Behavioral Genetics

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Behavioral Genetics
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The Lemonade Analogy

• Lemonade is made up of water, sugar and lemon
  juice. All are necessary to make lemonade.
• In the same fashion, all behavior is made up of
  genetics, experience, and cultural and familial
  influences.

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Why are People Different?

• The fundamental focus of Behavioral Genetics is
  specific differences among individuals, rather
  than average differences between groups of
  individuals.
• Behavioral Genetics is the study of genetic and
  environmental factors that create behavioral
  differences among individuals.

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Why are Behavioral Geneticists interested in
Individual Differences?

• There is substantial variability among
  individuals in both behavior and ability.
• Differences among individuals are far greater
  than average differences between groups.
• Understanding individual differences is socially
  important.
• The causes of I.D.s may not be the same as the
  causes of group differences.

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Thinking about Heredity

• One of the best ways to begin thinking about
  Behavioral Genetics is to think of Individual
  Differences that interest you personally.
• Musical ability
• Athletic ability
• Academic ability
• Then ask yourself WHY?

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Thinking about Environment

• Many people think that environmental differences
  can account for most individual differences.
• There are several reasons for this belief
• The Constitution states that all men are created
  equal.
• The influence of Behaviorism.
• There is no such thing as an inheritance of
  capacity, talent, temperament, mental
  constitution and characteristics. These things
  depend on training that goes on mainly in the
  cradle J.B. Watson, 1925

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Thinking about Environment

• Environmental explanation seem to fit with our
  day to day experience.
• Example Shyness
• Environmental explanations give us a greater
  feeling of control over our lives.

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Genes and Behavior

• Law 1 Environmental factors always contribute to
  individual differences in human behavior.
• Law 2 Genes contribute to every dimension of
  human behavior studied so far.
• Personality
• Vocational interests
• Mental illness
• Divorce
• Age at first sexual intercourse
• Motion sickness
• Anxiety

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Thinking about the Nature vs. Nurture Issue

• Even though both genes and environment contribute
  to a given trait we can still ask the question
  how much?
• Example Area of a rectangle
• A single rectangle
• A population of rectangles

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Historical Perspective

• One of the most important events in the
  development of behavioral genetics was the
  publication of Charles Darwin's The Origin of
  Species in 1859.
• The principles of evolution by natural selection
  laid out in The Origins sparked the imagination
  of Darwins cousin Francis Galton.

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Francis GaltonThe Founder of Behavioral
Genetics(1822-1911)

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Background

• Galton was born in England into a family of
  considerable wealth.
• Entered Cambridge to obtain a medical degree, but
  graduated with a liberal arts degree instead.
• Traveled extensively in Africa and the Middle
  East. Produced first accurate maps of central
  Africa.
• Began corresponding with his cousin Darwin in
  1853.

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Achievements

• Awarded a Fellowship at the Royal Geographical
  Society.
• Drew some of the first weather maps and
  discovered the importance of low an high pressure
  gradients in weather prediction.
• Invented several instruments to measure various
  meteorological factors.
• Pioneered the use of finger prints to identify
  individuals.
• Obsessed with counting.

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Here is the Cover Piece to one of Galtons books
on Fingerprinting.
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Galton and Darwin

• It was widely held in Victorian-era England that
  the aristocracy was the product of good
  breeding.
• When The Origin of Species came out in 1859
  Galton used evolutionary theory to develop his
  own ideas concerning individual differences.
• Example Intelligence, Hereditary Genius, 1869

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Galton and the Mechanism of Inheritance

• During Galtons time DNA, genes and chromosomes
  were unknown.
• Darwin had proposed that the mechanism of
  inheritance was pangenesis, in which gemmules in
  bodily fluids mixed during mating.
• Galton tested this in a series of experiments
  involving blood transfusions in rabbits.
• What do you think his results were?

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Galtons Methods

• The Survey
• In the 1870s Galton wrote a questionnaire and
  distributed it to 180 fellows of the Royal
  Society.
• The survey asked respondents to describe their
  personalities, physical attributes, family
  characteristics and the details of their
  up-bringing.
• English Men of Science Their Nature and their
  Nurture, 1874.

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Galtons Methods

• The Twin Study
• Galton was the first to use twins to investigate
  hereditary questions.
• Galton sent questionnaires to 94 pairs of twins.
• Eugenics
• The concept that society should take active steps
  towards improving its genetic material.

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Galton and Statistics

• Galton developed a mathematical equation for
  measuring the strength and direction of the
  linear relationship between two variables.
• His student Karl Pearson developed the equation
  that we use today.
• The Pearson Product Moment Correlation
  Coefficient is used in Behavioral Genetics.
• The correlation coefficient is generally denoted
  as r

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A brief Correlation Tutorial

• The value of r always falls between 1 and 1.
• A value of 0 indicates a very weak relationship
  between the two variables.
• Correlation does NOT imply causation.

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•  
• In a scatterplot each dot represents data for one
  person for example, each point in the center
  graph tells us one persons weight and that
  persons grade on the psychology final exam, in
  this case using hypothetical data. A positive
  correlation indicates that, as one variable
  increases, the other generally does also. A
  negative correlation indicates that, as one
  variable increases, the other generally
  decreases. The closer a correlation coefficient
  is to 11 or 21, the stronger the relationship.

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Eugenics

• Galton believed that society should promote the
  reproduction of talented and intelligent
  individuals Positive Eugenics.
• He also believed that society should restrict the
  reproduction of below average individuals
  Negative Eugenics.
• To that end Galton founded a Anthropometric
  Laboratory in 1880 and The Eugenics Society in
  1908.
• The Eugenics movement found a sympathetic ear in
  the United States.

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Eugenics

• During the early 19 century it was held that the
  environment contributed to degeneracy.
• Onanism
• After the publication of Galtons work the view
  turned towards heredity as the casual factor.
• Rediscovery of Mendels work
• Charles Davenport- Initially interested in
  agricultural genetics.
• Developed the lab at Cold Springs Harbor
• Several decent studies on eye color.

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Eugenics

• The Big Fear Highly desirable families have
  few children. Less desirable families have more.
• Problem If behavioral traits are inherited how
  does the eugenicist identify the good ones from
  the bad?
• Problems with measurement
• Subjectivity

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The traits

• Alcoholism
• Sexual immorality
• Wanderlust
• Feeblemindedness
• Degeneracy

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Eugenics becomes Popular

• Strong eugenics movements in US, Germany and
  Scandinavia.
• Fitter Family Contests
• Biology Textbooks
• 1906, J.H. Kellog Race Betterment Foundation
• Harvard, Columbia, Cornell, Brown offer eugenics
  courses.

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Eugenics Legalized

• Bans against Interracial marriage
• Racial Integrity Act
• White if less than 1/16 N.A.
• Sterilization
• 1924-3,000
• 1930-8,300
• 1970- Still permitted in institutions

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Where did eugenics go?

• Effect of WWII/Holocaust
• What is the difference between Behavioral
  Genetics and Eugenics?

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The Three General Areas of Genetics

• There are three different areas of research on
  genetics
• Classical Genetics Concerned with the
  chromosomal theory of inheritance.
• Molecular Genetics The study of genetic
  material.
• Evolutionary Genetics The study of the
  mechanisms of evolutionary change.

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Classical Genetics

• Mendels Principles
• Meiosis and Mitosis
• Sex Determination
• Sex linkage
• Chromosomal mapping
• Cytogenetics

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Molecular Genetics

• Structure of DNA
• Chemistry of DNA
• Transcription
• Translation
• DNA cloning and genomics
• Control of gene expression
• DNA mutation and repair
• Extrachromosomal inheritance

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Evolutionary Genetics

• Quantitative genetics
• Evolution
• Speciation
• Assumptions of equilibrium