Progress Daily

For thousands of years, the number of people in the world inched up. Then there was a sudden spurt during the industrial revolution which produced, between 1900 and 2000, a near-quadrupling of the world’s population.

Numbers are still growing; but recently the rate of population increase began to slow. In more and more countries, women started having fewer children than the number required to keep populations stable. Four out of nine people already live in countries in which the fertility rate has dipped below the replacement rate. Last year the UN said it thought the world’s average fertility would fall below replacement by 2025. Demographers expect the global population to peak at around 10 billion (it is now 6.5 billion) by mid-century.

There doesn’t seem to be much danger of a Malthusian catastrophe. Mankind appropriates about a quarter of what is known as the net primary production of the Earth (this is the plant tissue created by photosynthesis) — a lot, but hardly near the point of exhaustion. The price of raw materials reflects their scarcity and, despite recent rises, commodity prices have fallen sharply in real terms during the past century. By that measure, raw materials have become more abundant, not scarcer.

Population has already begun to decline in 3 areas of the world — central and eastern Europe, from Germany to Russia; the northern Mediterranean; and parts of East Asia, including Japan and South Korea.

State pensions systems face difficulties now, when there are 4 people of working age to each retired person. By 2030, Japan and Italy will have only 2 per retiree; by 2050, the ratio will be 3 to 2.

“How to deal with a falling population,” The Economist

Worldwide, 10% to 40% of children grow up in households with no father. In the U.S., more than half of divorced fathers lose contact with their kids within a few years. By the end of 10 years, as many as two-thirds of them have drifted out of their children’s lives. According to a 1994 study by the Children’s Defense Fund, men are more likely to default on a child-support payment (49%) than a used-car payment (3%). In intact U.S. families, fathers spend an average of less than an hour a day (up from 20 minutes a few decades ago) focussed on their children.

Homo sapiens produces the most slowly maturing young of all mammals. Among foraging humans, children need 19 years — and consume 13 million calories — before producing more food for their community than they take from it, according to Hillard Kaplan. There is more variation in fathering styles across human cultures than in any other primate species.

One thing that draws a human male to a child of his is that, hormonally speaking, men are similar to women, during the period approaching a child’s birth and its infancy. As in some other mammalian species, human males have high levels of prolactin (a hormone usually associated with lactating mothers) toward the end of a partner’s pregnancy.

Katherine Wynne-Edwards and Anne Storey have shown that new or expectant fathers holding either their baby or a doll wrapped in a blanket that recently held — and still smells of — a newborn experienced a rise in prolactin and cortisol (a stress hormone associated with mothering) and a drop in testosterone. When the men listened to a tape of a crying newborn and were shown a videotape of a newborn struggling to nurse, the ones who reported the greatest urge to comfort the baby were the ones whose hormone levels had changed the most.

Dads have to spend time close to babies for hormones to kick in.

In traditional societies, 40% of offspring might die before age 5.

Among some West African Mandinka, the help of a maternal grandmother has been linked with a halving of the under-5 mortality rate. Similar benefits were shown in Finnish farming communities in the 18th century.

It was this cooperative system that allowed mothers to have more babies than they could support and fathers to vary in how they cared for them.

“The Psychology of Fatherhood,” by Sarah Blaffer Hrdy

Wage gaps between rich and poor nations are huge. A migrant from Guatemala to the US increases her income by a factor of 6 (PPP adjusted). From Kenya to the UK is a factor of 7; from Vietnam to Japan, a factor of 9.

A century ago, factors of 3 were sufficient to spark the migration that helped build America and partially empty Ireland, Italy and Poland.

Book review. No, not THAT book,” Ethan Zuckerman’s review of Lant Pritchett’s Let Their People Come

Zindel Segal, Helen Mayberg, etc., had 14 depressed adults undergo cognitive behavior therapy (CBT), which teaches patients to view their own thoughts differently — to see a failed date, for instance, not as proof that “I will never be loved” but as a minor thing that didn’t work out. Thirteen other patients received paroxetine (generic Paxil). All experienced comparable improvement after treatment. Brain scans showed that the patients responded differently to the 2 kinds of treatment: CBT muted overactivity in the frontal cortex, the seat of reasoning, logic and higher thought (as well as of endless rumination). Paroxetine, by contrast, raised activity there. On the other hand, CBT raised activity in the hippocampus of the limbic system, the brain’s emotion center. Paroxetine lowered activity there. As Mayberg explains, “Cognitive therapy targets the cortex, the thinking brain, reshaping how you process information and changing your thinking pattern. It decreases rumination, and trains the brain to adopt different thinking circuits.”

Greater activity in the left prefrontal cortex than in the right correlates with a higher baseline level of contentment. The relative left/right activity is seen as a marker for the happiness set point, since people tend to return to this level no matter whether they win the lottery or lose their spouse.

Richard J. Davidson wondered if mental training could produce changes that underlie enduring happiness. To find out he (with the help of the Dalai Lama) recruited Buddhist monks to meditate inside his functional magnetic resonance imaging tube while he measured their brain activity during various mental states. For comparison, he used undergraduates who had had no experience with meditation but got a crash course in the basic techniques. During the generation of pure compassion, a standard Buddhist meditation technique, brain regions that keep track of what is self and what is other became quieter.

The monks showed a significantly greater activation in a brain network linked to empathy and maternal love. Connections from the frontal regions to the brain’s emotional regions seemed to become stronger with more years of meditation practice, as if the brain had forged more robust connections between thinking and feeling.

While the monks were generating feelings of compassion, activity in the left prefrontal (the site of activity that marks happiness) swamped activity in the right prefrontal (associated with negative moods) to a degree never before seen from purely mental activity. The undergraduate controls showed no such differences between the left and right prefrontal cortex. This suggests that the positive state is a skill that can be trained.

“How The Brain Rewires Itself,” by Sharon Begley

Meditators sometimes identify the negative emotions they are feeling in order to free themselves of them, and brain scans have recently shown that this process calms the part of the brain associated with emotional processing.

Matthew Lieberman hooked 30 people up to functional magnetic resonance imaging machines, & asked them to look at pictures of faces making emotional expressions. Below some of the photos was a choice of words describing the emotion — such as “angry” or “fearful” — or 2 possible names for the people in the pictures, one male name and one female name.

When the participants chose labels for the negative emotions, activity in the right ventrolateral prefrontal cortex region — an area associated with thinking in words about emotional experiences — became more active, whereas activity in the amygdala, a brain region involved in emotional processing, was calmed.

By contrast, when the subjects picked appropriate names for the faces, the brain scans revealed none of these changes — indicating that only emotional labeling makes a difference.

“In the same way you hit the brake when you’re driving when you see a yellow light, when you put feelings into words, you seem to be hitting the brakes on your emotional responses,” Lieberman said.

In a second experiment, 27 of the same subjects completed questionnaires to determine how “mindful” they are.

Meditation and other “mindfulness” techniques are designed to help people pay more attention to their present emotions, thoughts and sensations without reacting strongly to them. Meditators often acknowledge and name their negative emotions in order to “let them go.”

When the team compared brain scans from subjects who had more mindful dispositions to those from subjects who were less mindful, they found a stark difference — the mindful subjects experienced greater activation in the right ventrolateral prefrontral cortex and a greater calming effect in the amygdala after labeling their emotions.

“Brain Scans Show Meditation’s Effects,” by Melinda Wenner

The U.S. Department of Education’s Early Childhood Longitudinal Study (ECLS) tracks more than 20,000 US schoolchildren from kindergarten through the fifth grade. The ECLS gathers each child’s test scores and demographic information, and asks the children’s parents questions.

According to the ECLS, a child with at least 50 kids’ books in his home scores roughly 5 percentile points higher than a child with no books, and a child with 100 books scores another 5 percentile points higher than a child with 50 books.

But the ECLS data show no correlation between a child’s test scores and how often his parents read to him.

And the number of books in a home is just as strongly correlated with math scores as reading scores.

Here is a sampling of other factors that correlate with high test scores, and factors that don’t:

Correlates: Highly educated parents. Parents have high income. Parents speak English in the home. The child’s mother was 30 or older at time of the child’s birth. Parents are involved in the PTA.

Doesn’t correlate: The child regularly watches TV at home. The child’s mother didn’t work between birth and kindergarten. The parents regularly take child to museums. The child attended Head Start. The child is regularly spanked at home.

The child of a young, single mother with limited education and income will typically test about 25 percentile points lower than the child of two married, high-earning parents.

“Do parents matter?,” by Stephen J. Dubner and Steven D. Levitt

CAPM is a model for valuing stocks, based on the idea that investors demand additional expected return to take on additional risk.

The risk is assessed on a stock or security’s “beta,” a measure of a company’s volatility and correlation with the market as a whole. A company with a share price that tends to rise and fall more than the market will have a high beta and vice versa.

Damning evidence that CAPM doesn’t work came from a 2004 study by Eugene Fama and Kenneth French, which looked at all stocks on the NYSE, the American Stock Exchange and Nasdaq from 1923 to 2003. The study shows CAPM underpredicts the returns to low beta stocks and massively overstates the returns to high beta stocks.

A similar study of the 600 largest US stocks by Jeremy Grantham showed that from 1969 to the end of 2005, the lowest decile of beta stocks – notionally the lowest risk – outperformed by an average 1.5% a year. The highest beta stocks actually underperformed by 2.7% a year.

“Pricing model that is fine in theory but worthless in reality,” by Tony Tassell

A small study (”Efficacy of physical activity in the adjunctive treatment of major depressive disorders“) has found that depressed women who exercised had significant improvements in their symptoms over the next 8 months. Those who didn’t exercise showed only marginal improvements.

Before the study, all of the women had tried taking antidepressant medication for at least 2 months but had failed to improve.

The study included 30 women ages 40 to 60 who’d been diagnosed with major depression. The researchers randomly assigned the women to either stick with antidepressants alone or to start an exercise program. All of the patients continued to take their medication.

The exercisers worked out as a group twice a week for one hour, using cardio-fitness machines. At the beginning of the study and 8 months later, women in both groups completed standard measures used to assess depression severity.

Women in the exercise group showed marked improvements in their depression symptoms, while those on medication alone made only modest gains.

Physical activity seems to affect some key nervous system chemicals — norepinephrine and serotonin — that are targets of antidepressant drugs, as well as brain neurotrophins, which help protect nerve cells from injury and transmit signals in brain regions related to mood.

“Exercise may help with hard-to-treat depression,” Scientific American

Since the origins of agriculture about 11,000 years ago, the story of food has also been one of globalisation.

The opening of the Silk Road in the first century BC meant that knowledge of winemaking passed eastwards from the Middle East to China, while the idea of noodles moved in the opposite direction. The “Columbian exchange” of foodstuffs between the Old and New Worlds was second in importance in food history only to the adoption of agriculture.

New foods are generally regarded with suspicion, as potatoes were in 18th-century Europe and genetically modified crops are by many people in the 21st.

But we are living at the end of food history. Spices that once commanded exorbitant prices can now be found in the supermarket. Tomatoes and maize from the New World were unknown to the Romans but are now central to Italian cuisine. India is now the biggest producer of peanuts, a South American crop. China is the largest producer of wheat, a Middle Eastern crop, and of potatoes, originally from South America. Brazil dominates the production of coffee, originally from Ethiopia, and of sugar, originally from New Guinea.

“History on a Plate,” The Economist

The music industry is growing. The record industry is not.

Seven years ago musicians derived two-thirds of their income, via record labels, from pre-recorded music, with the other 1/3 coming from concert tours, merchandise and endorsements. But today those proportions have been reversed. Concert-ticket sales in North America increased from $1.7 billion in 2000 to over $3.1 billion last year.

Pre-recorded music increasingly serves merely as a marketing tool for T-shirts and concert tickets. The best seats for The Police’s world tour this summer cost over $900; the group’s entire catalogue on CD costs less than $100.

Record labels have come up with a remedy: the “360° contract.” Instead of settling for a cut of CD sales, they increasingly offer artists broader contracts that encompass live music, merchandise and endorsement deals. Such deals, also known as multiple-rights or all-rights contracts, are particularly important in regions with rampant CD piracy, such as Africa, Asia and Latin America.

Free downloads have given music fans more money to spend on other things. And they have switched their spending from CDs to tickets and merchandise.

The logical conclusion is for artists to give away their music as a promotional tool.

“A change of tune,” The Economist