Evolution and Culture Final

maladaptive culture traits

damaging inclusive fitness; reducing the number of organism’s genes that make itinto the next generation

not imposed

long-lasting

clearly reduces its carriers’ inclusive fitness

widespread

deleterious culture traits

costly in some way but not necessarily reducing the organism’s inclusive fitness

St. Jude “mind virus” chain letters

chain letters that’s been around the world many times

promises good luck if you pass it on, bad luck if you don’t

a successful culture trait? yes

a deleterious culture trait? yes

a maladaptive culture trait? no

food taboos in the Ituri forest

food taboos are very complex and different individuals in the same group different, personalized rules

• some are inherited

• some are associated with life phases (pregnancy or childhood)

• all concern specific animal species only

deleterious? yes

maladaptive? for some individuals but not most

cannibalism and kuru among the Fore of New Guinea

the culture trait: cannibalism

the benefit: nutrition, good-tasting food. mainly eaten by women because pork was reserved for men

the cost: the spread of brain-wasting disease called kuru, similar to “mad cow disease,” kills virtually everyone who gets it, and accounted for more than 2/3 of the female mortality

the reaction: kuru recognized as a problem; Fore tried local solutions, such as help from native curers

the problem: the connection between cannibalism and kuru was very hard to spot, even for Western medical science

a maladaptive culture trait? yes

• freely chosen, not imposed

• widespread

  • persistent

gene-culture coevolution

describes how human genetic evolution and cultural evolution constantly influence each other

two modes: genetic meditation and cultural meditation

genetic mediation

genes create an environment in which memes are selected

• color terms are not all the same across languages

  • similarity of visual perception across cultures can be established by color term’s focal referents

• the similarities among all human languages

  • any baby can grow up and learn to speak any language, indicating that we share a common, genetically inherited framework for learning and using language

cultural mediation

culture sets up an environment in which genes are selected

• environmental buffering and relaxed selection

• farming malaria, and sickle-cell anemia

  • dairying and adult lactose absorption

farming malaria and sickle-cell anemia

the culture trait: farming in the West African rain forest

the environmental effect: open pools of water, more mosquitos, more malaria

the genes: those that cause blood cells to take on sickle-like shape. homozygous individuals, who have sickle-cell anemia, usually die in childhood if not treated; heterozygous individuals are resistant to malaria

dairying and adult lactose absorption (cultural mediation)

the culture trait: using non-human milk as food for adults. the sugar in milk is lactose

the enzyme: lactase, breaks down lactose

the gene: those that continue lactase production into adulthood

the benefit: nutrition

the cultural alternative: don’t drink fresh milk, eat cheese and yogurt

the less-obvious benefit: calcium absorption where “vitamin” D is a problem due to low levels of sunshine. lactose acts like vitamin D in the calcium absorption process, but only if you can digest it

lipid digestion among Maasai

traditional Maasai diet consists of milk, meat, and blood (lots of fat)

most Maasai can consume a high fat diet without developing heart disease

genes responsible: amylase—enzyme involved in digestion of starch

farmer diets are usually high in starch, more amylase found in saliva of people whose ancestors have been farming for a long time than in saliva of current or recent hunter-gatherers

amylase

enzyme involved in digestion of starch

cultural transmission and the creation of group-group differences

drift

social coordination conventions (languages, holidays, technical standards)

imposition

adaptation to different environments

cultural group seleciton

ways cultural groups can succeed: simply persistent, gaining members, gaining resources, creating daughter groups

ways a cultural group can fail: not persisting, shrinking, losing resources

ways cultural groups compete with each other: directly (combat, sports competitions) indirectly (attracting or failing to attract new members, attracting or failing to attract resources or the things that bring resources, such as customers)

may lead to a type of gene-culture coevolution

types of groups: categories, groups, corporate groups

flexible coalition psychology

an evolutionary adaptation allowing humans to form, shift, and dissolve alliances easily

coalitional psychology

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

during the filming of Planet of the Apes, actors sat with members of their own “species” to eat meals, an instinctive segregation

racial categorization

the social and scientific process of grouping humans into categories based on perceived shared physical traits (like skin color, hair, features) or cultural/ancestral origins

no reason for racism to be an evolved propensity because our ancestors would have encountered people who were phenotypically very different from themselves rarely or never

perception of “races” may therefore be an outgrowth of our coalitional psychology

memory confusion protocol

show statements about coalitional memberships associated with photographs of people of difference “races” and wearing different team uniforms

errors when recalling who said what reveal whether people are sorting based on “race” or on uniform

categories

people who share some characteristic

groups

people who interact repeatedly in an interconnected set of roles

corporate groups

people who interact repeatedly in an interconnected set of roles in a group that is treated by society as a legal individual

signal

any act or structure that is designed to alter the behavior of other organisms, regardless of whether it is a product of natural or cultural selection

in order to change another organism’s behavior without coercion, a signal must convey information (whether correct or incorrect)

signals vs cues

example: a cloudy sky conveys information about impending rain

example: an individual’s height conveys information about their parents’ heights

those are cues, not signals

manipulation

if the purpose of signals is to change the behavior of others

a parent may “manipulate” the behavior of its offspring by signaling to it about danger

• “look out for the bus!”

extended phenotype

an organism’s phenotype including not only its own body but also its impact on the rest of the world, including other organisms

the phenotypic gambit

behavioral ecologists focus on phenotypes, not on

• genotypes

• mechanisms of inheritance

• the process of genetic expression

because in the long run natural selection should favor adaptive phenotypes regardless of their underlying genotypes and the rest, and the phenotypes are usually all we have to go on, anyway

the phenotypic gambit extended to signaling

the design principles should be the same regardless of how the signal came to exist

receiver psychology

understanding signal design

consider the intended receiver

human example: teddy bear evolution

non-human example: male túngara frog calls, intended for mating

human example: kin terms in political rhetoric

human example: teddy bear evolution

human example: motherese (baby talk)

conflict of interest

individuals have a conflict of interest if selection acting on them separately would favor a different outcome from an encounter for each one

example: predator and prey

confluence of interest

the coming together or alignment of different interests

if selection acting on them separately would favor the same outcome for both of them, they have common interests or at least a temporary confluence of interests

hard-to-fake signals

costly, effortful, or physically constrained displays that honestly reveal an individual’s true quality, commitment, or resources, making them reliable indicators in situations where deception is common

• two types:

  • indices (or indexes)

  • costly signals

indices (or indexes)

signals that are hard-to-fake because deceivers simply cannot send them

examples:

• male red deer roars

• tiger tree-scratching

• product demos

  • ethnic identity

costly signals

signals that are hard-to-fake because only honest signalers can afford to send them, these are called strategic costs

examples:

• gazelles “stotting” when predators are around

• grassroots lobbying

• product guarantees

handicap signals

a type of signal that is costly because it imposes a handicap on the signaler

example:

• peacock tails and other male ornaments

• testosterone, immunocompetence, and facial anatomy

honest signaling theory

the signal has to convey two types of information

1. that the signaler and receiver have common interests despite the receiver’s skepticism

2. whatever the signal is really about

in this situation, signals need to be hard to fake, otherwise, receivers have no reason to believe them

hard-to-fake signals may not remain hard-to-fake forever

star-belies on Sneetches after Sylvester McMonkey McBean arrived

lace when it was all handmade versus lace after the industrial revolution

signalers and receivers have a conflict of interest without any temporary confluences of interest between individual signalers and receivers

two possible outcomes

1. no signal. whatever attempts the signalers might have made to manipulate the receiver with signals have been thwarted by the receiver (through learning or coevolution). It no longer pays the signaler to send any signal at all, and it never did pay the receiver to pay attention to any signal from that signaler

2. an ongoing arms race between signaler and receiver, with improved signals being met by improved resistance

deception

a problematic area in signaling theory

signaling theorists don’t think deceptive signals will last because receivers will evolve or learn to ignore them and signalers will evolve or learn to stop sending them

circumstances in which deception might arise and persist:

• it might be hard to costly for receivers to assess the honesty of a signal

  • a male might be sending a false signal of his quality, but if there are a few males around or if the mating season is about to end, it might be worthwhile mating with him anyway

• The cost of being deceived might be low but the benefit of deceiving might be high

  • even a bad product can make someone a lot of money if a lot of people buy it, if it’s cheap enough, it also won’t impose much of a cost on the people deceived by its advertising

human example: deceiving enemies in wartime

• a mock Sherman tank being flipped by soldiers during WW2

nonhuman example: the anglerfish’s lure

information theory

the mathematical study of quantifying, storing, and communicating information

courtship signals

males will send signals regarding qualities females should care about

females will send signals regarding qualities males should care about

• lonely hearts advertisements

  • each gender tends to offer what the other tends to seek

• the burger king study

• male facial masculinity and femininity

cosmetic and contrast

because of gestation, women need to absorb more calcium than men do

one way to get more vitamin D is to have. lighter skin

this may come at a cost in terms of reduced protection from the harmful effects of UV

estrogen lightens skin

in any human population, males’ skin is, on average, darker, than females

on average, women have more contrast in their faces than men

cosmetics, at least as used by women, enhance this contrast and thus makes faces look more feminine

Yanomamo kin term manipulation and receiver psychology

receiver psychology is not just a matter of the senses and innate aspects of psychology; it also includes aspects of psychology that are influenced by culture

this includes things like opinions about the appropriateness of different types of relation ships among kin

the yanomamo use the Iroquios-Dravidian kinship teminolgoy, in which cross-cousins are designated as preferred marriage partners but marriage with paralle cousins is considered incestuous

the Iroquois-Dravidian kin term system

1. same-sex siblings are terminologically equivalent

2. potential marriage partners are indicated by the term for cross-cousin

   1. cross-cousins versus parallel cousins:

      1. cross-cousins: linked by different-sex siblings

      2. parallel-cousins: linked by same-sex siblings

Ifaluk

an island in Micronesia in the Pacific Ocean

torch fishing

one of many types of fishing on Ifaluk; involving uses torches to attract flying fish at night and using them as bait for dog-toothed tuna. very laborious and ritualized as not very productive

hypothesis: torch fishing is a costly signal of one’s work ethic

prediction: torch fishing involvement and productivity correlate with more productive aspects of men’s lives, such as other types of fishing

turtle hunting on Mer

Mer: also known as Murray Island; in Torres Strait between Australia and New Guinea

there are two ways to get turtles (collecting and hunting) and many ways to get food

turtle hunting is difficult, risky, and not very productive, so why do it?

hypothesis: it’s a costly signal of one’s quality

findings: successful hunters have:

• an earlier onset of reproduction

• higher age-specific reproductive success

• have mates who also achieve above-average reproductive success

• have more mates

• have younger mates

receiver psychology approaches to religion

religious concepts often involve limited violations of our expectations about the world. they are literally counter-intuitive: the run counter to our intuition

hypothesis: this quality makes religious concepts more attention-grabbing and easier to remember than non-religious concepts

social control approach to religion

religious rhetoric is often used to try to influence people’s behavior

the association between social complexity and beliefs in moralizing gods judgmental afterlives could have two origins

1. such beliefs may have bee what made it possible for societies to grow complex

   1. such beliefs may have arisen after social complexity as a cheap way for elites to maintain control over the masses

costly signaling approaches to religion

collective action dilemmas and free riders: groups and the individuals in them might benefit from cooperative activities, but how do you motivate people to contribute when it’s easy to get the benefits without paying the costs?

field of inquiry

religion is a category or field of inquiry, not a technical term. while technical terms need precise definitions, it’s all right for fields of inquiry to have fuzzy boundaries

kibbutzim

men in religious kibbutzim are more cooperative in an experimental game than men in secular kibbutzim and those who attend synagogue more often are more cooperative than those who attend less often

evolutionary aesthetics

explores the origins and evolution of aesthetic preferences and artistic behaviors

attempts to understand the judgment of humans and their distinction between “beauty” and “ugliness” as an adapted ability to make decisions throughout life

female preferences for male faces and body types

feminized male face:

• men with more feminized faces score higher on an “interest in infants test”

• prediction: males with relatively feminine facial morphology will be preferred when parental investment is important and the likelihood of conception is low

masculinized male face:

• masculinized faces reflect higher testosterone levels

• testosterone correlates with things that might benefit offspring, like male dominance

• testosterone also reduces immune function

• evidence of testosterone combined with overall good health might server as a signal of high genetic quality

• prediction: females will prefer masculinized faces when investment is not a concern and when the likelihood of conception is high

evidence of physical strength may have been a cue of male formidability, i.e., a male’s ability to fight and maintain control of resources

upper body strength has been shown to correlate with formidability among modern human males

male preferences for female faces and bodies

females rated as “more attractive” have features indicative of more estrogen (e.g., more fuller lips) and less testosterone (e.g., shorter, narrower, longer jaws)

• these hormonal markers appear at puberty and are associated with higher than average fertility

waist-to-hip ratio (WHR)

• a low ratio = a smaller waist relative to hips

• a high ratio = a larger waist relative to hips

• “pears” (low WHR) have

  • better health

  • higher fertility

  • less masculine hormonal profiles

• WHR reflects fat distribution, not underlying pelvic anatomy

• key to low WHR: more gluteofemoral fat

  • a woman’s gluteofemoral fat is especially important for nervous system (including brain) development in her fetus

baby schema

set of infantile physical features, such as large head, big eyes, chubby cheeks, and plump body shape, that is perceived as cute and motivates caretaking behavior in individuals

strong stimulus for parental behavior because the evolutionary function of this schema is enhancing the survival of offspring

biophilia

love of life and living things

describes the theory that humans have evolved alongside the living world. asserts that a human’s dependence on nature extends beyond the need for material and physical sustenance and encompasses the human craving for aesthetic, intellectual, cognitive, and spiritual meaning and satisfaction

the savanna hypothesis

the idea that, because savanna environments would have offered our ancestors much of what they needed to live (e.g., large herbivores, trees with fruits and nuts, evidence of nearby water sources), we may have an evolved preference for savanna-like landscapes