The evidence suggests that as the number of cyclists in a city increases, the level of safety-per-cyclist increases so quickly that more bike riders leads to fewer bike accidents.
Africa is the fastest-growing and fastest-urbanising continent. Its population has grown from 110m in 1850 to 1 billion today. The average African woman born today is expected to have about 5 children, compared with just 1.7 in East Asia. In 1950 there were two Europeans for every African; by 2050, on present trends, there will be two Africans for every European.
The past 15 years have seen Africa’s fastest-ever period of economic growth, & it appears to be following the rest of the world through a demographic transition (falling birth rates as people get richer), which should increase the size (relative, as well as absolute) of their working-age population.
According to a study by the Harvard Initiative for Global Health (”Realizing the Demographic dividend: is Africa any different?” By David E. Bloom), the share of the working-age population will rise in 27 of 32 African countries between 2005 and 2015. On other continents this phenomenon has led to increased productivity.
Africa today produces less food per head than at any time since independence. Only 4% of Africa’s farmland is irrigated.
According to the UN Population Division, Africa’s overall population is 8% lower today than it would have been if its fertility rate had stayed at its 1970s level.
The use of modern contraceptives in sub-Saharan Africa is only 12% (though it has doubled since 1994). The rate in Asia and Latin America is over 40%, so contraceptive use is likely to rise sharply.
J Curve
Unless trends change, by the middle of the century, populations in the most developed countries will have shrunk and the number of retired individuals supported by each person of working age will increase significantly.
A study by Mikko Myrskyla, Hans-Peter Kohler, & Francesco Billari (”Advances in development reverse fertility declines“) suggests that the trend may change: as development continues, the demographic transition goes into reverse.
The researchers looked at two years 1975 and 2005, and analyzed countries using two factors, total fertility rate (the number of children that would be born to a woman in a particular country over the course of her life if she experienced the age-specific fertility rates observed in that country during the calendar year in question) and human development index or “HDI” (a measure used by the UN that includes life expectancy, average income per person, and level of education), which has a maximum possible value of one.
In 1975, of the 107 countries analyzed, the best was Canada, with an HDI of 0.89. By 2005, two dozen countries (of 240 analzyed) had HDIs above nine. In 1975, a graph plotting fertility rate against the HDI fell as the HDI rose. By 2005, though, once the HDI rose above 0.9 or so, it turned up, producing a “J-shaped” curve (the mirror image of a letter J).
In many countries with very high levels of development (around 0.95) fertility rates are now approaching two children per woman.
The nadir of fertility appears to be 1.3 children per woman but this new data suggests the ultimate outcome of development may be zero population growth.
According to the UN’s latest biennial population forecast, the median age for all countries is due to rise from 29 now to 38 by 2050. At present just under 11% of the world’s 6.9 billion people are over 60. By 2050 that share will have risen to 22% (of a population of over 9 billion), and in the developed countries to 33%.
In 1900 average life expectancy at birth for the world as a whole was only around 30 years, and in rich countries under 50. The figures now are 67 and 78 respectively.
In the early 1970s women across the world were, on average, having 4.3 children each. The current global average is 2.6, and in rich countries only 1.6. By 2050 the global figure will have dropped to just two, and the world’s population will begin to level out.
“A slow-burning fuse,” by Barbara Beck
Non-kin altruism among non-human animals is rare, & altruism fares poorly in computer simulations — when altruistic individuals emerge in a community characterized by self-interested behavior, selfishness triumphs.
Group selection could explain the prevalence of human altruism but probably only if the ancestral environment included high levels of violence and inbreeding.
Sam Bowles showed in 2006 that genetic analyses of tribes still living a Stone Age life suggests there was enough inbreeding to make group competition a driver of genetic change.
In ancient graves excavated previously, Bowles found that up to 46% of the skeletons from 15 different locations around the world showed signs of a violent death. More recently, war inflicted 30% of deaths among the Ache, 17% among the Hiwi, & just 4% among the Anbara. Combat between groups accounted for about 14% of all deaths in these hunter-gatherer societies.
After estimating the rate that altruism would reduce an individual’s chances of reproducing, Bowles plugged the numbers into a model of intergroup competition where an individual’s altruism would also improve a group’s chances of combat triumph. In the absence of war, a gene imposing a self-sacrificial cost of as little as 3% in forgone reproduction would drop from 90% to 10% of the population in 150 generations. Bowles predicts that much higher levels of self-sacrifice — up to 13% in one case — could be sustained if warfare were brought into the equation.
“Did Warfare Among Ancestral Hunter-Gatherers Affect the Evolution of Human Social Behaviors?” By Samuel Bowles
“Altruism’s Bloody Roots,” by Brandon Keim
“Ancient warfare: Fighting for the greater good,” by Ewen Callaway
“Blood and treasure,” The Economist
According to data compiled the US Department of Labor’s Bureau of Labor Statistics, total private-sector employment rose by nearly 20 million between 1993 and 2002. A breathtaking total of 330 million jobs were added, while 310 million jobs were lost.
Between 1983 and 2002, the number of managerial and specialized professional jobs rose from 24 million to 43 million — from 23% of total employment to 31%.
Between 1980 and 2003, American manufacturing output climbed a dizzying 93 percent. Yes, production fell during the recent recession, but it is now recovering: the industrial production index for manufacturing rose 2.2 percent in 2003.
Manufacturing’s share of gross domestic product declined from 27% in 1960 to 14% in 2002, during which time the percentage of workers employed in manufacturing fell from 28% to 12%. The primary cause of these trends is the superior productivity of American manufacturers. Output per hour in the overall nonfarm business sector rose 50% between 1980 and 2002; by contrast, manufacturing output per hour shot up 100%. In other words, goods are getting cheaper and cheaper relative to services. Since this faster productivity growth has not been matched by a corresponding increase in demand for manufactured goods, the result is that Americans are spending relatively less on manufactures.
Similarly, in 1870, 48% of total US employment was in farming. By 2002 the figure had fallen to 2%.
Studies by William Maddux & Adam Galinsky (”Cultural Borders and Mental Barriers: The Relationship between Living Abroad and Creativity“) have proved that there is a link between creativity and living in a foreign country.
The researchers presented 150 US business students and 55 foreign ones studying in America with a test used by psychologists as a measure of creativity. Given a candle, some matches and a box of drawing pins, the students were asked to attach the candle to a cardboard wall so that no wax would drip on the floor when the candle was lit. (The solution is to use the box as a candleholder and fix it to the wall with the pins.) They found 60% of students who were either living abroad or had spent some time doing so, solved the problem, whereas only 42% of those who had not lived abroad did so.
A follow-up study with 72 Americans and 36 foreigners explored their creative negotiating skills. Pairs of students were asked to play the role of a seller of a gas station who then needed to get a job and a buyer who would need to hire staff to run the business. The two were likely to reach an impasse because the buyer had been told he could not afford what the seller was told was his minimum price. Where both negotiators had lived abroad 70% struck a deal in which the seller was offered a management job at the petrol station in return for a lower asking price. When neither of the negotiators had lived abroad, none was able to reach a deal.
When the researchers used statistical controls to filter out personality traits (such as openness to new experiences) that are known to predict creativity, the statistical relationship between living abroad and creativity remained. According to the researchers, this suggests that living in foreign parts that helps foster creativity, rather than the correlation being due to creative people’s penchant for moving to foreign countries.
“Expats at work, The Economist
According to Abhijit Banerjee & Esther Duflo (of the Poverty Action Laboratory), among the rural poor, fewer than half have children aged 13-18 in education, whereas among those living in cities and earning over $2 a day the figure is over three-quarters.
In emerging markets, among the very poorest (those living on less than $1 a day), the number of children in the household ranged from 1.8 to 3.6 per adult woman. In families that live on $6-10 per person, the average number of children per household was between 1 and 1.3 (these figures do not include China so they are not influenced by that country’s one-child policy).
Based on the 2007 Pew Global Attitudes survey, the attitudes of people in emerging nations whose household income can be considered at least “middle income” by international standards (more than $4,300-per-year in standardized international dollars) differs from those of poorer citizens.
Middle class respondents are more likely to say it is very important to live in a country with key institutional features of democracy, such as fair multiparty elections and a fair judiciary, are more likely to emphasize the importance of the rights enshrined in the First Amendment (free speech, a free press, and freedom of religion).
When asked to choose which is most important to them personally — free speech, freedom of religion, freedom from hunger and poverty, or freedom from crime and violence — they are more likely to prioritize being able to speak freely in public (lower-income respondents were more likely to emphasize being free from hunger and poverty).
People in the global middle class are less likely to consider religion central to their lives, and less likely to believe faith is essential for morality. (See “Unfavorable Views of Jews and Muslims on the Increase in Europe” and “World Publics Welcome Global Trade - But Not Immigration.”)
Similar differences characterize views about homosexuality, especially in Eastern Europe.
Middle-class respondents are more likely to consider global warming a very serious problem; and they are more likely to say that pollution is a very big problem for their country.
Life satisfaction tends to be higher in wealthy countries (see “A Rising Tide Lifts Mood in the Developing World“); and in developing countries, it tends to be higher among wealthy people.
Across the 13 nations, the median percentage rating their current life in the range of seven to 10 is 50% among the global middle class and just 31% among poorer respondents.
The median percentage of middle-class respondents saying their life five years ago rated at least a seven was 45%, compared with 33% of the less affluent.
The 13-country median percentage among the middle class saying their lives would rate a 7-10 in the future was 71%; in contrast, 58% of less wealthy respondents felt this way.
Joel Weinstock has used worms (found in dirt) to both prevent and reverse autoimmune disease in mice.
Immunologists now recognize a four-point response system of helper T cells: Th 1, Th 2, Th 17 and regulatory T cells. Th 1 inhibits Th 2 and Th 17; Th 2 inhibits Th 1 and Th 17; and regulatory T cells inhibit all three.
A lot of inflammatory diseases — multiple sclerosis, Crohn’s disease, ulcerative colitis and asthma — are due to the activity of Th 17. If you infect mice with worms, Th 17 drops dramatically, and the activity of regulatory T cells is augmented.
Children who grow up on farms and are frequently exposed to worms and other organisms from farm animals are much less likely to develop allergies and autoimmune diseases. Weinstock advises: “Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat.” Also: “let kids have two dogs and a cat” (which will expose them to intestinal worms that can promote a healthy immune system).
“Babies Know: A Little Dirt Is Good for You,” by Jane E. Brody