A Time to be Born Varies by Latitude

What's your latitude? It turns out the answer to that question will influence the likelihood of when babies will be born in your area. Boer Deng of Slate discusses an article published today in the Proceedings of the Royal Society B: Biological Sciences (which is behind a paid subscription). 

A comprehensive analysis of when people give birth was recently published in theProceedings of the Royal Society B. Micaela Martinez-Bakker and Kevin Bakker, both of the University of Michigan, and their colleagues observed a previously unnoticed phenomenon: Peak months for births change with latitude. The most popular month for birthdays occurs earlier and earlier in the year the farther north you travel from the equator.

For the United States, the researchers looked at birth records by state from the Census Bureau dating back to 1931. They found that a surge in births happens at the same time every year for particular locations. Before the baby boom era, November was the most common month to be born in Florida. In Ohio, it was June. More recently, the top birth times for each state have shifted. Peak months in the United States are now later in the year and occur closer together, but the pattern has remained, with northern states having slightly earlier peak birth months than southern states.

The new analysis of births covers 118 countries, mostly in the Northern Hemisphere. It revealed that this pattern holds true outside the United States...Doing the math, this means that people in more northern latitudes are conceiving successful pregnancies more often in autumn, and those farther south are doing so in winter.

Deng notes that we aren't sure why these patterns exist, but they obviously are related to patterns of sexual activity nine months earlier. Nonetheless, the knowledge of seasonal clusters has useful health policy implications, in terms of knowing, for example, when to set up the most effective immunization campaigns.

The Economics of Aging

I am just finishing up the 12th edition of Population (it's already in production), and recently I analyzed the data from the latest Forbes list of the richest 400 Americans. Although people aged 65 and older comprise only 14 percent of the US population, they account for 60 percent of the richest Americans. The richest person in the world, Bill Gates, is only 58, but #2 in the world, Carlos Slim of Mexico, is 74, and #3, Warren Buffet, is 83. It is the latter who caught the eye of editors at The Economist and this week's cover story reflects on the potential economic effects of an aging, well-off older group of people. And they also give some thought to those who aren't going to be so well-off. 

The experience of the 20th century, when greater longevity translated into more years in retirement rather than more years at work, has persuaded many observers that this shift will lead to slower economic growth and “secular stagnation”, while the swelling ranks of pensioners will bust government budgets.

But the notion of a sharp division between the working young and the idle old misses a new trend, the growing gap between the skilled and the unskilled. Employment rates are falling among younger unskilled people, whereas older skilled folk are working longer. The divide is most extreme in America, where well-educated baby-boomers are putting off retirement while many less-skilled younger people have dropped out of the workforce.

These are important issues that I have been talking about for a long time. The better educated you are, the more money you make, and save (building your wealth), and the more you enjoy your work, which keeps you at it longer, benefitting you and the wider economy. At the same time, it seems to me that economists worry that as people get older and start spending their savings, the amount of capital in the system will diminish and the economy will suffer. This seems at odds with the idea that people need to spend money in order to stimulate the economy. In all events, I'm on board with the basic policy ideas floated in the main article about aging and the economy--push retirement age to older ages, and provide lifelong learning programs in order to promote the skills needed by the economy that will also provide the kind of work that will keep people productively in the labor force. This, of course, requires substantially more public investment in education. We need fewer student loans and more public investment, in my opinion.

Does Christianity Reduce Societal Corruption?

Over the years, Abu Daoud's comments on this blog have led to me to some interesting places demographically and I thank him for that. His latest suggestion is that maybe Christianity is associated with less corruption in the world. This is reportedly based on some work by Bob Woodberry, an American sociologist who teaches at the National University of Singapore. Woodberry received his doctorate in sociology at Chapel Hill under Ken Bollen, a world-famous social researcher. In a 2012 paper published in the American Political Science Review, Woodberry thanks two former Presidents of the Population Association of America--Barbara Entwisle of UNC-Chapel Hill (and spouse of Ken Bollen), and Bob Hummer of UT-Austin (site of Woodberry's first academic appointment). I provide this background only to suggest that Woodberry has the credentials to be listened to. His basic argument is that proselytizing Christians laid the foundation for liberal democracies in many of today's developed nations. His statistical analysis of that idea notwithstanding, I cannot help thinking about Chinua Achebe's unflattering characterization of the arrival of the missionaries in Nigeria as depicted in his classic "Things Fall Apart," and I laugh at my memories of twice having seen "Book of Mormon" on Broadway. 

It strikes me, however, as a bit of a leap to go from missionaries laying the groundwork for liberal democracy to the idea that Christianity per se is associated with low levels of corruption. That idea does seem to lie behind a set of graphs that Abu Daoud directs us to at this site. Indeed, the creator of the graph goes only so far as to conclude that: 

Does the Christian faith transform societies? The analysis of this chart would give a mixed report. Clearly, there is some influence on corruption: rare is the country that is both less corrupt and less Christian (and those that are, are either small populations or rigidly controlled). Nevertheless many nations claim a high affiliation with Christianity, yet rank among the most corrupt. Some variations of Christian practice have yet to transform society. Still, we should note that with few exceptions church growth is fastest where corruption is highest: it seems light burns brightest in the darkest places.

My interpretation of the data is a bit different. You know from my book that my perspective is that religious preference is far less important a predictor of human behavior than is religiosity (the degree to which a religion is practiced). I look at the least corrupt countries in the world and see nations that are heavily secular, whether they be ethnically Christian, ethnically Muslim, ethnically Shinto, or whatever. The most corrupt societies are those that are most heavily religious, whether that religion be Christianity, Islam, Hinduism, or something else. Indeed, I would argue that the "light burns brightest in the darkest places" precisely because the most religious places tend to be the most corrupt. That was what the Enlightenment was/is all about, after all.

American Middle Class No Longer on Top

Income inequality has been a hot agenda item recently, as I've noted before, and yesterday's New York Times inserted a study into the discussion that reveals the way in which the middle class in the U.S. has fallen behind middle classes in other rich countries.

The American middle class, long the most affluent in the world, has lost that distinction.
While the wealthiest Americans are outpacing many of their global peers, a New York Times analysis shows that across the lower- and middle-income tiers, citizens of other advanced countries have received considerably larger raises over the last three decades.
After-tax middle-class incomes in Canada — substantially behind in 2000 — now appear to be higher than in the United States. The poor in much of Europe earn more than poor Americans.

What happened in Canada, eh? The NYTimes piece has some insights, but so did Stephen Colbert--"All Canada has is universal health care, subsidized child care, and higher taxes on the rich." Of course, his answer for regaining America's place as having the richest middle class is...even lower taxes on the rich.

Don't Be a Teenage Mom

Now, I don't expect that any potential teenage moms will ever read my blog, but anyone who is in contact with teenagers needs to keep in mind that one of, if not the, most tragic things a teenage girl can do is to get pregnant, especially if she decides to have the baby. My first book, based on my doctoral dissertation, was on teenage marriages, which were almost always inspired by a teenage pregnancy. Times have changed. A smaller fraction of teenagers in the U.S. now get pregnant than at any time since at least the 1970s, and when they do get pregnant they almost never marry. But, the sad tale is that when they do pregnant and have that baby, their life chances are pretty dismal--maybe even worse than ever, according to a new study just published in Demographic Research. Anne Driscoll of the U.S. National Center for Health Statistics (part of the US Centers for Disease Control), used data from the National Surveys of Family Growth to examine the outcomes of women who bore children as a teenager compared to women who waited to have children. This is an article with a lot of good material, but let me highlight her main findings:

Comparisons between teen mothers and both young adult and all adult mothers within cohorts suggest that gaps in single motherhood and poverty between teen and adult mothers have widened over time, to the detriment of teen mothers. Teen mothers have become more likely to be single and poor than in the past and compared to older mothers....The findings of this study suggest that women in more recent cohorts who became teen mothers as it is becoming less common will experience greater hardships as adults in a time of greater economic inequality and greater emphasis on education as a means of economic mobility.

This is not an outcome that we should wish on anyone, which is why sex education for teenagers, and the availability of birth control to teenagers needs to be even more widespread than it is today--along with more education about how a poor education can ruin your life.