Tuesday, December 8, 2009

Cardio = higher IQ (?)

During early adulthood, a phase in which the central nervous system displays considerable plasticity and in which important cognitive traits are shaped, the effects of exercise on cognition remain poorly understood. We performed a cohort study of all Swedish men born in 1950 through 1976 who were enlisted for military service at age 18 (N = 1,221,727). Of these, 268,496 were full-sibling pairs, 3,147 twin pairs, and 1,432 monozygotic twin pairs. Physical fitness and intelligence performance data were collected during conscription examinations and linked with other national databases for information on school achievement, socioeconomic status, and sibship. Relationships between cardiovascular fitness and intelligence at age 18 were evaluated by linear models in the total cohort and in subgroups of full-sibling pairs and twin pairs. Cardiovascular fitness, as measured by ergometer cycling, positively associated with intelligence after adjusting for relevant confounders (regression coefficient b = 0.172; 95% CI, 0.168-0.176). Similar results were obtained within monozygotic twin pairs. In contrast, muscle strength was not associated with cognitive performance. Cross-twin cross-trait analyses showed that the associations were primarily explained by individual specific, non-shared environmental influences (≥80%), whereas heritability explained <15% of covariation. Cardiovascular fitness changes between age 15 and 18 y predicted cognitive performance at 18 y. Cox proportional-hazards models showed that cardiovascular fitness at age 18 y predicted educational achievements later in life. These data substantiate that physical exercise could be an important instrument for public health initiatives to optimize educational achievements, cognitive performance, as well as disease prevention at the society level.

IQphys.pngThe figure to the left is pretty striking, though the general correlation between intelligence and overall health has been long known. I'm not too sure if I really accept that this correlation is as causal as they say it is, but it probably can't hurt to encourage for moderate exercise within the population. So even if this is another spurious correlation which leads to educational programs which don't have the effect intended (increase IQ), it wouldn't do that much harm, and perhaps might result in some good.

"Americans" don't like Barack Hussein Obama

I post some data analysis over at my other weblog. For example, today I looked at the relationship between food stamp usage and unemployment. The Census makes a lot of county-level data available, though it's often slapdash and disorganized. But using R I've constructed some pretty large data sets. I don't post here much because I concentrate more on science in this space, and the 500 pixel width means that integrating scatter plots into a post seamlessly is pretty much impossible.

But since readers of this weblog are much more liberal than over at GNXP Classic, I thought you'd be interested in what demographic variables predict voting for Barack Obama on the county-level. So the dependent variable is the 2008 results for Barack Obama by county.

The independent variables are:

% of non-Hispanic whites who identify German
% of non-Hispanic whites who identify as "American"
% black
% Median household income
% Median home value
% with a college degree
% on food stamps
% obese

Below are the coefficients with errors and p-values if not significant).

% of non-Hispanic whites who identify German 0.13 (0.032)
% of non-Hispanic whites who identify as "American" -0.89 (0.046)
% black 0.20 (0.022)
% Median household income ~ 0
% Median home value ~ 0
% with a college degree 0.33 (.037)
% on food stamps 0.008 (0.0006)
% obese -0.0012 (0.001, p-value 0.23)

r-squared = 0.52

I also calculated earlier the white vote for Obama using a combination of county-level data and state-level exit polls. So here are the coefficients for prediction of the white vote for Obama:

% of non-Hispanic whites who identify German 0.27 (0.026)
% of non-Hispanic whites who identify as "American" -0.68 (0.045)
% black -0.25 (0.023)
% Median household income ~ 0
% Median home value ~ 0
% with a college degree -0.089 (.036)
% of whites on food stamps 0.008 (0.0006)
% obese -0.0037 (0.0092)

r-squared = 0.56

"Americans" are generally those of British or Irish ancestry who live in the South.

Which religious groups are Creationist?

The main surprise here are Mormons. I knew that they had become much more Creationist over the past 3 generations due to their identification with conservative Protestants, but I didn't know that it went this far. In The Creationists Ronald L Numbers states:

In 1935 only 36 percent of the students at the Mormons' Brigham Young University denied that humans had been "created in a process of evolution from lower forms." By 1973 the figure had risen sharply to 81 percent.

This is interesting because Mormons have no objections to evolution which are distinctively Mormon. This is why a prominent Mormon such as Mitt Romney didn't have a problem taking a relatively strong position in favor of evolution.

The data above was from the Pew Religious Landscape Survey. I decided to see how various parameters would predict acceptance of evolution for these groups.

Levels of selection & the full Price Equation

In the post below on the Price Equation I stayed true to George Price's original notation in his 1970 paper where he introduced his formalism. But here is a more conventional form, the "Full Price Equation," which introduces a second element on the right-side.

Δz = Cov(w, z) / w

One can specifically reformulate this verbally for a biological context:

Change in trait = Change due to selection on individuals + Change due to individual transmission

The first element on the right-side is explicable as selection upon a heritable trait. w is the conventional letter used for "fitness," so w is population mean fitness, and serves to normalize the relation. "z" is the trait. The term "individual" can mean any set of entities. The straightforward plain interpretation may be that "individual" means a bounded physical entity, so that the covariance is measuring selection across individuals within a population conditional upon a correlation between trait value and fitness.

What then is the second element? The "E" represents expectation, just as "Cov" represents covariance. Purely abstract statistical concepts which can be drafted to various ends. In the frame I presented above, it is transmission bias from the individual to their offspring. In a deterministic system without stochasticity this is often just 0, so it is omitted from original Price Equation, but, it can be understood genetically as meiotric drive, mutation, random drift or biases introduced through Mendelian segregation. In other words, the covariance is measuring the change across the whole population due to processes which apply on the level of the population, while the expectation is simply tracking parent-offspring dynamics independent of that covariance.

But "individuals" need not be conceived of as physical individuals. One could imagine individuals being cells within a multicellular organism. The application of this in terms of the spread of cancers is obvious. Or, one could move "up a level," and conceive of the individuals as a collection of individuals, groups. Then, the second element, the expectation, could be transmission bias within the groups. So the verbal form of the equation would be:

Change in trait = Change due to selection on groups + Change due to group transmission

"Change due to group transmission" simply refers to within group selection. In the context of what I've been talking about the past week that refers to selection against altruism within groups. There will be a bias, all things equal, to favor cheaters and selfish strategies within groups. "Change due to selection on groups" simply refers to group fitness conditional upon the frequency of altruists. The more altruists, the more likely that the group is to be selected.

Here is the full Price Equation expanded to show within and between group dynamics (assume "population mean fitness" = 1, so omit the denominator):

Δz = Cov(wi, zi) + {Covj(wji, zji) + Ej(wjiΔzji)}

The subscript refer to:

i = group
j = individual

Though really they're simply referring to levels of organization or structure. The following would be acceptable:

i = species
j = group

i = individual
j = cell

i = culture
j = subculture

i = religion
j = sect within religion

(and of course, you could continue to "expand" across levels of organization)

In concrete terms, let's imagine that "z" is an allele. A gene variant. Also, let's focus on group & individual scales. Again, the first element, Cov(wi, zi), refers to the covariance between fitness of the groups and frequency of genes within those groups. The second element is more complex now, as a covariance term is nested within the expectation. The expectation is evaluated over all the groups, as you have to assess transmission bias on a group by group basis. The within group covariance is now evaluating evolutionary dynamics in terms of relative fitness of individuals within the group, with specific individuals being referred to by the subscript "j." The more individuals within the group, the greater the weight of this covariance. This is important, because you need to weight the effect within the groups by the sizes of the groups. Additionally, there is still the issue of transmission bias, the expectation of change from parent-to-offspring which isn't a function of the covariance between the trait (gene) and fitness.

In sum:

1) The existence of a formalism does not entail that it is empirically ubiquitous. Because it can be does not mean it is.

2) For a less agnostic and more verbal treatment, see David Sloan Wilson.

3) Much of the above is based on Steve Frank's review (PDF) of the Price Equation.

The Faith Instinct: How Religion Evolved & Why It Endures

During the first few years of ScienceBlogs there was a lot of talk about religion. Yes, there's talk about religion now, but it's toned down in the wake of the ebbing of the publicity around The God Delusion. Naturally in the wake of the New Atheism a raft of conventional apologetics have been published, The Dawkins' Delusion being a typical example. More recently more nuanced books which wend the middle ground between militant atheism and conventional apologetics have taken center strage. Karen Armstrong's The Case for God approaches this from a philo-theistic angle, while Robert Wright's The Evolution of God is predicated on materialist presuppositions.

Nicholas Wade's The Faith Instinct: How Religion Evolved and Why It Endures is of the same genre as Robert Wright's The Evolution of God, though of its own particular flavor (see Wade's review of Wright's book). In particular, Wade admits that the The Faith Instinct fleshes out aspects of his earlier contribution, Before the Dawn: Recovering the Lost History of Our Ancestors. With his bailiwick at The New York Times in evolution and genetics Before the Dawn is an explicable extension of his reporting. What does religion have to do with evolution and genetics in any constructive sense (as opposed to Creationism)? In Wade's telling quite a bit.

In fewer than 300 pages you are treated to a weaving together of evolution, genetics, psychology, history, philosophy and sociology. Many books on religion tend to put the lens on one particular manifestation of the phenomenon, and often treat the rest as somehow marginal or deviations from the type. In Karen Armstrong's The Case for God it seems that she considers philosophical mystics as the apotheosis of the religious. In Religion Explained and In Gods We Trust cognitive anthropologists Pascal Boyer and Scott Atran explore religious phenomenon as an outgrowth of our innate psychologies. In Darwin's Cathedral David Sloan Wilson attempts to resurrect functionalism. Other scholars focus on the specific details of the emergence of ethical monotheism, the explosion of Islam in the world of Late Antiquity, the swelling of secularization in the our own times. There is of course so much to cover because religion is an incredibly expansive and diffuse behavioral phenomenon, which in many societies pervades nearly all of life.

To approach this tractably Wade divides religion at its joints into its distinctive parts. He distinguishes between the horizontal function of religious faiths in cementing group identities and reflecting group will, as well as the individual level psychological predispositions and biases which lead many to supernatural intuitions. The former is the reality of behavior operating visibly, rituals. Rites, communal revivals, and symbolic markers. The latter is the more subtle aspect of the interface between one's inner world, one's mental representation of the universe, and the sensory cues and inputs one receives from the outside world. Many specific behaviors obviously operate at the intersection of the two categories. Early on in The Faith Instinct there is a chapter on our innate moral intuitions, what Jonathan Haidt and Marc Hauser explore in their research programs. Innate cognitive reflexes have a clear effect on our external action, and these moral reflexes seem to be genetically specified on some level. Though the relationship between religion and morality is not a necessary one, historically it has often been intimate. Wade points to how our genes shape our behaviors, and how those behaviors are integrated into the phenomenon of religion. It may not be a seamless web, but the patches of the narrative are stitched together by common threads.

Moral intuitions and how they bleed into the religious domain is not a novel topic. Rather, perhaps the most original chapters in The Faith Instinct are those which focus on music and dance. The ecstatic and communal aspect of faith is one of the most salient visible manifestations, from the cult of Dionysus in the ancient world down to the circuit riders of the early 19th century Second Great Awakening. This sort of populist religion ebbs and flows, erupting onto the scene for a few decades, but eventually fading into the background. Religious professionals, from their literal ivory towers, tend to be fearful of it because of its bottom-up revolutionary power. In the United States where state religion was less of a force than elsewhere populist religion shunted elitist denominations to marginality (Congregationalism), and fostered the rise of other sects to central prominence (Methodism). Through ethnographic surveys of small-scale Wade suggests this sort of religion, in which dance and music in a collective context are the primary manifestations of worship, was the ancestral religion. The ur-religion if you will. It is notable that both music and dance are human universals, and like language there are forms of brain damage which can selectively impair one's appreciation or perception of music (and, there are forms of brain damage which can impair speech but leave singing intact!).

But is this all incidental? Moral & supernatural intuitions, facility for music and dance, these things are not necessarily associated with religion as such. No, rather, it seems that Wade believes that these traits tend to be associated with religion, can be co-opted by religion, and that religion itself is a phenotype which was subject to natural selection. That is, religion is an adaptation. There is of course an alternative view, and that is that religion is a byproduct of other traits which have survival value. It is here that the cognitive anthropologists emerge, because they make a compelling case that the sub-components of religious belief, an ability to engage in abstraction, intuitions about agency and teleology, as well instincts such as a fear of death, all synthesize together to generate a strong religious intuition as a byproduct. To use an analogy, the components of a car's engine operate in sync to generate power which drives it forward, but the nature of combustion is such that heat is produced naturally out of the chemical processes. It may be that a normal and intelligent human being who is sociable and inclined toward imagination finds supernatural concepts extremely plausible, and will converge upon these concepts through group socialization even without outside indoctrination. In this telling the gods naturally emerge in the normal course of events not through any benefit to the belief in gods, but to the benefit in other instincts which make such beliefs probable. Indoctrination's role, and more generally organized religion, is to channel and constraint these beliefs and impute specific characteristics to the intuitions.

Wade is having none of this. His refutation of this admittedly speculative model is rather thin, verging on incredulity and skepticism as to the motives of militant atheists such as Richard Dawkins, who no doubt as an adaptationist might prefer that religion was not an outcome of the Darwinian process of selection which he has built his career around. But the primary rejoinder is an alternative mode, a speculative one in its own right, that religion is a trait which aided humans in vicious intergroup competitions in the pre-modern era. It is a vision of tribes who worship together, propitiate the gods together, and die together. Though surely religion has a role in giving one individual solace in the face of death, Wade's primary adaptive focus is on the level of the group, and the role religious activities and beliefs play in cementing bounds and coordinating collective action more coherently. In a multilevel selection framework those who were not favored by the gods of war died, while whose who held faith in their gods flourished. Here The Faith Instinct draws upon Samuel Bowles' models which combine within group altruism and between group conflict. Religion then is a trait which at the group level fosters altruism and coherency to tribes, who then go out and slaughter their enemies, who they naturally may dehumanize as followers of alien gods. It is a brutal hypothesis cloaked in the language of evolution and ethology. I think back to Matthew 10:34, where Jesus asserts, "I come not to bring peace, but to bring a sword." Perhaps this was the "Prince of Peace" reverting to type?

These basic units of psychology and ethology, selection operating at higher levels of organization, are scaled up then in the second half the narrative, as Wade races from the transformation of the Hebrew tribal god into the God, the rise of Christianity and Islam, and the early modern relationships between religion, state and nationalism. Some of the historical material is almost out of place in The Faith Instinct, for example the fascinating but tendentious Hagarism Hypothesis for the origin of Islam. While the traditional model is well known, a central Arabian prophet founding a new faith, and the believers crashing the gates of Persia & Byzantium and founding a new empire as well as religion. Hagarism argues that what we believe about Islam is false, that in reality the religion was constructed in the 8th century, and that the first "Muslim" century was not a Muslim one at all, but dominated by a heretical Arab Christian dynasty, the Umayyads. The evolution of Islam in the 8th century was a matter of politics, with the Arab ruling class seeking a new and distinctive religion. Though I found this interesting, I was a bit curious as to what this material had to do with the faith instinct. Additionally, though there is time to explore this obscure and provocative thesis about the origins of Islam, there very little on the religions outside of the Abrahamic tradition. This is a conventional oversight, as it disrupts the linear Western progression from tribal paganism to modern monotheism, but religion is by its nature complex and I believe that a cross-cultural survey can be very informative of both inevitabilities and contingencies as they serve as "independent experiments."

As the narrative approaches its denouement you are treated to ancient customs in modern garb. Yiddish speaking Orthodox Jews do not engage in violent intergroup competition, but they look to each other's needs and live apart from the rest of society. "Cults" aroused to mass paranoia and hysteria are driven to such irrational self-sacrificing heights that they occasionally are witness to mass suicides. Mormons with high fertility rates and a strong communitarian tradition are arguably the first new world religion to emerge since Islam. The modern world is rife with illustrations of ancient dynamics. As the subtitle asserts, religion evolves, and, it endures.

It is clear that Wade approaches the topic as a nonbeliever in the tenets of specific religions, but admiring of the outcomes and actions of many believers. Like David Sloan Wilson he seems to look to a future when a religion arises which is rid of its primitive legacies of Bronze Age sky gods. E. O. Wilson has also expressed a hope for this sort of evolution. Call it religion without the superstitious silliness. Wilson grew up an evangelical, and was Born Again at one point in his life, and he has claimed that even today Baptist church services can arouse his emotions and inspire awe. And at these services he knows once more that he is "among his people." Carl Sagan once spoke of a "God Shaped Hole" in our brain, but it seems rather more accurate to speak of numerous holes into which the pegs of religion pit, allowing the gods to hitchhike along where our brains lead. For the mystical there is withdrawal and communion with God, for the philosophical there are arcane texts, for the emotional there are revivals, for the bloody-minded there are subhuman unbelievers, and so forth. The psychologists who are skeptical of religion being an adaptation, such as Scott Atran, nevertheless argue that the basal intuitions make supernaturalism compelling to the human race in a way that is impossible to eliminate. I have pointed to data which shows that though organized religion has collapsed in much of Europe, the slack has been taken up more by unaffiliated theism than atheism. The star in The Faith Instinct is the horizontal and integrative dimension of religion, but it seems that in the developed world a combination of rampant pluralism as well as a general weakening of organized religions is breaking bonds which tie people together in a sacred body. Rather, it is a more atomistic faith instinct on the individual level which persists once the communal aspect is stripped away, a world of ghosts, energies and spirits. The future may be Sedona and not Ethical Culture

Those humanitarian founders!

Truths that America's founding fathers had held to be self-evident - that all men were created equal and endowed with certain inalienable rights - were now scorned as gross sentimentalities that had been overtaken by Darwinian science. Within a decade the self-styled "scientific racialists" had begun to classify other groups as genetically inferior. Immigrants from Spain and Italy were held to be a threat to the quality of the American gene pool and spurious scientific evidence was adduced to "prove" that Jewish immigrants were near-imbeciles whose admission in large numbers might lead to a lowering of the average level of intelligence of the American people. In fact, this cohort of Jewish immigrants would go on to supply more Nobel Prize winners than any other immigrant group. But in the early Twenties it was the voice of the genetic-alarmists in the science establishment that prevailed and the US Congress imposed strict quotas on the admission of Jewish and south European immigrants. One unforeseen consequence of the quotas was that many Jews seeking to escape Nazi persecution in the Thirties found the doors to the United States barred to them.

I have no interest in defending Charles Darwin as a 21st century humanitarian liberal, or his intellectual successors up until World War II. The author is above recounting an incident where a Congolese Pygmy was placed in the "Monkey House" to show the progression of human evolution. But it seems much to refer to the founding fathers as paragons of human egalitarianism in comparison to the eugenicists of the early 20th century. After all, many of the founders were slave-holders, and even those who objected to the moral acceptability of slavery conceded the reality that ~20% of the American population was to be held as property and accounted as 3/5 of a human in electoral allocations.

The past is complex. Children are often taught history in cut-outs because they easily see the world as heroic and villainous. Intellectuals who attempt to do the same do a disservice to their audience, as they are unable help us move past our baser tribal natures. Rather, they are seek to profit from it. I am personally uncomfortable with the hagiography around Charles Darwin, though I understand that that is generally a response to his singular vilification as the prophet of all the abominations of the 20th century. Those who wish to point to the past moral failings of science in its applied sense might wish to uphold a higher standard of objective analysis themselves if they aim to maintain their credibility.

Note: I'm not a major critic of the Founding Fathers because I'm a temporal moral relativist. Judge not the past too harshly lest ye be judged by the future by standards yet unknown!

America’s Role in Mexico’s Drug War

Forty years ago, the United States government began a "war on drugs" whose cost so far is estimated at $1 trillion, and rising. In 2006, newly elected Mexican President Felipe Calderón began a crackdown on the drug-smuggling cartels—a "war on drugs" that really is a war, involving military troops and weapons and more than 10,000 dead so far. Americans buy drugs from the cartels and sell them guns, and Washington arguably provided the example for the Mexican government's hard-line tactics. So is America to blame for Mexico's drug war?

If you look at any metric —the availability of drugs, the potency, the price—they suggest the drug war declared by Richard Nixon has failed, has done nothing to dampen demand, and has increased criminality. The effect outside the United States has been to internationalize the problem. We began by interdicting drugs in Miami, then moved offshore and to Central America. We had the heroic war of liberation in Panama, where [President] Manuel Noriega was indicted in a U.S. court for drug dealing. Then the supply shifted to Colombia, where the United States has now spent something like $10 billion, and the GAO recently reported it has had virtually no effect. So Mexico is only the last in a long line of these drug wars, and you have to ask: are we not in some way responsible? We are the largest consumer of drugs in the world. We have the largest supply of weaponry in the world. Two thousand guns cross the American border every day into Mexico. If the supply of weapons is coming from one place, and the demand for drugs is coming from one place, it seems self-evident that we are responsible.

The culture of corruption that has developed in Mexico, the failure of the rule of law in Mexico, is one of the largest contributing factors to the violence we see today. Mexico has allowed itself to be a major transit and source country. They resisted U.S. help. In 1985 Kiki Camarena, a wonderful DEA agent, was tortured and murdered in Guadalajara, and there was a massive manhunt for the perpetrators, and Mexico [took the position] that we were infringing on their sovereignty. They have resisted any U.S. assistance ever since. The cartels have operated with impunity, and that is not the fault of the United States.

Is America to blame for Mexico's wars? Indisputably yes. No one disputes that the U.S. consumes drugs produced or shipped through Mexico, but that's not the whole issue. The reason there are drug wars is because the drug trade is prohibited. Whether you think drugs should be legal or not, it's a fact that when you drive a market underground, it becomes violent. Why? Because participants cannot resolve their disputes with lawyers, or by complaining to the Consumer Product Safety Commission, but only by shooting each other. Prohibition creates the violence, and the U.S., far and away above any other country, has foisted drug prohibition on the rest of the world. Let me read you a quote: "While every Mexican administration since the '60s has piously declared that it intended to intensify its drug enforcement efforts for domestic motivations, the real reason has always been American pressure."

The cartels post profits of $14 to $25 billion every year, and they can buy whatever weapons they want, no matter what it costs. Judging from the weapons that are seized, it's fully automatic machine guns, RPG's, hand grenades, airplanes, armored personnel carriers. This type of weaponry comes from the international black market, places like China and Guatemala. It doesn't come from American gun shows or a mom-and-pop gun store, because you can't buy fully automatic weapons there, and you sure as hell can't buy hand grenades and helicopter gunships. But there's another place it's available. According to The New York Times, in the last seven years more than 100,000 soldiers have deserted the Mexican army. How many here think all of them turned in their guns? If you want to talk seriously about the drug war, you've got to talk about the institutionalized corruption within the Mexican government.

We Americans need to make a choice. Either we get serious about clamping down on the consumption of illegal drugs, or we should legalize them. We can't have it both ways. Let's not be distracted by talk of corruption in Mexico or about America's gun laws. This is about what happens to a nation that shares a 2,000-mile border with the richest nation on Earth, that consumes some $65 billion worth of drugs a year and cedes control of that market to offshore criminal organizations. Geography sometimes is destiny: there's an old saying, "Poor Mexico, so far from God, so close to the United States." I recently read a best-selling book on Mexico, and the author wrote that the U.S. wants Mexico "to wage the war and provide the corpses, so it doesn't have to."

My point is very simple here. The United States is not to blame for Mexico's drug war, Mexico is not to blame for Mexico's drug war. President Felipe Calderón is to blame for Mexico's drug war, a war of choice that he should not have declared, that cannot be won, and is doing enormous damage to Mexico. Why did President Calderón declare this war? Because he felt he needed to legitimize himself in the view of the Mexican people, because his election was questioned. I tried to run against Calderón, and I wasn't allowed to, and [then] I supported him actively during the campaign. I thought he won, but he decided that he had to legitimize himself, by calling the Army out into the streets. This war cannot be won, because it is failing to comply with the tenets of a good friend of mine, Colin Powell. To go into a war like this, you need to have overwhelming force, and we don't have it. You need a definition of victory, we don't have it. And you should have the support of the Mexican people, which President Calderón does have, but he's running out of it very quickly.