Task 5 Evolution Flashcards
Physiological traits
including large body size, metabolic rates and prolonged development
o Larger bodies have more energy which they can devote to the brain development
Ecological problem solving
larger brain species have larger home ranges
o Frugivores have larger brains than folivores (fruits are less predictable in their location than leaves)
Selection
Cannot account for larger brain size
Social brain hypothesis
Individuals living in stable social groups are facing more complex cognitive demand than those who do not
o They have to look and act with others than themselves
o Behavioural flexibility is important
Monogamy in ungulates
large relative brain size is associated explicitly with pair bonded monogamy
Group size
There is a correlation between group size and brain size
Fruits
Population which ate mostly fruits had bigger brain size than those who ate leaves because they are more easy to digest
o Better diets merely provided the fuel for that evolutionary change
o Fruits are more challenging to consume, bc. of place and time of growing, so this might form a need for better brains
Allometry
As an organism increases in size, there is no reason to expect the dimensions of its parts, such as limbs or internal organs, to increase in proportion to mass or volume
o Brain size= C(body size)k = C(W)k
o C and K are constants
Expensive tissue hypothesis
increases in the brain size of hominins must have been balanced by a reduction in the demands of other organs
Physical performance
monkeys can use their feet as good as their hands. Humans can only use their hands properly
Social performance
is especially due to the frontal cortex which is larger in primates than in other animals
Genes that make humans unique
o the gene (ARHGAP11B) plays a pivotal role in human cognition by ramping up dramatically the number of neurons in the neocortex, a brain region that is central to reasoning, language and sensory perception
also carried by Neanderthals
o 56 genes that affect stem cells in the brains of primates, about a quarter of which are unique to humans
o Connection between neurons are important next to the simple quantity
Meat preparation and consumption (difference to other species)
hard to get but beneficial for brain development
Tool use (difference to other species)
is not unique to humans but the diversity of applicability and dependence is
Brain size (difference to other species)
the size of the brain is bigger in humans which is not accounted for by their large body size
o Social groups became bigger
o Learning and memory was enhanced too
Life history (difference to other species)
o Human babies are born with relative undeveloped brains and after birth there is a strong development that gets less until adolescence
o Menopause is used that females can look after the reproduction of their offspring rather than their own because they might be to old to care for a new baby by themselves
o Humans have a higher reproductive rate
The learning niche (difference to other species)
o Humans have a lot of strategies for the same goal e.g. hunting which enquire more complex skills
Language (difference to other species)
o It is productive so meaningful untis that can be combined to sentence (provides variety)
o Important for social learning
ballistic
Fine motor tuning and planning/calculating actions (e.g. throwing a stone)
Intelligence hypothesis
larger brains enable humans to perform all kinds of cognitive operations more efficiently: greater memory, faster learning, faster perceptual processes
o Physical and social skills are always more developed in humans than in other primates
Adapted intelligence hypothesis
Cognitive abilities evolve in response to relatively specific environment, so other species can develop “intelligence” for the fitting action
Ecological intelligence hypothesis
primate cognition evolved mainly in response to especially challenging demands of foraging for seasonal fruits and resources embedded in substrates
Social intelligence hypothesis
Primates cognition evolved because of more complex social life consisting of cooperation and competition
Socio-cultural intelligence hypothesis
Humans powerful skill of socio-cultural cognition early in life might serve as predisposition for the complex human cognition in general
o There is an early development stage where physical skills might be same in animals but the socio cultural skills are already adult like
Monogamy
o Monogamous animals have larger brain than non-monogamous, in primates it is switched because of they have to keep relationships
Dominance hierarchies
emerges when groups are getting larger. Some animals are then able to displace recourses.
o Different ranks are based on factors such as size, or fighting
o Being high in rank benefits reproductive success so it is good to be high ranked
Primates
have four fingers that can be used to grasp, binocular vision, brain size is relatively large
monkeys
are animals such as baboons, macaques and colobus. They are found in large areas in Asia and Afrika.
Apes
Are the larger and tailless monkeys to which humans belong
Gibbons
the lesser apes
o 13 species found in southeast Asia
o Brachiation: a mode of locomotion which enables them to swing from branch to branch using their arms ´
Orang-utans
lives only in Indonesia
o They are polygamous
o Males are larger than females
The gorilla
lives in Africa
o Live on the ground
o Knuckle walking
o Polygnous group structure with one dominant male and multiple females
chimpanzees
live in Africa
o Knucklewalk
o Live in an open multiple male and female population
Hominins
: Intermediate forms between chimpanzees and humans
o Fossils only found on Africa
o Australopithecines: from 4 to 1 million years ago
Could walk on 2 feet still spent time in the trees
Origin of the genus homo
first primates where brain size moves from chimpanzee pattern to human pattern (2.5 millions years ago)
o Stone tools start to appear
o Two feet walking was now fully developed
the archiacs
origin in Africa (0.8 million years ago)
o Proportion of body to brain size is human like
o E.g. Neanderthal
Origin of Homo sapiens
o Extinct 30000 years ago in Europe and 50000 years ago in Asia
Out of Africa model
AMH were a new kind of humans which replaced the other hominins without interbreeding
Morphology: AMH from all over the world look relatively like each other and most resemble the early African AMH fossils
Genetics of living humans:
• There are African and non African species still all living humans can be traced back to a small set of ancestors
• A small ancestral population 150000 years ago for all living humans
Neanderthal DNA:
• Much more human than ape like
• The divergence of ancestors between humans took place 500000 years ago
Bottleneck effect
Some species did not survive the Pleistocene
Pleistocene: A epoch in which the weather switched between warm, wet and cold (ice age)
Holocene: the current relatively warm epoch
Implicit social contact
To form a group that provides a benefit of cooperation (for example, reducing predation risk), members are necessarily obliged to trade off short-term losses in immediate benefits in the expectation of greater gains in the long term through cooperation.
Encephalisation quotient
The departure of brain size from the allometric line
o Better measure for intelligence than total brain size
Encephalized
animals that occupy point above the line; has brain larger than expected for animal of its body mass; result of 1) relative growth in brain size (= positive encephalisation +E) OR 2) reduction of body size relative to brain mass (= negative somatization –S)
Phylogeny
study of evolution of species and relationships amongst groups of individuals (all species are related because they have a common ancestor)
