What makes human typical human Flashcards
allometry
as an organism increases in size, the dimensions of its parts do not increase proptionally
What are the costs of a large brain?
- it is metabolically expensive -> BUT there is no correlation bw brain size across mammals and metabolic rate
- > larger brian will only envolve if payoffs are even greater
metabolic rate
amount of energy used by an animal per unit of time
expensive tissue hypothesis
metabolic requirment of large brains are offset by corresponding reduction of the gut
-> human gut is significantely smaller than predicted by patterns in other species -> need for high quality diet
lifting energetic constraint
1 change in diet to fruit 2 meat eating 3 cooking food 4 cooperated breeding 5 alloparental care
evidence for change in diet
Howler and Spider Monkey
howler ( leaf eater) x spider monkey (fruit eater)
- > monkeys of the same size differ in degree of brain development
- > fruit eating spider monkey has a much better developed and larger brain
What are payoffs that make animals want a bigger brain?
1 Ecological hypothesis
2 social / machiavellian hypothesis
3 cultural intelligence hypothesis
Ecological intelligence Hypothesis
Selective pressure due to change in diet
- > need to monitor the availability of dispersed food supply
- > extractive foraging
- > requirement of mental map in order to find food
- > knowlege when food is ripe
extractive foraging
removal of food items from an embedded matrix
Does lifting constraint or selective pressure lead to larger brains?
higher diet quality leads to an (1) increased energy availabiltiy (2) more complex foraging behaviors and (3) more rapid assimiliation -> smaller gut -> increased energy availability
all these factors end up in larger brain
-> see graph in lecture 3
skills that are distinctly to human
there is something special about social domain ( physical domain monkeys and children are quite similiar )
social hypothesis
= large brains have envolved via intense social interactions and competition
1 Social Hypothesis (Dunbar)
individuals living in a stable social group face cognitive demands that individuals living alone dont
large brains of primates reflects the computational demands of the complex social systems that characterize the order
(-> pairbonded species have larger brains)
-> linear correlation between group size and neocortex
Machiavellian Hypothesis
what differentiates primates from other species is complexity in social life -> requieres domiance rank means who is dominant, is standing above you -> leads to need of face recognition
Cultural Intelligence Hypothesis
argues that humans unique cognitive skills is mainly due to species specific set of social cognitive skills for participating and exchangning knowledge in cultural groups
merging ecological and and social drivers
Ecological factors drive growth brain
Cooperation shapes brain (limited because it is often associated with cheating)
Culture may be crucial to rapid increase in skill learning needed for brain growth
-> three aspects are not in conflict with each other
dominance hierarchies
some individuals consistently able to displace others from the resource -> rank depends on strength , size age etc
stable hierarchy vs unstable hierarchy
stable hierarchy : low ranks have worse health and increased stress
unstable hierarchy : vice versa
social brain hypothesis
idea that maintaing social relationships requires devoted brain mechanisms -> social species tendence to have larger brains -> evidence is found in primates
Which features do humans and primates share?
1 grasping by using their hands and feet 2 highly dependent on vision 3tend to hav forward facing eyes 4binocular vision and colour vision 5 larger brains for their body size
What are new world monkeys?
Platyrrhines
Gibbons
long term bonds and social groups consist of monogamous pair plus one or more dependent offspirng
Brachiation :mode of hand, arm and shoulder anatomy -> involves swinging from branch to branch using only arms
Orang Utans
fruit eaters and arboreal ( living in trees)
Polygyny with much larger males than females
Gorillas
lives on ground ; knuckle walking
highly sexual dimorphic -> polygynous group structure ( single dominant maleand multiple female )
Chimpanzees
knuckle walk, arboreal, omnivorous ( allesfresser) and occasionally hunt
fluid multiple male
multiple female social groups with a promiscious ( häufig wechselnde sex partner) mating structure
The ape phylogeny
Humans belong to the great apes -> not equally related to but close to chimpanzees (99 % DNA resemblance)
Phylogeny
Phylogeny, the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of org
Hominins
intermediate form of chimpanzees and humans
australopthecines
4-1 million years ago
- > skulls are chimpanzee like
- > back then there were new savannahs and lots of the apes died bc they were more adapted to the forest
-> scenario for evoloution of BIPEDEL LOCOMOTION
disadvantage : time spent in trees
advantage: moving on the ground -> more energy efficient at slow speeds and upright absorbs less heat bc smaller surface to sun
Origin of the genus Homo
- 5 million years ago
- > brain size moves away from chimpanzee to human
- migration from africa to southeast asia
- appereance of stone tools
The archaics
- 8 million years ago
- larger brains and bodies and more complex stone tools
the origin of Homo Sapiens
200.000 years ago -> referred to as anatomically modern human
What are old world monkeys?
catarrhines : baboons, macaques
Were AMH a distinct species which replaced Neanderthals in Europe without interbreeding ?
AMH entering europe replaced neanderthals with little or no interbreeding
pleistocene
fast and repeated oscillation between warm and wet climates and glacial periods
holocene
current warm period that started 10.000 years ago -> metal working, agriculture and settled towns
General intelligence hypothesis
larger brains enable humans to perform all kinds of cognitive operations more efficiently than other species
Adapted intelligence hypothesis
cognitive abilities evolve in response to relatively specific environmental challenges
A gene that makes human brains unique
- found in modern human as well as it was carried by neanderthals
- testing in mice embryos showed that it has profound impact -> BUT gene does not have same impact evry time
- gene is highly active in stem cells that make neurons in neocortex
- > gene does not make us smarter than animals but it is seen as key part what makes us human
- > proximate explanation
Chimps vs cows
- both have brains about 400grams
- > whatever chimpanzees exhibit more flexible, complex behaviors , have wider behavioral and vocal repetorie and larger learning capacities
Encephalization quotient (linked to brain size relative to body size
as an organism increases in size, the dimensions of its parts do not increase proportionally
Brain size = C (Body size) *k
Where are most neurons in the brain located?
98% in Cerebellum
-> humans have 16 billion neuron and gorillas and orang utans 9 billion in cerebral cortex
-> high number of neuron provide us with capacity or potentially to learn (=innate capacity to learn)
Factors for evolution of learning
1 innate capacity to learn
(without training and learning children arrest at stage of raw material -> no problem solving skills)N
2 modern life -> people are exposed to challenges
3 increased genetic improvement
HAR1
cortical expansion, increased cortical control of behavior (less by spinal cord)
FOXP2
enhanced the capacity to speak and learn a language
srgap2
enhanced learning (synaptic plasticy)
FOXP2 in mice
lead to increase of vocalizations and better learning capacities
FOXP2 contribution to language evolution
- > you can teach apes symbols to a certain extent but never how to speak
- > FOXP2 led to an increase in vocal flexibility
