Genetic Roots of Behavior

Meghan Fraley, PhD

Skyline College, Summer 2015

Memory Review

If you could wave a magic wand that would

eliminate your ability to forget, would you do it?

Should we allow eyewitness

testimony? Why or why not?

Genetic and Evolutionary

Psychology

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

Heredity Crash Course

I. Genetics

Genes

Genes & DNA- Parts of a Cell

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 is a term used in genetics that describes 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…

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.

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.

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

Types of

Chromosomes

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.

Heredity

Genotype and Phenotype

Genetic and Chromosomal

Abnormalities

Klinefelter’s

Syndrome

Turner’s Syndrome

Down’s Syndrome

PKU

Hemophilia

Sickle Cell Anemia

Influences on Development

Genotype versus Phenotype Genotype: Set of genes

Phenotype: What is observable

Polygenic (many-genes): most traits are influenced by

multiple genes

RNA has significant role in memory

Chromosomal Defects Down syndrome

More susceptible to alzheimer’s, leukemia, and heart disease

Klinefelter syndrome (XXY)

Turner syndrome (X): short, drooping eyelids, webbed neck

II. Evolution by Natural

Selection

Focus: Proximate to Ultimate

Causes

Proximate: Within the lifetime

Ultimate: Why change has

occurred over years

What is Evolution?

Changes that occur in a population over time

Theory of Evolution

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

Myths & Misconceptions about

Evolution

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?

III. The Genetics &

Evolution of Behavior

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?

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?

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.

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 phenotypewill be expressed.

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.

Twin Studies

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.

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

Evolutionary Psychology: A Brief

Overview

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?

Break: Discuss ideas you have about how our behavior now

is influenced by our ancestors

Genetics & Evolutionary

Psychology AppliedIntelligence and Sexuality

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?

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.

Discussion the Impact of Low SES

on Intelligence

Genes have a weaker effect

on intelligence without

adequate health care,

stimulation, and

nourishment.

Potential may not ever be

realized

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

Why are genes not everything?

Not all traits are equally heritable or unaffected by shared environments

Some studies may underestimate the impact of the environment

Even traits that are highly heritable are not rigidly fixed and can be modified by experience.

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

Genetic Assignments

• Main Concepts in Genetic & Biological Psychology

Review:

• Can Your Genes Predict Whether You’ll be a Conservative or a Liberal? –The Atlantic

Read:

• What are characteristics you think you learned from your family? What are personality characteristics that you think might in the genetic makeup?

Journal:

Forum: Post on forum on at least one critical thinking question