TASK 5 Flashcards
Humanity
Dominance hierarchies
- Some individuals are “higher” in rank than others and are constantly able to displace others from a resource
- dynamic ranking: can be challenged (by fighting) and reversed; higher ranks more stressed
- stable ranking: lower ranks more stressed
Social-brain hypothesis idea
= Machiavellian intelligence hypothesis
- maintaining social relationships requires devoted brain mechanisms –> social species will have larger brains compared to non-social ones
- bigger brain size must have evolved as a result of bigger group size
- only focus on social knowledge
Cultural intelligence hypothesis
- human’s unique cognitive skills is mainly due to species-specific set of social-cognitive skills for participating and exchanging knowledge in cultural groups
- humans only differ in cultural intelligence (proven in example with child and chimpanzee)
- can explain all knowledge (because it is derived from cultural intelligence)
General Intelligence hypotheses
- larger brains enable more efficient use of all cognitive operations
Adapted intelligence Hypothesis
- cognitive abilities evolve in response to relatively specific environmental challenges
- ecological theories and social theories combined
Bottleneck effect
- Sharp reduction in the size of a population due to environmental events or human activities
- African bottleneck: 172,000 years ago
- -> small set of ancestors expanded out of Africa
Allometry
= y = c * (w)^k
- Y (brain size) can be related to a more fundamental one W (body size)
- C and k are constants
- -> an increasing size does not have to result in an increase of its parts
Encephalisation quotient (EQ)
= (actual brain weight)/(brain weight predicted from allometric line)
- departure of brain size from the allometric line
Chihuahua fallacy
- Intelligence is too complex to have such a simple relationship
- small dogs (chihuahuas): body can be bred smaller but the brain size is less variable
Basic metabolic rate (BMR)
- rate of energy expenditure per unit time by endothermic animals at rest
- Metabolism: comprises processes that the body needs to function
Machiavellian intelligence hypothesis
- what differentiates primates from all other species was the complexity of their social lives and environment
- Machiavellian: misleading –> got replaced by the social brain hypothesis
Apomorphies
- traits that are defining for all species afterwards
- a novel evolutionary trait that is unique to a particular species and all its descendants
- can be used as a defining character for a species/ group in phylogenetic terms
Homology
similarity resulting from common ancestry (i.e. bones in hand and arm)
Convergent evolution
gain of new, similar features independently (trait that develops independently)
Pleistocene
- Ice Age = geological epoch that included the world’s most recent period of glaciations
= ‘winter’
Holocene
- Current geological epoch
- began after the last glacial period
= warm period, ‘summer’
Strepsirrhines
Suborder of primates that includes the lemuriform primates in Africa, Madagascar
Haplorrhines
“dry-nosed” primates, suborder of primates containing the tarsiers as a sister of the strepsirrhines
Prosimians
Group of primates that includes all living and extinct strepsirrhines and haplorrhines
Platyrrhines
- Group of primates that includes the new-world apes, marmosets and tamarins
- distinguished by having nostrils that are far apart and directed forwards or sideways and typically have a tail
Catarrhines
- Group of primates that include the old-world apes
- characterised by having nostrils close together with an opening in front of the face
Brachiation
mode of locomotion involving swinging from branch to branch using only arms
Hominins
- intermediate forms between chimpanzees and the humans today
- not a single evolving lineage –> branching of multiple forms, many of which go extinct and only some of which are on the line leading to living humans
Out-of-Africa model
- AMH is a new species that replaced the other living hominins without interbreeding
- Morphology: universal similarity; not Asians resemble Erectus more etc.
- Genetic evidence: deep branches between contemporary Africans
- -> African bottleneck: small set of ancestors expanded out of Africa
- Neanderthal DNA
Ecological intelligence hypothesis
- cognitive skills evolved mainly in response to the especially challenging demands of foraging for seasonal fruits and resources embedded in substrates
Expensive tissue hypothesis
- increases in brain size fmust have been balanced by a reduction of demands of other organs (gut reduction)
- Carnivores need to kill (requires speed, strength & adequate perception to catch the prey) –> hunting & gathering intellectually demanding –> larger brain
Arboreal theory
- moving & feeding on land required stereoscopic vision and dextrous hands –> both of required a large brain to coordinate and control
Fruit hypothesis (Diet hypothesis)
- leaves are harder to digest
- -> Fruit: lots of calories in easy to digest package (no thick cell walls)
- Diet & sociality as complementary explanations
What makes us human?
- Bipedialism: walking on 2 feet
- Meat eating
- Tool use
- Brain size
- Life history
- Learning niche
- Language
- Ballistics: enhanced lateralisation of the brain
Meat eating
- high-quality resource used to fund metabolic cost of large brains
- guts became smaller (meat is easier to digest) –> freed up energy for brain
Tool use
- not restricted to humans –> humans greater dependency + more sophisticated use
- appearance of new tools not well correlated with anatomical changes
Brain size
- larger brains relative to chimpanzees (not accounted for by larger body size)
- -> Allometry (positive EQ)
Life history
- lifespan and period of development have increased/ elongated
- born rather undeveloped (head otherwise too big for birth) –> fast post-natal developments
- outweigh cost of investment in development –> live longer
- family structure follows extended developmental period –> relatives help out
Learning niche
- high-skill foraging makes humans able to occupy very different environments in many ingenious ways
- need more time to learn skills –> chance of inventing things
- Long period of childhood: enables communication between preformed brain modules –> allows cognitive fluidity
Language
- productive language: produce nearly everything with different parts (words to produce sentences)
- refer to things that aren’t present –> increased efficiency of social learning
- gossip & the maintenance of cooperation by indirect reciprocity
- FOXP2 mutation
Australopithecines
- 4 million - 1 million years ago
- climate change: drying of climate, fragmenting of forest –> increased fitness of bipedalism
- size of chimpanzees
- mostly depends on plants
- robust: more robust teeth/jaws
- gracile: evolved into Homo
Early Homo
- 2,5 million years ago
- brain size begins to clearly move toward human pattern
- stone tools
- full bipedalism & long-range mobility in place –> wander from Africa to Asia
- began to depend on meat
- -> Homo habilis
- -> Homo erectus: Asia
- Homo floresiensis: island; dwarf human
Archaics
- 0,8 million years ago
- expanded size of body & brain, more complex tools
- Homo neanderthalensis: Europe;
Homo sapiens
= AMH (anatomical modern human)
- Bottleneck effect: expansion & divergence began with small population in Africa
ARGHAGAP11B gene
- drives the expansion of the human brain
- needs other genes to make those neurones form functional networks in brain
