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Brain Evolution

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Title: Brain Evolution


1
Brain Evolution
In the distant future psychology will be based
on a new foundation, that of the necessary
acquirement of each mental power and capacity by
gradation. --Charles Darwin, 1859
2
What is this course about?
  • The what?
  • The why?

3
The what
  • What do we know about the structures of the
    brain? What are the functions of the different
    brain areas? How can neuroimaging inform us?
  • Evolutionary cognitive neuroscience
  • Biological mechanisms underlying cognition, as
    studied from an evolutionary theoretical
    perspective
  • Platek et al. (Eds.) (2007). Evolutionary
    Cognitive Neuroscience. Cambridge, MA. MIT Press.

4
The why
  • What is the biological reason for gossip?
  • For laughter? For the creation of art?
  • Why do dogs have curly tails?
  • What can microbes tell us about morality?
  • Wilson, D. S. (2007). Evolution for everyone How
    Darwins theory can change the way we think about
    our lives. New York, NY. Delacorte Press.

5
Taking a Comparative PerspectiveIntegrating
Neuroscience, Cognitive Psychology,
Evolutionary Biology
6
Comparative Psychology
  • Uncovering similarities differences between
    human animal behavior
  • Comparative cognition concerned with comparing
    cognitive processes
  • Wasserman Zentall (2006). Comparative
    Cognition Experimental Explorations of Animal
    Intelligence. Oxford University Press.

7
Why compare brains?
8
What is Comparative Psychology?
  • the comparative study of brains and behavior in
    human and nonhuman animals
  • Biological psychology (aka behavioral
    neuroscience) relates behavior to bodily
    processes, especially the workings of the brain
  • Neuroscience the study of the brain
  • We compare species to learn how the brain and
    behavior have evolved
  • Continuity of behavior and biological processes
  • Species-specific differences in behavior and
    biology

9
Questions for you
  • Are some species more evolved than others?
  • Does evolution have a goal?
  • Can we say that humans (or other animals) have
    adapted to their current environment?

http//rainbow.ldeo.columbia.edu/courses/v1001/ear
th1.gif
10
Common Misunderstandings
  • Human behavior is genetically determined
  • If its evolutionary, we cant change it
  • Current mechanisms are optimally designed
  • Buss, D. M. (2004). Evolutionary Psychology The
    New Science of the Mind. Boston, MA. Pearson.

11
Natural Selection
  • There is variation in traits.
  • There is differential reproduction.
  • There is heredity.
  • End result The more advantageous traits, that
    allow for more offspring, become more common in
    the population

12
Three Products of Evolution
  • Adaptations
  • Ex umbilical cord
  • By-products
  • Ex belly button
  • Noise
  • Ex shape of a persons
  • belly button
  • Buss, D. M. (2004). Evolutionary Psychology The
    New Science of the Mind. Boston, MA. Pearson.

13
Other examples of adaptations.
14
Examples of by-products
15
Proximate vs. Ultimate Causation
  • Proximate cause
  • event immediately responsible
  • HOW something works
  • Ultimate Cause
  • The real reason something occurred
  • Evolutionary cause
  • WHY something works

16
Example
  • The ship sank.
  • Proximate cause water entered the hull and the
    ship became heavier than the water which
    supported it, so it couldnt stay afloat
  • (HOW it happened)
  • Ultimate cause ship hit a rock which tore open
    the hull
  • (WHY it happened)

17
Example
  • We can see.
  • Proximate cause light enters the cornea, moves
    through the pupil then hits the retina and is
    transmitted to the brain
  • (HOW it happens)
  • Ultimate cause it is adaptive to be able to see
    things around youimproved survival/reproduction
  • (WHY it happens)

18
Adaptations
  • Traits formed directly by selective pressures
  • Dont necessarily increase reproductive success
    in current environment

http//evolution.berkeley.edu/evosite/evo101/image
s/katydid_225.jpg
19
Adaptations
  • Current environment is different from ancestral
    environment
  • Example trees seeds on sidewalk

http//static.flickr.com/54/131303743_d14f0aba83.j
pg
20
Adaptations
  • Current environment is different from ancestral
    environment
  • Example North American pronghorn antelope

http//www.kvmr.org/pgm_images/pronghorn.jpg
21
Adaptations
  • Current environment is different from ancestral
    environment
  • Example Obesity!

http//www.zapad.cz/fotos/zdravi/cholesterol/fat_m
an_large.jpg
22
Natural Selection
  • Works only in relation to what has evolved,
    therefore many features seem poorly designed
  • Ex human throat
  • Not all aspects of living organisms are
    adaptations
  • Ex Fox following snow tracks to hen house

http//www.childhoodhealth.com/images/strep_throat
.jpg
http//www.cameraontheroad.com/photos/mammals/foxc
loseup.jpg
23
Is there anything that natural selection cannot
explain?
  • Hints

24
Sexual Selection
  • Natural selection has trouble explaining some
    things
  • creativity, art, language, music, morality
  • Whats the survival value?
  • Sexual selection our minds evolved not as
    survival machines, but as courtship machines
  • Miller, G. (2001) The mating mind How sexual
    choice shaped the evolution of human nature.

25
Intersexual selection Preferential Mate Choice
  • What were looking for Whats looking for us

26
Different Levels of Analysis
Brain structures
Behavior
(Rosenzweig et al., 2005)
27
Neuroscience is virtually an evolutionary-free
zone
  • Is it not reasonable to anticipate that our
    understanding of the human mind would be aided
    greatly by knowing the purpose for which it was
    designed? (Williams, 1966, p.16)
  • WHY???
  • Psychology as a disparate set of fields

28
Metatheory
  • Evolutionary theory as a metatheoretical
    framework within which all psychological science
    can be organized.
  • Theory
  • Testable hypotheses
  • Predicts

29
Standard Social Science Model (SSSM)
  • "Much of what is commonly called 'human nature'
    is merely culture thrown against a screen of
    nerves, glands, sense organs, muscles, etc."
    (Leslie White, 1949, cited in Degler, 1991, p.
    209)
  • What does this mean? Do you agree???
  • Organisms possess general-purpose learning
    mechanisms
  • Biology plays little if any role in the
    manifestation of behavior
  • "blank slate" or "cultural determinist"
    perspectives
  • However, many studies have demonstrated this is
    not the case

30
Standard Social Science Model (SSSM)
  • Much evidence against the SSSM (there is a
    human nature!)
  • Example
  • Prepared learning
  • Difficulty to fear modern threats (e.g. guns
    cars) vs. Effortless learning to fear ancient
    threats (e.g. snakes spiders) (Ohman Mineka,
    2001)
  • All learning is a consequence of carefully
    crafted modules dedicated to solving specific
    evolutionary problems (Platek et al., 2007,
    p.xiv)

31
Environment of Evolutionary Adaptedness
  • What is this?
  • Not a place or time in history, but a statistical
    composite of the selection pressures of ancestral
    past, the adaptations that characterized that
    past
  • Pleistocene (1.81-.01mya) human EEA

32
Evolutionary Perspective
  • How would you describe Evolutionary Psychology?
  • Evolutionary biology cognitive psychology
  • Mental psychological traitssuch as memory,
    perception, or languageare adaptations
  • i.e., the functional products of natural
    selection
  • Cognition has a functional structure (the brain)
    that has a genetic basis
  • be universally shared
  • solve problems of reproduction

33
Modularity of the brain
  • Modules separate innate structures in the
    brain with evolutionary-developed functions
    units of mental processing that evolved in
    response to selection pressures
  • Language acquisition device (Noam Chompsky)
  • Cheater detection mechanism (Cosmides Tooby)
  • Fusiform Face Area (Kanwisher et al.)

Can you think of other modules our brains might
have?
34
Basic Principles
  • 1. The brain is a physical system that functions
    as a computer.
  • 2. Our neural circuits were designed by natural
    selection to solve problems that our ancestors
    faced during our species' evolutionary history.
  • Stone age minds

35
Basic Principles
  • 3. Consciousness is just the tip of the iceberg
    most of what goes on in your mind is hidden
  • Ex vision
  • Ex attraction
  • http//www.pbs.org/wgbh/evolution/library/01/6/
    l_016_08.html

36
Basic Principles
  • 4. Different neural circuits are specialized for
    solving different adaptive problems.
  • Localization of function specific brain regions
    are responsible for various types of experience,
    behavior, and psychological processes.
  • Examples
  • function location
  • vision occipital lobe
  • audition top of temporal lobe
  • speech comprehension "Wernicke's" area
  • voluntary movement back edge of frontal lobes
  • bodily sensations front edge of parietal lobes
  • emotion regulation limbic system
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