Introduction to Psychobiology NOH Hope Park 2006

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Introduction to Psychobiology NOH Hope Park 2006
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The ghost in the machine
Modern views of the mind are based upon a
Cartesian world view (which saw a split between
the body and the mind/soul)

• The soul/reason is the animating principle
  without which the body would seem just a machine
• The rational principle was key to identity and
  to truth (cogito ergo sum I think, therefore I
  am)
• Later thinkers (e.g. de la Mettrie) omitted the
  idea of the soul and pursued a purely mechanistic
  vision of the world

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Modern psychology

• Biological, cognitive and evolutionary psychology
  are mechanistic and reductionistic
• Mind is modular, physical and reducible to
  neurochemistry, specialist neural architecture
  and adaptive mechanisms
• Atomistic view suggests that the body/mind
  consists of smaller structures that can be
  studied in their own right

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Roots of modern biopsychology

• Location of mind heart or brain?
• Galen mind was in the brain (animal spirit)
• The vital spirit was in the heart (animates body
  and brain)
• The natural spirit was in the liver

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Assumptions of Biopsychology

• Assumes that even quite complex human behaviour
  and thought can be explained according to
  physiological mechanisms, e.g. hormones,
  neurotransmitters
• Genes (and gene-environment interactions) often
  assumed as ultimate causes of behaviour that help
  structure physiology and hence behaviour
• Research focuses on detecting ever-finer levels
  of physiological functioning in order to discover
  the causes of behaviour

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What can evolution tell us about human nature?
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Evolutionary Psychology
EVOLUTIONARY PSYCHOLOGY Evolutionary basis of
behaviour and culture Humans are animals and have
been subjected to the same processes of
evolutionary change as all other living things on
earth (e.g. John Tooby, Leda Cosmides, David
Buss, Martin Daly, Margo Wilson, Donald Symons,
Laura Betzig, Steven Pinker
SOCIOBIOLOGY Evolutionary explanations of social
behaviour (e.g. Wilson, 1975)
Criticises the SSSM (Standard Social Science
Model) as being cut off from the natural
sciences We are products of biology and culture,
nature and nurture
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Natural Selection
Organisms struggle for limited resources
Individuals vary in their physical behavioural
characteristics
NS shapes the characteristics of organisms and
those that survive are better adapted to the
environment
Some characteristics give organisms an advantage
over other organisms and thus enable them to
leave more offspring
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Key factors in evolution

• Variation behaviour or physical
• Inheritance - genes
• Differential survival
• Adaptive traits
• Genotype Environment Phenotype

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Galapagos IslandsHome to Darwins finches

• A single species of finch landed on one of the
  islands thousands of years ago
• Due to overcrowding and food shortages the
  finches spread to the other islands
• Because the food on different islands was
  different, a variety of beaks was usefull

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Tinbergens 4 WhysExample Human Language

• Mechanistic (or proximate cause)
• Developmental (or ontogenetic)
• Historical (or phylogenetic)
• Functional (or ultimate)

Have a go at working out the 4 whys for bird song!
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Study of human behaviour

• Human behavioural ecology (HBE) focuses on
  behavioural traits that promote differences in
  fitness between individuals (i.e. leave more
  offspring)
• Evolutionary psychology focuses on what has
  shaped the human psyche over evolutionary time
  and whether our psychological mechanisms are
  designed to solve adaptive problems (e.g.
  detecting cheats)

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Universal human nature
Gradually shaped by NS over time
Help shape culture
Evolved psychological mechanisms
Mental mechanisms seen as domain-specific modules
to solve specific problems (e.g. finding food,
mates)
Adapted to problems found in EEA
Adaptations
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The modular mind
Cheat detection
Mate choice
Face Recognition
Tool Use
Theory of Mind
Language
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• Evolutionary psychology sees the mind as a bit
  like a Swiss army knife consisting of
  domain-specific modules (sets of algorithms or
  rules) evolved to solve specific problems our
  ancestors faced, e.g. spatial cognition, mate
  selection, parenting. This is essentially a
  mechanistic view of the mind as an
  information-processor.
• Investigators might infer psychological
  mechanisms from knowledge about ancestral
  adaptive problems, or use evidence of existing
  psychological mechanisms to infer details of
  ancestral conditions and problems in the EEA.

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Environment of Evolutionary Adaptiveness (EEA)
Modern history and culture, including
agriculture, only dates back to the last few
thousand years.
Yet the earliest human species dates back 2.5
million yrs. Thus the time since the beginnings
of agriculture (10,000 yrs ago) is less than 1
of the 2 million yrs our ancestors spent as
hunter-gatherers in the Pleistocene. The EEA
therefore shapes our modern psychology and
behaviour.

• Stone age minds in modern world??? Perhaps some
  of our behaviour is not adapted to modern day
  living.

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Levels of selection
Basic unit of selection is the gene, bodies are
simply vehicles for genes NS acts on
individuals, since it is individuals who live or
die NS acts on groups on a long term view it is
groups that survive or die out
GENE
INDIVIDUAL
GROUP
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Evolutionary Psychology

• 1. Problems humans encountered in the ancestral
  environment
• a) Finding a vigorous healthy mate
• b) Forming reciprocal co-operative relationships
• c) Avoiding brother-sister mating
• 2. Psychological tools that evolved to help solve
  those problems
• d) Vigourous dance/sports indicating health
  strength
• e) Detecting cheaters in these relationships
• f) Adult sexual aversion to childhood intimates
• 3. The way those tools function now
• g) Vigorous movements in dance sport
• h) Gossip that helps us learn about cheaters
• i) Shim pau marriages, kibbutzim sexual
  attraction, attraction between brothers sisters
  reared apart

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Criticisms of evolutionary psychology

• All behaviours are not adaptive
• Researchers disagree as to the nature of EEA
• Finding adaptive explanations for behaviour
  leads to Just-so stories
• Researchers infer causes from results
• Gradual view of evolutionary change has been
  criticised
• The role of culture is given little importance

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The charge of Panglossianism

• Evolutionary psychology attempts to find an
  adaptive reason behind every physical, mental and
  behavioural characteristic.
• Even though some behaviours are not adaptive, it
  is assumed that they were at one time (in our
  evolutionary past).
• For example, Wright (1994) - fondness for sugar
  (cited in Gould, 2000).

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Gould spandrels e.g. reading and writing
Since organisms are complex and highly
integrated entities, any adaptive change must
automatically throw off a series of structural
by products spandrels. The triangular space
left over between a rounded arch and the
rectangular frame of wall and ceiling. Gould,
2000, p95.
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Continuous slow change or Punctuated Equilibrium??
Key element of EP approach is that features are a
result of slow adaptation over evolutionary time.
Gould and Lewontin (1972) and Gould (2000)
suggested that EP plays down role of evolutionary
developmental constraints upon adaptation. For
example, there are important developmental
constraints upon basic features like body
structure. The theory of punctuated equilibrium
holds that most species are stable over long
periods of geological time. New species may form
through branching at specific geological periods.
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Understanding the EEA

• The problem is that we cannot know for sure what
  our hunter-gatherer ancestors lived like 2
  million years ago.
• Fossil record is fragmentary and there is little
  evidence of the details of their social or
  psychological life.
• In addition, the EEA was not just one period
  sometime in the Palaeolithic, but is best
  conceptualised as a number of different periods
  in historical time. We know little about how
  different psychological characteristics of our
  ancestors were developed to fit these different
  environments.

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The role of culture

• EP stresses universality of human nature, e.g.
  race does not determine intelligence. However,
  the role of many cultural aspects in shaping many
  aspects of modern life is ignored, while other
  features of culture are seen as universal.
• Learning does play a part in human behaviour!
• Memes

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A short note about Fitness

• Fitness is a measure of the genes passed on to
  the next generation by an individual.
• Direct Fitness the number of genes that
  individual directly contributes usually
  measured by the number of offspring that survive
  to reproductive age
• Indirect Fitness the genes indirectly
  contributed by an individual to the next
  generation. For example, helping relatives
• Inclusive Fitness Direct Fitness Indirect
  Fitness
• Fitness benefit, Fitness costs
• Behaviours are often assessed on their
  cost/benefit ratio.

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A short note about Selection.

• Selection is the differential capacity of
  individuals to transmit copies of their genes to
  the next generation

Natural Selection aka Direct selection. The
process that occurs when individuals differ in
their traits, and these differences are
correlated with reproductive success.
Sexual Selection A form of natural selection
that occurs when individuals vary in their
ability to compete with others for mates. This
can be direct e.g. fighting, or via
attractiveness.
Runaway Sexual selection where traits get out of
hand. Due to gender preferences
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• Artificial Selection human controlled e.g.
  animal breeding.

Group Selection the process that occurs when
groups differ in their collective attributes, and
these differences are correlated with differences
in group survival.
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Summary key concepts

• EP approach assumes people show physical and
  mental adaptations to ancestral environments
  (EEAs). These adaptations, shaped by NS, can be
  assumed to be universal.
• Evolved psychological mechanisms, shaped during
  EEA, can explain complex human behaviour (from
  altruism to religion). These mechanisms/modules
  originally helped our ancestors to solve specific
  adaptive problems.
• Critics of EP challenge its assumptions about
  adaptation, the EEA and the universality of human
  nature.

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The problem of altruism

• Altruistic act an act that has a cost to the
  actor but increases the fitness of the recipient
• Reduces personal fitness
• Increases the fitness of competitors
• Shouldnt it be selected against?

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How to Solve the Puzzle of Altruism

• See how selfish (nonaltruistic) genes can
• give rise to unselfish (altruistic) individuals.
• An important distinction! Metaphorical
• selfishness of the genes does not imply real
  selfishness of people.

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The problem of altruism

• Problem
• The selfish individuals
• contribute more to the
• next generation
• UNLESS
• Some other selection
• pressure selects for
• altruism

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So, how can altruism evolve?

• Kin selection
• Reciprocity
• Competitive (indirect) altruism
• Altruistic punishment

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Kin selection and Hamiltons Rule

• A gene can benefit copies of itself that reside
  in other individual
• bodies, i.e. close relatives carry some of our
  own genes (hence kin selection)
• Inclusive fitness direct fitness indirect
  fitness

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Hamiltons rule c lt rb

• c cost of altruistic act
• b benefit to recipient
• r coefficient of relatedness
• Coefficient of relatedness proportion of genes
  that are identical by descent from recent
  common ancestor

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Examples of r

• You to yourself 1.0
• Parent/child .5
• Full sibling .5
• Half sibling .25
• Grandparent/Grandchild .25
• Uncle/Aunt/Niece/Nephew .25
• First Cousin .125
• Identical twins 1.0
• Id give my life for 2 brothers or 8 cousins. -
  J.B.S. Haldane

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Imagine this situation . . .

• Your 7-year old cousin, your 75-year-old
  grandmother, and a 21-year-old acquaintance are
  all asleep in different rooms of a rapidly
  burning house, and you have time to rescue only
  one.
• Who are you most likely to help? Who are you
  least likely to help?
• from Burnstein et al. (1994) JPSP 67 773-789

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Some other examples of kin selection

• Alarm calls frequency of alarm calls given by
  Beldings ground squirrels in response to a
  predator is a function of the genetic relatedness
  of other squirrels present (Sherman, 1977, 1980).
• Helping at the nest Florida Scrub Jays
  Woolfenden and Fitzpatrick (1984)
• Inheritance Smith et al. (1987) inheritance
  more likely to go to close relatives.

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How does kin selection operate?

• Familiarity it is likely that familiar
  individuals are related, so it pays to favour
  familiar animals
• Location in social groups it is likely that
  neighbouring individuals are kin
• Phenotype matching related individuals usually
  resemble each other
• Recognition allelles e.g. the green beard
  effect.

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Reciprocal altruism

• Food Sharing in Vampire Bats, Wilkinson (1984,
  1990). Can also be thought of as delayed
  mutualism
• Mutualism helper and recipient both gain
  through their interaction e.g. co-operative
  hunting by lionesses Stander (1992)
• Cooperative courtship in the Long-tailed Manakin
  (bird) Mc Donald (1989)

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Competitive altruism

• Not all behaviour is explained by reciprocity or
  kin selection
• Individuals might get indirect benefits for being
  altruistic, people might compete for the
  attention of other altruists
• Competitive altruism could work as a form of
  sexual selection i.e. make you more attractive
• Sexual advertising Arabian babbler

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Altruistic Punishment

• Fehr Gachter (2002) The fear of punishment
  might induce altruism. People will pay to
  punish selfish others
• Mealey et al (1996) faces of cheats were
  remembered better than faces of truthful
  individuals.

Cooperation depends on reciprocity (Ill scratch
your back etc.) but also on retribution (if I
scratch your back, and you dont reciprocate, I
will punish you, no matter what the cost to me)
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Altruism and group selection

• A more sophisticated explanation of altruism
  necessitates the use of group selection accounts
  as well as gene-centred views. Sober and Wilson
  (1998) - suggest that altruism could only have
  evolved through the process of group selection.
• Groups showing altruistic behaviour and high
  levels of cooperation may do better than groups
  who are less cooperative. Does this explain the
  evolution of human morality?

The tragedy of the commons (Hardin)
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Altruism and culture

• Midgley (1979) has suggested that we need to
  consider altruistic behaviour, not in isolation,
  but as part of the rich emotional and social
  context in which it occurs.
• This necessitates considering cross-cultural
  variation in notions of morality and altruism.
• But evolutionary psychology assumes a universal
  human nature and insists that moral reasoning is
  not culture specific from the EEA.
• Henrich et al (2001) conducted cross cultural
  experiments on altruism in 15 small scale
  societies e.g. Papua New Guidea and the Asche of
  Paraguay

What examples of human altruism can you think
of?????
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Key Points

• In understanding altruistic behaviour we must
  look at the level of the group as well as the
  level of the gene/individual
• Many accounts of altruism in animals rely on the
  theories of kin selection and reciprocal
  altruism, whereas some human behaviour seems to
  warrant more complex explanations
• Evolutionary psychology asserts that human
  morality is an adaptation to ensure the cohesion
  of groups. However, it tells us little about the
  psychological or cultural context of such
  behaviour.