Progress Daily

Dean Ornish, et al., just published a study (”Changes in prostate gene expression in men undergoing an intensive nutrition and lifestyle intervention“) showing that improved nutrition, stress management techniques, walking, and psychosocial support changed the expression of over 500 genes in men with early-stage prostate cancer.

The researchers studied gene expression in biopsies from 30 men who were diagnosed with low-risk prostate cancer. These men had decided not to undergo conventional treatments such as surgery, radiation, or chemotherapy for reasons unrelated to the study. They had early, small-volume prostate cancer with stable prostate specific antigen (PSA) levels and Gleason scores of six or less, meaning that their tumors were not aggressive.

The changes included a plant-based diet (predominant fruits, vegetables, legumes, soy products, and whole grains low in refined carbohydrates), moderate exercise (walking 30 minutes per day), stress management techniques (yoga-based stretching, breathing techniques, meditation, and guided imagery for one hour per day), and participating in a weekly one-hour support group. The diet was supplemented with soy, fish oil (three grams/day), vitamin E (100 units/day), selenium (200 mg/day), and vitamin C (2 grams/day).

After three months, the researchers repeated the biopsy and looked at changes in normal tissue within the prostate. We found that many disease-promoting genes (including those associated with cancer, heart disease, and inflammation) were down-regulated or “turned off,” whereas protective, disease-preventing genes were up-regulated or “turned on.” A set of cancer-promoting oncogenes called RAS was down-regulated. The Selectin E gene (which promotes inflammation and is elevated in breast cancer) was down-regulated. A gene called SFRP that suppresses tumor formation was up-regulated. These genes are the target of many new drugs that are being developed.

“Changing Your Lifestyle Can Change Your Genes,” by Dean Ornish M.D.

About one in 20 children have a group of symptoms that has come to be known as attention-deficit hyperactivity disorder (ADHD). About 60% of them carry those symptoms into adulthood. ADHD is believed to be genetic, and is associated with particular variants of receptor molecules for neurotransmitters (chemicals that carry messages between nerve cells) in the brain. In the case of ADHD, the neurotransmitter is often dopamine, which controls feelings of reward and pleasure. People with ADHD apparently receive positive neurological feedback for “inappropriate” behaviour.

ADHD sufferers are impulsive. They have trouble concentrating on any task unless they receive constant feedback, stimulation and reward. They tend to perform poorly in modern society and are prone to addictive and compulsive behaviour.

Dan Eisenberg speculated that such behavior may be advantageous for people who lead a peripatetic life. Since today’s sedentary city dwellers are recently descended from such people, natural selection may not have had time to purge the genes that cause it.

Eisenberg tested this by studying the Ariaal, a group of pastoral nomads who live in Kenya. The receptor Mr Eisenberg looked at was the 7R variant of a protein called DRD4, a variant is associated with novelty-seeking, food- and drug-cravings, and ADHD. (See “Dopamine receptor genetic polymorphisms and body composition in undernourished pastoralists.”)

The researchers looked for 7R in two groups of Ariaal. One was still pastoral and nomadic. The other had recently settled down. They found that about a fifth of the population of both groups had the 7R version of DRD4. However, the consequences of this were very different. Among the nomads, who wander around northern Kenya herding cattle, camels, sheep and goats, those with 7R were better nourished than those without. Among their settled relations, those with 7R were worse nourished than those without it.

This discovery fits past findings that 7R and a set of similar variants of DRD4 (the “long alleles”) are more common in migratory populations.

There remains the question of why 7R is found in only a fifth of the Ariaal population. One possibility is that its effects are beneficial only when they are not universal, and some sort of equilibrium between variants emerges.

“The misfits,” The Economist

The age-adjusted US death rate dropped roughly 3% from 2005 to 2006 — reaching an all-time low of 776 deaths per 100,000 individuals — according to a CDC review of national mortality data (pdf file here).

Deaths due to either influenza or pneumonia saw the biggest decline, a 13% drop.

Mortality from other leading causes — for example, chronic lower respiratory diseases, heart disease, diabetes, and essential hypertension or hypertensive renal disease — also fell significantly.

Parkinson disease, Alzheimer disease, and homicide saw drops in mortality, but these did not reach significance.

Life expectancy at birth reached a record high of 78.1 years, up 0.3 years from 2005.

“US Death Rate Hit Record Low in 2006,” Physician’s First Watch

 

Using selective breeding, researchers can make rats, bees and flies a lot better at learning. Animals that are better learners should over time come to dominate a population. Yet improved learning ability does not get selected amongst these animals in the wild. Tadeusz Kawecki may have discovered why.

Kawecki gave flies two different fruits as egg laying sites. One of these was laced with a bitter additive that could be detected only on contact. The flies were then given the same fruit but without an additive. Flies that avoided the fruit which had been bitter were deemed to have learned from their experience. Their offspring were reared and the experiment was run again.

After repeating the experiment for 30 generations, the offspring of the learned flies were compared with normal flies. Learning ability was bred into the flies, but it shortened their lives by 15%. And when flies were bread to live abnormally long lives, they learned less well than even average flies.

“Critical thinking,” The Economist

Reading the 3bn “base pairs” in human DNA — akin to letters, encoding a total of between 20,000 and 30,000 genes that are the “words” of genetics — is getting faster as companies find quicker ways to “read” entire stretches of DNA at a time, like reading a sentence in chunks rather than letter by letter.

The cost of sequencing an individual genome is thus falling exponentially — just as the cost of hard disk space or transistors on a chip did when computing took off.

The rapidly falling cost and time needed to map your DNA:

2003
$440M
13 years to map

2007
$10M
4 years

2008
$100K
4 weeks

2012
$100*
2 days

*Forecast

“Mapping the individual - cheaply,” by Charles Arthur

Robert J. Barro and Rachel M. McCleary (”Religion and Economic Growth Across Countries” & “Religion and Political Economy in an International Panel“) researched the relationship between religion and development.

Their cross-country analysis shows that per capita gdp has a significantly negative effect on religion, both in terms of beliefs and participation. This tendency is gradual as countries grow richer. A steady pattern of secularization has only applied to a few countries, such as Britain, France, and Germany.

For a given level of religious participation, increases in core religious beliefs — notably belief in hell, heaven, and an afterlife — tend to increase economic growth. In contrast, for given religious beliefs, increases in church attendance tend to reduce economic growth. In other words, the main growth effect is a positive response to an increase in believing relative to belonging (attending).

A certain amount of participation in religious activities is positive, in that people acquire useful beliefs. But if people spend too much time in religious activities, there is a negative effect on economic growth.

Religious participation is correlated with a lower probability of substance abuse, juvenile delinquency (Michael J. Donahue and Peter L. Benson, “Religion and the Well-Being of Adolescents“),  and depression (”Immigrant Generation, Assimilation and Adolescent Psychological Well-being“), and positive attitudes toward marriage and having children (Elaine Marchena and Linda J. Waite, “Re-assessing Family Goals and Attitudes in Late Adolescence”).

Overall, urbanization has a negative effect on religiosity, particularly in terms of participation.

“Religion and Economic Development,” by Rachel M. McCleary

The tallest quarter of the US population earns 9-10% more than the shortest quarter, according to two recent studies. Nicola Persico, Andrew Postlewaite and Dan Silverman (”The Effect of Adolescent Experience on Labor Market Outcomes“) think this is because height gives adolescents self-confidence. Anne Case and Christina Paxson (”Stature and Status“), on the other hand, argue that people who grow to their full potential are smarter, on average.

“Feet, dollars and inches,” The Economist

According to research by Warren Sanderson et al., (”The coming acceleration of global population ageing“), the mean age of the world population is 30, with 44 years left to live on average. By the end of the century, the mean age is expected to be 45, with 41 years left. So both measures, mean age and average years of life remaining, show aging.

In North America, the average age will go up through the end of the century, (from 37 to nearly 50), but the average years remaining also will go up (from 43 to 48). North America is the only region to show that pattern.

The increase in average age is caused by people living longer, and also fewer babies being born.

As longevity has increased, people have invested more in education (presumably since they’ll have more time to reap the benefits).

The researchers’ model shows an 88% probability that world population growth will end before the end of the century.

“Getting Old, Faster and Faster,” by Julie J. Rehmeyer

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