COMPARATIVE PSYCHOLOGY Evolutionary explanations of human behaviour by kcf19835

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									COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour



        EVOLUTION OF INTELLIGENCE




          1.Chimpanzee       4.Dolphin           7.Manatee
          2.Cat              5.Capybara          8.Least Weasel
          3.Spiny Anteater   6.Squirrel Monkey   9.Beaver

A2 PSYCHOLOGY                 Lana Crosbie                        Slide 1
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Intelligence: The ability to think flexibly.

  Why did we need to become so intelligent?...

     [1] Foraging demands?
     [2] Social?
     [3] Language?

  …Maybe all Three, we will have a look at the first Two.

A2 PSYCHOLOGY               Lana Crosbie                Slide 2
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Foraging demands – Finding food.
  Dunbar (1992) suggests that intelligence evolved
 because of an increased cognitive demand on fruit-
 eaters to monitor a food supply that was spatially and
 temporally dispersed.
  Fruit-eaters must remember the location of their food
 supply, evaluate ripeness, develop a harvesting plan and
 decide how they will survive in the interim.

A2 PSYCHOLOGY            Lana Crosbie                     Slide 3
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Foraging demands – Extracting food: tool use.
  Mercader et al. (2002) studied chimpanzees in a
 remote West African rain forest where they used stones
 and branches as hammers to crack open nuts when
 foraging. Mercader et al. claimed that many of the stone
 by-products of chimps nut cracking are similar to those
 found in early human archaeological sites in East Africa.
                                                 Cont…

A2 PSYCHOLOGY            Lana Crosbie                   Slide 4
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Foraging demands – Extracting food: tool use.
  Some of the most successful human hunter-gatherers,
 such as the !Kung San, use highly elaborate tools.
  Some less successful groups like the Tasmanian
 Aborigines, used only very simple tools.
  Tool use is thus an indication of intelligence in both
 human and non-human species.

A2 PSYCHOLOGY            Lana Crosbie                 Slide 5
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories.
  Theorists such as Humphrey (1976) argue that social
 objects (members of the same sex) offer a completely
 different order of complexity from the relatively stable
 word of physical objects.
  Individuals who best dealt with these demands to their
 advantage would be more successful at increasing their
 reproductive fitness.

A2 PSYCHOLOGY             Lana Crosbie                  Slide 6
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – Machiavellian intelligence .
  Whiten and Byrne (1988) Human intelligence may be
 an adaptation not just to social life, but to social problem
 – solving.
  Individuals able to use and exploit others in their social
 group without causing aggression would be favoured
 (Byrne, 1995). This Machiavellian intelligence may
 appear cooperative but ultimately selfish.

A2 PSYCHOLOGY              Lana Crosbie                    Slide 7
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – Machiavellian intelligence …cont
  Forming alliances – Power in complex social groups
 is often determined more by having the right allies than
 by physical strength.

  Harcourt (1992) suggests that although other animals
 form alliances, only catarrhine primates (e.g. baboons,
 apes and humans) cultivate alliances based on
 individual’s ability.
A2 PSYCHOLOGY            Lana Crosbie                   Slide 8
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – Machiavellian intelligence …cont
  Manipulation and deception – Among social-living
 animals, individual can use behavioural tactics to
 manipulate those who are not allies or relatives into
 unwitting help.
  The ability to understand and plan deception appears
 to be restricted to great apes, although other primates
 seem to be able to learn such tactics by watching.

A2 PSYCHOLOGY            Lana Crosbie                    Slide 9
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – Machiavellian intelligence …cont
  Byrne (1995) Manipulative ‘tricks’ include the
 management of attention, in which the target’s attention
 is diverted towards or away from something to profit the
 agent of the deceit. Deception also serves to change
 how other animals view the agent.




A2 PSYCHOLOGY            Lana Crosbie                  Slide 10
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – The meat-sharing hypothesis
  The importance of meat – Our ancestors and modern
 day chimpanzees, meat was important source of
 saturated fat – vital for survival.
  Stanford (1999) studied chimps in Tanzania’s Gombe
 National Park and found for a few months they starved
 themselves, when they did kill, the chimps went straight
 for the fattiest fleshy parts instead of the most nutritious.

A2 PSYCHOLOGY              Lana Crosbie                    Slide 11
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – The meat-sharing hypothesis cont…
  Meat sharing – Because the importance of meat,
 Stanford believes that the strategies sharing of meat
 paved the way for human intelligence.

  Meat could be used to forge alliances and persuade
 females to mate…


A2 PSYCHOLOGY            Lana Crosbie                    Slide 12
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – The meat-sharing hypothesis cont…
  …Stanford observed a number of instances supporting
 this ‘meat for sex hypothesis’:
 [1] Males chimpanzees used meat to entice females, often withholding it
 until mating.
 [2] Hunting was more prevalent in the months when females chimps were
 sexually receptive.
 [3] When begging for meat, swollen (sexual receptive) females had more
 success than non-swollen females.

A2 PSYCHOLOGY                    Lana Crosbie                          Slide 13
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Social theories – The meat-sharing hypothesis cont…
  Stanford believed that strategic meat-sharing required
 considerable cognitive abilities as males had to
 recognize individuals and keep a ‘running score’ of
 debts, credits and relationships.




A2 PSYCHOLOGY            Lana Crosbie                 Slide 14
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Comparative studies of brain size and intelligence.
  The human brain is a metabolically expensive organ.
  Although it accounts for only 2% of total body mass, it
 uses about 10% of the basic metabolic rate in rhesus
 monkeys and about 20% in humans.
  Large brains would not have evolved if it did not give
 humans a significant advantage.

A2 PSYCHOLOGY             Lana Crosbie                  Slide 15
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Comparative studies of brain size and intelligence.
  Brain quantity – If           Approx. brain & body weight of selected
                                 mammals (Klinowska, 1994)
 Intelligence were
                                 Species         Brain weight   Body weight
 determined by brain size,                           (KG)        (tonnes)
 the sperm whale would be        Sperm Whale         7.8          37.00
 at the top (see table right).   Dolphin             1.6           0.17
                                 Human               1.5           0.07
                                 Cow                 0.5           0.60


A2 PSYCHOLOGY              Lana Crosbie                            Slide 16
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Comparative studies of brain size and intelligence cont…

  We a get better indication of the intelligence of a particular
 species by considering brain size relative to body size.

  Jerison (1978) developed the encephalization
 quotient (EQ), in which the actual brain mass of a species
 Is divided by its ‘expected’ brain size for that body size…


A2 PSYCHOLOGY              Lana Crosbie                   Slide 17
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Comparative studies of brain size and intelligence cont…
  …Higher quotients indicate species with
 larger-than-expected brains.
  An EQ greater than 1 indicates a brain size greater
 than predicated (which could be an indicator of
 intelligence) and visa versa.
  Using this scale, humans have the highest EQ (7) of
 any animal (Jerison 1978).
A2 PSYCHOLOGY            Lana Crosbie                    Slide 18
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  Comparative studies of brain size and intelligence cont…
  The idea of an EQ is appealing but has unfortunately
 not been supported by research – relative brain size
 is not necessarily related to intelligence.
  Macphail (1982) found that rats and squirrels
 performed at about the same level on a learning
 task, but rats had an EQ of only 0.40, whereas that
 of squirrels was 1.10.

A2 PSYCHOLOGY            Lana Crosbie                  Slide 19
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  The relationship of brain size and intelligence
  Head size and IQ – Sir Francis Galton (1888) found that
 head size and intelligence to be low and insignificant.

  Wickett et al. (1994) looked at 25 separate studies,
 comprising over 50,000 individual samples, the majority
 of studies fell between 0.10 and 0.30, with a mean of just
 under 0.20.

A2 PSYCHOLOGY             Lana Crosbie                 Slide 20
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  The relationship of brain size and intelligence cont…
  Andreasen et al. (1993) have found (using MRI scans)
 significant correlations of around 0.40 between brain size
 and intelligence.

  Haug (1987) estimated a correlation of 0.48 between
 brain size and number of cortical neurones…


A2 PSYCHOLOGY            Lana Crosbie                  Slide 21
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  The relationship of brain size and intelligence cont…
  …A person with a brain size of 1400cm3 would have an
 average 600 million fewer cortical neurones than a
 person with a brain size of 1500cm3.
  The difference between the low end of the normal
 distribution for brain size (1000cm3) and the high end
 (1700cm3) is a fact a staggering 4.2 billion neurones
 (Haug, 1987)…

A2 PSYCHOLOGY            Lana Crosbie                     Slide 22
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour

 EVOLUTIONARY OF INTELLIGENCE
  The relationship of brain size and intelligence cont…
  …It seems reasonable to assume that such a difference
 would have a pronounced effect on cognitive ability.




A2 PSYCHOLOGY           Lana Crosbie                Slide 23
COMPARATIVE PSYCHOLOGY
  Evolutionary explanations of human behaviour


                    EXAM QUESTIONS
 Discuss the relationship between brain size and intelligence. [24 marks]

 Outline and evaluate the explanation of two or more mental
 disorders from an evolutionary perspective.                [24 marks]

 Discuss the relationship between sexual selection and
 human reproductive behaviour.                                [24 marks]




A2 PSYCHOLOGY                    Lana Crosbie                           Slide 24

								
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