Task 5 Flashcards
On what factors does the ranking in the hierarchies depends?
ranks depend on factors
- size
- strength
- age
- coalitional support within the group
what is a dominance hierarchy?
hierachy in a group, where some individuals can displace others
- reproductive success is higher for high ranked vs. low
- for low ranked, there is high cost to get up, therefore stay down
- when stable: low ranked are more stressed
- when unstable: high ranked stressed, need all the time fight for their place
What are the evidence of the Out of Africa model?
- Morphology
- AMH (anatomically modern human) all over the world look relatively like each other - Genetics of living humans
- all current humans can be traced back to a small set of ancestors - Neanderthal DNA
- AMH and Neanderthal did not reproduced offspring
therefore NT genes are more similar to themselves than to AMH
- if they mated, we must have found similar mutations in the mtDNA
What makes humans different?
- Meat eating
- provides a lot of energy, can be used for the brain
- smaller gut then herbivores - Tool use
- Brain size
- large brain size compared to other primates - Life history
- lifespan has generally increased
- increasing brain size associated with increased lifespan - Learning niche
- use different strategies - Language
- can communicate about what is going on and can make plans
What is allometry?
The study of the relationship of body size to shape, anatomy, physiology and behavior
(allometric line is the expected brain size of an animal depending on those factors)
Brain size = C (W)^k
c and k = constant
w = body weight
- brain size grows more slowly than body size
- our brain is 5x larger than expected for mammals and 3x larger than for primates
=> we lie above the allometric line seen for mammals!
What is the Encephalisation Quotient (EQ)?
EQ = actual brain weight / brain weight predicted from allometric line
=> its a better measure of intelligence than the absolute brain size
e.g. whales have a way bigger brain but we are more intelligent than whales
Our human brain takes around 20 % of our energy, while it is only 2% of our whole body mass!
what strategies do we have for energy supply?
- increase energy inputs relative to body size overall (eating meat, cooking food)
- reduce energy in other bodily functions
What is the Machiavellian intelligence hypothesis => social brain hypothesis (SBH)
Machiavellin intelligence hypothesis = old version
- hierachies, dominance
- need to keep track of whom is in higher rank and who is lower
- require cognition = face recognition
SBH = associate brain enlargement with increasingly large and complex social groups
evidence: relative brain size of the neocortex is corrected with social complexity in primates
Social cognition
- early in evolutionary history also bonding between non- reproductive partners = friendship
- bonding between same sex and opposite sex
Why are social demands so cognitively demanding?
because:
1. A lifelong monogamy is a risky commitment
- need to be careful whom to choose
- it involves substantial postnatal parental investment and close coordination
General intelligence hypothesis
- larger brains enable humans to perform all kinds of cognitive task more efficiently than other species
=> predicts no differences between physical and social cognition
e.g. greater memory, faster learning, planning beforehand
Adapted intelligence hypothesis
- cognitive abilities evolve through environmental challenges
(ecological or social)
Ecological intelligence hypothesis
- primates cognition evolved through challenging demands of foraging for seasonal fruits and resources
- need to remember the place where fruit last found (spatial map)
- seasonal fruit, toxic fruits
e. g. searching for berries, or cracking nuts etc
social intelligence hypothesis
is kinda similar to SBH
- cognition evolved through challenging demands of complex social life and of constant competition and cooperation
cultural intelligence hypothesis
- humans cognitive skills due to species- specific set of social-cognitive skill for participating and exchanging knowledge in cultural groups
What is the outcome of the experiment testing children with monkeys in physical and social domain?
- chimpanzees and children do not differ much in physical domain
- BUT they significantly differ in social domain
- human beings are more cooperators than monkeys
=> strong support for the cultural intelligence hypothesis
(human being have evolved some specialized social-cognitce skills for living and exchanging knowledge
=> NO support for general intelligence hypothesis
(human cognition differs only in general cognitive processes such as memory, learning etc
Is fruit eating responsible for larger brains? (article)
- fruit is the only thing that predicts larger brain size
- leaves e.g. long digesting time, nutrients looked in thick cell walls
- fruit are easy to digest, give a big amount of energy
- eating fruit is more cognitive challenging than eating leaves
- developing larger brains to deal with these complex conditions
- Diet and sociality are not alternative explanations => they are complementary
A gene (ARHGAP11B) makes human brain unique (Article)
- gene produces more brain cells in neocortex => region central to reasoning, language and sensory perception
evidence:
- injected in mice = grew crinkled brain surface like humans
but intelligence or high cognition does not only depend on this gene, it depends on many genes to create a functional network
