CHAPTER 3: - PowerPoint Presentation

Slide1

CHAPTER 3:

Genetic and Evolutionary Foundations of BehaviorSlide2

Why Genetics?

Behavior is hereditary!

Our environment has shaped our behavior across generations



EVOLUTION

We can learn much about our behavior by studying our animal relatives

Did you know: we share 98.8% of our genes with chimpanzees?

50% with a bananaSlide3

How Genes Affect Behavior

GENE: the basic physical unity of heredity

Genes code for protein molecules

Structural proteins

Enzymes – control the rate of every chemical reaction in every cell

Genes are composed of long molecules called DNA (deoxyribonucleic acid)Slide4

From Cells to Genes…

cell

nucleus

chromosome

DNA

geneSlide5

Genes Provide the Code for Proteins

Proteins are comprised of amino acids

Coding vs. “junk” DNA

CODING GENES: code for unique protein molecules

REGULATORY GENES: help activate or suppress specific coding genes and thereby influence the body’s development

Genes do not “code for” behaviors.Slide6

Gene/Environment Interaction

ENVIRONMENT: every aspect of an individual and his or her surroundings except the genes themselves.

Geneticists use the term

genotype

to refer to the set of genes that the individual inherits and the term

phenotype

to refer to the observable properties of the body and behavioral traits. Slide7

Genes and Replication: Mitosis

MITOSIS: the form of cell division involved in normal body growth, which produces cells that are genetically identical to each other

MEIOSIS: The form of cell division involved in producing egg or sperm cells, which results in cells that are genetically

dissimilar

and that each have half the number of chromosomes of the original cell.Slide8

The Genetic Diversity of Offspring

ZYGOTE: The single cell that is formed when an egg and sperm cell uniteSlide9

Consequences of Gene Pairing

LOCUS: a position on a chromosome that contains the DNA of a single gene

ALLELES: different genes that can occupy the same locus on a pair of chromosomes and can potentially pair with one another

Homozygous vs.

heterozygous

Dominant vs. recessiveSlide10

Consequences of Gene PairingSlide11

Mendelian Genetics

Gregor

Mendel, Mid-19

th

CenturySlide12

Mendelian

GeneticsSlide13

Polygenic Characteristics

POLYGENIC CHARACTERISTICS: any trait or characteristic for which the observed variation is affected by many genes

SELECTIVE BREEDING: the mating of those members of a strain of animals or plants that manifest a particular characteristic to affect the genetic makeup of future generations of that strainSlide14

Evolution by Natural Selection

NATURAL SELECTION: selective breeding that results from the obstacles to reproduction that are imposed by the natural environmentSlide15

Core concepts of Darwin’s theory of natural selection

There is overproduction of offspring in each generation.

There is

variation

in features or traits within members of a

generation

. Individual differences are inherited from one generation to the next. Individuals with collections of traits that fit well with the local environment are more apt to survive and have more offspring than individuals whose traits do not fit as well with the local environment.

The Peppered Moth

(from 98% down to 2%)Slide16

Genetic VariabilitySlide17

Environmental Influence on Natural Selection

Evolution is contingent on environmental change

Evolution can progress slowly, rapidly, or almost not at all

More complex changes require much more time

A

ll

species are to varying degrees similar to one another because of common ancestrySlide18

Evolution in Action

Before the industrial revolution, a uniformly dark variant of the peppered moth made up 2% of the species. After the industrial revolution, 95% of peppered moths showed this dark coloration.

Skinks living on the coast tend to lay

eggs.

Those skinks living in the cooler mountains tend to give birth to live

young.

The Blue Moon

Butterfly

of the Samoan islands was being attacked by a parasite which destroyed male embryos. This led to a gender imbalance whereby males made up only 1% of the butterfly population. However, within ten generations (~1 year) males had returned to 40% of the population.

Over time the bacteria have become far more efficient at growing under the conditions used.

One

of the populations developed the ability to utilize citrate as a

nutrient.

Malaria

MMRSlide19

Mistaken Beliefs about EvolutionSlide20
Slide21

Functionalism

FUNCTIONALISM: a school of psychological thought, founded by William James and others, that focuses on understanding the functions, or adaptive purposes, of mental processes.

Why do giraffes have long necks?

Why do male songbirds sing?

Why do humans have the ability to

learn language?Slide22

Functionalistic Explanations of Behavior

Ultimate

(Distal) Explanation

Functional explanations at the evolutionary level;

how

the

behavior plays or played a role in survival and reproduction

Proximate (Proximal)

Explanation

Explanations that deal with the immediate environmental conditions or the mechanisms within the individual that cause the behavior to occur

Why do

birds migrate?Slide23

Limitations on Functionalist Thinking

VESTIGIAL CHARACTERISTICS: inherited characteristics of anatomy or behavior that are no longer useful to the species but were presumably useful at an earlier time in evolution

E.g. appendix, grasp

reflex,

goosebumps

Some traits are side effects of natural selection for other traitsSlide24

Limitations on Functionalist Thinking

3. Some traits result simply from chance

Variation due to chance alone without selection is known as GENETIC DRIFT

4. Evolved mechanisms cannot deal effectively with every situationSlide25

Species-Typical Behaviors in Humans

Any behavior pattern that is so characteristic of a given species of animal that it can be used to help identify that species

However, these behaviors are not rigid and uninfluenced by learning!Slide26

The Role of Learning in Species-Typical Behaviors

Walking

LanguageSlide27

Biological Preparedness

BIOLOGICAL PREPAREDNESS: organisms have physical and anatomical structures that predispose them to engage in certain (species-specific) behaviors

The environment

also plays a role!Slide28

Cross-Species Comparisons of Species-Typical Behaviors

HOMOLOGY: any similarity among species that exists because of the species’ common ancestrySlide29

Cross-Species Comparisons of Species-Typical Behaviors

ANALOGY: any similarity among species that is not due to common ancestry but has evolved independently because of some similarity in their habits or lifestylesSlide30

Evolutionary Analyses of Mating PatternsSlide31

Parental Investment

The time, energy, and risk to survival involved in producing, feeding and otherwise caring for each offspring

If parental

investment is unequal, the more parentally invested sex will be

(

a) more vigorously competed for than the other and

(b) more discriminating than the other when choosing matesSlide32

Mating Patterns and Parental InvestmentSlide33

Human Mating Patterns

Humans fall on the boundary between monogamy and

polygyny

Long-term mating bondsSlide34

Sex Differences in Aggression

AGGRESSION: fighting and threats of fighting among members of the same species

In primates, males are more aggressive than

females (humans are no exception; female bonobos are)

Sexual jealousy

These behaviors

are advantageous(evolution is not a moral force)Slide35

Patterns of Helping

HELPING: any behavior that increases the survival chance or reproductive capacity of another individual

COOPERATION: a type of helping behavior in which interaction among two or more individuals increases the survival chance or reproductive capacity of each individual involved in the interaction

E.g. living in groups or coloniesSlide36

Altruism

ALTRUISM:

helping

behavior in which an individual increases the survival chance or reproductive capacity of another individual while

decreasing

its own survival chance or reproductive capacitySlide37

Kin Selection Theory of Altruism

Apparent acts of altruism have come about through natural selection because such actions are disproportionately directed toward close genetic relatives and thus promote the survival of others who have the same genesSlide38

Reciprocity Theory of Apparent Altruism

Apparent acts of altruism have come about through natural selection because they are actually forms of long-term cooperation rather than true altruismSlide39

Evolutionary Fallacies

Naturalistic Fallacy

The mistaken belief that whatever is natural (and particularly whatever is a product of natural selection) is right, good or moral

Morality is a product of the human mind!

Beware the phrase “more evolved”

Deterministic Fallacy

The mistaken belief that genes control, or determine, behavior in a manner that is independent of environmental influences

We humans can control our environment and thereby control ourselves!