Genetics and Intelligence II

Testing, scientific racism, IQ, gender

Who’s smart, who’s not?

• Are you smarter than a 5 th grader?

• Fascination with brilliance • Equal fascination with ‘stupidity’

What is intelligence?

Cognitive Ability: a hard fact, like an atom that can be determined and measured or is it an amalgam of abilities: a qualitative assessment, ill defined, undetermined, as yet not measurable?

What is race and does it relate to intelligence?

A genetic reality or a social construct?

Are there really no differences in intelligence between genders?

If not, why don’t we see more women doing “hard” science?

How has information from intelligence tests been proposed to help design social policy?

Jean Agassiz (1807-1873)

• Very important in early American science • Personal repulsion to African-Americans • Self evident that whites>blacks • Legal equality yes; social equality no • Polygeny

Samuel Morton (1799-1851)

• Also a polygenist • Had a large collection of skulls from American Indians. Began to measure the size of the skull (filling it and measuring volume) •

Crania Americana

and

Crania Aegpytiaen

• At least three errors in analysis (likely unconscious)

Sir Francis Galton (1822-1911)

Hereditary Genius: An Inquiry into its Laws and Consequences

1869.

Alfred Binet (1857-1911)

The Binet-Simon scale, later Stanford- Binet scale.

Most of these researchers believed intelligence to be of the first camp. A hard, stable fact that can be measured.

Early Conclusions

These men concluded (except Binet): 1) Intelligence can be measured using tests and these tests provide a

g

factor that is a hard number representing person’s intelligence 2) Races and genders differ in

g

(hence they differ in intelligence) • • Caucasians superior to all Men superior to women 3)

g

(like eye color) is a heritable genetic trait.

Gould and Lewontin 1960-1980s

• Rejected idea of biological determinism • Rejection of race as a real biological construct • Rejection of g as a meaningful measure (factor analysis flawed) • Misuse of heritability

Correlation and

g

• Correlation- relationship between two or more variable (not causation!) • Example: 10 different subtests for IQ. Some correlated and some not.

• Factor analysis boils subtests down to one value (g), but if all subtests are correlated, then they’re all testing for same things (one aspect of intelligence) • And if some subtests are correlated and other subtests aren’t correlated, g is less meaningful

Heritability

• What do we mean by this?

One measure of heritability is correlation (or the relationship) of a character value (height) between parent and offspring

Heritability

• Not nature vs. nurture (e.g. height of 5 ft. woman can’t be parsed into 3 ft came from genes and 2 ft came from environment) • Her height result of genes in a particular environment

Heritability

• We ask whether the short woman is shorter than a tall woman because of her environment?

• Identical twin studies allow us to test this • Heritability is only relevant within populations (site specific)

Heritability

Scientists who study heritability ask: In this population, how much of the variation in heights is due to variation in genes and how much is due to environment?

So, measures of heritability are specific to a specific environment

Heritability misused

1) Heritability measurements only relevant to the population

and

environment from which they came. 2) Cannot compare heritability between populations because that doesn’t control for environment 3) Heritability tells us nothing about role of genes in traits shared by all (e.g. nose number) So what’s it good for?

The impossible human experiment

IQ measures some hard trait that governs our cognitive ability, often called

g

factor

g

is directly related to a person’s ability that it’s relatively stable throughout life and time, determined by genes not environment Higher IQ results in more proficient employees who make more money. Among lawyers, those with highest IQ are at the top IQ can be used in hiring to predict success

Why do Herrnstein and Murray believe this?

Look at extremes: we know that there are people with mental retardation (low IQ) We also know there are some children that are brilliant If we follow argument logically, the rest of us fall out in middle.

But where in the middle? They believe there is a direct continuum (112 > 110)

Mean is stable; IQ is stable

• Among white Americans- average IQ 103. • Among Asian-Americans, 106. • Among Jewish Americans,113. • Among Latino Americans, 89.

• Among African-Americans, 85. • Around world: similar trends sub-Saharan Africans around 70.

Racial and ethnic differences obvious.

Heritability (twin studies) Historical attempts to raise IQ (e.g. nutritional programs, additional formal schooling, government preschool programs (such as Head Start) have had little if any lasting impact on intelligence as measured by IQ tests.

Murray takes on policy: what to do about this undeniable reality?

Jan 16, 2007,

The Wall Street Journal

“Today's simple truth: Half of all children are below average in intelligence.” 1) Schools cannot —no matter how good they are —help children in the 49% or lower 2) Low IQ good predictor of poverty and correlates with crime, dependence on welfare, low citizen involvement, etc.

3) This is an unalterable truth that we should accept when designing policy.

“Too many Americans are going to college.” January 17, 2007

The Wall Street Journal

1) If you’ve got an IQ of 100 and went to a good high school, this is about the upper end of your abilities.

2) “Traditionally and properly understood, a four-year college education teaches advanced analytic skills and information at a level that exceeds the intellectual capacity of most people.” 3) You need a 110 minimum to excel at college; only 15% of population meets that. Currently more than 45% of population enrolls. Conclusion: only 3-5 of you should be here!

4) Most students don’t want to be in college, they’re just there because 1) it’s a way to a better job and 2) their parents are paying for it. When we include these students in college, we must lower our standards to accommodate them and this brings down our gifted: the dumbing down of American schools, which will have negative consequences for society as a whole.

Why don’t we give them other options, like really good vocational schools?

“Those with superior intelligence need to learn to be wise.”

Jan 18, 2007,

The Wall Street Journal

1) What about those people with IQs of 120+ ?

2) We need to focus our college education dollars on those who make up our intellectual future (doctors, lawyers, engineers, scientists) —society’s big thinkers.

3) They must be taught wisdom, humility and good

judgment

.

“They should not be taught to be equally respectful of Aztecs and Greeks; they should focus on the best that has come before them, which will mean a light dose of Aztecs and a heavy one of Greeks.”

Murray and Herrnstein Conclusion

• Let’s not deny differences in intelligence • Denying inequality doesn’t help society • Everyone is valuable • Unfortunately, even though we don’t like the reality, different races fall out on ends of spectrum

Assumption 1 Measuring Intelligence

Tests, such as WISC, IQ, measure intelligence.

But, traditional tests, like the IQ, WISC, measure past learning, mostly verbal.

Assumption 2 IQ tests/scores are stable

• “The Flynn Effect” refers to the fact that during the 20th century, there were enormous gains in IQ from one generation to another, about 0.3 points per year. • In other words: how come our grand parents were so dumb?

Flynn’s Conclusions

• There is a problem with g; it’s not stable • Why not? • IQ tests are highly culturally bound

How about Murray & Herrnstein’s idea that race and IQ linked?

• Gap between African Americans and white Americans no longer decreasing • But see Flynn’s graph here

Chinese-American Story

• “the American natural aristocracy” Weyl 1966 •

The abilities and achievements of Orientals in North America

, Vernon 1982.

• Based on 1975 test scores from Chinatown, but used 1950s norms.

• Flynn re-analyzed data with 1975 norms.

• Chinese Americans excel despite lower scores! Achievement a cultural trait?

What about gender?

• Unlike race, there is little debate about the fact that there are two genders: male and female • Do they show differences in intelligence?

President Summers speaks

• Women are underrepresented in hard sciences at Research I universities • Conclusions: this reflects innate aptitude Hence the “math is hard” Barbie doll?

“At Colleges, Women Are Leaving Men in the Dust” The New York Times July 2006

• Less likely to go to college (Only 42% of college students are men) • Regardless of ethnic group, men less likely to complete Bachelor’s degree • Compared to women, men get lower grades • So following Summers logic, we now conclude that women are smarter than men?

Gender and Science

• Men tend to test higher in spatial abilities (on average) but does this matter for those who do science?

• For example: Since 1980, roughly 50% of all PhDs in biological sciences have been earned by women. In 2005, women held only 20% of faculty positions.

• Social issues and unconscious bias might play a role?

Birth order and family size?

• Trend: first borns have higher test scores and achieve higher eminence in society – Increase is slight (1 point) – Other factors obviously important • Larger families have lower IQ scores – Dilution of intellectual, emotional and monetary resources

Correlation versus Causation

• What do these relationships mean?

• How does correlation differ from causation?

Genotype + Environment= Phenotype