Heredity and Intelligence

1. Heredity and Intelligence A History of the Abuse of Science

2. Naturalistic Fallacy • "Ought" and "Is" • Claims containing the concepts of "ought" or "should" or similar obligations do not generally follow from purely descriptive claims. • The naturalistic fallacy occurs when a description of a situation is taken to provide sufficient justification for creating or accepting some duty or obligation.

3. Socrates

4. Socrates • “…you are brothers, yet God has framed you differently. Some of you have the power of command, and in the composition of these he has mingled gold, wherefore also they have the greatest honor; others he has made of silver, to be auxiliaries; other again who are to be husbandmen and craftsmen he has composed of brass and iron; and the species will generally be persevered in the children…An oracles says that when a man of brass or iron guards the State, it will be destroyed.”

5. Carolus Linneaus • 1735 Carolus Linnaeus “The Father of Taxonomy”, offers first systematic organizational schema to understand the variety of life in the natural order, which is the basis of taxonomical nomenclature.

6. Physical Differences • Early attempts to understand intelligence utilized unrefined examinations of group differences among people’s physical structure. Investigators primarily examined these areas by studying group averages for skull capacity or actual brain size.

7. Phrenology

8. Body Morphology

9. Morphological assessments: From the head to the body • Phrenology (Gall, early 1800s) – skull shape = personality • Sheldon’s body types (1950) • Based on photographs of all incoming freshmen at Ivy league schools in the 1930s • Endomorph – jolly/happy, lazy • Mesomorph – dominant, athletic • Ectomorph – smart, shy • Body type and criminality (Lombroso)

10. Monogeny The belief that all humans belong to a single species Difference such as skin color, size, culture are superficial. Polygeny The belief that what we perceive as racial differences are in fact different species of human. One Species, or Two?

11. Louis Agassiz • “There are upon earth different races of men, inhabiting different parts of its surface, which have different physical characters; and this fact…presses upon us the obligation to settle the relative rank among these races, the relative value of the characters peculiar to each, in a scientific point of view… As philosophers it is our duty to look it in the face.” (1850)

12. Samuel George Morton (1799 -1851)

13. Samuel George Morton • Morton (1799 -1851) was Philadelphia physician who collected and examined1,849 skulls of Americans. Most of these skulls came from the various Native American tribes that had once inhabited the land. Morton believed that a ranking of the races could be established objectively by looking at the cranial capacity of the skulls. He used his detailed research on cranial capacity to support his theory of intellectual superiority of different racial groups.

14. Samuel George Morton • Stephen Jay Gould (1981) criticized his work with four general problems: • (1) He chose to include/delete sub-samples of skulls form his calculations based on how they fit his theory; • (2) He measured skull capacity with seeds which is inaccurate and subject to bias; re-measurements with more precise tools indicated that Caucasians were typically over-estimated and other groups were underestimated; • (3) He assumed that cranial size indicated intelligence and didn’t considered the impact of one physical stature or gender on the skull size; • (4) He miscalculated rounding estimates that consistently favored his hypothesis.

15. Morton’s Measurements • Morton cared about accuracy. • Started by using mustard seed. • Changed to using lead pellets because they were more exact. • Still got it wrong.

16. Dr. Paul Broca (1824-1880)

17. Dr. Paul Broca (1824-1880) • Broca was a chief of surgery at a major Parisian hospital who was interested in the variations found among people’s skeletal structures, particularly their skulls. He developed several instruments for measuring these variations.

18. Dr. Paul Broca (1824-1880) • Dr. Broca’s examination of brain size was influenced by his desire to demonstrate physical evidence for his belief that Caucasian males were intellectually superior to women and men of other races.

19. For example: • When Broca found that criminals mean brain size was larger than honest people’s average brain size, he dismissed this information stating that the executions caused the brain structure to change or that the mean age at death was younger.

20. More Examples • When Gratiolet (an opponent of the belief that brain size was correlated with intelligence) indicated that French brains were smaller than German brains, Broca correctly adjusted the German brain sizes to account for differences in body stature. • However, he did not use this type of adjustment when he examined the differences between men and women’s brain sizes.

21. Charles Darwin

22. The End of Polygeny • Darwin’s theory of evolution posits a common ancestor for all humans, thus eliminating the possibility of claiming that different races are separate species.

23. Darwin’s Theory Three major principles: 1. heredity characteristics are passed from one generation to the next 2. variability characteristics vary across members of a species some individuals will be more successful in their environment than others demand for resources produces selective pressure

24. Darwin’s Theory Three major principles: 3. natural selection how species change, or evolve, over time only those members of a species able to compete successfully for limited resources will survive and reproduce

25. Social Darwinism • The general misapplication of Darwinian principles to society in order to justify the social order. • Spencer • Galton • Sumner

26. Sociology • Sociology needed a theoretical structure. Natural Selection provided a basis on which to explain why societies have taken the forms they have. • British popular philosopher Herbert Spencer (1820-- 1903) wrote extensively on the bases of many social sciences. He is the person who coined the term “Survival of the Fittest,” in 1858 the year before the publication of the Origin of Species.

27. Herbert Spencer (1820-1903) Argues that domains of the universe are subject to objective laws and that the goal of science is to discover the principles of morphology and physiology of all organic and superorganic forms. Argues that sociology is to discover the universal and enduring properties of human social organization.

28. Selected Bibliography The Proper Sphere of Government (1843). Social Statics (1851). First Principles, 1862. Principles of Biology, 2 vols (1864-1867). The Principles of Psychology, 2 vols (1870-1872) The Study of Sociology (1874). The Principles of Sociology, 3 vols (1882-1898). The Man versus the State (1884). The Factors of Organic Evolution (1887). The Principles of Ethics, 2 vols (1892). Herbert Spencer was a prolific writer.

29. Social Darwinism Once discovered, people should obey the laws of societal evolution and resist trying to create, via state and legal mechanisms, societal forms that transgress objective societal laws. Argument attempts to scientize laissez-fair political ideology. Spencer took the standard classical liberal view of freedom: Individuals should satisfy needs and desires without interfering with the needs and desires of others. Individuals should be free as possible from external regulation. Moral law and laissez-faire capitalism are thus co-extensive; both reflect biological laws of survival of the fittest—the eternal struggle among species.

30. Francis Galton (1822-1911)

31. Francis Galton (1822-1911)

32. The life of Galton • Born on Feb. 16, 1822, in Birmingham • Younger relative of Darwin • Child prodigy, independently wealthy, very poor student • Birmingham Medical School, doesn’t finish • Trinity College, Cambridge, medicine (1840), doesn’t finish • Cambridge, mathematics, doesn’t finish • Inherited a fortune (1844) • Noted explorer, geographer, meteorologist, balloonist, biological researcher… and psychologist • Became interested in individual differences at Cambridge • Hereditary Genius (1869) eminence and intelligence are inherited • Coined the word ‘eugenics’

33. Galton’s Contributions and Influence • Developed both intelligence tests and statistical correlation • Fingerprints: classified into ‘loops’, ‘arches’ and ‘whorls’ • Self-report questionnaires in psychology • Questionnaires on mental imagery • Word-association studies (cf. Psychoanalysis) • Beauty maps of Britain (?) • Influenced geography, meteorology, biology, statistics, criminology and psychology

34. Hereditary Genius • Galton drew on Darwin’s ‘Origin of Species…’ • most important human evolutionary characteristics = intellectual and psychological • Noted that eminence ran in families = inherited

35. Conceptualization of Intelligence • Our knowledge of the environment reaches us through the senses (from John Locke) • Therefore, those with more acute sensory processes should be more intelligent • Created tests of sensory discrimination and motor coordination to assess mental function

36. Heredity is Key • Human abilities are genetically determined and the human species can be improved through controlled breeding practices • I.e., Eugenics.

37. Hereditary Genius • Three pieces of ‘evidence’: • The Normal Distribution. Quetelet had already shown height, etc. = normally distributed. • Pedigrees of Genius. Imperfect, but clear tendency for relatives to excel and excel in similar fields • Adoptive vs Biological Relatives Studies. Adopted “nephews” of Popes did not grow up to be eminent

38. Correlation and regression • Galton sought to express strengths of hereditary relationships mathematically • noticed tendencies (e.g height) • cast various measurements into scatter plots • observedregression towards the mean • Noted steepness of any regression linevaried directly with strength of the relationship between two variables • Correlationrefined by Karl Pearson (Pearson’s r)

39. Eugenics • Galton had a utopian vision • ‘Eugenics’ = improving human race via selective breeding • Eugenic parents to be identified via intelligence tests administer to all

40. Eugenics • Measures of Intelligence : • head size: power of the brain indicated by its size • reaction time: neurological efficiency related to speed • sensory acuity: retarded people (and women!) less likely to feel pain/be able to discriminate tea and coffee • IQ tests not meaningful until Alfred Binet (1905)

41. Cyril Burt • Intelligence is strictly inherited • No influence of teaching, training, or environment • Thus, income levels are determined by intelligence, not environment • Unfortunately, it appears as though old Cyril manufactured much of his data.

42. Hereditarianism Today Hereditarians (Galton, Arthur Jensen, Rushton, Hernnstein and Murray)

43. What’s Wrong? • What went wrong in the thinking of the hereditarianists? • Naturalistic Fallacy. • Darwinian Principles.

44. (Mis)interpreting Darwin Two common errors: 1. assuming that evolution means “progress” Or, as species evolve, they improve Evolution simply means change and adaptation to an environment Not “better,” but “better adapted”

45. (Mis)interpreting Darwin Two common errors: 2. “survival of the strongest” fit simply means best able to survive and reproduce in the environment

46. False Assumptions • Reification - “Intelligence” actually represents a complex, multifaceted set of human aptitude, yet it is typically treated as a unitary entity. • Ranking - Our propensity to place arbitrary order to complex variations. • Reification & Ranking are both manifested in our societies effort to represent intelligence with one number such that the numbers can be used to rank people’s worthiness.

47. Group Differences in IQ

49. IQ Changes • Worldwide improvement in IQ scores • 3pts. per decade • Hard to account for this change genetically • Why?