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Michael Vo

on 22 April 2010

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Transcript of Hyenas

Brains have a high
metabolic cost Why do humans have
such huge brains!? What's the fitness benefit? Two main hypotheses... "Physical Environment" hypothesis Social Complexity Hypothesis "... complex cognition and enlarged 'executive'
brains evolved in response to challenges associated
with social complexity. "(Holekamp 2007) Enlarged brains favored by
selective forces in physical
environment Prediction: Convergent Evolution Distantly related animals with similar societies should have similar cognitive functions
Vervets have troops of 10-50
Linear dominance hierarchy
Females stay with natal group, males don't
Maternal rank acquisition
Vervet Society Domain Specific Hypothesis Primates perform better with social problems in nature
than on logically equivalent lab tests

Domain specific hypothesis: strong selective pressure
for solving social problems, and abilities aren't easily
extended Cheney and Seyfarth Study vervet monkeys in the field comparing
performance on non-social vs. social problems

Advantages of field:
no motivation problem
familiar with both non-social and social stimuli
biologically and non-biologically relevant Can Vervet Monkeys interpret Starling calls? CAW! Vervet Monkey Calls Different alarms for different predators,
and therefore elicit different reactions Procedure Three types of calls: aerial, terrestrial, song
Hide loudspeaker near 1-5 vervets
Filmed 10 s, played call, then 10 more seconds Do vervet monkeys care about
irrelevant behaviors of other species? To compare we need:
1 social and biologically relevant situation
1 non-social and biologically irrelevant situation Monkey ranging Play intergroup call from the correct territory
Play intergroup call from incorrect territory
Monkeys increased vigilance at incorrect call Appropriate Inappropriate Vervets associate cries of juveniles
with the juveniles'
mothers... Can they form similar
non-social associations? Cow Wildebeest Will monkeys associate cow noises with Maasai, who occasionally
annoy them? Biologically irrelevant and non-social Biologically relevant and social Secondary cues of danger Non-social biologically relevant stimuli Surprisingly, monkeys were dumb and did not notice.


Auditory vs. visual salience

Social vs. non-social Conclusions on Vervets

Can form complex social associations
Can sometimes form non-social associations
... but seems to be much more difficult
Don't care about irrelevant stuff Hyenas: A great species for intelligence research Eerily similar social structure to primates
Only very distantly related to primates (90-100 million years)
Four species of various levels of gregariousness
So far, all cognitive abilities seen in primates have also been seen in spotted hyenas Spotted Hyena Social Structure Linear dominance hierarchy
6-90 individuals
Alpha female
Maternal rank acquisition
"Youngest Ascendancy"
Males migrate, nadir
Primate and Hyena Differences Patriarchal vs. matriarchal
Cohesion: Fission-fusion society
Cooperative hunting
Hyenas lack curiosity Hyena Social Cognition recognize individuals and ranks
only initiate attacks vs inferiors
prefer high-ranking friends
Tertiary relationships....
Predictions involving Tertiary Relationships

1: Hyenas can figure out ranks of two fighting hyenas
II:Hyenas will be more aggressive towards kin of opposition In hyena fights... Normally, all attackers are dominant to victim...

"Only attack a stronger hyena when there
are higher ranks than yourself"

Let's say hyena A attacks hyena B, and hyena C joins A

If A>C>B ever occurs, then this rule breaks down

Also, C>A>B & A>B>C occur often, and A<B almost always results in B getting help. A B C Four types of Hyena Species See if spotted are smarter than striped (Brad?)
Measure skulls to compare frontal cortex size between species Studies involving Hyena Species Social Knowledge in Human Babies Old view: humans learn social
and non-social things at same rate

Babies understand causal information
involving people at 2-3, 7 for objects
(Hood and Bloom 1978) Wason Card Puzzle What card(s) must you turn over to test this claim? "If a card has a vowel on one side, it has an
even number on the other." Wason Reframed Who do I have to ID? Holes in the Social Complexity
Hypothesis Object Permanence Primates have "stage 6"

carnivores only at "stage 5"

Stage 6:Invisible displacements Arms race Other problems... Social Complexity Hypothesis Presented by Michael Vo
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