Progress Daily

Sexual selected traits come in two main forms: weapons, which are used to fight off competitors; and ornaments, which are used to advertise genetic fitness to the opposite sex.

According to David Puts, human masculine traits — big muscles, facial hair, square jaws, deep voices and a propensity to violence — evolved for their usefulness in fighting with or indimidating other men (”Beauty and the beast: mechanisms of sexual selection in humans“).

In species whose males do not fight for access to females, males are generally the same size as, or smaller than, females. Human males have 40% more fat-free mass than women, which to the difference in gorillas, a species in which males unquestionably compete with other males for exclusive sexual access to females.

“To get the girl,” The Economist

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 research by Ivan Arreguín-Toft, in asymmetric military conflicts (those where one party possessed, on average, ten times the population and armed forces of their adversary) during the past two centuries the weak actors won nearly a third of the time.

When divided into four 50-year periods, strong actors lost to the weak more and more often. By the final 50-year period, the weak won a majority of engagements.

Strong powers excel at large, mechanized, combined-arms militaries in relatively open terrain. But small powers have increasingly used an indirect strategy that trades the protection of population for time.

Of the 202 lopsided conflicts in Arreguín-Toft’s database, the underdog fought conventionally 152 times — and lost 119 of those times. When they used an unconventional strategy they won almost two-thirds of the time. (”How David Beats Goliath,” by Malcolm Gladwell)

“How a superpower can end up losing to the little guys“

Researchers from Save the Children UK, found a simple way of measuring child welfare, using (1) the mortality rate among under-fives; (2) the percentage of under-fives who are moderately or badly underweight; and (3) the proportion of primary-school-age children who are not enrolled in school — from 1990 to ‘94; 1995 to ‘99; and 2000 to ‘06. (See The Child Development Index.)

Almost every region of the world improved. Latin America and the Caribbean were the best performing area, with a 57% leap in child welfare between the first period and the third. China was the driver of a 45% improvement in East Asia. India’s poorish record with respect to malnutrition (at a time of impressive economic growth) dragged down the improvement (32%) registered by South Asia as a whole.

The worst-performing countries are mostly in Africa, though there was a 56% improvement in Malawi (and a 52% decline in war-ravaged Congo).

“The best places to breed,” The Economist

Ara Norenzayan and Azim Shariff (”The Origin and Evolution of Religious Prosociality“; .pdf file here) analyzed 3 decades of empirical evidence looking for examples of religious prosociality (”the idea that religions facilitate acts that benefit others at a personal cost”). They found that religion encourages prosociality because the sense of being watched makes believers nervous about being selfish.

A study by Melissa Bateson & Gilbert Roberts (”Cues of being watched enhance cooperation in a real-world setting”; .pdf file here) found that just being under the gaze of eyes on a poster nearly tripled the contributions to an office coffee kitty.

Exposing participants in a laboratory economic game by Daniel Fessler to computer-generated eyespots while they played made them twice as generous as those who were not (”Nobody’s watching? Subtle cues affect generosity in an anonymous economic game“).

A study by Kevin McCabe & Vernon Smith found that participants in a laboratory economic game were nearly 4 times stingier with other players when they thought they were anonymous than when they thought they were being observed (”Social Distance and Other-Regarding Behavior in Dictator Games”; .pdf file here).

In an experiment by Richard Sosis and Bradley Ruffle (”Religious Ritual and Cooperation: Testing for a Relationship on Israeli Religious and Secular Kibbutzim”; .pdf file here), two players would simultaneously decide how much money to withdraw from the same envelope — if their combined withdrawals exceeded the amount in the envelope, neither would get any money. Systematically, less money was withdrawn when the game was played at religious kibbutzim than when it was played at secular kibbutzim.

In a 1989 study (Religious prosocial motivation: Is it altruistic or egoistic?“), volunteers were given the option to raise money for a sick child’s medical bills. Some would-be volunteers were told that it was very likely that they would be asked to help, while others were told that there was only a small chance that they would be called on. Only in the latter situation was a link between religiosity and volunteering evident. Religion played a role when it appeared that volunteering would improve one’s reputation without much personal cost.

In an experiment by Jesse Bering (”The Cognitive Psychology of Belief in the Supernatural“), when participants were told that the ghost of a dead student was haunting the experimental room, they cheated less on a computer test.

Brandon Randolph-Seng & Michael Nielsen report (”Honesty: One Effect of Primed Religious Representations“) that when experimental subjects were primed with religious words, they cheated significantly less on a subsequent task.

A cross-cultural analysis of 186 societies (”Belief in moralizing gods”; .pdf file here) by Frans Roes suggests that the larger a society, the more likely its members believe in deities that are concerned about human morality. In small hunter-gatherer bands or subsistence farming villages, it’s easy to keep track of how cooperative your neighbors are. But when groups grow, an all-seeing deity may help watch and punish.

“Does Religion Make People Nicer?” by Ronald Bailey

A comprehensive RAND National Defense Research Institute study by Seth G. Jones & Martin C. Libicki (”How Terrorist Groups End“) analyzed 648 terrorist groups that existed between 1968 and 2006, drawing from a database maintained by RAND and the Memorial Institute for the Prevention of Terrorism.

The most common way that terrorist groups ended — 43% — was via a transition to the political process. The possibility of a political solution was more likely if (unlike al Qaida) the group had narrow goals.

The second most common way that terrorist groups ended — 40% — was through police and intelligence services either apprehending or killing the key leaders of these groups.

Military force was effective in only 7% of the cases.

Terrorist groups achieved victory in 10% of the cases.

Since 1968, approximately 62% of all terrorist groups have ended, while only 32% of religious terrorist groups have done so. No religious terrorist group has achieved victory since 1968.

Groups of more than 10,000 members were victorious more than 25% of the time, while victory was rare when groups were smaller than 1,000 members. When terrorist groups became involved in an insurgency they ended with a negotiated settlement with the government nearly 50% of the time, achieved victory 25% of the time, and were defeated by military groups 19% of the time.

Terrorist groups from upper-income countries were much more likely to be left-wing or nationalistic, and much less likely to be motivated by religion.

“U.S. Should Rethink ‘War On Terrorism’ Strategy to Deal with Resurgent Al Qaida,” Rand Corporation

Physiognomy, the art or science of predicting inward character from outward form, is undergoing something of a revival. It has recently been found, for example, that women can predict a man’s interest in infant children from his face. Trustworthiness also shows up, as does social dominance.

Now a study by Justin Carré and Cheryl McCormick (”In your face: facial metrics predict aggressive behaviour in the laboratory and in varsity and professional hockey players“) suggests that it is also possible to look a man’s face and read his predisposition to aggression.

Aggressiveness is predictable from the ratio between the width of a person’s face and its height. This ratio differs systematically between men and women (men have wider faces) and that the difference arises during puberty, when sex hormones are reshaping people’s bodies. The cause seems to be exposure to testosterone, which is also known to make people aggressive.

Carré & McCormick obtained photographs of several university and professional Canadian ice-hockey teams, and measured the facial ratios of the players. They also obtained those players’ penalty records. The wider a player’s face, the more time he spent in penalty box.

Carré and McCormick then recruited several dozen university undergratuates of both sexes and got them to play a game against what they thought was a person in another room but was actually a computer. Various measures of aggression taken during this game suggested the same result as with the hockey players. Aggression was not, however, predictable in women students.

“Facing the truth,” The Economist

Vera Morhenn examined whether munificence towards strangers could be manipulated through touch. In her experiment (see “Monetary sacrifice among strangers is mediated by endogenous oxytocin release after physical contact“), she split 96 male and female graduate students into three groups. The first and second received a professional massage but the third did not. Then the first and third group took part in a “trust game.”

Participants were paired at random and seated in front of a computer, physically removed from their anonymous partner. Each also got $10 in cash, supposedly for showing up. The rules stipulated that for each pair, one person, the giver, could cede a part of their money to the other, the trustee. This amount would then be tripled and credited to the trustee, who was subsequently prompted by the computer to sacrifice a part of his stash by returning some to the giver.

Morhenn took blood samples at the start and end of each game and looked for changes in oxytocin levels. She found no effect in the massaged group who did not participate in the game, implying that trust acts as some sort of trigger. But in the players the hormone rose in those who were massaged and fell slightly in those who were not.

Despite receiving statistically identical trust signals from givers, the massaged trustees with their higher oxytocin levels returned a whopping 240% more than their unrubbed counterparts. Women appear more susceptible than men to tactile manipulation.

“A touch of generosity,” The Economist

Corey Fincher and Randy Thornhill hypothesized that in places where disease is rampant, it behoves groups not to mix with one another more than is strictly necessary, in order to reduce the risk of contagion. They therefore predicted that patterns of behaviour which promote group exclusivity are stronger in disease-ridden areas. Since religious differences are in that category, they predicted that the number of different religions in a place will vary with the disease load. [See "Assortative sociality, limited dispersal, infectious disease and the genesis of the global pattern of religious diversity."]

Using accepted definitions, they calculated that the average number of religions per country is 31. The range, though, is enormous — from 3 to 643. Côte d’Ivoire, for example, has 76 while Norway has 13, and Brazil has 159 while Canada has 15. They found that the average number of parasitic diseases per country is 200, with a range from 178 to 248.

Some of the differences between countries are caused by differences in their areas and populations. But these can be accounted for statistically. When they have been, the number of religions in a place is strongly correlated with how disease-ridden it is. There is less than one chance in 10,000 that it has come about accidentally.

The researchers also looked at anthropological data on how much people in “traditional” (ie, non-urban) societies move around in different parts of the world. They found that in more religiously diverse — and more disease-ridden — places people move shorter distances than in healthier, religiously monotonous societies.

“Praying for health,” The Economist

For the third successive year, America’s Border Patrol reports a sharp drop in arrests on and near the frontier. In 2006 the figure dropped 8% to around 1m. Last year it dropped by a full fifth. The six months to March showed a year-on-year drop of 17%. By the (imperfect) measure of border arrests, the migrant flow today is roughly half that of 2000, when 1.6m arrests were made.

Mexico’s central bank reports that, after years of rapid growth, the amount of cash sent home by migrants inside America is falling. Last year such flows were worth $24 billion (more valuable than tourism). But in the first quarter of this year the year-on-year figure was down 2.9%.

A poll of migrants across America published by in April confirmed that fewer are sending money back regularly: in 2006 three-quarters of migrants did, this year only half report doing so. Brazil, the second-largest recipient of remittances in the region, saw them slide by 4% last year, to $7.1 billion.

A study by the Institute for Public Policy Research (IPPR) this year noted that of the 1m or so East Europeans who came to Britain since 2004, around half have already left. The inflow of migrants to Britain from this region has also dropped sharply, by 17% last year.

In Britain the economy is slowing, and the sharp drop in the value of the pound has cut the attraction of the country to foreign workers. Every pound a Pole sent home in May 2004 earned him seven zloties; today he gets little more than four.

East European economies have grown relatively fast in recent years, their labour forces are shrinking fast (partly because of emigration, partly because of ageing populations) and unemployment has dropped quickly in the past half-decade.

Kathleen Newland suggests that based on the experience of countries like Spain, Portugal, Greece and South Korea, emigration usually slows when income per person approaches a threshold level in relation to income in the richer countries where the migrants are heading. The tipping point is when the ratio of incomes reaches about 1:4 or 1:5, especially if the upward trend seems stable. For migrants looking to go to western Europe and North America, this would imply a threshold level of $6,000-7,000.

“A turning tide?,” The Economist