Thursday, May 31, 2012

Helmuth Nyborg interviews Richard Lynn

The current issue of Personality and Individual Differences is a tribute to Richard Lynn at age 80. Here is a portion of his conversation with Helmuth Nyborg that reviews his career:

HN: So then you needed a job.

RL: Yes, and I obtained a lectureship at the University of Exeter. I was now to enter the wilderness years and did not succeed in doing anything that I considered significant for the next twelve years. In 1959 I published a paper Environmental Conditions Affecting intelligence, in which I said that it was now established that genetic factors are the major determinant of intelligence, but that environmental factors are also involved. I proposed that these consisted of the quality and quantity of cognitive stimulation from others in the family. I suggested that this explained the tendency for only children to have the highest IQs, and for IQs to decline with increasing family size, and also that eldest and youngest children have higher average IQs than those in the middle of the family. I sent the paper to Sir Cyril Burt, who replied with a friendly letter saying that he agreed with me. After this, I corresponded with Sir Cyril from time to time and I always found him very friendly and helpful.

Monday, May 28, 2012

Prussian Americans most likely to serve in the U.S. military

Memorial Day is a good day to look at military data, and it happens to be an opportunity to echo Razib's call to mend, not end, the American Community Survey. The survey asked respondents their ancestry, and if they are now serving or ever served in the military. I limited the sample to native-born Americans and to people ages 20 to 39 in order to focus on a single cohort. I list the percentages who answered yes by their ancestry (sample size = 1.74 million) and since there are as many categories as countries in the world I only list groups with the highest and lowest numbers. The mediocre middle is left out.

Percent serving in the military now or in the past

Above-average groups

Prussian 12.7
South African 12.3
Guamanian 12.2
Germans from Russia 11.4
Okinawan 11.1
Panamanian 10.2
West Indian 9.9
Belizean 9.8
Indonesian 9.8
Scottish 9.4
Dutch West Indies 8.7
Pacific Islander 8.6
Sicilian 8.6
Scots Irish 8.1
Australian 8.0
African 8.0

Below-average groups

Haitian 3.8
Turkish 3.7
Arab 3.4
Egyptian 3.3
Vietnamese 3.0
Israeli 3.0
Iranian 3.0
Armenian 2.8
Palestinian 2.6
Chinese 2.4
Hmong 2.0
Asian Indian 1.9
Taiwanese 1.8
Pakistani 1.3
Macedonian 1.2
Iraqi 0.0

It's great that Prussians come out on top, but I suspect that some military folks are being selective in which part of their ancestry they identify with. The high-serving groups are an interesting assortment. Using GSS data, I reported in an earlier post that West Indians like Colin Powell are more likely to serve than most groups. Pacific Islanders have high numbers as do your well-known tough guys: the Scots Irish and Sicilians.

On the low end, you have Asians and Middle-Easterners. It looks like Muslims (and Israelis for that matter) don't like to serve, but does anyone know the religion of most American Indonesians?  Are they Muslims?

Also--Mexican-Americans, contrary to the claims of some, do not serve in high numbers. Between 4.4 and 5.3 percent serve or have served (depending on whether you focus on the "Mexican" or "Mexican-American" category). That's below the national average of 6.3 percent.

Monday, May 21, 2012

Predictors of support for gay marriage

Audacious Epigone has a great post on attitudes toward gay marriage. It made me wonder what best predicts support (sample size = 3,399, GSS, blacks and whites):

OLS standardized regression coefficients

Age -.11*
Sex .14*
Race -.02
Size of place .02
IQ .08*
Education .18*
Income -.01
Church attendance -.30*

*statistically significant

Irreligiosity is clearly the stongest predictor of support. Education, being young, and being female are in the middle, and a high IQ is the weakest significant predictor. Race, the size of your town, and income don't matter.

UPDATE: If I add political orientation to the model, there are two noteworthy changes: 1) being liberal becomes the strongest predictor of support, and 2) race becomes significant. When you remove the influence of liberalism, blacks become signficantly less supportive of gay marriage than whites.

Saturday, May 19, 2012

Gender nonconformity and homosexuality

In the comments of an earlier post, someone wrote that there is very little relationship between masculine or feminine behavior and sexual orientation. From a 2003 review:
There are two main correlates of sexual orientation that point to an early developmental genesis. The first is the relationship between childhood gender nonconformity and adult sexual orientation (Bailey and Zucker 1995), which is generally considered one of the strongest of all developmental associations in humans (Bem, 1996). Homosexual men typically recall having been feminine boys, whilst homosexual females were masculine girls. Prospective work confirms this relationship for men (Green, 1987; Zucker and Bailey, 1995). In their meta-analysis, Bailey and Zucker (1995) report large effect sizes for the degree of this association (d=1.31 for men, d=0.96 for women). The gender nonconforming behaviours appear to be specific to childhood sex-typed activities and interests, rather than playmate preferences. Given evidence for an early formative role for androgens in the development of such behaviours, these data are consistent with neurohormonal differentiation theory (Berenbaum and Hines, 1992; Berenbaum and Snyder, 1995). These large heterosexual–homosexual differences in childhood sex atypicality also extend to adulthood, when assessed by “gender-diagnosticity” measures (the extent of male versus female typicality of interests). On these measures (as well as on traditional masculinity–femininity scales; Haslam 1997) gay men are typically more feminine and lesbian women more masculine in adulthood than their same-sex heterosexual peers (Lippa, 2000; Lippa and Arad, 1997).

IQ and religiosity

In the comments of the last post, it was stated that smart people are less religious. Let's remind everyone what the GSS says (sample size = 4,784, surveys 2000-2010, whites):

Scoring six out of ten on the vocabulary test is the mean. Whites in the highest IQ category are slighly more religious than average. Another way of looking at the question is the Pearson correlation. It is .01--overall the two variables are unrelated. (GSS is not able to isolate really smart people, so we can't talk about those folks.)

On the other hand, I know I've got some readers who think of religiosity in terms of belief rather than attendance. If this is what you have in mind, there is a weak negative relationship between intelligence (as measured by the vocab test) and confidence in the existence of God: it is -.14 (p < .01, sample size = 6,849 whites).

Wednesday, May 16, 2012

Atheism and crime

In Breaking the Spell, Daniel Dennett claims that atheists are as law-abiding as believers.

The MIDUS study asked people their religious affiliation and if they had ever been in jail. The results (sample size = 2,183):

Percent ever in jail

Atheist 0.0
Agnostic 17.4*
No preference 13.0*
Spiritual 17.6*
Has a religion 4.8

*significantly higher than people with a religion

Zero of 18 atheists report any jail time. By contrast, agnostics, spiritual people, and those with no religion have significantly higher rates of incarceration. On the various measures of functioning that I've studied, the squishy middle categories often have the worst numbers.

UPDATE: Keep in mind that the current trend is toward more people having no religious preference (but still believing in God) or saying they are spiritual rather than having a religion.

While we're at it, MIDUS gives us another estimate of the percent of Americans who are atheist. The survey asked people to describe their religious affiliation, and "atheist" is one option. Only .8 percent of participants gave that answer. (The study was conducted 2004-2006.)

Tuesday, May 15, 2012

Vitamin B12 and infant brain development

In a new study in the European Journal of Paediatric Neurology, cranial MRI images were taken of 15 infants with vitamin B12 deficiency.
In our study, thinning of the corpus callosum was detected in 6 (40%), cortical atrophy in 5 (33.3%), ventricular dilatation in 3 (20%), large sylvian fissures in 5 (33.3%), hydrocephalus in 3 (20%), asymetric large lateral ventricule in 2 (13.3%) and retardation in myelination in 2 (13.3%) patients and 4 infants had normal MRI findings, respectively.
In conclusion, vitamin B12 is important for development of brain. Severe and various neurological and neuroradiological findings may be seen in infants due to vitamin B12 deficiency. Vitamin B12 deficiency should be considered in infants with hypotonia or neurodevelopmental retardation and with neuroradiological findings such as thinning of the corpus callosum, cortical atrophy and retardation in myelination. The early diagnosis and treatment of vitamin B12 deficiency is crucial for significant neurological impairment and long-term prognosis. Vitamin B12 supplementation of pregnant women may prevent neurological and neuroradiological findings of the infants.
It is infants breastfed by vegetarian mothers who are most at risk of vitamin B12 deficiency. This is true in both undeveloped and developed countries.

Sunday, May 13, 2012

Fertility among educated, never-married white women

In the recent post on the fertility of never-married women, Audacious Epigone suggested I look at trends over time. I calculated the mean number of offspring for white women ages 40 to 59 who completed at least 16 years of education:

Mean number of offspring

Fifties .00
Sixties .00
Seventies .00
Eighties .14
Nineties .16
Aughts .14
This decade .18

From the 50s through the 70s, educated, never-married white women had no children. Since that time, perhaps one out of six has a single child. The trend suggests that if all educated white women never got married, the numbers of educated white Americans would dwindle rapidly.

This graph shows trends in marital status among educated white women:

Singlehood among educated white women has been increasing for several decades but is still short of twenty percent.

Thursday, May 10, 2012

Infant testosterone predicts toddler behavior

A new study from Hormones and Behavior:
The testes are active during gestation, as well as during early infancy. Testosterone elevation during fetal development has been shown to play a role in human neurobehavioral sexual differentiation. The role of early postnatal gonadal activation in human psychosexual development is largely unknown, however. We measured testosterone in 48 full term infants (22 boys, 26 girls) by monthly urinary sampling from day 7 postnatal to age 6 months, and related the area under the curve (AUC) for testosterone during the first 6 months postnatal to subsequent sex-typed behavior, at the age of 14 months, using the Pre-School Activities Inventory (PSAI), and playroom observation of toy choices. In boys, testosterone AUC correlated significantly with PSAI scores (Spearman's rho = 0.54, p = 0.04). In addition, play with a train and with a baby doll showed the anticipated sex differences, and play with the train correlated significantly and positively with testosterone AUC in girls (Spearman's rho = 0.43, p = 0.05), while play with the doll correlated significantly and negatively with testosterone AUC in boys (Spearman's rho = − 0.48, p < 0.03). These results may support a role for testosterone during early infancy in human neurobehavioral sexual differentiation.

Monday, May 07, 2012

Increases in suicide by sex

These graphs show 1999-2009 suicide trends for U.S. men (top) and women (bottom) separately (CDC) :

Both sexes ages 45-64 show large increases over the past decade.

Sunday, May 06, 2012

Head Start does not work

A comprehensive study by DHHS shows that Head Start does not work:
Indeed, Head Start did work well in several pilot programs carefully run by professionals in the 1960s. And so it was "taken to scale," as the wonks say, as part of Lyndon Johnson's War on Poverty.  
It is now 45 years later. We spend more than $7 billion providing Head Start to nearly 1 million children each year. And finally there is indisputable evidence about the program's effectiveness, provided by the Department of Health and Human Services: Head Start simply does not work. 
According to the Head Start Impact Study, which was quite comprehensive, the positive effects of the program were minimal and vanished by the end of first grade. Head Start graduates performed about the same as students of similar income and social status who were not part of the program. These results were so shocking that the HHS team sat on them for several years, according to Russ Whitehurst of the Brookings Institution, who said, "I guess they were trying to rerun the data to see if they could come up with anything positive. They couldn't."

Saturday, May 05, 2012

More suicide among people in 40s and 50s

The graph below shows 1999-2009 suicide rates by age group (CDC data):

Rates (not shown) are stable for children, adolescents, and younger adults, but suicides have been increasing for middle-aged people. By contrast, they have been dropping among those 75 and over.

How do we explain these trends?  Have advancements in medical care improved the quality of life for the elderly? Are people in their 40s and 50s increasingly feeling like failures at work?  More relationship, marriage and family disintegration?

Friday, May 04, 2012

Rushton on the skin color/behavior correlation

Phil Rushton and colleagues at the journal Personality and Individual Differences continue to push the the theory that genes explain the worldwide correlation between skin tone and important behaviors:
Pigmentation of the hair, skin, cuticle, feather and eye is one of the most salient and variable attributes of vertebrates. In many species, melanin-based coloration is found to be pleiotropically linked to behavior. We review animal studies that have found darker pigmented individuals average higher amounts of aggression and sexual activity than lighter pigmented individuals. We hypothesize that similar relationships between pigmentation, aggression, and sexuality occur in humans. We first review the literature on non-human animals and then review some of the correlates of melanin in people, including aggression and sexual activity. Both within human populations (e.g., siblings), and between populations (e.g., races, nations, states), studies find that darker pigmented people average higher levels of aggression and sexual activity (and also lower IQ). We conceptualize skin color as a multigenerational adaptation to differences in climate over the last 70,000 years as a result of “cold winters theory” and the “Out-of-Africa” model of human origins. We propose life history theory to explain the covariation found between human (and non-human) pigmentation and variables such as birth rate, infant mortality, longevity, rate of HIV/AIDS, and violent crime.
As Razib Khan has explained on this blog, pleiotropy as the explanation of these correlations simply does not work. So what plausible theories remain? Any ideas?

Are gun owners mentally ill?

  Some anti-gun people think owning a gun is a sign of some kind of mental abnormality. According to General Social Survey data, gun owners ...