Progress Daily

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

The US spends 1/6 of national income on medicine, more than on all manufacturing.In the aggregate (in studies with good controls), variations in medical spending usually show no statistically significant medical effect on health.

For example, a 2007 study (”Health care funding levels and patient outcomes“) found no significant mortality effects of funding variations across 22 U.S. Veterans Affairs regions over six years.

A 2003 study of 18,000 patients (”The Implications of Regional Variations in Medicare Spending“) confirmed a 2000 study (”Associations among hospital capacity, utilization, and mortality of US Medicare beneficiaries“), and a related 1998 study (”How Much is Enough?“), which together used a huge dataset: 5 million Medicare patients in 1989 and 1990 across 3,400 U.S. hospital regions.

Regions that paid more to have patients stay in intensive care rooms for one more day during their last 6 months of life were estimated, at a 2% significance level, to make patients live roughly 40 fewer days, even after controlling for: individual age, gender, and race; zipcode urbanity, education, poverty, income, disability, and marital and employment status; and hospital-area illness rates. The researchers estimated that a region spending $1,000 more overall in the last 6 months of life gave local patients somewhere between a gain of 5 days of life and a loss of 20 days of life (95% confidence interval).

The tiny effect of medicine is in striking contrast to the large effects of other influences. For example, a 1998 study (”Socioeconomic Factors, Health Behaviors, and Mortality“) of 3,600 adults over 7.5 years found significant lifespan effects: a 3 year loss for smoking, a 6 year gain for rural living, a 10 year loss for being underweight, and about 15 year losses each for low income and low physical activity (in addition to the usual effects of age and gender).

These studies look at correlation, not causation, between health and medicine. But not so the RAND health insurance experiment.

From 1974 to 1982 this experiment spent about $50 million to randomly assign over 2000 non-elderly families in 6 US cities to 3 to 5 years of a specific medical price, ranging from free to full price, provided by the same set of doctors. (See “The Effect of Coinsurance on the Health of Adults” and Free for All?.) Being assigned a low price for medicine caused patients to consume about 30% (or $300) more in per-person annual medical spending.

The result: “For the five general health measures, we could detect no significant positive effect of free care for persons who differed by income … and by initial health status.”

There were no significant differences in either severity of diagnosis or appropriateness of treatment between common and extra medicine.

Other studies suggest larger benefits in particular areas, e.g., immunization, infant care, and emergency care. (See “The impact of public spending on health” and “Returns to Local-Area Health Care Spending“.)

“Cut Medicine in Half,” by Robin Hanson

A 1987 study (”Applying the acute ischemic heart disease predictive instrument“) showed that a successful predictive instrument for acute ischemic heart disease (which reduced the false positive rate from 71% to 0) was, after its use in randomized trials, all but discarded by doctors (only 2.8% of the sample continued to use it).

Most doctors do not like decision aids. And patients think less of doctors’ abilities who rely on such aids. (See “Patients Derogate Physicians Who use a Computer-Assisted Diagnostic Aid.”)

Doctors cannot outperform mechanical diagnoses because their own diagnoses are inconsistent. An algorithm guarantees the same input results in the same output, and this maximizes accuracy.

Physicians can find “exceptions” everywhere they look, and, augmenting a decision aid as they see fit, will only end up lowering its overall diagnostic accuracy — because doctors are subject to random fluctuations in diagnosis caused by judgmentally-irrelevant factors including availability, priming, recency effects, inconsistent weighting of information, fatigue, etc., all of which reduce accuracy. (See “Clinical versus mechanical prediction” and “Clinical versus Actuarial Judgment.”)

“How Doctors Think They Think,” by Charles Lambdin

The largest-ever global study of abortion (”Abortion: Worldwide Levels and Trends“) has found that restricting abortions has little effect on the number of pregnancies terminated. Rather, it drives women to seek illegal, often unsafe backstreet abortions leading to an estimated 67,000 deaths a year. A further 5m women require hospital treatment as a result of botched procedures.

In Africa and Asia, where abortion is generally either illegal or restricted, the abortion rate in 2003 was 29 per 1,000 women aged 15-44. This is almost identical to the rate in Europe — 28 — where legal abortions are widely available. Latin America, which has some of the world’s most restrictive abortion laws, is the region with the highest abortion rate (31), while western Europe, which has some of the most liberal laws, has the lowest (12).

A woman’s likelihood of having an abortion is similar whether she lives in a rich country (26 per 1,000) or a poor or middle-income one (29).

The same point can be made by looking at those countries which have changed their laws. Between 1995 and 2005, 17 nations liberalised abortion legislation, while three tightened restrictions. The number of induced abortions nevertheless declined from nearly 46m in 1995 to 42m in 2003, resulting in a fall in the worldwide abortion rate from 35 to 29. The most dramatic drop — from 90 to 44 — was in former communist Eastern Europe, where abortion is generally legal, safe and cheap. This coincided with a big increase in contraceptive use.

According to a report published this month by Population Action International women in poor countries are 250 times more likely to die in pregnancy or childbirth than women in rich ones.

A woman in Africa has a one in 16 chance of dying in pregnancy or childbirth, compared with one in 3,800 for a woman in the rich world.

“Safe, legal and falling,” The Economist

From the Stone Age to 1800, there was no gain in average living conditions. Now incomes rise steadily.

The average Briton in 1788 ate only as many calories a day as hunter-gatherers (2,300). And the British diet was more monotonous. Life expectancy was only slightly above that of hunter-gatherers (38 years). Height is a good guide to nutrition and health: men in England averaged 5ft 6in, the same as males in the Stone Age. Men then worked 60 hours a week. Compared to hunter-gatherers’ 35 hours.

Englishmen who were economically successful, from the Middle Ages to 1800, left 4 or 5 surviving children at their deaths. In contrast, landless labourers left fewer than 2 children.

Preindustrial England was thus a world of constant downward mobility. Given the static nature of the preindustrial economy, the superabundant children of the rich had to, on average, move down the social hierarchy to find work. Attributes that ensured later economic dynamism – hard work, ingenuity, innovativeness, education – were thus spread throughout the population.

From 1200 to 1800 interest rates fell, murder rates declined, work hours increased, the taste for violence declined, and numeracy and literacy spread to even the lower reaches of society.

In both preindustrial Japan and China the rich had more children than the poor, but in a more modest way. The samurai in Japan in the Tokugawa era (1603-1868), for example, produced on average little more than one son per father.

In modern affluent societies, the higher income a person has, on average, the less leisure he has. The source of our compulsion to work may lie in our ancestors’ passage through a preindustrial world that rewarded a compulsion to work and accumulate with reproductive success.

“England’s success may be in our genes,” Gregory Clark

Steve Cole and John Cacioppo, used a “gene chip” to look at the DNA of isolated people and found that people who described themselves as chronically lonely have distinct patterns of genetic activity, almost all of it involving the immune system.

The study does not show which came first — the loneliness or the physical traits.

Many studies of large populations have shown that people who describe themselves as lonely or as having little social support are more likely to die prematurely and to have infections, high blood pressure, insomnia and cancer.

When the researchers studied and compared all 22,000 human genes, 209 stood out in the loneliest people.

Many of the these genes seemed to be involved in the basic immune response to tissue damage and others were involved in the production of antibodies (the tag the body uses to mark microbes or damaged cells for removal), suggesting that the loneliest people had unhealthy levels of chronic inflammation, which has been associated with heart and artery disease, arthritis, Alzheimer’s, etc.

“Sick? Lonely? Genes tell the tale,” Reuters