© kip smith, 2003 part 2 nature evolution, language, and species-typical (innate) behavior patterns
Post on 21-Dec-2015
220 views
TRANSCRIPT
© Kip Smith, 2003
Part 2
Nature
Evolution, language, and species-typical (innate) behavior patterns
© Kip Smith, 2003
Outline of the course
Foundations The science of mind and behavior
Nature How evolution has shaped mind and behavior Species-typical behavior patterns Examples:
Sticklebacks Language
Later: Nurture, (Ab)Normal minds
© Kip Smith, 2003
Today
Evolution, what it is, how it works Random variation, genes Natural selection Sexual selection
Its implications for psychology Some of our behavior patterns are innate They have been shaped by millions of years of
adaptation to our environmental niche
© Kip Smith, 2003
Next
The curious behavior patterns of the stickleback
Curious behavior patterns of humans Mate selection Casual sex Jealousy Aggression Altruism
© Kip Smith, 2003
Next +
Language, a uniquely human behavior Syntax Semantics
Evidence for the innate nature of language & for Chomsky’s generative grammar
Children and the emergence of creole The language developed by the deaf children
of Nicaragua
© Kip Smith, 2003
Schedule
Wenzday Jan 29
Friday Jan 31
Monday Feb 3
Wenzday Feb 5
Friday Feb 7
2.1 Evolution
2.2 Curious behavior Muddiest point
2.3 Language Study guide
Review
Test
© Kip Smith, 2003
2.1 How evolution has shaped mind and behavior
© Kip Smith, 2003
An Evolution Primer
Evolution has three components Random Variation Natural Selection Sexual Selection
Your textbook, like most books since Victorian times, discusses only the first two
© Kip Smith, 2003
1 Random variation
Variation is the engine of diversity
Sexual reproduction&
Genetic mutation
Produce minute, random genetic differences
© Kip Smith, 2003
Minute, random genetic differences
Make you different than your parents
Accumulate to make different species
© Kip Smith, 2003
Genes
Biochemical units of heredity
Segments of chromosomes, of DNA
Humans have 46 chromosomes 23 from mother, 23 from father
Everything about genes and how they do what they do is more appropriately discussed in biology class.
© Kip Smith, 2003
Minute random changesin genetic code
If the variation does not harm or interfere with the organism’s ability to fit its niche, the organism has the opportunity to mate and pass those genes on to the next generation
Most variations are not helpful They are unlikely to survive and be passed on Some are monstrous and are spontaneously aborted
© Kip Smith, 2003
Random vs. Directed
Evolutionary Has no direction Has no purpose Has no moral status or
implications Does not care
Evolution happens
Teleological change Has a purpose Has a goal
Examples Goal-directed behavior Moral training
© Kip Smith, 2003
Evolution is NOT directed
The random nature of genetic variation has significant implications that some people find unsettling:
We humans are NOT the pinnacle of creation We just happen to be the way we are If the world were to have another go at it, human may
not have evolved
Bats have a much better claim to the pinnacle than humans
They FIT their niche perfectly
© Kip Smith, 2003
Myth 1
“Evolution says that humans are descended from monkeys”
Humans, apes, and monkeys have a common ancestor
Random variation has made us different than that ancestor and each other
© Kip Smith, 2003
2 Natural selection
Natural selection eliminates species that fail to match their niche
Natural selection winnows random variations that do not FIT
Fitness refers to the organism’s match to its ecological niche
Fit = the organism's match to its ecological niche
© Kip Smith, 2003
Fit is the match to a niche
If a species fits its niche, it is likely to survive
Natural selection and fit IS all about the survival of the survivors
It is NOT about the survival of the fittest, the healthiest, the smartest, or the most beautiful
© Kip Smith, 2003
Natural selection works at the species level
Utterly impersonal
If you don’t fit your niche, you die
If your species doesn’t fit its niche, you go extinct
Those who survive are likely to breed and pass their genes to the next generation
© Kip Smith, 2003
Nature and evolution are impersonal
If your environment changes and your species does not adapt, you go extinct
Large dinosaurs Mammoths Whales? Beatles
© Kip Smith, 2003
The role of the environment
The environment provides the niche The species has to adapt to it Random variation is the engine of
adaptation Natural selection gauges the fit
© Kip Smith, 2003
The human niche
The human niche is hunter-gatherer / predatory nomad / prey
Humans evolved to solve the problems faced by a predatory species that was easy prey on the Pleistocene African savanna
© Kip Smith, 2003
Our adaptation
We evolved as we did to fit the hunter-gatherer niche
Bipedal Eyes forward
We are social We form groups for protection and the
exchange of goods and services
© Kip Smith, 2003
Our adaptation
We can eat almost everything Three kinds of teeth We store fat to help us survive lean times We crave salt and sugar
We grew big brains Why?
© Kip Smith, 2003
Our quandary
We are biologically & genetically prepared for hunting & gathering, for a predatory, nomadic life style
We are adapted for a niche that no longer exists
We have changed our environment and we don’t fit it
© Kip Smith, 2003
3 Sexual Selection
In most mammalian species, including humans, females choose which male they will mate with
Males develop sexual displays to attract and retain females
The peacock’s tail The stag’s horns …
© Kip Smith, 2003
Sexual displays
Are ‘expensive’
Are an indicator of the male’s fitness
© Kip Smith, 2003
Sexual selection works at the individual level
The peacock with a fine fine superfine tail is advertising his fitness to all the peahens
Every peahen knows it is wiser to mate with a fit peacock than with an unfit peacock
© Kip Smith, 2003
Puritanical censorship
Victorian male chauvinist scientists had a real problem with Darwin’s theory of sexual selection
Females choosing males? Totally scandalous !
© Kip Smith, 2003
Bi-directional sexual selection
Darwin suggested that in some species, including humans, sexual selection works both ways
Females choose the males with the best displays
Males choose the females with the best displays
© Kip Smith, 2003
For next time
Read
Scientific American article 1:
Timbergen, N. (1952). The curious behavior of the stickleback
Chapters 1, 2, 3