4/27 & 4/29 - Cognition, Social Learning, Tradition, Teaching

How does relative brain size of primates compare to other mammals?

In what way are large/dense brains costly?

size:

• Bigger animals have bigger brains (line above line for body size average)

• Primate brains are much larger than those of insectivores (ancestral shock, 4x larger in strepshirine, 7x larger in haplorhine)

• Human brains are 3x larger than those of monkeys, apes

costliness:

• Brains are metabolically expensive

  • Human brains accounts for 20-25% oxygen consumed, human brain accounts for 2% of body mass, neocortex metabolizes at the highest rate of all brain parts

Why do we consider relative (not absolute) brain size in comparisons of different species?

• Size vs information processing capacity (more neurons despite similar body size and same brain size, indicates more intelligence)

• bigger species have bigger brains, intelligence comes from number of neurons relative to size

• Primates aren’t unique in having larger brains relative to body size

Why consider neuron density rather than brain mass?

• more neurons = greater processing capacity = greater intelligence

Why is an evolutionary explanation for primate intelligence called for? (Consider

the anatomy and physiology of the brain.)

• Nature doesn’t tolerate needless extravagance, if brains are big there is a reason

define and contast the ecological intelligence and social intelligence hypotheses.

ecological:

• Primate intelligence evolved to solve ecological problems, such as efficiently finding and accessing food and avoiding predators (predators go for dumber prey without ability to avoid predation, graph shows predators prefer smaller brains)

social:

• Primate intelligence evolved to solve social problems, that is, to function in a complex social world

  • Larger group size correlated with higher neocortex ratio

  • The most intelligent animals are social

What are encephalization quotients and neocortex ratios? How does their

variation among species with different feeding ecology support the ecological

intelligence hypothesis?

• Encephalization quotient: observed brain mass relative to expectation based on body size, how much deviate from expectation

• Neocortex ratio: ratio of neocortex size relative to rest of brain

w/ hypothesis:

• Higher EQ in more frugivorous species

• Higher NR in more frugivorous species

• Prediction: animals eating dispersed, patchy foods, need larger brains to keep track of info (what food, where, how much)

How might brain evolution be related to predation pressure? What evidence

supports this idea?

idea:

• larger brains allow more flexible anti-predator behavior:

• neuroanatomy/idea: primates brains evolved circuitry to detect venomous snakes (camouflage-breaking, depth perception), brains “fear module” especially closely tied to visual cortex in primates

• biogeography: evolutionary exposure to venomous snakes predicts visual acuity (eyesight) among primates on diff land masses, more snakes better eyesight

evidence:

• Best visual acuity, 140 my venomous snakes: OWM, apes

• Med visual acuity, 60 my venomous snakes: NWM

• Worst visual acuity, 0 my venomous snakes: lemurs (no snakes in madagascar)

Review examples of what non-human primates know about features of their

environment.

• medicinal plants, eat certain plants only w upset stomach

• alarm calls of other species

• mental maps & spatial memory

  • Japanese macaques know where to look for akebi fruits, even out of season

  • Take shortcuts through land when they know the way around

• Do non-human primates differ from other animals? Possibly more developed spatial memory

Review evidence that suggests that non-human primates know about the

friendship and kinship relations of members of their own species. Why is

knowing about third-party relationship more cognitively demanding than knowing

about one’s own relationship to other group members?

evidence:

• Capuchins solicit help from high ranked group-mates that have closer relationship with self than with opponent, must assess others’ relationships in addition to their own

knowing about 3rd party:

• have to be more aware of others

aspects of recognition of others’ relationships, 3

• Social bonds

• Kinship, recognize their own kids and who the parent is, animals look at speaker and at mom

  • Evolutionary advantage bc want someone you know to help you in a conflict, make better social choices w recognition

• Rank, keeping track of others’ relationships means that social knowledge must increase exponentially with group size

What is a theory of mind? Do non-human primates have a theory of mind?

• Theory of mind: attribution of mental states to others

• inconclusive if non-human primates have ToM, evidence can point both ways

How might a non-human theory of mind differ relative to that of typical human primates? Review Evidence.

• Being a social strategist doesn’t mean you have a theory of mind, you might just be good at reading and influencing another’s behavior

• Example of female doing predator call to lure others into trees away from food, deceiving them that a predator is around so intentionally deceiving the other monkeys by making them think there is a predator present, 

  • Way to perceive it without thinking about caller’s theory of mind?, she just knows if she calls she gets to eat tangerines, not what others are thinking

• In humans ToM develops during childhood

Why would it be useful to have a theory of mind?

• Helps in dealing with novel situations

• Can predict another’s likely behavior

• More economical than memorizing many contingencies

Practice interpreting explanations for behavior that do vs. do not rely on the actor

having a theory of mind (example of capuchin deception in class).

• low-ranking females give terrestrial predator alarm calls when they sit near a rich food patch, even though no predator is present

• ToM: they know that this will make others feel fear from predators, which means they are thinking about the states of mind of other animals (deception relies on this)

• non ToM: they have just learned that if they make this call, others will leave, giving them more access to food

talk about ToM in human children

• Very young children may not realize that others have mental states, but toddlers attribute motivation to others

• Young children up to 4yo have trouble w idea that another person doesn’t see, know, and think what they do

• Sally-Anne test, sally puts marbles in basket, sally leaves, anne moves marbles to box, sally looks for marbles in basket

evidence of ToM

• sarah the chimp attributes motivation to people on a videotape, young chimps spontaneously assist a human who tries to accomplish a task (involving reaching for a clip)

• Does one individual know what another can see? Experiment on chimps

  • Dominant and subordinate looking into area in separate rooms, have 2 walls and subordinate can see 2 bananas and dominant can see 1, later released into middle room

  • If subordinate has head start would he go for one banana over the other? Would he know the dom cannot see one of the bananas? Expectation is to go to hidden banana, that is what happens, subordinate goes to hidden banana, based on assessment of what the dom individual can see

    • Non-ToM explanation: maybe ind goes to hidden banana bc dom isn’t looking at it

  • Experiment 2: see-through barriers, dom can see banana, subordinate goes to both bananas equally, no longer goes only to one on left

  • Suggests chimps know what another individual can see

  • Repeated on capuchins, went 50-50 whole time, capuchins dont prefer banana dom ind can’t see, not acting as if they can tell what the dom ind sees

• Eye tracking study of false beliefs

  • Watch soap opera, track eye movements

  • Chimp observer, mysterious primate comes in and makes lots of noise, red dots show tracks primate, hides thing under left box and primate moves it to right, chimp eye movement looks to left, looks where they think human would go, apes understand inds have unique perception of world

evidence of deception in primates? motivation, false beliefs, etc?

• Not lotta evidence monkeys compassionate towards groupmates, associates interested in wound rather than expressing compassion towards wounded individual, not treat wounds as handicaps, mothers not treat dying/sick young different than normal

• Kids bring food to sick mother, compassion

• Deception: do exhibit, do predator call so others get away so they can eat, but animals who exhibit may not do so knowingly, hard to tell whether understand mental state of others or learns that actions cause rewards

  • Gombe get food and does food call and gets food taken, doesn't do food call so gets more food

  • (de waal) 2 males fight, one limps after but only when the other can see him, Yeroen & Luit

  • Nikkie runs up into tree, makes fear grimace and uses hands to get rid of fear grin and not look scared, try to change signal given

difference between monkeys and apes minds?

yes

What is social learning and why might it be advantageous (adaptively speaking) relative to individual trial-and-error learning?

• social learning: a process in which social interactions bias what individuals learn

• Advantages relative to individual trial and error:

  • No errors (lower potential death)

  • Learn faster

  • Pool collected knowledge

  • Accumulation of skill complexity

• Assuming they depend on social learning to form culture

Other than traditions, what two explanations might explain locale-specific behavioral variation?

• Caution: group or locale specific behaviors are not necessarily socially transmitted traditions

  • They may result from heritable/genetic differences that influence social behavior

  • They may result from habitat differences that reinforce diff forms of behavior in diff locales

  • Need to make sure these arent the causes if doing a study

• Non-humans have “preculture” & “protoculture” vs some/many non-humans have “traditions/culture”

What features of a behavior might lead a biologist to recognize it as a ‘tradition’?

• Tradition = “a distinctive behavior pattern shared by two or more individuals in a social unit, which persists over time and that new practitioners acquire in part through socially aided learning”, common and long lasting and acquired via social learning

  • 2+ inds, persists, new inds acquire through learning, common, long lasting

Review a research strategy used in studying animal traditions, what do they reveal? Critiques? field surveys

• Systematic field surveys

  • definition: documenting several locale-specific behaviors and ways of processing food

  • reveal: closer friends share ways of food processing, suggests social learning

    • Capuchin traditions: body part sucking, fingers up nose, eyeball poking

    • Chimp traditions: grass in ear

  • critiques: hard to reject genetic, ecological, asocial explanations for behavioral variation, “method of exclusion” / social learning is a credible explanation only after alternativs ruled out

Review a research strategy used in studying animal traditions, what do they reveal? Critiques? diffusion studies

• definition: documenting diffusion patterns

• result: observing the spread, national diffusion only to those who have been exposed

  • Ex: chimp uses moss as a drinking sponge

  • Yerkes field station, 2 large social groups, Two Cultures Project, Panpipe technique diffusion, chimpanzees

    • Create 2 separate cultural traditions, repeat method they say proves learning

    • Some corruption in FS1 of poking but eventually changed back to lift, robust, possible explanations: wanna be like everybody else

    • FS1, 15 chimps, train to lift, FS2, 14 chimps, train to poke

    • Each group train chimp to be model and get food from contraption, would they learn from her? Impact of learning? 

    • Had control group with no model, 3G2A design

    • Control chimpanzees non-specific

    • Social learning must be responsible for differences in the behavior of 2 populations 

    • Highlights importance of “open-diffusion” and “transmission chain” experiments

  • Vervet culture

    • Create 2 specific group cultures of food choice, see if choose local food or not

    • Expose groups to pink and blue corn, one made yucky, remove corn for some months, replace colored corn, neither color yucky

    • Do monkeys maintain their preference? Do youngsters copy their moms? What happens when a male transfers to a group with a different preference?

    • Found: youngsters chose same color as mom, monkeys maintain preference but if low rank around high rank then forced to choose previously-yucky color, new males adopt color preference of group they go into not the one they grew up with, change from pink to blue or vv

• critique: *******************

How might culture and traditions differ? Is there better evidence of one or the

other in non-human primates?

• see other slide for tradition definition

• Culture: >1 tradition aka collection of traditions, more varied content, “ratcheting up” in complexity over time, emotional connection, group identity

• Are differences between animals and humans a matter of degree, not kind?

  • Pyramid, social info transfer at bottom, then traditions, then culture, then cumulative/ratcheting culture at top

  • animals may be capable of only the basic elements of a human-like culture (social learning and traditions) but not a multi-faceted rich culture, or a cumulative ratcheting one