NS evolution Flashcards
morphological difference between skull of homo sapien vs non homo sapien
homo sapiens have larger room for brain
brain weight
insufficient predictor of ‘smartness’
elephants aren’t smarter than us
brain weight as % of BW
still not good enough either
mouses are not smartest animals
encephalisation factor
brain weight / BW^0.69
good predictor (puts humans at top)
increase in relevant brain size
birds, mammals and cartilaginous fish
FISH: big brain because a lot of olfaction
how have brains changed?
increase in relative brain size and increase in relative regional sizes
are bigger brains more sophisticated?
not necessarily
whale brains also have 6 layers with very complex folding, however are much simpler (less neuron presence)
are small brains more sophisticated?
Maybe, small brains might be more complex
Goldfish brain has 15 layers
primates show different levels of gyrification
Primate brains show different levels of gyrification
Big brains are really folded
Cerebral cortex thickness is the same
what hasn’t changed over time / across animals
cortical thickness
gyrification - why?
folding increases surface area
(allows more cortex in smaller volume)
packing through layers
gets suboptimal as layers increase
primates?
bigger brains (in relation to body size), more neocortex, more distinct architectures
afarensis vs homo erectus
getting bigger (bones and skull)
why did brain increase?
body grows bigger, therefore requires a bigger brain for that body
evolution of grassland
driver of evolutionary change towards intelligence
(e.g. needing to free forelimbs to make tools)
BUT brain size increased AFTER bipedalism (wasnt a trigger for cerebral expansion)
what was driver for cerebral expansion?
rapidly changing environment required ability to adapt to survive -> bigger brain more able to adapt
brain size at birth
need to fit through pelvis
either have a small brain or be birthed with an undeveloped brain
organisation of pfc in mammals
macaque same as us but lab rat has no organisation of PFC
organisation of language areas in macaque vs human
upstream from motor area in both
what gene expression characteristics are same / diff between us and chimps
same: liver, blood
different: brain
costs of big brain
require long gestation, big head = difficult birth, more genes (and more mutations), large energy expenditure / heat production
high culture relation to brain size
increase in high culture (e.g. writing, cities, art) kind of corrrelate with bigger brain size NOT bipedalism though
lunate sulcus
divides visual from other neocortex
lunate sulcus positions (in Australopithecus) suggestive of bigger proportion of non-visual cortex - which includes association cortex
