Progress Daily

As human societies grow richer, people have fewer children. In most species, such an increase in available resources leads in the opposite reproductive direction. What makes the “demographic transition” even more paradoxical is that in less developed times and places, the rich do not have smaller families than the poor.

Most explanations of the demographic transition are social, and none is really satisfactory.

A study by Agnar Helgason, of deCODE Genetics, has recently provided a new explanation: that the mixing-up of people caused by the urbanisation which normally accompanies development is, itself, partly responsible — because it breaks up optimal mating patterns.

Iceland’s records since its founding by a few Vikings are so good that the antecedents of today’s inhabitants (apart from a handful of recent immigrants) are known with precision. Its medical records are also good, and most Icelanders have given genetic samples to deCode.

The study’s principal finding is that the most fecund marriages are between distant cousins. The optimum degree of outbreeding (measured in terms of the number of children and grandchildren produced) lay somewhere between cousins of the third and fourth degrees.

(”Kissing cousins, missing children,” The Economist)

Icelandic women born between 1800 and 1824 who mated with a third cousin had significantly more children and grandchildren (4.0 and 9.2, respectively) than women who hooked up with someone no closer than an eighth cousin (3.3 and 7.3). Those proportions held up among women born more than a century later when couples were, on average, having fewer children.

Despite the general pattern for reproductive success favoring close kinship, couples that were second cousins or more closely related did not have as many children.

With close inbreeding — between first cousins — there is a significant increase in the probability that both partners will share one or more detrimental recessive genes, leading to a 25 percent chance that these genes will be expressed in each pregnancy.

Mating with a relative might reduce a woman’s chance of having a miscarriage caused by immunological incompatibility between a mother and her child. Some individuals have an antigen (a protein that can launch an immune response) on the surface of their red blood cells called a rhesus factor. In some cases — typically during a second pregnancy — when a woman gets pregnant, she and her fetus may have incompatible blood cells, which could trigger the mother’s immune system to treat the fetus as a foreign intruder, causing a miscarriage. This occurrence is less probable if the parents are closely related, because their blood makeup is more likely to match.

It may be that the enhanced reproductive success at the level of third and fourth cousins (who on average would be expected to have inherited 0.8 percent to 0.2 percent of their genes from a common ancestor) represents a point of balance between the competing advantages and disadvantages of inbreeding and outbreeding.

(”When Incest Is Best,” by Nikhil Swaminathan)

Daniel Esty analyzed the Environmental Sustainability Index, which grades the “environmental health” of 150 countries. He found that the single biggest variable in determining a country’s ranking is income per head.

Economic growth offers solutions to the sorts of environmental woes (local air pollution, for example) that directly kill humans. About a quarter of all deaths in the world have some link to environmental factors. Among these killers (especially of children) are diarrhoea, respiratory infections and malaria.

As poor countries get richer, they usually invest heavily in environmental improvements, such as cleaning up water supplies and improving sanitation, that boost human health. (Their economies may also shift gear, from making steel or chemicals to turning out computer chips.)

But the link between growth and environment is much less clear when it comes to the sort of pollution that fouls up nature (such as acid rain, which poisons lakes and forests) as opposed to directly killing human beings.

A mixture of factors related to good government -— accurate data, transparent administration, lack of corruption, checks and balances — all show a clear statistical relationship with environmental performance. Among countries of comparable income, tough regulations and, above all, enforcement are the key factors in keeping things green.

“How green is their growth,” The Economist

In China 25 years ago, over 600m people — two-thirds of the population — were living in extreme poverty (on $1 a day or less). Now, the number on $1 a day is below 180m. Worldwide, 135m people escaped dire poverty between 1999 and 2004. This is more people, more quickly than at any other time in history.

In 2007 Unicef said that for the first time in modern history fewer than 10m children were dying each year before the age of five. That represents a fall of a quarter since 1990. Three-quarters of people aged 15-25 were literate in 1975; now the rate is nearly nine-tenths.

The fertility rate in low- and middle-income countries has crashed. In East Asia and the Pacific, the rate was 5.4 in 1970. Now it is 2.1. In South Asia, the fertility rate halved (from 6.0 to 3.1). In the world as a whole, fertility has fallen from 4.8 to 2.6 in a generation (25 years).

The biggest decline is in those countries that are most involved with globalization (especially in East Asia, though China is a special case because of its one-child policy). With the exception of Yemen, all the countries with fertility rates over 5.0 are in Africa.

In closed agrarian societies, families need a lot of children as insurance against disaster. But in countries that have opened themselves up, families can rely on other sorts of protection, such as urban jobs or trade.

These demographic changes help to create a virtuous circle of growth. When fertility rises then falls, you get a bulge of people at and just after the inflection point. Between 1960 and 1990 Europe and America had relatively few old people (because mortality rates had earlier been high), relatively few children (because fertility had fallen) and a disproportionately big number of economically active adults.

Developing countries are seeing a similar confluence now.

A World Bank study of 19 poor countries concluded that every 1% increase in national income per head translates into a 1.3 point fall in extreme poverty.

Last year the global economy entered its fifth year of over 4% annual growth — the longest period of such strong expansion since the early 1970s. Unlike previous expansions, inflation remained relatively tame.

During this boom, according to the World Bank, national income in the European Union rose slightly more than in America for the first time in a decade. Growth in East Asia was 10%, in South Asia over 8%, in eastern Europe almost 7% and in Africa, thanks to the commodity boom, over 6%. Almost half of humanity, spread over more than 40 nations, lives in countries growing at 7% a year or more (a rate that doubles the size of an economy in a decade). This is twice the number of fast growers that existed in the years between 1980 and 2000.

The world’s economic balance is tilting from rich industrialized countries to emerging markets. Their share of world output in 2006 was just below half, and rising.

Since the mid-1990s, the incomes of the poorest fifth have risen everywhere except, marginally, in Latin America, where they have been affected by the after-shocks of debt crises. In Asia, the real incomes of the poorest fifth rose 4% a year; in Africa, by 2% a year, faster than the rise for other income groups.

The World Bank labels as “fragile” (as opposed to “failed”) troubled countries where the government has partial control of territory (Sudan), where it cannot deliver basic services (Zimbabwe) and places with high levels of political conflict (Nigeria).

Fragile states contain roughly half the developing world’s childhood deaths. About a third of their people are undernourished and more than that do not have access to drinking water. Most of the countries with fertility rates over 5.0 are fragile. They are much more likely to be affected by wars, refugees and every sort of political crisis.

“Somewhere over the rainbow,” The Economist

The cost of developing drugs for rare and common diseases are about the same, but the revenues aren’t. Pharmaceutical companies concentrate on drugs with larger markets because larger markets mean more profits.

As a result, patients diagnosed with rare diseases — those ranked at the bottom quarter in terms of how frequently they are diagnosed — are 45% more likely to die before age 55 than are patients diagnosed with more common diseases.

If China and India were as wealthy as the U.S., the market for cancer drugs would be 8 times larger than it is today.

Cancer is now China’s leading killer, with spending on treatment increasing by 17% per year. AstraZeneca and Novartis are building major research facilities in China, which will benefit patients everywhere.

There are only about 6M scientists and engineers in the entire world, nearly a quarter of whom are in the U.S. If the world as a whole were as wealthy as the U.S. and were devoting the same share of population to research and development, there would be more than 5 times as many scientists and engineers worldwide.

Even small changes in economic growth rates produce large benefits. At current income levels, with an inflation-adjusted growth rate of 3% per year, America’s real per capita gross domestic product would exceed $1 million per year in just over 100 years, more than 22 times higher than it is today.

“Dismal Science Sees Upbeat Future,” Alexander Tabarrok

Givers are happier people than non-givers. According to the Social Capital Community Benchmark Survey, a survey of 30,000 American households, people who gave money to charity in 2000 were 43% more likely than non-givers to say they were “very happy” about their lives.

Similarly, volunteers were 42% more likely to be very happy than non-volunteers. It didn’t matter whether gifts of money and time went to churches or symphony orchestras — givers to all types of religious and secular causes were far happier than non-givers.

According to the University of Michigan’s Panel Study of Income Dynamics, people who gave money away in 2001 were 34% less likely than non-givers to say that they had felt “so sad that nothing could cheer them up” in the past month. They were also 68% less likely to have felt “hopeless,” and 24% less likely to have said that “everything was an effort.”

15% of Americans donate blood at least once each year.

According to the National Opinion Research Center’s General Social Survey, in 2002, 43% of the American adults who gave blood 2 to 3 times during the year said they were very happy versus only 29% of those who did not give blood.

Researchers have conducted experiments in which people are queried about their happiness before and after — sometimes long after — they participate in a charitable activity, such as volunteering to help children or serving meals to the poor. The result: giving has a causal impact on happiness.

In one 1998 experiment at Duke University, adults were asked to give massages to babies — the idea being that giving a baby pleasure is a compassionate act with no expectation of a reward, even a “thank you” — in return. After they performed the massages, the seniors were found to have dramatically lower levels of the stress hormones cortisol, epinephrine, and norepinephrine in their brains.

“Why Giving Makes You Happy,” by Arthur Brooks

Humans have spent most of their time as hunter-gatherers — from at least 85,000 years ago to the birth of agriculture around 73,000 years later.

Human height shrank by nearly six inches after the first adoption of crops in the Near East.

Farmers also had more skeletal wear and tear from the hard work, their teeth rotted more, they were short of protein and vitamins and they caught diseases from domesticated animals: measles from cattle, flu from ducks, plague from rats and worms from using their own excrement as fertiliser.

From the !Kung in the Kalahari to the Inuit in the Arctic and the aborigines in Australia, two-thirds of modern hunter-gatherers are in a state of almost constant tribal warfare, and nearly 90% go to war at least once a year. Usually around 25-30% of adult males die from homicide. The warfare death rate of 0.5% of the population per year that Lawrence Keeley calculates as typical of hunter-gatherer societies would equate to 2 billion people dying during the 20th century.

Richard Wrangham says that chimpanzees and human beings are the only animals in which males engage in co-operative and systematic homicidal raids. The death rate is similar in the two species.

Constant warfare was necessary to keep population density down to one person per square mile. Farmers can live at 100 times that density.

Notice a close parallel with the industrial revolution. The urban poor were overworked and underfed. But 18th-century rural England was a place where people starved each spring as the winter stores ran out, and where where the “putting-out” system of textile manufacture at home drove workers harder for lower pay than the factories would. The industrial revolution caused a population explosion because it enabled more babies to survive.

There is no longer much doubt that hunter-gatherers were the cause of the extinction of the megafauna in North America 11,000 years ago and Australia 30,000 years before that.

At first, modern humans around the Mediterranean relied almost entirely on large mammals for meat. Then they switched their attention to smaller animals, and especially to warm-blooded, fast-breeding species, such as rabbits, hares, partridges and smaller gazelles. The archaeological record tells this same story at sites in Israel, Turkey and Italy.

Human population densities were growing too high for the slower-reproducing prey such as tortoises, horses and rhinos. Only the fast-breeding rabbits, hares and partridges, and for a while gazelles, could cope with such hunting pressure. This trend accelerated about 15,000 years ago as large game and tortoises disappeared.

The belief that hunter-gatherers have plenty of free time turns out to be a bit of a myth. The measurements of time spent getting food by the !Kung omitted food-processing time and travel time, partly because the anthropologists gave their subjects lifts in their vehicles and lent them metal knives to process food.

Even 40,000 years ago, technology and lifestyle were in a state of continuous change, especially in western Eurasia. By 34,000 years ago people were making bone points for spears, and by 26,000 years ago they were making needles. Harpoons, bone spear throwers, and string appeared 18,000 years ago.

15,000 years ago people first domesticated another species — the wolf. 12,000 years ago came agriculture.

Just as we rebounded from the extinction of the megafauna and became even more numerous by eating first rabbits then grass seeds, so in the early 20th century we faced starvation for lack of fertiliser when the population was a billion people, but can now look forward with confidence to feeding 10 billion on less land using synthetic nitrogen, genetically high-yield crops and tractors.

“Noble or savage?,” The Economist

Dr Randy Thornhill manipulated pictures to make people’s faces appear more and less symmetrical, then asked volunteers of the opposite sex rank them for attractiveness. Symetery and attractiveness correlated. His later experiments have shown that all aspects of bodily symmetry contribute, down to the lengths of corresponding fingers, and that the assessment also applies to those of the same sex.

Perfect symmetry is hard for a developing embryo to maintain, so one that can maintain it must have good genes (and luck).

Other aspects of beauty, too, are indicators of health. Skin and hair condition are sensitive to illness and malnutrition.

Leslie Zebrowitz and Gillian Rhodes found 9 past studies on attractiveness and IQ, and subjected them to a “meta-analysis.”

The studies’ researchers had photographed people and asked them to do IQ tests, then showed the photographs to other people and asked them to rank the intelligence of the first lot. The results suggested that people get such judgments right often enough to be significant.

Dr Daniel Hamermesh presided over a series of surveys in the USA and Canada that showed that when all other things are taken into account, ugly people earn less than average incomes, while beautiful people earn more than the average. The ugliness “penalty” for men was -9% while the beauty premium was +5%. For women, the ugliness penalty was -6% while the beauty premium was +4%.

He found the figures for men in Shanghai are –25% and +3%; for women they are –31% and +10%. In Britain, ugly men do worse than ugly women (-18% as against -11%) but the beauty premium is the same for both (+1%).

Dr Hamermesh found that those members of a particular (anonymous) US law school rated attractive on the basis of their graduation photographs went on to earn higher salaries. Moreover, lawyers in private practice tended to be better looking than those working in government departments.

Hamermesh’s study of Dutch advertising firms showed that those with the most beautiful executives had the largest size-adjusted revenues — a difference that exceeded the salary differentials of the firms in question. Finally, he found that attractive candidates were more successful in elections for office in the American Economic Association.

Working in Shanghai, where his research indicated the difference between the ugliness penalty and the beauty bonus was greatest, Dr Hamermesh looked at how women’s spending on their cosmetics and clothes affected their income.

The beauty premium generated by such primping was worth only about 15% of the money expended.

Niclas Berggren’s research team looked at almost 2,000 candidates in Finnish elections. They asked foreigners (mainly Americans and Swedes) to examine the candidates’ campaign photographs and rank them for beauty. The more beautiful candidates, as ranked by people who knew nothing of Finland’s internal politics, tended to have been the more successful — the effect was larger for women than for men.

“To those that have, shall be given,” The Economist

Only a decade after their commercial introduction, genetically modified (”GM”) crops are now cultivated in 22 countries on an area more than 4 times the size of Britain, by over 10 million farmers, of whom 9 million are resource-poor farmers in developing countries, mainly India and China. Most of these small-scale farmers grow pest-resistant GM cotton. In India, production tripled last year. GM cotton benefits farmers because it reduces the need for insecticides, thereby increasing their income and improving their health.

Every academy of science — the Indian, Chinese, Mexican, Brazilian, French and US academies as well as the UK’s Royal Society — has confirmed that there is no evidence of risk to human health from GM crops. In 2001, the research directorate of the EU commission released a summary of 81 scientific studies financed the EU, and conducted over a 15-year period: none found evidence of harm to humans or to the environment.

Researchers at PG Economics studied the global effects of GM crops (”Global Impact of Biotech Crops“), and concluded that the “environmental impact” of pesticide and herbicide use in GM-growing countries had been reduced by 15% and 20% respectively. Energy-intensive cultivation is being replaced by no-till or low-till agriculture. More than a 1/3 of the soya bean crop grown in the US is now grown in unploughed fields. Apart from using less energy, avoiding the plough improves soil quality, causes less disturbance to life within it and diminishes the emission of methane and other greenhouse gases. The study concluded that “the carbon savings from reduced fuel use and soil carbon sequestration in 2005 were equal to removing 4m cars from the road….”

James Lovelock has estimated that if all farming became organic, we would only be able to feed 1/3 the present world population.

“The real GM food scandal,” by Dick Taverne

Place a rat in a cage with an electrified floor and subject it to repeated shocks; it will show many signs of stress, at first flinging itself against the walls with each shock. But after a while, it just sits there apathetically, showing no inclination to escape from its painful prison. When autopsied, it will be found to have oversized adrenal glands and, frequently, stomach ulcers, both indicating serious stress.

Now repeat the experiment, but with a wooden stick in the cage alongside the rat. When shocked, the rat chews on the stick, and as a result, it can endure its experience much longer without burnout. At autopsy, its adrenal glands are smaller, stomach ulcers fewer.

Put 2 rats in the electrified cage. Shock them both. They snarl and fight. At autopsy, their adrenal glands are normal, and, even though they have experienced numerous shocks, they have no ulcers.

Recently physiologists have uncovered the hormonal basis for such behavior. Animals and people subjected to attack or threat experience “subordination stress,” as a result of which their adrenal hormones go up, along with blood pressure and the probability of developing ulcers. But when given the opportunity to “take it out” on someone else, victims show no sign of stress.

“The Targets of Aggression,” by David P. Barash

The 2007 Statistical Abstract of the United States lists death rates per 100,000 population.

The 1951 Statistical Abstract of the United States lists death rates per 1000 population.

In 1949, the death rate of 1-4 year olds per 1000 population was 1.5 (itself a huge improvement over 1900’s 20). In 2003, the death rate of 1-4 year olds per 100,000 population was 32.

If the denominator hadn’t been changed, modern tables would be hard to read because the numbers would not be whole numbers.

“Julian Simon Moment of the Day,” Bryan Caplan