertility preferences has changed values. The decline in birthrates may reflect a universal revealed preference for smaller families, and that people have more ability to exercise those preferences than in the past. These individual preferences may then be accelerated by changes to norms -- as people have fewer children, it becomes more common to have fewer children, resulting in a runaway feedback loop.
From an evolutionary perspective, our psychology hasn't necessarily evolved to maximize a desire for large families, but rather to engage in behaviors that increase reproductive success on average over time. In the context of global fertility declines, these two things may have become decoupled.
As we continue to debate the causes and consequences of declining fertility, it's important to keep in mind that oversimplifications are unlikely to explain a complex trend. Instead of searching for singular causes of the fertility decline, we should recognize that many different things are happening at once. Anyone offering simple solutions is unlikely to have considered the real complexity of the issue.
(Theodore Samore) Dr. Theodore Samore, Ph.D., is a postdoctoral research associate in biological anthropology at Baylor University, living in Salt Lake City.
Dr. Theodore Samore, Ph.D., is a postdoctoral research associate in biological anthropology at Baylor University, living in Salt Lake City. He studies religion, culture and cooperative childcare across the globe.
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