Sunday, November 14th, 2010
Each year, we hear that people are gaining weight and that chronic health problems like obesity, heart problems, and diabetes are on the rise. It’s commonplace to ascribe these trends to personal lifestyle choices, such as the lack of exercise and diet, as well as the increasingly pervasive nature of fast food and processed, high-sugar foods.
However, there may be additional risk factors that are harder to control, such as genetics, and—as a provocative new article in PLoS One (open access) suggests—birth order. Specifically, first-born children might be more prone to these kinds of chronic health issues later in life:
Recent work has suggested that birth order may be a non-modifiable risk factor for obesity. Current evidence suggests that first-born infants grow faster than later-born infants. Dunger et al. suggest that the in-utero growth of first-born babies may be restrained as they have lower birth weight and accelerated post-natal catch-up growth, both of which are risk factors for obesity and cardiovascular and metabolic diseases, in adult life. However, whether first-born individuals have elevated metabolic risk in adulthood remains unknown. A recent study found that first-borns had a 4-fold risk of increased fat mass in early adulthood compared to later-borns. Neither of these studies evaluated the magnitude of metabolic risk induced by such greater weight and adiposity.
…Here we investigate the associations of birth-order with metabolic phenotype in early adulthood using data from a birth cohort of Brazilian young men. We tested two hypotheses. First, we wanted to confirm that first-born status was associated with low birth weight and faster infant growth. Second, we tested the hypothesis that metabolic risk was increased in first-borns compared to later-borns.
What did they find? What implications might their work have for public health given the kinds of global population changes we expect over coming decades?
Monday, November 8th, 2010
In a forthcoming article in the Proceedings of the National Academy of Sciences, Patric Allard and Monica Colaiácovo use a nemotode (round worm) system to explore how BPA damages genetic processes in animals.
BPA ranks among the highest production volume chemicals with a global annual production scale of ≈4 million metric tons. It is commonly used in the manufacture of several polymers, including polycarbonate and epoxy resins. Thus, BPA is found in a variety of items such as plastic bottles, the lining of both food and beverage cans, and dental sealants. Consistent with its widespread presence, urinary BPA is detected in >90% of the population in the United States. Higher levels of urinary BPA have been correlated with cardiovascular diseases and diabetes and may be associated with an increased risk for miscarriages.
Tuesday, October 12th, 2010
In 40 years, there will be about 3 billion additional people living on the Earth (~9.5 billion total). With all of these new folks, it’s easy to think about the added demands of energy, food, and water required to sustain their lifestyles. And in terms of climate warming, it’s hard to escape the fact that significantly greater energy consumption will lead to rising rates of carbon emissions, unless there’s a shift to decarbonize the economy.
In this week’s early Edition of the Proceedings of the National Academy of Sciences (open access), Brian O’Neill and colleagues note that emissions are not just controlled by the sheer size of the human population but also by important demographic changes.
For example, how might an aging or more urban population affect emissions? How about changes in household size? Modelers of carbon emissions don’t usually ask these kinds of questions, so the conventionally projected emissions might be off if these additional demographic details matter.
The researchers developed a global economic model (Population-Environment-Technology, or PET) in which they specified relationships between demographic factors like houshold size, age, and urban/rural residency and economic factors like the demand for consumer goods, wealth, and the supply of labor. Here’s a bit more on how this works:
In the PET model, households can affect emissions either directly through their consumption patterns or indirectly through their effects on economic growth in ways that up until now have not been explicitly accounted for in emissions models. The direct effect on emissions is represented by disaggregating household consumption for each household type into four categories of goods (energy, food, transport, and other) so that shifts in the composition of the population by household type produce shifts in the aggregate mix of goods demanded. Because different goods have different energy intensities of production, these shifts can lead to changes in emissions rates. To represent indirect effects on emissions through economic growth, the PET model
explicitly accounts for the effect of (i) population growth rates on economic growth rates, (ii) age structure changes on labor supply, (iii) urbanization on labor productivity, and (iv) anticipated demographic change (and its economic effects) on savings and consumption behavior.
Although there are some exceptions, households that are older, larger, or more rural tend to have lower per capita labor supply than those that are younger, smaller, or more urban. Lower-income households (e.g., rural households in developing countries) spend a larger share of income on food and a smaller share on transportation than higher-income households. Although labor supply and preferences can be influenced by a range of nondemographic factors, our scenarios focus on capturing the effects of shifts in population across types of households.
To project these demographic trends, we use the high, medium, and low scenarios of the United Nations (UN) 2003 Long-Range World Population Projections combined with the UN 2007 Urbanization Prospects extended by the International Institute for Applied Systems Analysis (IIASA) and derive population by age, sex, and rural/urban residence for the period of 2000–2100.
What did they find?
Monday, October 4th, 2010
There has been a lot published recently on the source of happiness and what constitutes the good life, with many articles focusing on levels of personal income that mark tipping points, such as the recent claim that we need $75,000 to be happy.
In this week’s Early Edition of the Proceedings of the National Academy of Sciences (open access), Bruce Headey and colleagues describe how happiness is also being explored in terms of fundamental differences between psychological and economic theory:
Research on life satisfaction or happiness used to be a minor branch of psychology, became a major branch, and then in the past decade has attracted huge interest among economists. Some of these economists now use satisfaction measures as proxies for the outcome which economic agents are assumed to maximize—namely, individual utility. But the assumptions and findings of psychologists and economists are contradictory.
In one corner, psychological theory:
The dominant theory in psychology is probably still set-point theory…[which] holds that long-term adult happiness is stable—it has a setpoint—because it depends mainly on genetic factors, including personality traits molded and expressed early in life. It has been shown that major life events can temporarily change happiness levels, but that most people revert to their previous setpoint within a year or two. The theory can be summarized by saying that, “We are all on a hedonic treadmill”.
…An obvious implication is that neither individual choices nor public policy can make a substantial long-term difference to happiness.
In the other corner, economic theory:
Economists who, following the recent advice of the Commission on the Measurement of Economic Performance and Social Progress, now intend to use direct satisfaction-based measures of utility [happiness] must necessarily assume the opposite. There is no point in deploying such measures if individual preferences, behavioral choices, and public policy could not increase long-term satisfaction.
Research on happiness (relabeled as subjective utility) by economists developed rapidly in the 1990s, ironically just as setpoint theory became dominant… Economists have not developed a counter theory, but pursue a strategy of seeking to account for variance in life satisfaction due to individual utility maximizing behavior and policy interventions.
Economists have also developed explanations for why happiness may not appear to change over time that have nothing to do with happiness set points:
…Contrary to what a layperson might suppose, modern economists, starting with Richard Easterlin (the Easterlin paradox), have repeatedly claimed that money does not buy much happiness, especially in wealthy Western countries. The paradox
has been challenged…but critics have never been able to show that long-term income growth produces long-term gains in happiness. This nonoutcome arises mainly because rising incomes are subject to social comparisons with the neighboring Jones’s, whose incomes also keep going up. People adapt to their own and their neighbors’ new levels of income by raising their expectations, with the result that no lasting increase in happiness occurs.
How do you study these ideas? By using an enormous data set:
…The German Socio-Economic Panel Survey (SOEP) provides by far the longest data series available worldwide. It reports interviews with a very large national representative sample aged 16 and over, who have answered questions about their life satisfaction every year from 1984 to 2008.
What did they find, and who cares?
During this quarter-century, large numbers of respondents recorded substantial and apparently permanent changes in satisfaction…[T]he scale of change indicates that set-point theory is seriously flawed. A key implication is that the economist’s goal of enhancing (subjective) utility via changes in individual behavior and public policy is not condemned to inevitable failure by human psychology. Nonfixed, nongenetic factors, including individual choices and public policy, may influence satisfaction levels, or utility so measured.
The authors go on to talk more about life factors that drive happiness, showing that things people can change about their lifestyle matter as much or more than personality traits or being married—things we might consider to be fixed in our lives. Some we’ve heard before, but other insights are new and interesting (emphasis mine):
…[W]e have shown that life goals, religion, and personal choices matter for happiness. Key choices relate to one’s partner, the tradeoff between work and leisure, social participation, and healthy lifestyle. Life goals and choices have as much or more impact on life satisfaction than variables routinely described as important in previous research, including extroversion and being married or partnered. If we use these last two variables as benchmarks, it appears that partner’s level of neuroticism, one’s own commitment to family and altruistic goals, church attendance, participation in social events, and regular exercise are all equally or more important than being extroverted.
…For both men and women, doing fewer paid hours of work than they want apparently has close to the same impact on life satisfaction as not being married/partnered. For women, being obese actually reduces life satisfaction more than not having a partner.
…people who find themselves working much more or less than they want are significantly less satisfied with life than those who come close to making their preferred tradeoff between work and leisure. For both men and women, being underworked is much worse than being overworked, presumably because lost consumption rankles worse than lost leisure.
…people who consistently prioritize non–zero-sum altruistic goals or family goals are more satisfied with life than people who prioritize goals relating to their own careers and material success. Giving priority to altruistic goals is strongly associated with higher life satisfaction, whereas family goals are also satisfaction enhancing. Corroborating some previous research, it appears that prioritizing success and material goals is actually harmful to life satisfaction.
Headey, B., R. Muffels, and G.G. Wagner (2010). Long-running German panel survey shows that personal and economic choices, not just genes, matter for happiness Proceedings of the National Academy of Sciences : 10.1073/pnas.1008612107
Photo credit: wili_hybrid
Sunday, September 19th, 2010
In the current issue of Population and Environment, Aaron McCright authors an article, The effects of gender on climate change knowledge and concern in the American public, in which he examines whether women and men perceive climate warming differently:
This study tests theoretical arguments about gender differences in scientific knowledge and environmental concern using 8 years of Gallup data on climate change knowledge and concern in the US general public. Contrary to expectations from scientific literacy research, women convey greater assessed scientific knowledge of climate change than do men. Consistent with much existing sociology of science research, women underestimate their climate change knowledge more than do men. Also, women express slightly greater concern about climate change than do men, and this gender divide is not accounted for by differences in key values and beliefs or in the social roles that men and women differentially perform in society. Modest yet enduring gender differences on climate change knowledge and concern within the US general public suggest several avenues for future research, which are explored in the conclusion.
McCright shares additional insights in a Michigan State University news story covering the article:
“Men still claim they have a better understanding of global warming than women, even though women’s beliefs align much more closely with the scientific consensus,” said McCright, an associate professor with appointments in MSU’s Department of Sociology, Lyman Briggs College and Environmental Science and Policy Program.
The study is one of the first to focus in-depth on how the genders think about climate change. The findings also reinforce past research that suggests women lack confidence in their science comprehension.
“Here is yet another study finding that women underestimate their scientific knowledge – a troubling pattern that inhibits many young women from pursuing scientific careers,” McCright said.
Understanding how the genders think about the environment is important on several fronts, said McCright, who calls climate change “the most expansive environmental problem facing humanity.”
“Does this mean women are more likely to buy energy-efficient appliances and hybrid vehicles than men?” he said. “Do they vote for different political candidates? Do they talk to their children differently about global warming?”
McCright analyzed eight years of data from Gallup’s annual environment poll that asked fairly basic questions about climate change knowledge and concern. He said the gender divide on concern about climate change was not explained by the roles that men and women perform such as whether they were homemakers, parents or employed full time.
Instead, he said the gender divide likely is explained by “gender socialization.” According to this theory, boys in the United States learn that masculinity emphasizes detachment, control and mastery. A feminine identity, on the other hand, stresses attachment, empathy and care – traits that may make it easier to feel concern about the potential dire consequences of global warming, McCright said.
“Women and men think about climate change differently,” he said. “And when scientists or policymakers are communicating about climate change with the general public, they should consider this rather than treating the public as one big monolithic audience.”
McCright, A. (2010). The effects of gender on climate change knowledge and concern in the American public Population and Environment, 32 (1), 66-87 DOI: 10.1007/s11111-010-0113-1
Photo Credit: BostonBill
Tuesday, January 12th, 2010
That’s the title of a new article1 by Suzanne Petroni in the latest issue of Population and Environment (subscription required). She begins by acknowledging the complex history between these issues:
There is, in the field of population and reproductive health, a present debate around the merits and deficiencies of bringing the issue of global population growth back to the public agenda. Many see the current attention to the issue of climate change as an opening in which to make the case that global warming can not be alleviated or reversed without slowing population growth. They believe that linking population growth and climate change will help governments to see the exigency of the matter, and will place family planning back into the political realm as an urgent matter of national and environmental security….
But others worry that focusing on the environmental impacts of demographic change places at risk the hard-fought and long-developed global consensus that individual rights and empowerment are what matters most in fostering just and sustainable development. They fear that a renewed focus on the impacts of the growth of our global population poses a risk of drawing the international community back to numbers-driven policies and programs, which have not always prioritized individual interests…
In light of these huge questions, what are her recommendations?
Wednesday, November 18th, 2009
Is climate change gender-neutral? Not according to the U.N. Population Fund, which earlier today released a report arguing that women suffer disproportionately from the impacts of global warming. Especially in developing countries, they can’t flee changes like desertification and sea-level rise as easily as young men, who aren’t as tied to children and households. They’re often caught up in civil conflicts ignited by scarce resources. And they’re more likely to fall victim to diseases caused by wetter weather patterns.
But on the flipside, the report argues, women are also in the best position to help mitigate both the causes and effects of rising temperatures—which is why policies to empower women, like targeted microloans and reproductive healthcare, shouldn’t be treated as separate from climate policy.
I love this conclusion. It’s one of the things that environmental studies (ES) programs in higher education need to focus on—better connections to groups not traditionally affiliated with ES, such as Gender and Women’s Studies, Africana Studies, Psychology, Religion, visual and performing arts, etc. For major environmental challenges like climate warming, everyone needs to be part of this conversation.
Sunday, November 15th, 2009
Every day, we are exposed to a cocktail of synthetic chemicals from consumer products. How harmful are these? In an earlier post, I described how risk analysis is an important scientific process for determining exposure, effects, and overall risk of these chemicals.
One thing missing from these analyses is how people respond to information about their chemical exposure. In a recent issue1 of the Journal of Health and Social Behavior, Rebecca Altman and colleagues addressed this by analyzing what they call the “exposure experience” of women in Cape Cod, MA—an area with elevated breast cancer rates.
What did they find?