Genetic and Evolutionary Roots of Behavior

1. Genetic and Evolutionary
Roots of Behavior
Course Structure
Meghan Fraley, PhD
Skyline College, Fall 2015

2. Overview of Genetic and
Evolutionary Roots of Behavior
Genetics
• Parts of Cell
• Gene Transmission
Natural
Selection
• Naturalistic
Fallacy
The Genetics
and Evolution
of Behavior
• Heritability
Estimate

3. Heredity Crash Course

4. I. Genetics

5. Genes

6. Genes & DNA- Parts of a Cell

7. Genetic and Environmental Influences
Heredity: Inborn genetic endowment
Genetic and environmental variables
transact continually over time
•Weight of genetic/environment changes over
time (personality/IQ)
•Environment more significant in early years.
•As people age, more diverse in their patterns
Penetrance
•the extent to which the properties controlled
by a gene, its phenotype, will be expressed.
Penetrance is the percentage of individuals
given a specific genotype which actually
express an associated phenotype. More…

8. The Secrets of Genes
 Genes - are the basic units of heredity located
on chromosomes which contain threadlike
strands of DNA.
 Egg and Sperm contain 23 chromosomes each.

9. What are chromosomes?
 Humans have 23 pairs of
chromosomes, with one
chromosome from each
parent.
 The chromosomes are
coiled up DNA.
 Under normal conditions
all of the chromosomes
are inherited in tact.

10. How Genes Interact! Mendel’s
Little Peas
Gregor Mendel- Basic laws of genetic inheritance
Mendel's Laws are as follows:
• 1. the Law of Dominance
• 2. the Law of Segregation
• 3. the Law of Independent Assortment

11. Types of
Chromosomes

12. Chromosomal Disorders
Chromosomal
deletion:
• when cells go
through
meiosis,
portions of the
chromosome
are lost.
Chromosomal
inversion:
• when cells go
through
meiosis, parts
of the
chromosome
are flipped.
Chromosomal
translocation:
• when cells go
through
meiosis, parts
of the
chromosomes
stick together
and switch.
Chromosomal
non-disjunction:
• when cells go
through
meiosis the
chromosomes
don’t separate
correctly and
either too
many or not
enough are
passed on.

13. Heredity
Genotype versus Phenotype
• Genotype: Set of genes
• Phenotype: What is observable

14. Genetic and Chromosomal
Abnormalities
 Klinefelter’s
Syndrome
 Turner’s Syndrome
 Down’s Syndrome
 PKU
 Hemophilia
 Sickle Cell Anemia

15. Influences on Development
 Polygenic (many-genes):
 most traits are influenced
by multiple genes
 RNA has significant role in
memory

16. II. Evolution by Natural
Selection

17. Evolutionary Psychology
Defined
the study of the evolution of
behavior and the mind, using the
principles of natural selection

18. What is Evolution?
Changes that occur in a
population over time

19. Evolutionary Psychology Basics
 Natural Selection
 the principle that, among
the range of inherited trait
variations, those that lead
to increased reproduction
and survival will most likely
be passed on to succeeding
generations
 Mutations
 random errors in gene
replication that lead to a
change in the sequence of
nucleotides
 the source of all genetic
diversity

20. Focus: Proximate to Ultimate
Causes
Proximate:
Within the
lifetime
Ultimate: Why
change has
occurred over
years

21. Theory of Evolution

22. The Principles of Natural
Selection
 Natural Selection
 Natural variations
 Less beneficial
characteristics don’t
survive
 Next generation has more
people with the beneficial,
and less with the
detrimental characteristics
 Evolution: Changes that
occur in a population over
time

23. Myths & Misconceptions about
Evolution

24. Evolution Misconceptions
Naturalistic Fallacy
 The idea that anything
“natural” is “good” or the
more recent traits are
“better”
 The process of evolution
has no foresight
 Discuss: Where do you see
the naturalistic fallacy
referenced?
“Survival of the
Fittest”
 Why is this not entirely
accurate?

25. III. The Genetics &
Evolution of Behavior

26. Behavior Genetics
 Behavior Genetics
 study of the relative power and limits of
genetic and environmental influences on
behavior
 Environment
 every nongenetic influence, from
prenatal nutrition to the people and
things around us

27. The Genetics of Behavior
 Both genes and environment
interact to shape human
behavior.
 The fundamental issue is
how much a role genetics
do play in shaping human
behaviors.
 Examples: psychological
disorders, weight gain,
personality, sexual
orientation?

28. The Genetics of Behavior
Both genes and environment
interact to shape human behavior.
The fundamental issue is how
much a role genetics do play in
shaping human behaviors.
• Examples: psychological disorders, weight
gain, personality, sexual orientation?

29. How much do Genes impact
Variation?
Heritability
The proportion of
variation among
individuals that we
can attribute to
genes.

30. Determining Heritability
Sibling Studies!
•Twin Studies
•Adopted Children & their
Bio Sibs
How do
Evolutionary
Psychologists
Attempt to
Determine the
Impact of
Genetics?
Compare
monozygotic and
fraternal twins
to infer how
much of a genetic
component exists
for a particular
behavior.
Study adopted
children and their
resemblance to
their biological
parents
to infer the
influence of
heredity.

31. Twins & Behavior
Genetics
 Identical Twins
 develop from a single
fertilized egg that splits in
two, creating two
genetically identical
organisms
 Fraternal Twins
 develop from separate eggs
 genetically no closer than
brothers and sisters, but
they share the fetal
environment
Identical
twins
Fraternal
twins
Same
sex only
Same or
opposite sex

32. Twin Studies

33. Twin Studies: The results
 To summarize the countless amount of studies: twins
(especially identical), whether or not they are raised in
the same environment are very much alike in many
ways.

34. Heritability
The proportion of
variation among
individuals that we
can attribute to
genes.
It is a
mathematical
formula!
Heritability: Determining the
Impact of Genes
Behaviors
have a genetic
component
Behaviors
have an
environmental
component.
Interaction

35. Heritability Estimate
 The contribution to an
observed characteristic is
expressed in terms of a
heritability estimate.
 Indicates the extent to
which the phenotype varies
within a group of people
 We use twin studies to
examine the genetic
influence
 Penetrance describes the
extent to the phenotype
will be expressed.

36. Environmental Influence
 Experience affects brain development
Impoverished
environment
Rat brain
cell
Rat brain
cell
Enriched
environment

37. Environmental Influence
 A trained brain

38. Environmental Influence
 Culture
 the enduring behaviors, ideas, attitudes,
and traditions shared by a large group of
people and transmitted from one
generation to the next
 Norm
 an understood rule for accepted and
expected behavior

39. What is Evolutionary
Psychology?
Goal: Understand how human
behavior as impacted by the
passing on of genes by…
Reconstructing problems of ancestors
Establishing common roots of behavior
and how they manifest today

40. Evolutionary Psychology: A Brief
Overview

41. Think like an Evolutionary
Psychologist
 Why do infants fear strangers
when they become mobile?
 Why are most parents
devoted to their children?
 Why do we divide people
into categories?
 Why do we have more
phobias about spiders and
snakes than electricity and
nuclear weapons?

42. Genetics & Evolutionary
Psychology Applied
Intelligence and Sexuality

43. Think like an Evolutionary
Psychologist, Revisited
 Why do infants fear strangers
when they become mobile?
 Why are most parents
devoted to their children?
 Why do we divide people
into categories?
 Why do we have more
phobias about spiders and
snakes than electricity and
nuclear weapons?

44. Evolutionary Psychology
 Gender
 in psychology, the characteristics,
whether biologically or socially
influenced, by which people define
male and female

45. Evolutionary Psychology
 Men preferred attractive physical features
suggesting youth and health
 Women preferred resources and social status

46. Evolutionary Psychology, What do
you think?
Critiquing the
Evolutionary Perspective
 Evolutionary psychologists
take a behavior and work
backward to explain it in
terms of natural selection.
 Evolutionary psychology
proposes genetic
determinism and undercuts
morality in establishing
society.
 Where genders are unequal,
gender preferences are
wide, but closely equal,
preferences narrow down.
Evolutionary
Psychologists Reply
 Evolutionary psychologists
argue that we need to test
behaviors that expound
evolutionary principles.
 Evolutionary psychologists
remind us how we have
adapted, but does not
dictate how we ought to be.
 Males and females are more
alike than different, if we
study these differences we
can establish their causes.

47. Love & Lust: Sexuality, the Brain,
& Evolutionary Psychology
Types of Mating Systems
Attitudes toward Mating
Humans & Other Mammals
Jealousy between the
Genders & Evolutionary
Perspective
Describe the Differences in
the way human males and
females view paternity

48. Genetics & Evolution Review:
Concepts to Know
Structure of DNA
Natural Selection
• Ultimate & Proximal Cause
The scientific study of evolution
Intelligence & Genetics
Genes, Sex, and Mating Behavior