Biological Determinism: the myth that our social status is written in our genes
(highlights from Stephen J. Gould's Mismeasure of Man)


        Human beings had a monogenetic origin in the recent past--there is little genetic difference between ethnic groups.

        The brain weight to body weight ratio of all ethnic groups and both genders are the same.

        There is a clear causal relationship between quality of education and intelligence measures.

        Yet history is full of attempts to show an innate (genetic) superiority for intelligence in the upper-class, for Europeans, and for males.

I. 19th century: attempts to show race and gender differences in intelligence via physiological measurements

A. Samuel George Morton in America:
Morton measures brain size by cranial capacity (pouring seeds into skulls and measuring the resulting volume). Claimed to have found the following differences in brain size: White brains > Native Americans brains > African brains


1)    Initial results using flax seed showed large differences

2)    Switched to metal shot – got much smaller differences: he was packing in the seeds with force in proportion to his prejudice (packed strongest for whites, less for native Americans, least for Africans).

3)    If you adjust for body size, differences are zero.

B. Paul Broca (France 1862)

1)    Examined arm bone ratios: whites closer to apes, so abandoned this criterion

2)    Examined brain size: abandoned upper end of scale because of white “inferiority”

3)    Examined brains of criminals: they were larger

4)    French v.s. Germans: correctly adjusted German brain size for body size.

5)    Cro-Magnon compared with modern European populations-- abaondoned

6)    Male vs Female: did not adjust for body size.


II. Hereditarian theory of IQ and Eugenics

A. Binet (France 1904): 

1)    Head size for best/worst students: “blind” testing removes difference

2)    Turns to testing – only as method to identify learning disability

3)    Cautions against using average of tests as a ranking system or inferring innate ability

H.H. Goddard (US 1912):

1)    Invents “morons” as borderline btwn normal and abnormal

2)    Prevent “interbreeding” that could lower quality of US “gene pool”

3)    Prevent immigrants from “polluting” the US with their “bad genes”

L. Terman (US 1916):

1)    Changes Binet’s system into unilineal ranking, from subnormal to genius.

2)    Disappointing lack of confirmation, eg hobo IQ higher than police and firefighters.

3)    His student Catherine Cox claims to confirm, but used estimated IQ of dead geniuses.

R. Yerkes (US 1917):

1)    WWI provides new testing opportunity

2)    Much of test biased to middle-class WASP culture. 

3)    White recruits who failed written test given image version, but not black recruits.

4)    Test results showed strong correlation with poverty – a problem for hereditarians. 

5)    Test results showed strong correlation with schooling– a problem for hereditarians.

6)    Black IQ scores in the 4 highest northern states greater than white ave in 9 southern states.

C. Brigham (US 1923):

1)    Defends work of Yerkes, supports application to immigration law

2)    Cultural bias is OK because we don’t want immigrants who “don’t think like Americans.”

3)    Explained correlation of IQ with amount of time in U.S. using absolute rather than relative time.

4)    Explanation for lower IQ in non-english speaking “Nordics”: “that’s just cultural difference”

5)    Impact of the Army IQ test results for African Americans and Jews: segregation and 1924 immigration restriction act.

III. IQ and Factor Analysis

Cyril Burt (UK 1940):

1)    Claimed to have found 53 twins separated at birth and raised apart. 

2)    Average correlation remained exactly the same across every sample.

3)    Collaborators Howard and Conway did not exist.

4)    Proof for genetic basis of econ class standing: IQ of parents estimated from class.

5)    Fraud exposed by Burt’s fan Hearnshaw.

Models of intelligence:g (“general intelligence”) versus PMA (“Primary Mental Abilities”)

1)    Eugenics requires single ranking parameter: g (like gas for all mental activities)

2)    Alternative model: PMA (like separate “engines” for each mental activity) 

3)    Most IQ tests show strong (PMA-like) variation between abilities (g 2ndary). 

Argument is actually irrelevant since it is only a necessary, not sufficient, condition for eugenics to be true – still says nothing about inheritance



Eugenics suddenly becomes unfashionable – Nazi attempts to eliminate “inferior genes” and breed a “master race” expose the political consequences of eugenics thinking.

1953: Crick and Watson (and Rosalind Franklin) show structure of DNA – the era of biotechnology begins.


V. Postmodern Biological Determinism

1966: Nobel prize winner William Shockly

1)    Presents paper at AAAS claiming that the work of Terman, Goddard, and Burt proves there is no point to social programs for African Americans.

2)    Encourages sterilization of anyone with IQ below 100, sperm bank for Nobel Prize winners.

1979: Arthur Jenson – 800 page book defending “g” as general principle of biological evolution.

1981: Harvard biologist Stephen J. Gould publishes The Mismeasure of Man; exposes the frauds of biological determinism. 

1994: Herrnstein and Murry publish The Bell Curve, again citing the work of Jenson and Burt.

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