Evolution and Human Behavior 01:070:201 Cronk | Test 3

Coefficient of relatedness (r)

r = Σ (0.5)^L

At each generation link there is a 0.5 probability that a copy of a gene will be passed on.
For L generation links the probability is (0.5)^L
If two people have more than one common ancestor, calculate r between them via both ancestors and then add them up

Social behavior

interactions with members of the same species

Altruism

social behaviors that are costly to the actor but beneficial to someone else

Costs and benefits of altruism

Costs and benefits have to be in terms of fitness (success of an organism getting its genes into future generations)
High fitness = more success getting its genes into future generations
Low fitness = less success getting its genes into future generations

Selfishness

social behaviors that are beneficial to the actor but costly to someone else

Cooperation

organisms working together, typically to achieve something

Interdependence

the degree to which two or more organisms positively or negatively influence with other's success in replicating their genes; the idea is that organisms are not fully dependent on each other (what is good for me may be bad for you, what is good for you could be bad for me)

- i.e. ferris wheel metaphor

Sources of fitness interdependence

being in the same group/sport as someone; being genetically related to someone; living with someone; sharing resources with someone; pooling risk with someone

Group selection

organisms that are much more likely to mate with each other rather than members of another group; selection pressures at the level of the entire group might give individual organisms enough of a stake in each others’ welfare that they would evolve to sacrifice themselves or their reproduction for the benefit of the group

Myxoma virus and Australian rabbits

Example of group selection...
- Rabbits were brought to Australis, but they are not native to Australia (=not good)
- They were competing with the sheep; sheep ranchers tried to kill them off (to no avail)
- Scientists introduced a virus to kill off the rabbits in a high rate (rabbit = the host)
- The rabbits that survived left more offspring, leading more rabbits that can survive the virus be born
- The virus started evolving; started killing the rabbits very quickly (bad bc the virus spreads through mosquito bites, but a mosquito will not bite a dead rabbit; the virus could not further evolve when the rabbits die too quickly)
- Then they introduced fleas (that will bite the dead rabbits) and the virus will spread quicker
- The rabbits are still there, but at least thanks to this we know how group selection works

Kin selection

another name for indirect reproduction;

Fitness

success in an organism getting its genes into future generations

Indirect reproduction

because your relatives also have copies of your genes, you can make copies of your genes indirectly by helping them reproduce

Inclusive fitness

an explanation for altruism that focuses on the adaptive benefit of transmitting genes, such as through kin selection, rather than focusing on individual survival

Textbook: not a property of an organism, but a property of its actions or effects; calculated from an individual's own reproductive success plus his effects on the reproductive success of its relatives, each one weighted by the appropriate coefficient of relatedness

Hamilton's rule (C<Br)

part of indirect reproduction
C = cost of a behavior to yourself, in terms of lost future reproduction; B = benefit of a behavior to the recipient, also in terms of future reproduction; r = coefficient of relatedness

basic idea: perform an altruistic act if the cost to yourself is less than the benefit to the recipient reduced by the coefficient of relatedness (r), if the inequality is met, the organism should help the other organism out

Hamilton's rule (C<Br) example

You are a 50 year old man with six cows and a 25 year old full brother. You can use your cows to pay the bridewealth for yourself or for your brother, who otherwise will not marry for at least a few years. If you marry, you will probably live long enough to have only one additional child. If your brother marries, he will probably have three more children than if his marriage were delayed. Should you marry or should you pay your brother’s bride wealth instead?

C = 1, B = 3, r = 0.5

C < B(r)

1 < 3(0.5)

1 < 1.5

Hamilton's Rule is met, so pay your brother’s bride wealth.

Alarm calls in Belding's ground squirrels

Example of indirect reproduction
Do alarm when they spot a predator; potentially self sacrificial, because making the alarm call tracks attention to them

Adult females do majority of the calling bc they do not have much life left, they have less to lose if they sacrifice themselves

Sex difference, males usually never call because they are the ones that leave when they become old enough; leave to avoid inbreeding

Kin recognition

Westermarck effect (we do not want to reproduce with people we grew up with)


The squirrels are agonistic (struggle--fight, chasing--for territory); when the squirrels are reared together they don't chase each other out (even non-siblings... as long as they are raised together they recognize each other)

When the squirrels are reared apart they chase each other out
(even siblings... if they do not recognize each other they kick them out)

Helpers at the nest in Pied kingfishers

One of the offspring (male) will stay at the nest to help parents reproduce (primary helper)
OR
Another offspring (male) from another group will come to a nest to help the parents reproduce (secondary helper)

The helpers help out only enough that they are tolerated; the pattern of helping at the nest is them waiting for the nest to free up

Hardworking Hadza grandmothers

post-menopausal Hadza women work harder and more
effectively than Hadza women of reproductive age, thus
helping their daughters and grandchildren; form of altruism helping their daughters so offspring is better taken care of

Ifalukese grandparents and grandchild survivorship

older men and women on Ifaluk work hard and help keep small children away from hazards (i.e. water, fire); as a result, children on Ifaluk are more likely to survive if they have living grandparents than if they don't

the grandparents help out during the day to babysit while parents are fishing, hunting, gathering, etc.

Reciprocity

the exchange of resources, goods, and services among people of relatively equal status; selection might favor organisms that behave altruistically towards other organisms if there's a chance that their kindness will be repaid in the future

i.e. a bank loan

Prisoner's Dilemma Game

a social dilemma scenario in which mutual cooperation guarantees the best mutual outcome; debt based transfers

best strategy would be to defect

cooperate behavior can be beneficial and so can evolve even if all parties are only looking out for their own gain

Iterated Prisoner's Dilemma

two players play the game many times, choose either co-operate or defect, taking into account what the other player did in previous rounds

iterate = many rounds

Tit-for-Tat

first cooperate, then do whatever the other player did during the previous round; long term payoffs are highest to those who stay in the "cooperate, cooperate" box for round after round (get 3's over again)

Likelihood of future interaction

related to the PD game; related to reciprocity;

there needs to be a chance that you will meet a person again for you to want to help them, and for them to want to help you

Grooming in primates & ungulates

they recognize each other as individuals and groom each other
(literally "you scratch my back I scratch yours")

WWI trench warfare

Deliberately tried not to kill the other guys when trying to get out of the trench, done with verbal agreements

Didn't last very long because it's colluding with the enemy; to counter this they used carefully placed gun shots, communicating, "I have to shoot in your direction but notice I am not aiming at you; please return the favor" while also communicating that he has good aim and could shoot someone in the trenches if need be

**To stop this, higher ups would switch soldiers' shifts in the trenches so no one knows who is in the trench on the opposite side (so there could be no future interaction between the same people)

Risk pooling

organizing people into a group to collectively absorb the risk faced by each individual; if the future is unpredictable, selection may favor generosity towards others without any creation of debt because you may be the one in need at some point in the future

i.e. insurance

Blood sharing in vampire bats

vampire bats drink blood (typically cattle); some are successful (find blood) and some are not

the bats that are successful feed the unsuccessful bats as it takes a vampire bat only a few hours to die without any food & sharing doesn't harm the successful bat

sometimes satiated bats even fight to feed a hungry bat so that they have someone to owe them

Central place foraging

eat as you forage and then bring food to those who didn't forage

those who are able to forage during the day do so, eating while they forage (i.e. hunt, fish, and gather plants & other foods, such as honey) but also bringing back any surplus they may have acquired; those who cannot forage because they are old, sick, injured, or have dependent small children stay at the camp

at the end of the day, food is shared with those who were unable to forage or who were unlucky while foraging

Osotua relationships among Maasai

Maasai economic theory
"human umbilical cord" / "gift giving relationship"

involves gifts & favors of many kinds, involves respect

not about payment or debt, no requirement to pay back; the obligation to help is mutual, but transfers do not need to be balanced

different from reciprocity where you give a favor and expect one back

example of risk-pooling through transfers to those in need

The Trust Game

one player given money and told to give some to other player that will be tripled by experimenter, second player has to give money back to first; amount sent back by second player was more than sent originally

Need-based transfers

resource sharing based on the need of the recipient; no expectations of repayment

need-based transfers pool risk better and lead to longer survival than debt-based transfers in which accounts are kept and relationships are ended if debts are not repaid

(like an insurance policy)

Debt-based transfers

resource sharing based on the need of the recipient, but they need to pay back

(like a bank loan)

Needs with predictable timing vs. unpredictable timing

unpredictable - if things come out of the blue (i.e. death, illness), they help their neighbors in case they need the same kind of help (i.e. Ranchers in the American Southwest engage in need-based transfers when needs arise unpredictably and in account-keeping reciprocity when needs arise at predictable times)
predictable - less likely to help

Indirect reciprocity

selection might favor organisms that behave altruistically towards other organisms if there's an audience that might repay the kindness in the future

i.e. may help someone who is in no position to help them so that someone else observes their helpful behavior

Reputation effects

the tendency for people to help other people based on the probability that they will receive help from that same person based on their reputation

Impression management

indirect reciprocity; when there is an audience present, people want to make a good impression on the audience

Audience effects

there is an audience and you want to impress them

Punishment models of cooperation

people spend more money to punish non-cooperators if there is an audience

(punishment game - can spend money to punish someone else in the game who has not been cooperative)

when anonymous - only you know your choice, little to no cooperation
when w/ experimenter - only experimenter knows, some cooperation
when w/ participants - everyone knows your choice, triggers greatest cooperation

Eyespot effects

triggered if you get a hint of an audience watching you (quick and subtle, system one); once system two notices this, you realize no one is actually watching you

i.e. Kismet study, Dictator game, postcard example, Dice example

Honor box study

honor box by the coffee pot at work to replenish the coffee & tea

when there was an image of flowers by the box, little people cooperated, when there was an image of eyes, more people cooperated

Social intelligence

ability to understand and navigate social situations; intelligence may have evolved more for its usefulness in social interactions

Theory of Mind module

the ability to imagine other people's internal mental states; a specific adaptive mechanism, not an aspect of general intelligence

Autism

Temple Grandin

Charlie task

a test that test people's cognitive mechanisms of eye directions

experimenter ask kids, "what does Charlie want"; tests kids to see if they could tell what Charlie wants based on what he his pointing/looking at in the image

Sally-Anne test

test to see if children have developed Theory of Mind

Two dolls (Sally & Anne), marble, basket, box
A child watches as Anne puts a marble in a basket and leaves the room. Sally puts the marble in a box. Sally comes back and the studier asks the child where Anne will look for the marble?

A kid who has an active & successful Theory of Mind will say that the marble is in the basket
A kid who does not will say the marble is in the box

Spotting cooperators

can identify helpers in social interactions

Infant favoritism toward cooperators

Yale study

babies choose helper in shape "helper vs hinderer" test

Conflicts of interest

also known as the collective action dilemma and the free rider problem
i.e. a group project, where everyone gets the same grade, but one person has to pay the price and do the whole project themselves, the people who do not work on the project are "free riders"

makes cooperation difficult even if people really want to cooperate

conflict due to incompatible needs or competition over perceived or actual resource constraints

Sculling game

free-riding has highest payoff in this game; hard to get cooperation going

(like PD game)

Rowing game

a little different than the sculling game as if both cooperate its a maximum reward but if only one rows they won't gain anything more than if they didn't row as they would just be tired and not have gone anywhere

what's best for one player is best for the other, as well, so cooperation is easy to get going (a cooperation game)

Coordination games/problems

everybody benefits if the problem is solved, so the trick is to get everyone common knowledge about the situation and its solution

Sclera, gaze-following, and coordination

we can see where people are looking; could lead to shared attention, shared intention

most nonhuman primates have sclera that match the iris and/or the surrounding skin or fur; humans have sclera that contrast with both the iris and the surrounding skin, making it easy to see where people are looking

Cooperative Eye Hypothesis

humans use eye movements instead of head movements to scan visual fields more than do nonhuman primates; humans are good at following gaze, nonhuman primates aren't

Shared intentionality

you have to have shared intentions with someone; you are hunting with someone, you notice that your hunting partner notices an animal---you noticed the animal because you were watching your partner

common knowledge

Common knowledge

shared beliefs or assumptions

Common metaknowledge

common knowledge plus common knowledge that there is common knowledge

it's not enough for everyone to know the solution to a coordination problem, they also need to know that everyone else also knows the solution

getting common metaknowledge can be difficult

shared intentionality is a stepping stone towards common knowledge; but common metaknowledge is the collective understanding of this

1984 Mac ad during Super Bowl

example of creating common knowledge; large proportion of country sees these; attempted to insure people were going to like Macs and that people should buy them

Battle of the Sexes Game

Real world example: Agenda-setting in Washington, people agree to work on issues on which they can make progress even if they would prefer to focus on another issue that is more important to them


husband and wife want to hangout; wife wants ballet husband wants to go to a football game; they can:
- go to the ballet together (wife gets what she wants, husband doesn't)
- go to the football game together (husband gets what he wants, wife doesn't)
- do nothing (neither gets what they want)
- each go alone (they each get what they want but they are not together)

Game of Chicken

i.e two people are arguing about who is braver, whoever swerves first is a chicken; if they both swerve they are both chickens; if they don't swerve they get 0 because they die

Bakers/Butchers Game

game involves two merchants, a butcher and a baker, who decide each day whether to work independently to sell chicken wings and dinner rolls, respectively, or to work together to sell complete hot dogs, for which they earn more; no one will buy just the buns or just the hot dog meat, so they risk earning nothing if they fail to coordinate their actions.

need for common knowledge

the baker and butcher will make the greatest profit if they work together

The Stag Hunt / Assurance Game

same as rowing game

coordinate to hunt stag or coordinate to hunt hare, stag is more valuable; interesting coordination game because it is a peer coordination game; no conflict of interest

"Rousseau's Whale Hunt" and Lamalera, Indonesia

go out in small boats, everyone has different jobs while hunting (harpooner, rowers, etc.), everyone who is on the boat gets a certain portion of the whale based on their job

Minimum Effort Game

a coordination game where players simultaneously choose an action, the player's payoff depends on the own effort level chosen as well as on the smallest effort level chosen within the group

Culture

socially transmitted information

helps shape our behavior

like genes, it is a replicator

Culture vs. behavior

culture does not include behavior or its products; culture is used to explain behavior and its products

Cultural transmission

the process by which one generation passes culture to the next

how people get their culture traits

The spread of obesity in social networks

obesity spreads through social networks, if you're close to an obese person socially, you are likely to be obese


i.e. if your friend starts going to the gym/eating healthy you are more likely to follow in their footsteps

Stimulus enhancement

one individual's behavior draws another's attention to something

Bumblebees

bumblebees are more likely to go to the petals with the fake bees than the ones with no bees when looking for nectar

Imitation

B learns how to do something by watching A do it

Octopuses

two octopuses; trained one octopus to attack a red ball; gave the other one an opportunity to attack a red or white ball, they attacked the red ball (because they watched the other octopus get rewarded for attacking the red ball)

Guppies

had a bunch of guppies in a tank, trained them that they had to go through a red shaded hole to get to food; then dump in a bunch of untrained guppies and they follow the trained guppies

there is a shorter route to get to the food but they are trained to go through the red hole; eventually they found that there was an easier entrance

Route following in humans

go through a door into a room where you have to go to do a puzzle, you take the long way with the experimenter. Having gone through one door, they will continue to take the long way they went through with the experimenter, even if they do not walk in with you

Mate choice copying

Individuals in a population copy mate choice of others

Drosophila

two females watch a copulating green male with a female; when given the option to choose a green or pink male they'd pick the green (and vice versa)

Japanese quail

normal male and pseudomutant male (has a white feather on head); female will choose a pseudomutant male if she witnessed another female with a pseudomutant male

Mate choice copying in humans

if the woman is smiling while facing the male, women will rate him as more attractive

if the woman is smiling while facing the male, men will rate him as less attractive because of jealousy (male-male competition)

Goal emulation

B learns not only how to do something but also what goal to pursue by watching A

Chimpanzee nut cracking

there is a clear goal to get the food when cracking nuts; the young chimpanzee learns the goal observing the older chimpanzee crack the nuts (hitting nuts with a rock) and then by starting to try to crack nuts on its own

Teaching

when humans do it, we know we're doing it; with animals it is hard to tell; ideally teaching is coordination not confliction

Possible teaching in ants

there is a leader and a follower; the leader monitors the progress of the follower; if the follower is not right behind them it pauses — how they get around, the leader is leading the follower to a food source

Meerkats

meerkats teach their pups how to handle dangerous prey

Dolphins

Atlantic spotted dolphin mothers chase prey longer when calves are present

mothers chasing without calves just go for it and catch their food no hesitation; others chasing with calves take longer to catch food

Vertical transmission

from parents → children

"Culture traits are like genes"

Horizontal transmission

among peers

"Culture traits are like viruses"

Oblique transmission

between generations but not from parents to children

associated metaphor: also viruses, but may be more gene-like if parents are involved (i.e. from teachers to students)

Yomut Turkmen

no birth control

Kipsigis

lived primarily in small farms and with livestock (early 1980s)

polygyny is possible; the wealthier, the more polygyny
**The more acres of land a male controls, the wealthier he is, the more kids & wives he has

Mukogodo

productivity is higher with more wives bc more kids

more kids = more daughters = more bride wealth

Yanomamo

would steal women (wife capture)

Ache

EPCs are fairly common

poor hunters = less survival; lower reproductive success
good hunters = more survival; higher reproductive success

19th century Swedes

women married to richer husbands had higher reproductive rates

monogamous

Cultural mutation

errors that occur during the transmission of cultural information

i.e. tweaking an old recipe and then sharing it with others

Dr. Cronk's Nike story

example of cultural mutation

"Mayieu kuna; incook inamuka sapukin." - "I don't want these, give me bigger shoes."

This went viral, but then died down

The internet provided a new environment in which this and other culture traits ("memes") could live

Went viral again because someone posted about it again because it was posted without the year (the removal of the year = mutation)

A mutation (=the deletion of the date associated with the story) increased its success in going viral again

Verb regularization in English

example of cultural mutation in English; used to be lots of ways to form the past tense in English, but now most words do it with the -ed suffix

often-used verbs were more likely to retain irregular forms (i.e. be, go, and come)

Cultural drift

directional pointers or "background noise" for the way society is moving

Frequently-used words vs. seldom-used words in related languages

frequently used words are more likely to remain similar in related languages
(i.e. two, deux, and zwei)

seldom-used words are more likely to differ
(i.e. bird, oiseau, and vogel)