Evolution and Human Behavior Midterm 1

Evolution

Evolution

change over time

Replicators

things that make copies of themselves

2 Properties of replicators to have evolution

1.Reproduction with inheritance - offspring that are similar to parents

2.Mutation - give you some variation

Differential Reproduction or selection

Different rates of reproduction due to natural, sexual and artificial selection.

Natural Selection

Differential survival leading to different reproduction rates

Sexual Selection

Differential mating success

Artificial Selection

Humans breeding animals

ex. wolves turned into dogs

Survival vs. Reproduction

For evolution reproduction is more important than survival. (only need to survive long enough to reproduce)

Evolution is not progress

Evolution is just change over time

ex. cave fish becoming blind

Evolution is not a developmental process

Evolution of living things on Earth is not analogous to the development of an individual organism

ex. acorn turning into a tree id development…not evolution

Is Evolution a fact or theory?

Evolution is both a fact(observation about the universe) and a theory(an explanation of that fact)

The “for the good of the species” fallacy

Evolution is primary driven by differential survival and reproduction of individual organisms, not species

Adaptationism

the approach that emphasizes how natural selection designs organisms to be well adapted

Phylogenetics

emphasis on the fact that natural selection can only work with what it has (genetics and fossil records)

Phylogenetic constraint/inertia

Emphasis on the limitations set in place based on previous genetics or adaptations

ex.due to the fact that nature can only work with what it has monkeys can’t grow wings

Another word for “jury-rigged contraption”

KLUDGE

Klumsy

Lazy

Ugly

Dumb, but

Good

Enough

Convergent evolution

Different species developing similar or identical traits based on their environments and function

ex. Humingbirds(Americas), Honeyeater(Australia), Sunbird(Africa) all have similar beaks

Vestigal organs

Organs or body parts of an organism that the organism no longer needs for survival and reflect the organisms phylogenetic history.

ex. whale’s pelvises or snake’s hind legs

The vertebrate eye vs. squid eye

Human eye is a well adapted structure but it can be better, squid eyes don’t have a blind spot while vertebrate eyes do.

Problem of novel environment

Evolution happens in specific environments. If you take them out of those environment or change it drastically, organisms wont necessarily adapt

ex. This is why deer keep running in front of cars and birds smashing into windows

EEA

Environment of Evolutionary Adaptedness: the environment thats relevant to explaining how an organism evolved

ARE

Adaptively Relevant Environment (another name for the EEA)

Melatonin

Some of our species EEA’s are very ancient and shared with many other species. Humans share the role of melatonin in sleep cycles with a microscopic marine warm which probably originates over 700 million years ago.

Deep Time

We live a short life and existed for a very small time compared to earth and other organisms

Todays environment vs. ancestor environment

Large scale, full of strangers vs. small scale, full of kin

Human ability to detect animals and humans vs. man made objects

What we find easier to spot is partly a result of adaptations that evolved in ancestral environments

Coalitional psychology

The tendency to quickly and easily identify social groups that ourselves and others appear to belong to

Memory confusion protocol

Show statements about coalitional memberships associated with photographs of people of different races in different jerseys. Errors when recalling who said what reveal whether people are sorting based on race or uniform. result: uniform over race

Levels of Explanation

In biology the same adaptation may be explained in multiple ways at different casual distances and time depths

Phylogenetic explanations

(Greatest distance) They focus on the phylogenetic heritage of the organism that made it possible for the adaptation to evolve “the raw materials that selection had to work on”

Ultimate or Distal explanations

(2nd farthest) They focus on the selection pressures that favored the evolution of adaptation

Ontogenetic or Developmental explanations

(2nd closest) They focus on how the adaptation develops in the individual organism whether before birth, after birth or both

Proximate explanations

(Closest) They focus on how the adaptation works in the moment. Such adaptations are often referred to as proximate mechanisms

Relationship between evolution, culture, and human behavior

Human behavior is formed by both evolution and culture

Hume’s “ought” vs. “is” statement

You can’t derive and “ought” statement from an “is” statement

Naturalistic fallacy

Those who morally justify behavior on the grounds that they are evolved or natural are committing the naturalistic fallacy.

Ex. “Child negligence is okay because certain evolutionary factors can explain it”

Behavior genetics or behavioral genetics

Identify specific genes that are associated with specific behaviors (one approach to studying behavior)

Twin Studies

Study twins that were raised apart and those raised together and compare.

Ex. Identical twins separated at birth still end up mostly having the same political views

Flaw in behavior genetics

Can say interesting things about behavioral differences between individuals but not much about behavioral differences in groups.

Reason: genetic variations among humans are greater among individuals in any single population of humans that they are between human populations.

Somewhat boring exception

Genetic variation and fresh milk consumption in adulthood

Behavioral Ecology

Looking for the ways in which species responses to different environments reveal how the behavior was evolved.(second and main approach of studying behavior)

Three-toed sloths, moths, algae - Mutualism

1. Sloths descend once a week to defecate

2. Species of moth that lives in sloths fur lay eggs in the feces

3. Eggs grow up and find new sloths to live in

4. Moths increase amount of nitrogen in the sloths fur allowing algae to grow

5. Sloths eat the green algae that grows on the sloths hair which has tiny holes to store water.

Genetic drift

A change in the population’s genetic pool by chance (founder effect, bottleneck effect)

Founder Effect

Small portion of a population with similar distinctive traits found a new colony and pass down their distinctive traits to their offspring

Ex. 200 red heads out of a diverse population go populate a new island and make more redheads. Even though the original population had many different hair colors this new island will mostly only have red hair.

Bottleneck effect

A catastrophe shrinks a population and only certain traits survive, therefore, those traits get passed down

Darwin’s Natural Selection

Organisms with some heritable variant leave more offspring because those traits help to survive and reproduce

Darwin’s Sexual Selection

Organisms with traits that help them acquire a mate and therefore reproduce get passed on even if they have nothing to do with survival

Modern Synthesis

Combination of Darwin’s theories and particular inheritance

Particular inheritance

Qualities of the parents are not blended together but passed on to their offspring in distinct packets called genes

Gene

Smallest discrete unit that is inherited intact/without being blended or smashed

Genotype

Collection of genes within an individual. The offspring gets ½ of fathers and ½ of mothers genotype making up their own full genotype.

Ethology

The study of the proximate mechanisms and adaptive value of animal behavior. (First major discipline of the study of evolution and behavior)

Tinbergen’s 4 Whys (4 focuses of ethology)

1. Immediate influences on behavior

2. Developmental influences on behavior

3. The function of the behavior, the “adaptive purpose”

4. The evolutionary or phylogenetic origins of behavior

Fixed action patterns

Stereotypical behavioral sequences an animal follows after being triggered by a well-defined stimulus

Ex. Male plastic duck forces female duck to start acting courteous

Adaptation defined by Williams

Evolved solutions to specific problems that contribute either directly or indirectly to successful reproduction

Textbook Misconception #1: Human behavior is genetically determined

Human behavior cannot occur without both evolved adaptations AND environmental input that triggers these adaptations

Ex.calluses evolved and repeated frictions activate them

Textbook Misconception #2: If it is evolutionary we cannot change it

Knowledge of certain environmental activations allows humans to not active certain adaptations

Ex.Humans can avoid hard friction surfaces and avoid activating calluses

Textbook Misconception #3: Current Mechanisms Are Optimally Designed

Again the concept of KLUDGE proves it wrong

3 products of evolution

adaptations, by-products, noise(random effects)

Adaptations

Inherited and reliably developing characteristics that came into existence through natural selection because they help with survival and reproduction

ex. umbilical cord

By-products

Characteristics that do not solve adaptive problems and do not have functional designs but are carried along with those that do.

ex. belly button

Noise

Random effects produced by forces such as chance mutations, sudden and unprecedented changes in the environment or chance effects during development.

ex.particular shape of a person’s belly button

Standards for evaluating a hypothesized adaptation

1. efficiency - solving a problem in a proficient manner

2. economy - solving a problem in a cost effective manner

3. precision - all the component parts specialized for achieving a particular end

4. reliability - performing dependably in the contexts in which it is designed to operate

General Evolutionary Theory (EP levels of analysis)

How evolution happens?

ex. Evolution by Natural Selection

Middle-level evolutionary theories (EP levels of analysis)

Broad theories covering domains of function

ex. Theory of Parental Investment and Sexual Selection

Specific Evolutionary Hypothesis (EP levels of analysis)

Hypothesis based off theory or that has to do with the theory

ex. Where males sometimes contribute resources to offspring, females will select mates in part based on their ability and willingness to contribute resources

Specific predictions based off hypothesis (EP levels of analysis)

Exactly what the name says

ex. Women have evolved preferences for, and attraction to, men who are high in status

Deduction

Top-Down strategy for generating and testing hypothesis

1. develop hypothesis from existing theory

2. test predictions based on hypothesis(experiment)

3. evaluate whether empirical results confirm prediction

Induction

Bottom - Up strategy for generating and testing hypothesis

1. create hypothesis based off an observation

2. test prediction based on hypothesis(experiment)

3. evaluate whether empirical results confirm prediction

Evolved Psychological Mechanism

Set of processes inside a mechanism with the following properties

• solves a specific problem of survival or reproduction

• takes in only a narrow slice of information

• the input tells the organism the particular adaptive problem its facing

• the input is transferred through decision rules or procedures into outputs

• the output is either a physiological activity, information to another psychological mechanism or manifest behavior

• the output is directed toward the solution to a specific adaptive problem

Domain specific vs. domain general

Domain specific are specific psychological adaptations for specific problems.

Domain general categorizes these solutions into broader sections made in order to solve non-recurrent problems for the species(ex. general intelligence, analytical reasoning, working memory and classical conditioning).

Learning and culture as evolved mechanisms

Framework for evolved psychological mechanisms

1. environments featuring recurrent selection pressure over deep time formed each mechanism

2. environmental input during a person’s development is necessary for the emergence of the mechanism

3. environmental input is necessary for the activation of the mechanism

Each concept we learn requires an evolved psychological mechanism.