Heredity and Intelligence

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Heredity and Intelligence
A History of the Abuse of Science
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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.

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Socrates
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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 childrenAn oracles says that
  when a man of brass or iron guards the State, it
  will be destroyed.

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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.

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Physical Differences

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

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Phrenology
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Body Morphology
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Morphological assessments From the head to the
body

• Phrenology (Gall, early 1800s) skull shape
  personality
• Sheldons 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)

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One Species, or Two?

• 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.

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Louis Agassiz

• There are upon earth different races of men,
  inhabiting different parts of its surface, which
  have different physical characters and this
  factpresses 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)

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Samuel George Morton (1799 -1851)
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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.

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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 didnt considered the impact of
  one physical stature or gender on the skull size
  
• (4) He miscalculated rounding estimates that
  consistently favored his hypothesis.

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Mortons Measurements

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

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Dr. Paul Broca (1824-1880)
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Dr. Paul Broca (1824-1880)

• Broca was a chief of surgery at a major Parisian
  hospital who was interested in the variations
  found among peoples skeletal structures,
  particularly their skulls. He developed several
  instruments for measuring these variations.

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Dr. Paul Broca (1824-1880)

• Dr. Brocas 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.

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For example

• When Broca found that criminals mean brain size
  was larger than honest peoples 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.

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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
  womens brain sizes.

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Charles Darwin
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The End of Polygeny

• Darwins theory of evolution posits a common
  ancestor for all humans, thus eliminating the
  possibility of claiming that different races are
  separate species.

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Darwins 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

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Darwins 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

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Social Darwinism

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

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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.

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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.
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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.
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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
fittestthe eternal struggle among species.
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Francis Galton (1822-1911)
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Francis Galton (1822-1911)
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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, doesnt finish
• Trinity College, Cambridge, medicine (1840),
  doesnt finish
• Cambridge, mathematics, doesnt 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

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Galtons 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

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Hereditary Genius

• Galton drew on Darwins Origin of Species
• most important human evolutionary
  characteristics intellectual and psychological
• Noted that eminence ran in families inherited

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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

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Heredity is Key

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

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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

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Correlation and regression

• Galton sought to express strengths of hereditary
  relationships mathematically
• noticed tendencies (e.g height)
• cast various measurements into scatter plots
• observed regression towards the mean
• Noted steepness of any regression line varied
  directly with strength of the relationship
  between two variables
• Correlationrefined by Karl Pearson (Pearsons r)

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Eugenics

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

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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)

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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.

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Hereditarianism Today

• Hereditarians (Galton, Arthur Jensen, Rushton,
  Hernnstein and Murray)

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Whats Wrong?

• What went wrong in the thinking of the
  hereditarianists?
• Naturalistic Fallacy.
• Darwinian Principles.

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(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

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(Mis)interpreting Darwin

• Two common errors
• 2. survival of the strongest
• fit simply means best able to survive and
  reproduce in the environment

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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 peoples worthiness.

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Group Differences in IQ
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IQ Changes

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