17 - Brains, cognition and culture Flashcards
drawbacks of a large brain?
- brains are extremely costly (humans 2% body mass, 20% metabolic rate)
- larger brains take longer to grow (longer gestation and juvenile periods)
- create an ‘obstetric dilemma’ - requires altricial young
- brain increases not universally beneficial in evolution
social brain hypothesis history
Alison Jolly - ‘primate social life provided the evolutionary context of primate intelligence’
Primate sociality examples!
evidence for the social brain hypothesis
- primates with larger social groups have a relatively large neocortex
- human group sizes may have an upper limit (Dunbars number -150)
Ecological hypothesis
several versions, common idea: larger brains required for complex ecologies
e.g. broad diets, larger home ranges, extractive foraging, seasonal variation
evidence for ecological hypotheses
- recent analyses with larger datasets suggest brain size is predicted by ecological variables, not group size
(look at studies)
is it over for the social brain hypothesis?
Dunbar -
“there exists an extremely robust statistical relationship between the typical size of a species social group and the size of its neocortex”
what does brain size mean?
- cognitive abiloties difficult to measure and compare across species
- brain size often used as a proxy variable
- but brains are large, complex and functionally heterogeneous organs
problem with brain size
brains vary widely in size, but also in structure and organisation
the majority of brain size is explained by body size
mosaic brain evolution
different areas of the brain can evolve at different rates
Barton & Venditti (2014)
moving forward
brain size at best a crude proxy for ‘intelligence’
not assume a single dimension of ‘intelligence’
control for body size, or look at relative size
don’t assume one ‘intelligent’ part of brain
human uniqueness with brain
brain expansion
