This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 13th (it will be out in January 2020), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

You can download an iPhone app for the 13th edition from the App Store (search for Weeks Population).

If you are a user of my textbook and would like to suggest a blog post idea, please email me at: john.weeks@sdsu.edu

Thursday, December 27, 2018

U.S. Population Growth Hits an 80-Year Low

Thanks to Rubén Rumbaut for pointing me to a nice summary of U.S. demographic trends by Brookings Institution demographer William Frey. The U.S. Census Bureau recently came out with its year-end summary of what happened between July 1, 2017 and July 1, 2018, and Bill gets right to the point--we're getting older and slowing down. Yes, I mean all of us, but this applies generally to the U.S. population.
Their data show that the national rate of population growth is at its lowest since 1937, a result of declines in the number of births, gains in the number of deaths, and that the nation’s under age 18 population has declined since the 2010 census. This is on the heels of recently released data showing geographic mobility within the U.S. is at a historic low. And while some states—particularly in the Mountain West—are growing rapidly, nearly a fifth of all states displayed absolute population losses over the past two years.
Here's what it looks like graphically:


As the baby boomers move into the older ages, the number of deaths is increasing, and since younger women are delaying having babies (and may have fewer than previous generations), and fewer immigrants are coming into the country, we are growing very slowly. This is probably good for the environment, but it introduces a lot of potentially unwelcome changes that we may all be coping with for the rest of our lives.
This week’s release of census estimates appears to put an exclamation point on what we should be preparing for as the country ages and grows less rapidly from natural increase. The latest national growth rate of 0.62 percent is noticeably below what we have experienced in decades prior. While it is still far higher than in countries like Germany, Italy, and Japan, it means that policymakers must place increased attention on caring for a larger and more dependent aging population, and dealing with the realities of a slower-growing labor force. In particular, it requires a more serious discussion of U.S. immigration policy because of the future contributions that immigrants will make to growing America’s society and economy.
I couldn't agree more. Immigration policy should be the #1 topic under discussion by Congress when they reconvene--right after they get the budget back on track and continue the funding of the Census Bureau!

Wednesday, December 26, 2018

Why Are More Boys Born Than Girls?

Thanks to both Justin Stoler and Debbie Fugate for linking me to a Christmas Day story from BBC News on the sex ratio at birth. I'm not sure if there was any significance to its publication yesterday, but the headline is a question: Why are more boys than girls born every single year?  This happens all over the world and has been going on for as long as people have been collecting such information. It is well accepted that the "normal" sex ratio at birth is 105 boys born for every 100 girls born. Why?The short answer is that we really don't know for sure. The first theory discussed in the article is the evolutionary theory, although here we can only describe what we see, without knowing for sure why the pattern has evolved as it has.

The article doesn't really articulate the evolutionary theory very well, so let me quote from the 12th edition of my text, first from Chapter 5 (p. 158):
The most basic health difference between males and females is that males have higher death rates than females from conception to the very oldest ages. Seemingly to compensate for this, more males are conceived than females. Fetal mortality is higher for boys than girls, but there are still typically more males born than females. Infant and childhood mortality rates are higher for males, with a roughly equal number of males and females being reached, quite conveniently from an evolutionary perspective, in the prime reproductive ages of the late teens and early twenties. After that, the only bump in the road for females compared to males is high maternal mortality, and by the older ages we can almost always expect to find more women than men.
And then from Chapter 8 (p. 305):
Despite the concern about the high and even increasing sex ratio in some countries, there is still the underlying question of why the “normal” sex ratio is not simply 100. The answer is that no one really knows (Clarke 2000). This is perhaps a biological adaptation to compensate partially for higher male death rates (or vice versa, since we also are not sure why death rates are higher for males, as I mentioned in Chapter 5). In fact, data on miscarriages and fetal deaths suggest that more males are conceived than females, and that death rates are higher for males from the very moment of conception. Thus, some of the variability in the sex ratio at birth could be due to differences in fetal mortality. But we aren’t sure why those differences exist, either. Research done as part of the human genome project suggests a role played by the X chromosome, but that is still just a guess (Gunter 2005).
That pretty well sums up what we know. The patterns are clear--the reasons for those patterns are not.

Wednesday, December 19, 2018

Set it and Forget it: Reducing Unwanted Pregnancy

Thanks to one of my readers, Du Elium Kayali Araujo, for the link to a story closely related to my recent post on the dangers of getting pregnancy in the United States. Yesterday the NYTimes Upshot writer Margot Sanger-Katz posted a story about how better contraception could be a key to reducing poverty. If you've followed my blog over time, you know that in my opinion this is not speculative ("could") but is definitive ("will").
Unplanned pregnancies remain astoundingly common. According to the Guttmacher Institute, they represented 45 percent of all pregnancies in the United States in 2011. The majority of abortions, which numbered more than 900,000 in 2014, are in response to unplanned pregnancy, and there are signs that the new program has pushed down Delaware’s abortion rate.
The new program referenced in the article is in Delaware and is a collaboration with a national organization called Upstream. The goal is to reduce unplanned pregnancies by providing women with a one-stop shop for contraception, with a particular emphasis on long-acting reversible contraceptives (LARC).
Without a LARC, preventing pregnancy means taking steps like filling prescriptions and remembering to take a pill every day. With one, a woman won’t become pregnant until she takes the step of removing it.

“Set it and forget it,” said Venus Jones, an Upstream trainer. “We call it the Crock-Pot method.”
The program has the very positive impact of reducing abortions, and it has the strong potential to improve the lives of women and their children:
Children whose births are unplanned are likelier to have health complications, to be born into poverty, to stop their education sooner and to earn less. Mothers of unplanned children tend to give birth when they are younger, leave school earlier and earn less when older.
Isabel Sawhill, a senior fellow at the Brookings Institution, has measured the wide gulfs in outcomes between young women with unintended children and those with planned pregnancies later on. She has written extensively in support of expanded LARC access.
“It’s very expensive and very hard to reduce poverty,” Ms. Sawhill said. “Reducing unplanned births is easy by comparison.”
I first made reference to Sawhill's book Generation Unbound more than four years ago, and I've commented on it in several other blog posts since then. If you haven't read her book, you should do so. 

Monday, December 17, 2018

The Dangers of Getting Pregnant in the U.S.

Last month I blogged about new data from the U.S. Centers for Disease Control & Prevention showing that pregnancy related deaths in the U.S. are higher than in any other rich country. A story appearing in the January 2019 issue of the National Geographic explores the problem in an up close and personal way. The title and subtitle summarize the situation very nicely:

Why giving birth in the U.S. is surprisingly deadly 

Black mothers are particularly at risk.

Better basic care could help.

In the United States the problem is marked by two particularly alarming statistics: African-American women are about three times as likely to die of pregnancy-related causes as white women, and more than 60 percent of maternal deaths are preventable, according to the Centers for Disease Control and Prevention (CDC).
“We have higher maternal mortality than much of the rest of the developed world; we are capable of doing the best in the world,” says William Callaghan, the CDC’s chief of maternal and infant health. The CDC defines a pregnancy-related death as a woman who dies while pregnant or within one year of the end of her pregnancy.
“When deaths are reviewed and we see what the contributing factors were, there are so many instances where communication was not carried out correctly, where people didn’t recognize urgency, or when the patient wasn’t listened to, or the delay in reaction.”
Why are death rates higher among African American women? Here is one possibility:
Valerie Montgomery Rice, president and dean of the Morehouse School of Medicine in Atlanta, Georgia, believes that not only do bias and racism build up to affect the health of black women over time, but that stress from racism and poverty may have adverse effects as early as in utero or soon after a baby is born.
This is consistent with the effect of Trump administration attitudes towards immigrants on the health of Latinas and their babies, as I noted not long ago

And, of course, I have often noted that the former slave states of the south have the highest death rates in the country, and these are areas with high proportions of African Americans. Where you live still matters when it comes to your health.

Saturday, December 15, 2018

Visualizing the Changing Urban Population

I happen to really like 3D maps. I think that they are terrific visualization tools, and so I was very pleased when Todd Gardner pointed us to a new set of such maps created by the Human Terrain project at Pudding, and yesterday summarized by Nick Routley at the Visual Capitalist. Here, for example, is the map for Dallas, Texas, showing the change in population at the local level between 1990 and 2015:



The green bars represent population increase over time, showing that the northern suburbs are where the metro area has. been growing. This helped explain to me why there is now a Frisco Bowl, where my San Diego State Aztecs will play the Ohio Bobcats next week. I've been in and out of Dallas many times over the years, but had not paid attention to those northern suburbs until I saw this map. And, while you might think that a 3D map should show a hole where there is population decline, these maps put the negative growth in red instead of green. Thus, you can see that the southern suburbs of Dallas have experienced a loss of population since 1990. My late father-in-law was born in Seagoville, just off the map below Mesquite, and I don't think he would be surprised at that demographic change.

Wednesday, December 12, 2018

Mexico is Now Dealing With the US Undocumented Immigration Issue--UPDATED

With any luck you saw the Pew Research report a couple of weeks ago in which they estimate that the number of undocumented immigrants in the U.S. has been declining. This is due mainly to the fact that the migration of undocumented Mexicans into the U.S. has dropped precipitously over the last decade as the birth rate in Mexico has fallen and the economy has grown. The “demographic fit” between the U.S. and Mexico has pretty much ended, but that doesn’t mean the end of undocumented immigration.

My thanks to Professor Rubén Rumbaut for pointing me to an article from the Center for American Progress highlighting the increasingly important role that Mexico is playing in coping with migrants. In the first place, they have been coping with a large number of Mexican migrants who have been deported from the U.S. back to Mexico. The Pew report reminds us that the number of deportations of people back to Mexico increased dramatically first under the Bush administration and then particularly under the Obama administration. Indeed, I noted a few years ago that Obama was being called the “deporter-in-chief.” This has not been easy for Mexico to deal with, as these people are typically dumped across the border with few resources of their own. The Mexican government’s programs are under-funded although at least some of the slack has been taken up by non-profit organizations.

The second and more dramatic issue is the role being played by Mexico as an increasing number of migrants leave the “northern triangle” countries of Guatemala, El Salvador, and Honduras, to seek refuge in the north from the horrific conditions they face in their respective countries.

Mexico is facing new challenges as millions of Mexican migrants return from the United States and Central Americans seek asylum and safe passage through the country. Historically, Mexico has been a predominantly immigrant-sending country. Political unrest and violence in Central America, heavy-handed immigration enforcement in the United States, and increased development in Mexico has made Mexico a country of destination, return, and transit. Each of these roles demands a unique, humane, and thorough policy response.
My own view is that the United States needs to provide governmental support to Mexico to deal with this situation, while at the same time encouraging public-private investments in Mexico and the northern triangle countries to improve the quality of life and thereby reduce the pressures people face to get out of there and head north. Like everything associated with migration, this won’t be easy, but the longer we wait, the harder it will be.

UPDATE: Today the Washington Post reported that the U.S. will provide more aid to Mexico and Central American governments in renewed attempts to cut down the migration from Central America.
The United States announced a total contribution of $10.6 billion, most of which will be allocated from existing aid programs. Around $4.5 billion of that sum comes from new loans, loan guarantees and other private-sector support that could become available through the Overseas Private Investment Corporation (OPIC).
The Mexican government said it would contribute $25 billion to development in southern Mexico over five years, which López Obrador has suggested could serve as a source of employment to Central Americans who are granted work visas. 
López Obrador “has to take advantage of this opportunity, this honeymoon with Trump and Mexico,” said Rafael Fernández de Castro, a former senior Mexican foreign affairs official and now director of the Center for U.S.-Mexican Studies at the University of California at San Diego.
The WP thinks this may be mostly symbolic, but at least it is a step in the right direction. 

Monday, December 10, 2018

UN Approves Migration Pact

The United Nations has been working on a global migration pact for quite a while now, and today there were 165 countries who signed on to it. The United States and several other countries chose not to participate, "citing concerns about migrant flows and national sovereignty" as the New York Times reported. 
The text of the accord was approved in July by every member of the United Nations except the United States. But it has since gotten caught up in a nationalist movement in Europe that has centered on the issue of immigration and prompted around a dozen countries to reject the compact outright, or to pull back from endorsing it in Morocco.
The United Nations has insisted all along that this pact was not a mandate for rich countries to take in poor migrants. Rather, it was an acknowledgement that migration is a fact of life, and every country should make good decisions about how to cope with it.
The Global Compact for Safe, Orderly and Regular Migration, a 34-page document, asserts that “no state can address migration alone” and outlines 23 objectives. They include the collection of better data on the movement of migrants, the strengthening of legal paths to migration, efforts to combat human trafficking and cooperation to ease the safe return of migrants to their countries of origin.
Most migration is not from “south to north” but between developing countries, he said, seeking to dispel other falsehoods and noting that there were more African migrants in other African countries than there are in Europe.
Moreover, migrants provide a boost to the economies of their host countries as well as to their countries of origin, he said. Migrants spend 85 percent of their earnings in the countries where they work. They send the remaining 15 percent home in remittances, providing vital lifelines to developing countries that add up to three times the value of official development assistance from richer nations.
The fact that most migration is not "south to north" is important to remember, but of course that does not assuage people who want to raise alarms about the south to north migration that they feel affects them. And, to be sure, part of the global compact is an attempt to address xenophobia and the integration of migrants into societies. These are not easy to do and almost always take more time than people think they should. 

Friday, December 7, 2018

Age at First Birth is Steadily Rising

A couple of weeks ago, I mentioned that data from the Current Population Survey show that the age at marriage in the United States has been been steadily rising. This week a closely related analysis shows that the age at first birth has also been going up. Indeed, between 1970 and 2017 it went from 21.4 years to 26.8 years. These data were put together by Karen Guzzo and Krista Payne at Bowling Green State University's National Center for Family & Marriage Research. 

The results are especially interesting because they show that there are clear geographic differences in the delay in first birth. Thus, while the age at first birth has been going up everywhere, it is going up much more in some states than in others, as you can see in the map below.


The increases have been greatest along the west coast and in the northeast. Two southern states--Arkansas and Mississippi--share the honors of having the lowest age at first birth in both 1970 and 2017. By contrast, Massachusetts, Connecticut, and New Jersey were all consistently at the older ages with respect to first births in both 1970 and 2017. However, in 1970 the difference between the youngest and oldest was considerably less (22.5 - 20.2 = 2.3) than it was in 2017 (29.7 - 24.1 = 5.6). 

These results suggest yet another way in which the population of the United States is growing more diverse, since the differences in delaying the first birth are both a cause and a consequence of a wide array of changes that are taking place all over the country. 

Wednesday, December 5, 2018

It's Still 1986 When it Comes to Immigration Reform

If you watched today's memorial service for President George H.W. Bush, you had to have laughed and cried a lot, especially at the stories told by Alan Simpson, a former Senator from Wyoming and a good friend of the late President Bush. He was essentially ambushed politically after co-sponsoring the Simpson-Mazzoli Immigration Reform and Control Act of 1986. The Daily Beast talked to him about it today:
Designed to stem the tide of illegal immigration, it was passed by a Democratic House and Republican Senate and signed into law by President Reagan. Former Wyoming Republican Senator Alan Simpson co-sponsored the legislation together with Democratic Rep. Romano Mazzoli from Kentucky. Neither lawmaker seemed an especially natural fit for an issue with little direct impact on their constituents, but as chairs of their respective immigration subcommittees, they were thrust together into a position of leadership.
It was a model for bipartisan congressional problem solving, but the legislation that resulted is widely viewed as a failure—part of the problem, not the solution. It built on a three-legged approach—controlling the borders, increasing the number of visas for agricultural workers, and offering “earned legalization” to immigrants who had illegally entered the country before 1982. Instead of slowing the flow of people across the border, illegal immigration accelerated, and the politics of reform stretched to a breaking point. The cross-party alliances that had worked so well in the ‘80s crashed and burned as an effort launched by President Bush together with Senators Ted Kennedy and John McCain in 2006 imploded in the face of grassroots opposition.
Why didn't it work? Simpson argues that the "guts" were taken out of the bill before it could be passed. The visas for agricultural workers--essentially a guest-worker program to replace the earlier Bracero program--were viewed as being dangerously close to a national ID card, to which people on both the political right and left objected. Without this in the bill, employers couldn't know who they were hiring and could thus be accused of hiring undocumented immigrants.

Three decades later, Simpson sums up where we currently stand with undocumented immigrants:
“They (critics of reform) think these people are expendable,” says Simpson. “If you think America is good to them, you’re crazy as hell. They’re used and exploited and they work for four bucks an hour. It’s a pretty sick country that uses human beings like this. They sit on corners waiting for some guy to come by to get the gardening done at his estate. It’s a sad situation; it’s not pleasant to watch.”
Also not pleasant, as I noted yesterday, is that living in fear is not good for women and their babies, either. 

Tuesday, December 4, 2018

Laws Threatening Immigrants Can Affect Birth Outcomes

My thanks to Professor Rubén Rumbaut for linking me to a paper just accepted for publication (and now available online) in the American Journal of Epidemiology. The paper is titled "Restrictive Immigration Law and Birth Outcomes of Immigrant Women," and its authors--Florencia Torche and Catherine Sirois--are at Stanford University. The paper examines what happened to pregnant women in Arizona when that state passed a very aggressive anti-immigration law (SB 1070) back in 2010. The short answer is that the probability increased that an undocumented woman would give birth to a low-weight baby.
Prenatal exposure to the bill resulted in lower birthweight among Latina immigrant women, but not among US-born white, black, or Latina women. The decline in birthweight resulted from exposure to the bill being signed into law, rather than from its (limited) implementation. The findings indicate that the threat of a punitive law, even in the absence of implementation, can have a harmful effect on the birth outcomes of the next generation.
The low birthweight data are especially noteworthy because many of us have over time demonstrated that Hispanic women in the United States tend to have better outcomes than non-Hispanic Whites. To be sure, Professor Rumbaut and I published research on this more than 20 years ago:Rubén G. Rumbaut and John R. Weeks, "Unraveling a Public Health Enigma: Why do Immigrants Experience Superior Perinatal Health Outcomes?" Research in the Sociology of Health Care, 13(B): 337-391, 1996. So, when the results show that birth outcomes are worse, not better, we know that something is going on. This is a case where correlation is apt to be showing causation.

As the authors point out, these children are now U.S. citizens and will be tomorrow's workers and voters. It was reckless and pointless to have harmed their health during pregnancy. These are among the many, many reasons why Congress needs to get together and craft a genuine immigration reform bill.

Sunday, December 2, 2018

Is 60 the New 50? Chronological vs. Biological Aging

CNN posted a very relevant demographic article a couple of days ago comparing biological aging with chronological aging. The focus was on the research of Morgan Levine at Yale Medical School:
Essentially, everyone has two ages: a chronological age, how old the calendar says you are, and a phenotypic or biological age, basically the age at which your body functions as it compares to average fitness or health levels.
People with a biological age lower than their chronological age have a lower mortality risk, while those aging older from a biological standpoint have a higher mortality risk and are potentially more prone to developing the diseases associated with the higher age range. 
But perhaps what's most important here -- unlike results from genetic testing -- is that these are measures that can be changed. Doctors can take this information and empower patients to make changes to lifestyle, diet, exercise and sleep habits, and hopefully take steps to lower the risk and improve their biological age.
This is very important and useful work, since very few of us want to experience a longer life expectancy that involves many more years of disability. Indeed, researchers at the Institute of Health Metrics and Evaluation at the University of Washington have given us Disability-Adjusted Life Years (DALYs) that attempt to take into account the difference between biological and chronological aging (see Chapter 5 of my text for a discussion). The article didn't mention that. 

However, the most important omission in the CNN article was not mentioning that Dr. Levine's work is being done in collaboration with Dr. Eileen Crimmins and her colleagues at the University of Southern California. Earlier this year the two of them published an article in the journal Demography titled "Is 60 the New 50? Examining Changes in Biological Age Over the Past Two Decades." And a clue to how important this is to demographers is the fact that Dr. Crimmins has just been elected President-Elect of the Population Association of America. 

Friday, November 30, 2018

Suicides and Drug Overdose Deaths are up; Life Expectancy is Down

I recently blogged about the upward trend in suicide in the U.S., which bucks the global trend of declines in suicides. Yesterday, the U.S. Centers for Disease Control and Prevention put out three new reports on death in America (no, not death "to" America)--the news is all-bad, as the Associated Press reports:
Suicides and drug overdoses pushed up U.S. deaths last year, and drove a continuing decline in how long Americans are expected to live. 
Overall, there were more than 2.8 million U.S. deaths in 2017, or nearly 70,000 more than the previous year, the Centers for Disease Control and Prevention said Thursday. It was the most deaths in a single year since the government began counting more than a century ago. 
The increase partly reflects the nation’s growing and aging population. But it’s deaths in younger age groups — particularly middle-aged people — that have had the largest impact on calculations of life expectancy, experts said. 
It is very clear that the widespread availability of opioids is a key factor behind this increase--the means available to kill yourself either deliberately (suicide) or accidentally (drug overdose) are more numerous than ever. But what is the underlying motivating factor? In my earlier blog I mentioned the "sea of despair" that seems to have engulfed middle-aged Americans--especially non-Hispanic Whites. The AP story has a similar story line:
Dr. William Dietz, a disease prevention expert at George Washington University, sees a sense of hopelessness. Financial struggles, a widening income gap and divisive politics are all casting a pall over many Americans, he suggested. “I really do believe that people are increasingly hopeless, and that that leads to drug use, it leads potentially to suicide,” he said.
This gets us back to the increasingly important issue of wealth and income inequality. It was brought to center stage a a few years ago by Thomas Piketty, and it is almost certainly at the root of many of the social problems we are seeing in the richer nations. 

Tuesday, November 27, 2018

Two New Cool Tools for Demographers

I learned today about two new cool tools for demographers interested in what's going on in the world. First, thanks to Debbie Fugate for alerting me to the new POPGRID website hosted by CIESEN at Columbia University. As usual, Alex de Sherbinin has assembled a lot of good interactive data. Here's how he explains what's available:
The POPGRID Data Collaborative brings together the major producers of gridded population and human settlement data, as well as key users and stakeholders, to coordinate efforts and better respond to user needs. POPGRID is pleased to announce the launch of a Web site that guides users on the products available and their characteristics (including comparison tables), and a map tool (POPGRID Viewer) that enables visual and quantitative comparisons among data sets.
Then Steve Ruggles alerted us to the second great thing coming along today--a new tool from the IPUMS project at the Minnesota Population Center:
IPUMS is proud to announce the arrival of a bouncing baby cross-tabulator to the family! Grab your mobile devices and give IPUMS Abacus a try. Cross-tabulated IPUMS USA Census/ACS data are now at your fingertips! Get started: http://usa.abacus.ipums.org
As always, you need to get out there and try these tools and see what works for you.

Sunday, November 25, 2018

Suicide Rates are Declining Globally, But Not in the U.S.

This week's Economist has a very nice summary of the global trends in suicide (or "intentional self-harm" as it is known in the International Classification of Diseases). In the world as a whole, the rates are declining, but the United States is bucking that trend.
Globally, the rate has fallen by 38% from its peak in 1994. As a result, over 4m lives have been saved—more than four times as many people as were killed in combat over the period. The decline has happened at different rates and different times in different parts of the world. In the West, it started long ago: in Britain, for instance, the male rate peaked at around 30 per 100,000 a year in 1905, and again at the same level in 1934, during the Great Depression; among women it peaked at 12 in 1964. In most of the West, it has been flat or falling for the past two decades.

America is the big exception. Until the turn of the century the rate there dropped along with those in other rich countries. But since then, it has risen by 18% to 12.8—well above China’s current rate of seven. The declines in those other big countries, however, far outweigh the rise in America.
There are a couple of important reasons for the global decline--urbanization and women's liberation. Although in most societies men (especially older men) tend to have the highest suicide rates, in China and India (the world's two most populous countries), the burden of suicide was often on women trapped in a relationship and family that was not of their choosing. Indeed, a few years ago I blogged about the fact that urbanization in China seemed to be lowering their suicide rate.

The graph below, based on data from the University of Washington's Institute for Health Metrics and Evaluation, compares the recent trends among several countries, and you can the U.S. pattern is different from the global pattern:



In the U.S., we have two important things that contribute to the rise, and I've blogged about both in the past: (1) the "sea of despair" that has taken root especially among white working class Americans; and (2) the availability of guns. Both of these are within the purview of public policy, and the lack of legislative initiatives on these underlying contributors to suicide almost certainly explains the rise in the rate of suicides in the U.S.

Friday, November 23, 2018

Is There a Looming White Minority in the U.S.?

A front page story in today's NYTimes by Sabrina Tavernise has the obviously provocative headline:
"Why the Announcement of a Looming White Minority Makes Demographers Nervous." At issue is the Census Bureau's classification of race and ethnicity, and how that factors into their population projections, and then how people interpret those data. Is the fear (stoked by Census Bureau projections) that Whites are on the verge of becoming a minority group in the country one of the things that has ramped up populist rhetoric?
In a nation preoccupied by race, the moment when white Americans will make up less than half the country’s population has become an object of fascination.
For white nationalists, it signifies a kind of doomsday clock counting down to the end of racial and cultural dominance. For progressives who seek an end to Republican power, the year points to inevitable political triumph, when they imagine voters of color will rise up and hand victories to the Democratic Party.
But many academics have grown increasingly uneasy with the public fixation. They point to recent research demonstrating the data’s power to shape perceptions. Some are questioning the assumptions the Census Bureau is making about race, and whether projecting the American population even makes sense at a time of rapid demographic change when the categories themselves seem to be shifting.
This is not a new topic of conversation. You may recall my blogging about it a few months ago. As Dowell Myers at the University of Southern California said back then, and again in today's story, the Census Bureau defines "white" in a very narrow way that does not take into account the kind of intermarriage that is going on and which, in essence, is continuing to have a "melting pot" effect. The way racial/ethnic categories are defined creates the image of a reality that doesn't reflect the real world. On that point, here is my favorite quote from the story:
Mary Waters, a sociologist at Harvard University [more about her at this blog post], remembered being stunned when she saw the research. “It was like, ‘Oh wow, these nerdy projections are scaring the hell out of people,” she said.
"The question really for us as a society is there are all these people who look white, act white, marry white and live white, so what does white even mean anymore?” Dr. Waters said. “We are in a really interesting time, an indeterminate time, when we are not policing the boundary very strongly."
Why does the Census Bureau even ask these questions? When Richard Nixon was President he wanted to get rid of them, but the argument then, as now, is that they help us track discrimination and other kinds of inequalities. But, are these data more dangerous than helpful? The country needs to have a big discussion about this.

A closely related problem is the extent to which the concern about race/ethnicity gets mixed in with the migration policy issue. Read the interview with Hilary Clinton about migration in today's NYTimes and see what you think...

Sunday, November 18, 2018

Pregnancy Related Deaths Higher in US than any other Rich Country

The New York Times today published an article that fortunately has gotten a lot of attention. It details the tragedies of women and their babies dying because of pregnancy-related problems. To be sure, there is a reason why people have always said that "getting pregnant may be the most dangerous thing a woman can do," but maternal mortality rates have come down dramatically all over the world. Yet, here in the United States the rates are higher than in any other rich country, according to data compiled by the World Health Organization, and they have been going up, not down, according to the U.S. Centers for Disease Control and Prevention. Here's their graph of the trend:


The reason for the increase, and for the fact that the U.S. is higher than other rich countries seems to have a simple remedy--examine every such incident and figure out what went wrong and circulate that information so health practitioners won't keep making the same mistakes. You might think that everyone would want to do that, but sadly you would be wrong.
It wasn’t until 2003 that states started adding a pregnancy check box to death certificates, and some didn’t do so until the past two years. “Thiscreated a data mess where nobody could figure out what the national trends were,” she said. She described this as “a huge missed opportunity for intervention in conjunction with the Millennium Development Goal.” At the same time, “the National Center for Health Statistics, which is the government agency responsible for publishing maternal mortality data, completely stopped publishing it.” 
The only exception in the United States was California, where, in 2006, the Stanford University School of Medicine worked with the state to create the California Maternal Quality Care Collaborative. The initiative developed “quality improvement tool kits” that doctors and hospitals could download. They included detailed instructions about best practices for various preventable complications that can arise during or after pregnancy, like hemorrhaging and pre-eclampsia.
As a result of this initiative, between 2006 and 2013, California saw a 55 percent decrease in the maternal mortality rate, from 16.9 to 7.3 deaths for every 100,000 live births. During that same period, according to The Washington Post, the national rate increased — from an estimated 13.3 to 22 deaths in 100,000.
Next door, in Canada, the rate is 7 per 100,000, and in Switzerland it is 5, just to give you a sense of where the U.S. stands. 

Wednesday, November 14, 2018

People Are Waiting Longer to Get Married

One of the central points raised by the theory of the Second Demographic Transition is that young people in richer countries are growing up with ideas of what to do with their lives besides the time-honored tradition of marrying and having kids. Today the U.S. Census Bureau reminded us of this trend with data from the Current Population Survey. Here's the pattern over time in average age at marriage for males and females in the U.S.:


The graph starts back in 1890 when the rise in the age at marriage (relative to earlier years not shown in the graph) was associated with the beginning of the decline in fertility. This was prior to the advent of effective methods of contraception, so delaying marriage (which in those days also meant delaying the onset of sexual activity) was a way of limiting fertility. The post-WWII period changed all of that and set in motion a round of early marriage and childbearing that produced the baby boomers. But the younger generations have been consistently delaying marriage, although not necessarily delaying sexual activity. In the process, they are creating a very different set of family and household relationships than we've experienced before. This is, of course, why family demography is such a key element in modern social science.

Thursday, November 8, 2018

The Demographics of the Far Right Movement in Germany

My thanks to a reader who pointed me to an article in the NYTimes that I had missed a few days ago, about the demographic factors in East Germany that are helping to drive the far right movement in that country. It seems to take us back to the "tearing down of the wall." From this distance that just seemed like a universally good thing (well, unless you were a big shot in East Germany's Communist Party). However, this article suggests that West German men came in to run businesses and governments in East Germany, and East German women were at the same time heading west, leaving behind a lot of spouseless and jobless East German men. The story starts out with an interview of one of these men...
...Frank Dehmel was on the streets of East Germany in 1989. Every Monday, he marched against the Communist regime, demanding freedom and democracy and chanting with the crowds: “We are the people!” Three decades later, Mr. Dehmel is on the streets again, older and angrier, and chanting the same slogan — this time for the far right.
He won freedom and democracy when the Berlin Wall came down 29 years ago on Nov. 9. But he lost everything else: His job, his status, his country — and his wife. Like so many eastern women, she went west to look for work and never came back. To understand why the far right is on the march again in Germany, it helps to understand the many grievances of its most loyal supporters: men in the former Communist East.
Although Angela Merkel--Germany's leader for the past 13 years--is from the East, there is the sense among these men that she betrayed them, and that was even before she encouraged a million asylum seekers (largely from the mess in the Middle East) to settle in Germany. 
“We have a crisis of masculinity in the East and it is feeding the far right,” said Petra Köpping, minister for integration in Saxony. When Ms. Köpping took office in 2014, she thought her job was to integrate immigrants. But as hundreds of thousands of asylum seekers began arriving in Germany a year later, a middle-aged white man heckled her at a town-hall-style meeting. “Why don’t you integrate us first?” the man had shouted. That question, which has since become the title of a book written by Ms. Köpping, prompted her to tour her eastern home state and interview dozens of angry men. The disappointed hopes and humiliations of 1989, she found, still fester.
And Ms. Köpping notes that when the wall came down, it was women who were most likely to jump at the new opportunities:
Long before the #MeToo movement, Communism succeeded in creating a broad class of women who were independent, emancipated, often better educated and working in more adaptable service jobs than eastern men.

After the wall came down, the East lost more than 10 percent of its population. Two-thirds of those who left and did not come back were young women.
It was the most extreme case of female flight in Europe, said Reiner Klingholz, director of the Berlin Institute for Population and Development, who has studied the phenomenon. Only the Arctic Circle and a few islands off the coast of Turkey suffer comparable male-female imbalances.
In large swaths of rural eastern Germany, men today still outnumber women, and the regions where the women disappeared map almost exactly onto the regions that vote for the Alternative for Germany today.
This is an important story for several reasons, including the fact that the rise of the Far Right in Germany seems to have a different set of underlying (albeit clearly still demographic) causes than those in the United States (and probably anywhere else). We need to keep that in mind as we digest the news. 

Tuesday, November 6, 2018

Demographics of Homelessness

Voters in San Francisco today will decide the fate of a local proposition aimed at coping with the growing number of homeless persons in that city. Indeed, homelessness is generally on the rise in California, and Los Angeles passed a proposition two years ago to deal with the issue. Although there are a variety of causes, a NYTimes story adds a new wrinkle:
Dennis Culhane, an expert on homelessness at the University of Pennsylvania, says there is also a much more unappreciated factor: demographics.
The current acute homelessness crisis in cities across California corresponds with the coming-of-age of the millennial generation, which at its peak in the mid-1990s had more births than at any time since the baby boomers of the 1950s and ’60s. A previous bout of severe homelessness came in the 1980s, when the second half of the baby boomers were in their 20s.
What does demography say about the future of homelessness in California?
Nationally, births declined for seven years from the millennial generation peak of 4.2 million. There may be some hope in that. Yet the millennial cohort will be with us for decades longer — and Dr. Culhane believes it will take a “massive infusion of resources” to assist the neediest among them. “At the scale of homelessness we are witnessing on the West Coast, little pilot efforts here and there are not going to make a dent,” he said.
There is also a state-wide initiative on the ballot--Proposition 10--that would allow widespread rent control in an attempt to keep rents from rising to the point that people are forced out of their homes--and thus into a state of homelessness. Rising rents and rising income inequality in California are also creating demographic pressures in the state. This is yet another good example of demography as "a drama in slow motion."  Stay tuned!

Thursday, November 1, 2018

Immigrants Actually Subsidize US Health Care, Rather than Bringing Diseases

There has been a huge deal made about the demographic characteristics of the "caravan" of immigrants heading through Mexico on their way from Central America to the United States, where they apparently hope to seek asylum. Fox News and the Trump administration have repeatedly suggested that they are bringing small pox and leprosy. This is clearly nonsense. The World Health Organization declared back in 1980 that small pox had been eradicated from the world (thank you, vaccinations!!). Leprosy is still with us, but almost all cases are concentrated in Africa and South Asia, so it is unlikely that anyone in this group heading north has been exposed to the disease. We can put those negative ideas to bed with regard to this group of migrants, or any other group of people coming into the U.S. (all of whom are, of course, subjected to medical exams in all events).

What about the positive aspects of immigrants? In my last post, I mentioned that the Baby Boomers are really going to need some young immigrant workers to help pay for their retirement. It also turns out that immigrants are a net economic benefit to the health care system in this country. Many thanks to Professor Rubén Rumbaut for a link to a blog post in AcademyHealth by a physician who is Director of Research at the Institute for Community Health in Massachusetts.
Published in the October edition of Health Affairs, findings from our study using nationally representative data show that immigrants heavily subsidize private insurance of US-born enrollees and boost profits of private insurers.
For many immigrants, such as undocumented immigrants or those residing legally in the US for fewer than five years, private insurance is often the only coverage option. Because immigrants are mostly working-age adults with high rates of labor force participation, many enroll in job-based coverage.
Our study was the first to look at immigrants' role in financing private health insurance. We used data from the Medical Expenditure Panel Survey and the Census Bureau’s Current Population Survey to determine immigrants' premium contributions to private insurance, including premiums that employers paid on their behalf. Then we tabulated all payments that private insurers made to doctors, hospitals, and other providers for immigrants' care to determine whether immigrants paid more or less into private insurance than they used. Undocumented immigrants, who generally use little medical care, generated the largest surplus at $1,445 per enrollee. The surplus contributed by immigrants offset a per enrollee deficit among US born individuals of $163. Previous research shows that insurance outlays for immigrants are low because they are relatively young and healthy, and often face linguistic and other barriers to care.
This is the "real" side of immigration. The U.S. is a nation of immigrants, and the only people who can realistically complain about that are Native Americans. 

Tuesday, October 30, 2018

How Big a Burden Will Boomers Be?

Much of the demographic "press" over the past few months has been about the increasing diversity in the ethnic identity of Americans. To be sure, this has been an underlying message of "concern" about this emanating from the Trump administration. However, in the background is a bigger demographic change--the aging of the Baby Boomers. The U.S. Census Bureau just today posted a demographic snapshot of the older population.
The growth of the U.S. population age 65 and older exceeds that of the total population and the popula­tion under age 65.  Lower birth rates and increased longevity have led to this rapid growth not just in the United States but across the world.  So what does it mean to be a part of this increasingly larger segment of American society?
The website allows you to click on different characteristics for different states and make your own comparisons about the current older population. Very cool!

But what those maps don't tell us is how well prepared the Baby Boomers are for old age as they rapidly move into this time of their life. A story on CBS News today suggests that the picture is not as good as we might hope.
Boomers have accumulated less household wealth and carry more debt relative to those who've come before them, according to the Sightlines report recently released by the Stanford Center on Longevity (SCL). Given that boomers will likely live longer and rack up higher lifetime medical costs than prior generations, the inevitable conclusion is that boomers will face some tough challenges during their retirement years.
The Sightlines report compares the household wealth of four generations as of 2014:
    Older silent generation, born before 1942
    War babies, born from 1942 to 1947
    Early boomers, born from 1948 to 1953
    Mid-boomers, born from 1954 to 1959
These are close to, although not identical to, the generational breakdowns that demographers typically use, but still useful.
Boomers are carrying more debt of all kinds -- mortgage debt, student debt and credit card debt -- compared to older generations. For example, the proportion of homeowners age 65 and older who haven't paid off their mortgage rose to 35 percent in 2012, up from 23.9 percent in 1998. The median outstanding balance almost doubled, from $44,000 to $82,000.
Boomers will need to learn how to move forward with their current circumstances. They can't go back in time and save more for retirement or accumulate less debt. And it'll be very difficult for them to save enough in their remaining work years to make up for retirement savings shortfalls.
The bottom line is that Baby Boomers are poised to be a larger burden to the younger generation than previous generations of people moving into the older years. There are lots of them, and they are not very well-prepared financially for retirement. Cutting Social Security and Medicare benefits (as some Members of Congress have proposed doing to pay for the big tax cuts earlier this year) will not help. The obvious solution is to recruit more immigrants, but that doesn't seem like a popular option at the moment...

Friday, October 26, 2018

Cohabitation and Divorce: A Case of Complicated Connections

Thanks to PAA President Wendy Manning for the link to a recent article in The Atlantic discussing two academic papers that seem to come up with different conclusions about the relationship between cohabitation and divorce after looking at the same dataset.
Late last month, the Journal of Marriage and Family published a new study with a somewhat foreboding finding: Couples who lived together before marriage had a lower divorce rate in their first year of marriage, but had a higher divorce rate after five years. It supported earlier research linking premarital cohabitation to increased risk of divorce.
That study was conducted by Michael Rosenfeld at Stanford and Katharina Roesler at Quora. 

As evidence of the importance of this topic to family demography, I noticed that the authors referenced four different Past Presidents of the PAA--Larry Bumpass, Andrew Cherlin, Arland Thornton, and Linda Waite. 
But just two weeks later, the Council on Contemporary Families—a nonprofit group at the University of Texas at Austin—published a report that came to the exact opposite conclusion: Premarital cohabitation seemed to make couples less likely to divorce. From the 1950s through 1970, “those who were willing to transgress strong social norms to cohabit … were also more likely to transgress similar social norms about divorce,” wrote the author, Arielle Kuperberg, a sociology professor at the University of North Carolina at Greensboro. But as the rate of premarital cohabitation ballooned to some 70 percent, “its association with divorce faded. In fact, since 2000, premarital cohabitation has actually been associated with a lower rate of divorce, once factors such as religiosity, education, and age at co-residence are accounted for.”
That report is actually based on a paper just accepted for publication in the journal Marriage & Family Review, and in that paper the author references six different Past Presidents of the PAA--Larry Bumpass, Andrew Cherlin, Paul Glick, Daniel Lichter, S. Philip Morgan, and Arland Thornton. 

Both papers utilize data from the National Survey of Family Growth and of considerable interest is that both papers include the following graph illustrating the genuinely revolutionary change in cohabitation patterns in the U.S. The chart below, taken from Kuperberg's article, graphs the percentage of first marriages preceded by cohabitation with the current spouse, according to the year of marriage.


Given the recent rapid rise in cohabitation in the U.S., it should not be surprising that researchers are finding what seem like conflicting findings. It is more likely the case that things are so complicated that it is very difficult to pin down patterns in and causes of the observed changes.



Sunday, October 21, 2018

The Second Demographic Transition Comes to America

The Washington Post recently published a widely retweeted story (at least among demographers!) about the continued decline in fertility in the U.S., focusing on the fact that every demographic group has experienced the drop. 
The CDC said Wednesday that the total fertility rate — a theoretical figure that estimates the number of births a woman will have in her lifetime — fell by 18 percent from 2007 to 2017 in large metropolitan areas, 16 percent in smaller metro areas and 12 percent in rural areas. A similar downward trend holds for white, black and Hispanic women.
Low fertility in the U.S. is not, in and of itself, news. I last blogged about this only three months ago. But this new analysis of the birth data takes us into the comparisons among groups that we hadn't seen before. So, what's going on? The Washington Post sought answers from demographers:
The University of Pennsylvania’s Hans-Peter Kohler, who studies fertility and birthrates, said the data indicated that many shifts affecting fertility are occurring “in the transition to adulthood.” The biggest recent drops in birthrate have been among teenagers as well as people in their 20s. In 2016, the teen birthrate hit at an all-time low after peaking in 1991.
“The declining total fertility rates are children not born in the moment, but the hope is that they are delayed, not forgone,” Kohler said. “The exact details we won’t know until the young adults who are currently delaying having children are in their 30s or 40s.”
William H. Frey, a demographer with the Brookings Institution, said that what struck him about the new report is the figures on Hispanic women, who have traditionally had high fertility rates. From 2007 to 2017, Hispanic women experienced a 26 percent drop in fertility rates in rural areas, a 29 percent drop in smaller metro areas and a 30 percent decline in large metro areas.
The reality is that the Second Demographic Transition--the decline of fertility to below replacement levels in rich countries--has finally caught up with America. It seemed for awhile as though we might somehow avoid it, but these new data illustrate the amazing changes in family demography that have been taking place over the past couple of decades. Women are delaying marriage and child-bearing--or avoiding one or both altogether at levels that are historically unprecedented. They are living for themselves, not just for their husbands and children. As in Europe, the percent of births that are out-of-wedlock is historically high, as Bloomberg reported a few days ago, building on data from the United Nations Population Fund (UNFPA). 
The data show such births in the U.S. and EU are predominantly to unmarried couples living together rather than to single mothers, the report says. The data suggest that societal and religious norms about marriage, childbearing and women in the workforce have changed, said Kelly Jones, the director for the Center on the Economics of Reproductive Health at the Institute for Women’s Policy Research.
Welcome, America, to the Second Demographic Transition. We don't know how this is going to turn out, but we're clearly in the middle of it. 

Monday, October 15, 2018

Tanzania Expels Pregnant Girls From Schools

Scarcely more than a month ago I blogged about the President of Tanzania telling women that they should stop using birth control. Their job was to have babies and, presumably, not try to compete with men in society. Another approach to this extreme level of gender inequality is to expel girls from school if they become pregnant. CNN reports that:
It happens twice a year at Arusha Secondary School. Each one of the school's 800 female students is accompanied into a toilet and told to pee in a jar. Outside the cubicle, a teacher waits to make sure the samples are not swapped. The girls are taking compulsory pregnancy tests. And if they come back positive, the student is expelled immediately. The tests have been happening at this school, for students from grades eight and up, for three years.
Tanzania uses a morality clause in a 2002 education law to give schools the legal framework needed to expel students -- the practice originally dates back to the 1960s. The law has been more widely applied since President John Pombe Magufuli took office in 2015.

Last June, Magufuli, dubbed "The Bulldozer," went a step further, announcing that pregnant students would not be allowed to return to school after giving birth. "In my administration as the President no pregnant girl will go back to school... she has chosen that of kind life, let her take care of the child," he said at a public rally in 2017. His speech removed any discretion schools had over how they enforced the morality rule.
Expelling a pregnant girl from school sets her life on a different course than if she were able to continue her education even while having to care for her child. Furthermore, the schools do not teach sex education nor are contraceptives available. If her parents don't teach her about sex, the CNN writers suggest that many of these girls will not be aware that sexual intercourse can lead to pregnancy. So, if the whole idea is to scare girls into not getting pregnant while in school, a little bit of education along those lines would clearly be beneficial. In theory, any male who impregnates a schoolgirl could be sent to prison, but the CNN report does not indicate that this has ever happened.

The CNN report also summarizes the situation in Tanzania with respect to teenage pregnancies:
Around a quarter of Tanzanian girls aged between 15 and 19 are mothers or pregnant. Child marriage is still prevalent in the country -- 37% of women aged 20 to 24 having been married before they turned 18, according to official data from 2010, the latest available. More than a quarter of girls married before the age of 19 have husbands who are 10 or more years older, according to the same survey.
I should note that the 2010 data are not the most recent. The results of the 2015-16 DHS in Tanzania are available online at DHSProgram.com. Sadly, they show that teenage pregnancy has increased slightly since 2010, rather than declined.

Saturday, October 13, 2018

The Power of Plants to Save the Planet

The new UN report on the quickness with which climate change will dramatically our lives has attracted more attention than I was worried it would, and I was especially drawn to an article in the Washington Post reminding us that it is not just cars, trucks, and planes that are the problem--we are ruining the environment with our unsustainable pattern of food production.
The human population has reached 7.6 billion and could number 9 billion or 10 billion by midcentury. All those people will need to eat. A sobering report published Wednesday in the journal Nature argues that a sustainable food system that doesn’t ravage the environment is going to require dramatic reforms, including a radical change in dietary habits. 
To be specific: Cheeseburgers are out, and fruits and veggies are in.
Global warming has typically been linked to the burning of fossil fuels, but food production is a huge and underappreciated factor, and the new report seeks to place food in the center of the conversation about how humanity can create a sustainable future.
I've discussed the planetary benefits of a plant-based diet on other occasions--check out this post from August or just search in the blog for "plant-based". In that August post I comment on the increase in meat consumption in China, which is a wrong-way trend that the whole world needs to reverse. Indeed, I was thinking about that today as I read another Washington Post article about the dilemma faced by North Dakota soy farmers who are caught up in the Trump administration's trade war with China:
For the past decade, North American soybean production has exploded, driven by an intense demand from China. Peterson and other Great Plains farmers directly fed the overseas markets, harvesting more than 243 million bushels in North Dakota, at a price of $2.1 billion in the last market year. The majority of that crop fattened Chinese livestock.
If the majority of that crop were to start going to soy-based food for humans (or if farmers were growing potatoes!), we would all be better off and, in fact, that is what we are going to have to do if we are to sustainably feed the next generation of humans and, more generally, sustain life on this planet. 

Wednesday, October 10, 2018

Demographics of Global Climate Change

I'm sure that you've seen the report that came out this week from the United Nations' Intergovernmental Panel on Climate Change projecting that the negative impacts of emissions on global climate change are likely to come about even sooner than previously thought. The NYTimes summarizes the report and reactions to it.
The authors found that if greenhouse gas emissions continue at the current rate, the atmosphere will warm up by as much as 2.7 degrees Fahrenheit (1.5 degrees Celsius) above preindustrial levels by 2040, inundating coastlines and intensifying droughts and poverty. Previous work had focused on estimating the damage if average temperatures were to rise by a larger number, 3.6 degrees Fahrenheit (2 degrees Celsius), because that was the threshold scientists previously considered for the most severe effects of climate change.
“This report makes it clear: There is no way to mitigate climate change without getting rid of coal,” said Drew Shindell, a climate scientist at Duke University and an author of the report.
Burning coal was, of course, a huge asset to the economic development that has brought us the current global prosperity. The same is true of petroleum. Population and prosperity have grown together over the past two centuries as a consequence not just of the spread of the potato, but because of human ability to harness energy sources. The problem is that both have the potentially disastrous side-effects of putting us on the path to unsustainability with respect to growing food, and putting people on the path--literally--to another home because rising sea levels are swamping the land they live on. As the NYTimes notes we can either act now and try to avoid those disasters, or decide to wait and see how bad the disaster is and act then. We know what to do--switch to sustainable energy sources like solar and wind power, and we need to do it sooner rather than later.

Monday, October 8, 2018

The Demographic Power of the Potato--UPDATED

The European "discovery" of the Americas was amazingly consequential in demographic terms. I discuss this in my text, of course, but a story in today's Washington Post has a pretty good summary of the three key elements: (1) bringing the potato to Europe to help fuel population growth; (2) the spread of disease that killed a huge proportion of the indigenous population; and (3) the enslavement of Africans to work on plantations created by Europeans in the Americas. Let me focus here on the first of these:
The potato alone gets credit for population booms in parts of northern Europe that paved the way for urbanization and, in turn, fueled the Industrial Revolution. Tobacco had such value it was used as currency in some places. Some American foods became staples abroad, from the tomato in Italy and cassava in Africa to the peppers that became the paprika of Hungary and the curries of India.
Eventually, starting with a group of monks on Spain’s Canary Islands in the 1600s, Europeans figured out how to cultivate potatoes, which form a nutritionally complete — albeit monotonous — diet when combined with milk to provide vitamins A and D. The effects were dramatic, boosting populations in Ireland, Scandinavia, Ukraine and other cold-weather regions by up to 30 percent, according to Qian’s [Nancy Qian, an economics professor at Northwestern University] research. The need to hunt declined and, as more land became productive, so did conflicts over land.
If you've read my book, you know that the statement above may give a bit more credit to the potato than it deserves. The potato arrived in Europe at about the same time that the plague was leaving, and at about the same time that the Little Ice Age was receding, thus opening up more farmland for cultivation. Still, were it not for the potato, it is unlikely that the health of the European population would have improved as it did, thus helping to set off population growth that eventually revolutionized the world. 

UPDATE:  Maybe this should really be a PRE-DATE instead of an update, but I just realized that I blogged about the demographic impact of the potato six years ago, based upon a paper just published at that time by Professor Qian, who was quoted in the above Washington Post story. Here's a link to that earlier blog post.