9 - WHAT EVOLUTION DOES Flashcards
(27 cards)
how does evolution work?
by tuning trade offs
what is the optimal phenotype
live forever and have an infinite number of babies per second (genetic algorithms)
- id reproduction and survival weren’t involved
why can’t be have the optimal phenotype?
- cost-benefit trade offs are the rule of life
- with finite resources, life must ‘choose’ (genetically) to favour one option over another
- more of one thing often means less of another
common trade offs (6)
1 speed accuracy trade offs 2 exploration-exploitation trade offs 3 size number trade offs (bigger => fewer) 4 growth reproduction trade off 5 cost-quality trade off 6 short-long teen trade off
speed-accuracy trade off
- fast + errors
- or slow + accurate
- makes us overly sensitive to potentially threatening stimuli
exploration-exploitation tradeoff
- eg exploit berry bush or explore for better
- exploitation is a type of FOCUS
size-number trade-off
- eg coconut trees = few large seeds
- eg maple trees = thousands of small seeds
growth-reproduction tradeoff
- reproduce a lot or help current ones grow
- eg small mustard plants reproduce a lot but don’t live long
- eg big trees grow for ages and then start seeds
short-long term trade off
- intertemporal discounting
- money today or more money tomorrow
- r vs k selected species
- r = quick (fast growth and reproduction)
- k = later successionist species (slow growth and reproduction) eg tortoise
why do we die?
- evolution explains (even predicts) death is an inter-temporal trade off and also why we don’t die
what four reasons explain why we die?
1 disposable soma theory
2 antagonistic pleiotropy
3 mutation accumulation
disposable soma theory
- extrinsic mortality weakens selection late in life
- if most part of a species die young, then selection can’t counteract kate acting deleterious mutations
- eg if 90% of wild mice die in first year (due to cold) then selection of long life genes only benefits 10% of the population
- if selection of long life genes requires resources that could keep them warmed then it’s not going to happen and be successful
- eg fruit flies in lab selected for long life (by artificially delaying reproduction) then long lived flies reproduce less - supporting disposable soma and pleiotropy theories
- lab animals still age and die as natural selection previously hasn’t had much of an impact on late life factors
antagonistic pleiotropy
- good early genes can be selected even if they have bad later effects
- death is a consequence of trading off future against the present
- focusing on behaviours that support reproduction and survival early in life but at the consequence of less support for survival later in life
what does pleiotropy mean
a gene can have more than one effect
what does antagonist mean
the effects are working against each other
- eg risk taking in males, using resources on offspring (instead of your own longevity)
- eg semelparous species reproduce only once and often go out a massive expenditure of resources into that one reproduction - die after reproduction
^ line salmon, wheat, many ‘annual spiders’
mutation accumulation
- not well supported evidence
- your cells don’t age because they suffer mutations
hydra
an organism that doesn’t die or age
henrietta lacks
HeLa cells do not die
- our germ line is immortal
- only our soma dies (senescence = gradual deterioration of functional characteristics)
- HeLa cell line = from a cancerous tumour she has
- 20 tonnes of these cells now exist
- leads to many medical breakthroughs
why arent we smarter already?
- why don’t we have a perfect focus/infinite will power/ remember everything?
- attention focus is a trade off (too little v too much)
- ATTENTION NEEDS TO BE TUNED
- too little = don’t attend long enough / don’t start
- too much = can never change your mind or attend to alternatives (eg OCD, PTSD)
- memory should be adapted to the stability of the environment
elman (1991) less is sometimes more
- a neural network designed to learn aspects of language performs better when the attention span (memory span) of the network starts off small and grows gradually
- make the memory span short to start with
- eg children only hearing parts of the sentence (eg phonemes) when learning a language
- he showed his neural network is exploration of language acquisition by providing appropriate inputs to a neural network, a network could be taught some rudiments of language acquistion
attention being an inversed U
- too little attention
- optimal time spent attending
- too much attention
- too much/little = potentially pathological region
is attention telling of being smart?
- things we think our smart might not be as smart as we think they are
- eg better memory
vertical transmission
evolution and inheritance
horizontal transmission
- culture (beliefs, social norms etc)
