Evolution and Psychology Dr Stephen Walker January 11, 2007

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Evolution and Psychology

  • Dr Stephen Walker
  • January 11, 2007

Aims and Objectives

  • Aims: These two lectures aim to refresh students’ knowledge of the theory of evolution, or to introduce them to it, and to introduce them to aspects of psychology which have been influenced by evolutionary approaches.
  • Objectives: By the end of the lectures the students should:
  • know the general outlines of the theory of evolution and the time course of human evolution

Objectives continued

  • be able to answer correctly a majority of the questions on the self-assessment test included in the handout
  • understand some of the key differences between nativist and empiricist theories in psychology
  • be aware of the sections of the course text (Gleitman, 1999/2004) where evolutionary approaches are applied to perceptual, cognitive, emotional and social aspects of psychology.

Topics to be covered

  • The theory of evolution
  • What Darwinians say about psychological topics
  • Schools of thought influenced by Darwinian approaches
  • Areas of psychology that have been or could be influenced by these approaches

Format of lectures

  • There will be a very brief coverage of a large number of areas
  • The question addressed is a general one: what is the relevance of evolution for psychological topics?
  • The answer to be given is in terms of the ‘nature/nurture’ issue.

Topic and essay question

  • “Does the theory of evolution have any relevance for psychological topics?”
  • Gleitman’s textbook mentions evolution, or evolutionary theorists, or “biological bases” in several places.
  • So to that extent evolution must be relevant for psychological topics, although —

Gleitman et al. (1999, page 436) agree that it is arguable that human social behaviour is “so thoroughly infused by culture” that comparisons with the Darwinian influences on animal behaviour are fruitless.

  • Gleitman et al. (1999, page 436) agree that it is arguable that human social behaviour is “so thoroughly infused by culture” that comparisons with the Darwinian influences on animal behaviour are fruitless.
  • “…there is no question that human social behavior is flexible and subject to cultural learning in ways that other species’ behaviour is not….. (Gleitman et al, 2004; p. 458)

Basic Reading see p. 1 of handout

Topics to be covered

  • I will look first at the analysis of instinctive behaviour in animals (ethology)
  • Then I will cover theoretical arguments about assuming innate capacities in human psychology (Pinker, 1984, 2003)
  • In the second lecture I will briefly outline the time course of human evolution (not in Gleitman)
  • — and also review the material in the textbook which supports the existence of innate biases in the perceptual, cognitive and emotional worlds of human infants

Darwin in Gleitman et al. 1999 p. 406 & 2004 p. 416

  • All Darwin’s publications are freely available online at http://darwin-online.org.uk

The Theory of Evolution

  • Resources are not unlimited
  • Some individuals will flourish more than others and produce more offspring
  • There are inherited differences between individuals, with some random changes
  • Natural selection occurs if a population changes over generations because of this (see e.g. Dawkins, 1995)

Evolution — II

  • The first point about evolution is that it connects the human species with the rest of the animal kingdom,
  • However, it is also possible and indeed likely that the course of human evolution has led to humans being uniquely different from all other currently living species

Common pattern for body plans: standard biology texts

  • Fly mutant restored with human gene
  • Fly mutant restored with mouse gene
  • Mouse mutant restored with fly gene

What Darwinians say about Psychological topics

  • Darwinians emphasise innate or “built-in” factors in psychology
  • They tend to emphasise nature rather than nurture and are “nativists” rather than “empiricists”
  • They are often interested in development during an individual’s life-span

Darwinian Schools of Thought (p 2 of handout)

  • Ethology: scientific study of innate factors in animal behaviour (N. Tinbergen and K. Lorenz, Nobel Prize, 1973)
  • Sociobiology: as above, but emphasis on social behaviour (E.O. Wilson, 1975)
  • Evolutionary Psychology: emphasis on the effects of human evolution on human psychology (Tooby and Cosmides, 1992; Pinker, 1994, 1998, 2002/3)

Pause before weaver bird next

  • I am going to look very briefly at animal behaviour. It is clearly not contentious to give evolutionary explanations for animal behaviour, but such explanations are not always completely obvious. But for questions such as “why do birds build nests?” there is not a problem.
  • Examples of natural selection in animal behaviour − instincts or “genetically determined behaviour patterns”

Gleitman, 1999, p. 407. Weaverbird nest: “Many (?) animals have genetically determined behavior patterns characteristic of their species.”

  • Gleitman, 2004, p.418. Bowerbird nest. “..natural selection will lead to an evolution of how animals behave..” (p. 417)

Life in the undergrowth

  • Beetles are .3 of all species and .4 of insects, thus insects are ¾ of all.

Ethological analyses of animal behaviour

Pecking 1

“Supernormal Stimulus”

  • Gleitman, 1999 p.409
  • 1995, p. 382
  • Not in Gleitman et al. 2004

Supernormal stimulus defined

Supernormal stimuli

  • Fig 3.8 in Manning and Dawkings (1992) p. 52
  • Supernormal stimuli − 2
  • Morrison, D. S., & Petticrew, M. (2004). Deep and crisp and eaten: Scotland's deep-fried Mars bar. Lancet, 364(9452), 2180-2180. (not on list)
  • We did a telephone survey in June, 2004, of random selection of the 627 fish and chip shops in Scotland …….. 66 shops sold deep-fried Mars bars
  • …….we did also find some evidence of the penetrance of the Mediterranean diet into Scotland,
  • …. albeit in the form of deep- fried pizza
  • Supernormal stimuli − 3
  • More animal behaviour in Gleitman et al.

Lorenz walking

  • Gleitman et al (2004) page 508

Built-in social behaviour p. 408, 1999 not in 2004

Parental feeding

  • Gleitman, 1995, p. 400
  • 1999, p. 427
  • 11. 6 Innate triggers In many species, the parents’ care-taking behaviors are elicited by specific signals from the young. (Gleitman, 2004; p. 430)


  • Gleitman, 1995, p. 400
  • 1999, p. 427
  • Not in 2004
  • Mentioned by Darwin (1859)

Cuckoos − one of Darwin’s examples

Evolutionary Psychology

  • Darwinian theory helps explain the behaviour of cuckoos, and almost all other animal species, but does it explain human behaviour in the same way?
  • One example follows of an evolutionary prediction for human behaviour which turns out to be wrong.

Kenrick et al, 2003 Psychological Review, 110(1), 3-28

  • “At the most general level, evolutionary psychology can be defined as the study of cognitive, affective, and behavioral mechanisms as the solutions to recurrent adaptive problems.”
  • “Along with the morphological features designed by natural selection, organisms also inherit central nervous systems……The behavioural inclinations of a bat would not work well in the body of a dolphin or giraffe and vice-versa.”

Kenrick et al. wrong

  • over a period of 35 years in Sweden (1965-1999), there was no overall over-representation of stepchildren as victims.
  • (Temrin, Nordlund, & Sterner, 2004)
  • In families with both stepchildren and children genetically related to the offender, genetic children tended to be more likely to be victims.

Animal psychology has been most influenced (ethology & sociobiology)

  • Animal psychology has been most influenced (ethology & sociobiology)
  • Psychologists interested in human language and perception now point to innate mechanisms (Pinker, 1994)
  • Social psychologists appeal to cultural influences and are generally against innate factors (Harre, 1986)
  • Areas of psychology influenced- see top of p. 3 and p. 6 of handout

Review of innate influence in areas of human psychology (p3 on handout)

  • Perceptual systems: vision; colour vision (olfaction: 2004 Nobel). Also motor systems, and eye-hand co-ordination.
  • Cognitive systems: built-in concepts of time, space and physical reality; the bioprogram for 1st language learning
  • Emotionality: facial expressions as displays
  • Social systems: bioprograms for social interaction? (Tomasello et al, 1993)

Social systems: extra comments (p3)

  • human intelligence may have evolved because of its importance in social interaction, especially to cope with social exchange rules (Gleitman et al., 1999; p. 494 | 2004; p. 440)
  • natural inclinations are not necessarily desirable: cultural systems may have often developed to supplant them (Hobbes, 1651; Gleitman, 1999, p. 405 & p. 437; Gleitman, 2004, p. 612)

Thomas Hobbes (1651)picture in Gleitman, 1999; p. 406 | text in 2004 edn p. 612


  • The next slide is 2x2 on page 7
  • Hobbes is useful as an example of syaing that the “state of nature is not where we are now, but nativists would say he was wrong about the original human state being solitary even though stone age life was probable more brutal and short in general than it is now

2 x 2

  • (page 7 of handout)


  • Pinker (1994, 1998, 2003) − an example of an evolutionary psychologist

Pinker, S. (1994) The Language Instinct. pp 419-20.

  • “So what are the modules of the human mind?”
  • “Using biological anthropology, we can look for evidence that a problem is one that our ancestors had to solve in the environments in which they evolved —
  • so language and face recognition are at least candidates for innate modules, but reading and driving are not.”

Genes and Language:

  • Psycholinguists such as Noam Chomsky and Steven Pinker have been convinced since the 1960’s that the human capacity for language capacity is innate.
  • In the last six years, particular genes involved with language capacity have been discovered. (Not covered in Gleitman et al.)

Genes and Language: BBC October 01

Pinker comments October 2001

From the Wellcome Trust web pages

National Geographic

Mice 05 foxp2

Nature 2002

  • Language is a uniquely human trait likely to have been a prerequisite for the development of human culture. The ability to develop articulate speech relies on capabilities, such as fine control of the larynx and mouth, that are absent in chimpanzees and other great apes. FOXP2 is the first gene relevant to the human ability to develop language. A point mutation in FOXP2 co-segregates with a disorder in a family in which half of the members have severe articulation difficulties accompanied by linguistic and grammatical impairment. This gene is disrupted by translocation in an unrelated individual who has a similar disorder. Thus, two functional copies of FOXP2 seem to be required for acquisition of normal spoken language. We sequenced the complementary DNAs that encode the FOXP2 protein in the chimpanzee, gorilla, orang-utan, rhesus macaque and mouse, and compared them with the human cDNA. We also investigated intraspecific variation of the human FOXP2 gene. Here we show that human FOXP2 contains changes in amino-acid coding and a pattern of nucleotide polymorphism, which strongly suggest that this gene has been the target of selection during recent human evolution.
  • Sun, T., & Walsh, C. A. (2006). Molecular approaches to brain asymmetry and handedness. Nature Reviews Neuroscience, 7(8), 655-662
  • see Gleitman et al 1999, p. 40 /2004, p. 60, for human cerebral lateralization which is associated with language capacities

Pinker, S. (1994) The Language Instinct. pp 419-20.

  • if there is a module for it, a task should seem easy, and we ought to be able to discover a subsystem of the brain that is responsible for it.
  • Pinker gives a long list of possible innate modules including:
  • 1.Intuitive mechanics: knowledge of objects
  • 2.Intuitive biology: understanding of how plants and animals work.
  • 3.Number.

Separated twins

  • Pinker 2003, p.46
  • Gleitman, 1999, p.698
  • Gleitman, 2004, p.605
  • 15,000 UK twins currently being studied, MRC funded (TEDS − Twins early Development Study
  • Separated at birth, the Mallifert twins meet accidentally…..

Pinker, S. (2002) The Blank Slate

  • p. 35. “This is not to say that cognitive scientists have put the nature-nurture debate completely behind them: they are still spread out along a continuum…..”
  • p. 31. “The first bridge between biology and culture is the science of mind, cognitive science.”
  • p. 60. Take the case of a person’s mother tongue, which is a learned cultural skill par excellence….The innate endowment for language is in fact an innate mechanism for learning language.


  • This is between pinker and Robert winston, but is also the start of human evolution, which is not really discussed by Pinker or other evol psych. And is not in Gleitman and the details can be ignored apart from a very broad brush view. It changes because of new fossils but there is good agreement about the broad timescale which you have on page 8 (not in Gleitman but the Grant to Robin Dunbar shows that there is a connection between knowledge of human evolution and evolutionary psychology
  • End of lecture 1

Evolution and Psychology — Lecture 2 Human Evolution and Human Infancy

  • Dr Stephen Walker
  • January 11, 2007
  • Psychology BSc –
  • General Foundations Module

Millions bottom

  • Bottom of page 8 of handout

Millions top

  • Top of page 8 of handout
  • “Lucy”

Family Tree: from Johanson’s site “Becoming Human”

Lucy to Language

  • Book by Johanson and Edgar −2 copies in Main Birkbeck Library, classmark=599.938 JOH − listed on p. 1 of handout.

Australopithecus afarensis

  • Fossilized footprints, discovered by Mary Leakey in Laetoli, Tanzania.
  • They are dated at 3.5 Mbp, and only the “Lucy” species is known from that time, but the imprints look very like modern human imprints.

A new early fossil (2006)

  • Alemseged, Z., et al. (2006). A juvenile early hominin skeleton from Dikika, Ethiopia. Nature, 443(7109), 296-301
  • Dikika is only 4km from where ‘Lucy’ was found (Australopithecus afarensis )
  • The Dikika specimen, from 3.3m yrs ago was about 3yrs old and probably female.
  • The legs were human-like for bi-pedal walking, but the arms and hands ape-like. The hyoid bone (for the larynx) was also ape-like

Napier chimp grip

  • Chimpanzees and other apes can hold small objects, but have lost, or never had, the opposable thumb

New Neanderthal data: Green et al., (2006)

  • Suggests common ancestor ~450,000 yrs ago

Psychologist cover

  • British Psychological Society news magazine, the Psychologist, August, 2001 see p. 4 for url
  • (http://tinyurl.com/y6qs9e)


  • Boxgrove,
  • West Sussex,
  • 500,000 years before the present.
  • Excavations funded by English Heritage.
  • Dept of Archaeology,
  • University College
  • Stone tools provide some evidence about prehistoric human activities

Oldowan tools >2m years

  • “Even 2.34m years ago there was a highly controlled technology for producing stone flakes following constant technical rules and resulting in high productivity.” (Delagnes and Roche, 2005: not on list)

Acheulian tools 1.5 m – 0.2 m yrs, mainly Homo erectus. Handaxes and choppers

Size of Handaxes

“Mousterian”tools, 200k yrs ago – 30k. Included a wider variety of flake tools. (used by Neanderthals)

Neanderthal hut

Mammoth remains

Approx 25 k years ago, modern homo sapiens used a wide variety of weapon heads and “microlith” stone blades


Selected small blades

  • Endscraper
  • Piercer or “hand-drill”
  • “spokeshave”
  • knifepoint
  • “Modern” Homo sapiens, approximately 25,000 years ago
  • Cave paintings do not go back as far as stone tools, only about as far as the most recent ones just shown, but demonstrate that capacities similar to those of current humans existed many millenia before the development of agriculture about 11 thousand years ago.

Chauvet fur clad

Chauvet (31k) bison with active legs

Detail of horses at Chauvet (31k)

Rhinos at Chauvet (31k)

Hand at Chauvet (31k)

Hands in Cave at Cosquer

  • 27K
  • 29K

Lamp at Lascaux (13k)

Bull at Lascaux (13k)

Cattle at Lascaux (13k)

Bison bellowing at Altamira (13k)

Honey gathering (Bicorp, Spain, 6K)

End of evolution, start of Gleitman

  • The most general message of human evolution is that it produced very large if not infite amount of blank space on the human slate. We did not develop fixed instincts for making stone stools, but a general purpose ability for learning and cultural innovation
  • But we are certainly not a completely blank slate since we are born with pre-existing concepts, biases and capacities
  • Next, evidence from human infancy in Gleitman et al., mainly in the areas of visual perception, language learning and facial expression

What is the cognitive starting point?

  • “Very young infants begin life with primitive concepts of space, objects, number, and even the existence of other minds.” (Gleitman, 1999, p. 552; 1995, p. 511; 2004, p. 479)
  • E.g. depth perception in the “visual cliff”.

Visual Cliff Gleitman 1999, p. 553; 2004, p.5

Visual Cliff Gleitman 1999, p. 553; 2004, p.5

Occlusion 1999, p. 553 2004, p. 479

Occlusion 1999, p. 553 2004, p. 479

Occlusion 1999, p. 553 2004, p. 479

Baby habituation 1999, p. 554

Baby habituation

Baby habituation

Occlusion in 4-month olds 1999, p. 554 2004, p. 480

Occlusion 1999, p. 554 2004, p. 480

Number in infancy 1999, p. 557 | 2004, p. 483 Starkey, et al., 1983)

Csibra web page

Csibra first

Csibra second

  • Nine- and twelve-month-old babies look longer at the scene on the left, so they see it more different from the previous one. Why? After all, the jumping movement pattern of the ball is more similar to the previous scene than the straight motion.

Csibra control

  • But jumping without an obstacle does not make sense if the goal is simply to reach a position. Indeed, the red ball in the right scene acts in a more sensible way, therefore it seems more similar to the previous scene.
  • This conclusion is supported by the fact that if the babies first see the ball hopping without reason (top), they do not prefer any of the scenes above.

Csibra duck

  • Csibra, G. (2001). Illusory contour figures are perceived as occluding surfaces by 8-month-old infants. Developmental Science, 4, F7-F11. (not listed in handout)

Pause before language in Gleitman

  • Sections of Gleitman et al., on Language Acquisition in Human Infants

Language learning can proceed despite severe environmental deprivation. This supports the contention that the mental machinery for language is innate. (Gleitman et al., 1999, p. 390 / 2004, pp 350-352)

  • “….language is an irrepressible human trait: deny it to the mouth and it will dart out through the fingers” (Gleitman et al., 2004; p. 350 − in relation to American sign language, used by the deaf)

Helen Keller conversing with Eleanor Roosevelt: 1999, p. 390.

Learning language requires a receptive human mind”, Gleitman et al. 1999 p. 374 — 2004, p. 352.

Word meaning at the one word stage: 1999, p. 375; 2004, p.342

  • Between the ages of 2 and 5 infants learn several new words each day (2004; p. 338)
  • Sections of Gleitman et al., and other sources relating to emotional expresion
  • Evolution of smiling p. 429 1999, not in 2004

Evolution of smiling p. 429 1999, not in 2004

Evolution of smiling p. 429, 1999 not in 2004

“Face” recognition in newborns p. 557-8, 1999, and p.484, 2004

  • 4. But newborns track "face" stimuli with head and eye movements. e.g. Expt (in Cognition) with 24 infants only 37 mins old (mean). Stimuli either face, scrambled or blank. Both eye and head turn were greatest for the face and least for the blank
  • Gleitman (1999 p 557) says that the “face”, “scrambled”, blank expt. was done on infants 9 minutes old. but that was just the youngest, the mean age was 37 minutes
  • Newborn infants have a predisposition to look at face-like objects. (41 newborns at University College Obstetrics Department between 15 and 69 minutes after birth)

Smiling in those born blind: only in Gleitman, 1995; p. 403 not in 1999 or 2004

  • So to begin to answer some of these questions JanaIverson and Susan Goldin-Meadow of Indiana University, Bloomington, Indianahave carried out an intriguing series of observational experiments on congenitally
  • blind children and adolescents, that they now report in Nature. The team compared
  • the amount, rate and type of gestures used by two groups of 9-19 year olds while
  • they carried out reasoning tests known to elicit easily recognisable and comparable
  • gestures. One group contained subjects who had been blind from birth and the other
  • comprised age-, gender- and ethnically- matched, sighted, children.
  • Iverson and Goldin-Meadow found that blind participants, even when speaking to
  • blind listeners, used gestures of more or less the same shape and rate as those
  • employed by their sighted counterparts when conveying the same concepts. Indeed,
  • all the youngsters, sighted or not, used their arms and hands while speaking,
  • whatever the visual status of their listeners
  • One popular theory holds that gesturing is learned behavior. Iverson and Goldin-Meadow decided to test this idea by comparing two groups of 12 children, one in which the children could see and the other in which the children were congenitally blind. The median ages of the blind subjects and sighted speakers were 12 and 11, respectively.
  • In a study conducted at the University of Chicago, each child was presented with two glasses containing equal amounts of water. The water from one glass was then poured into a shallow but wider dish. The children were asked whether there was the same amount of water in the dish as the glass, and to justify their answers. The blind children were allowed to examine the containers with their hands throughout the experiment.
  • "It's the kind of task that really gets kids' thinking and reasoning processes going," Iverson explained. "This is a really novel thing for them to do, and they have to be engaged and think hard when they're coming up with an answer."
  • The study found that all 12 blind speakers gestured as they spoke, despite having never seen a gesture. The blind group gestured at a rate that was not reliably different from that of the sighted group and conveyed the same information using the same range of gesture forms.
  • "In this task, the kids tended to make a lot of gestures related to the height of the containers," Iverson said. "They would also hold their hands up at different levels indicating the height of the containers, or they would hold hands apart at different distances to indicate that one container was wide and another skinny, or they would gesture as if they were pouring the contents of one container into another."


Peleg et al. (2006). Hereditary family signature of facial expression. PNAS 103(43), 15921-15926

Darwin’s “Expression of the Emotions”

  • See “The universality of emotional expressons, p. 451, Gleitman et al. (2004

Darwin’s “The expression of the emotions in man and animals” (1872)

  • All Darwin’s publications are freely available online at http://darwin-online.org.uk

Darwin’s cats

Darwin’s dogs

Darwin’s babies

Darwin terror and horror

Quotes from Archer (2001) “Evolving theories of behaviour” see p. 4 for url(http://tinyurl.com/y6qs9e)

  • “… a single unifying starting point for understanding why we think and behave as we do today: natural selection has made us this way”. (p. 414)
  • “A ‘sweet tooth’ is adaptive when sugar is relatively rare, but not in present conditions when sweet foods are constantly available.” p. 417.
  • “The fight –and-flight response is adaptive for responding actively to predators, but not when trapped in a traffic jam.” p. 417.

Quotes from Segal (2001) “Main agendas and hidden agendas” see p. 4 for url(http://tinyurl.com/y6qs9e)

  • “Yes, the human species evolved and has survived; but natural selection made us in what way, exactly?” (p.422)
  • “In the UK in the 1990s, women overall delayed giving birth until their thirties. The proportion of women remaining childless increased steadily over recent decades.” ( p 412)
  • “What millions of years of genetic change have actually produced is the potential for human cultural invention.” (p.423).

Review of innate influence in areas of human psychology (p3 on handout)

  • Perceptual systems: vision; colour vision (olfaction: 2004 Nobel). Also motor systems, and eye-hand co-ordination.
  • Cognitive systems: built-in concepts of time, space and physical reality; the bioprogram for 1st language learning
  • Emotionality: facial expressions as displays
  • Social systems: bioprograms for social interaction? (Tomasello et al, 1993)

Conclusion (p. 4 of handout)with added bullet points

  • Darwinian evolution has shaped many aspects of human cognition
  • starting with the capacities of our perceptual systems
  • and arguably including higher-order aspects of cognitive and emotional biases.
  • But biologically based predispositions do little to diminish the profound role of cultural and historical influences on uniquely human intellectual achievement and social diversity

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