Evolution, Psychology, Evolutionary Psychology and Human Uniqueness

1. Evolution, Psychology, Evolutionary Psychology and Human Uniqueness Stephen Walker MSc Psychological Research Methods PSYC073P Epistemology and Philosophy of Science December 12th 2006

2. Overview • There will inevitably be some overlap with nature/nurture issues (Dec 5th) • There is also a a contrast between evolutionary or biological psychology and social constructionist or psychosocial approaches (Nov 28th) • At least two kinds of reductionism will be illustrated: explaining behaviours as adaptations, and explaining behaviours in terms of neural circuits that control them.

3. Outline • I will start off by looking at animal behaviour, where evolution has relevance. • “Evolutionary Psychology” is based on the claim that human psychology is strongly determined by human evolution. • The evidence for these claims is often extremely weak, but I will look at a few recent examples. • I will also look briefly at the evidence concerning the course of human evolution.

4. Paper Handout • *NB* the paper handout includes only a small fraction of the slides in this presentation: a pdf of most of the slides will be available on the intranet • The paper handout includes a list of alternative books on human evolution which are in BK library on page 6 • Any pieces of work mentioned in the presentation should have its citation listed on pages 7 & 8 of the handout.

5. Fossils versus Genomics • There are epistemological difficulties in studying human evolution. • The difficulties are in inferring the past course of human evolution from a limited number of fossil finds. • But in the last 10 or 15 years technologies have become available allowing geneticists to pinpoint where and when the human genome has undergone significant changes.

6. Evolution and DNA There is a huge amount of information pertinent to evolution produced by recent technologies: these are citations for the paper by Altschul et al. (1990) about a search tool for DNA and protein sequence databases Wikipedia says this was the most widely cited of all scientific papers published in the 1990s

7. Genomics and Bioinformatics • DNA sequencing, inc human and chimpanzee • Gene splicing and genetic engineering • Gene expression data from ‘Microarrays’

8. The Darwinian Theory of Evolution − “Descent with Modification” • There are inherited differences between individuals • These include random variations • Resources are not unlimited • Some individuals will flourish more than others and produce more offspring • Natural selection occurs if a population changes over generations because of this

9. 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

10. Human Uniqueness on behavioural grounds Almost all animal behaviour is genetically pre-programmed (by evolution) to fit an ecological niche (Darwin, 1859; Tinbergen, 1951; Manoli and Baker, 2004) Almost all human behaviour involves cultural learning (Tomasello and Razoksky, 2003; Tomasello et al., 2005)

11. Darwin (1859) The Origin of Species • Chap VII “Instinct”. Not defined, but three main examples • The instinct of the female cuckoo to lay small eggs in other bird’s nests, and the egg-ejection behavior of the newly hatched cuckoo chick; • Slave-making instincts in some species of ant • The cell-making instinct of the honeybee • The behaviors were seen by Darwin as not necessarily dependent on anatomical characteristics

12. Darwin on Honey bees • Darwin thought that the honey comb was “absolutely perfect in economising labour and wax” on the grounds of geometry. • But it also “can be explained by natural selection having taken advantage of numerous, successive, slight modifications of simpler instincts”. These were based on spheres as in bumble bees, with S. American stingless bees intermediate. NB thousands of solitary bees which do not store honey

13. Another of Darwin’s examples:cuckoos

14. Another of Darwin’s examples:cuckoos

15. Darwin (1859) page 185 function and formhttp://darwin-online.org.uk • “…. the acutest observer by examining the dead body of the water-ouzel would never have suspected its sub-aquatic habits; yet this anomalous member of the strictly terrestrial thrush family wholly subsists by diving,—grasping the stones with its feet and using its wings under water.” • Actually has some anatomical adaptations: 3rd eyelid, nostril flaps and oil gland 10 times larger than non-aquatic perching birds. • But Voelker (2002) agrees that the thrush is the closest relative and suggest that dippers diverged only 4m years bp

16. Darwin (1859) page 185http://darwin-online.org.uk • And the behavioural adaptation would have come first − • Thrushes foraging in streams instead of solid ground would then find enlarged oil glands useful

17. Dipper diet includes aquatic insect larvae • Caddis fly larvae build themselves cases, in various ways depending on the species. • The Darwinian position would be that they inherit the behaviours required for this task. • But in fact Stuart and Currie (2002) found that there was little relation between the types of behaviours and the structural end-product across a variety of species. • Do species need a ‘genetic blueprint’ for the end-product?

20. Evolution connects the human species with the rest of the animal kingdom

21. Era Period, begins (Million Years) Quaternary Holocene 0,01 Pleistocene 1.6 Tertiary Pliocene 5 Miocene 23 Oligocene 35 Eocene 56 Paleocene 65 Cenozoic Man Cretaceous 145 Jura 210 Trias 250 Dinosaurs Mesozoic Permian 290 Carboniferous 360 Devonian 410 Silurian 440 Ordovician 505 Cambrian 545 Reptiles, birds, mammals (Amniotes) Paleozoic Primitive fish Oldest fossils of complex animals Creation of extant phyla Proterozoic 2500 Archean 3800 Precambrian First multicellular organisms First bacteria

25. Lappin et al., 2006; standard texts

26. EVOLUTIONARILY CONSERVED MOLECULAR GENETIC MECHANISMS FOR PATTERNING THE EMBRYONIC BRAIN . Reichert, H., & Simeone, A. (2001) Fly mutant restored with human gene Fly mutant restored with mouse gene Mouse mutant restored with fly gene

27. Bishop et al., 2002

28. Ethological analyses of animal behaviour Vitalists believed in the instincts as mystical…. and behaviourists were preoccupied with learning…the way out was focussing on the survival value of behaviour patterns. “Behaviour patterns become explicable when interpreted as the result of natural selection, analogous with anatomical and physiological characteristics.”

29. Tinbergen

30. 1951, title and frontispiece

31. Genome news network

32. Zig-zag dance

33. Experimental stimulus variation

34. A Study of Instinct1951 • There is no entry for gene in the 1951 index • But instinct and “innate” are the themes, and refers to genetics and mutations in the chapter on “The Evolution of Behaviour” • Tinbergen included some ill-advised evolutionary psychology • But there is a case that explanations for stickleback and human behaviour should be fundamentally different.

35. Instinct - 2 • Tinbergen (1951) stressed two key concepts • 1. “sign stimuli” e.g. redness for sticklebacks. • 2. The “innate releasing mechanism”, by which particular sign stimuli release particular instinctive behaviour patterns • He believed these concepts applied to mammals • But the evidence is much clearer with lower vertebrates and invertebrates

36. E.g. Spiders The orb web A first attempt

37. e.g. spiders 2

38. Darwin’s comment on spiders “Thus everywhere in nature are battle, craft, and ingenuity, all following the merciless law of egoism, in order to maintain their own lives and to destroy those of others” Charles Darwin writing in Animal Intelligence by G.J. Romanes (1882), commenting on wolf and trapdoor spiders, p. 213

39. Innate behaviours e.g. fruitfly courtship Kimura, K. I., Ote, M., Tazawa, T., & Yamamoto, D. (2005). Fruitless specifies sexually dimorphic neural circuitry in the Drosophila brain. Nature, 438(7065), 229-233. “…..we identify a subset of fru-expressing interneurons in the brain that show marked sexual dimorphism in their number and projection pattern……. Fru expression can produce a male-specific neural circuit,” “Throughout the animal kingdom the innate nature of basic behaviour routines suggests that the underlying neuronal substrates necessary for their execution are genetically determined and developmentally programmed” Manoli & Baker (2004).

40. e.g. fruitfly aggression Vrontou et al., (2006) fruitless regulates aggression and dominance in Drosophila Nature Neuroscience, 9,(01 Dec 2006), 1469 - 1471 When competing for resources, two flies of the same sex fight each other. Males and females fight with distinctly different styles, and males but not females establish dominance relationships. Here we show that sex-specific splicing of the fruitless gene plays a critical role in determining who and how a fly fights, and whether a dominance relationship forms. “our data indicate that aggressive behaviors are hardwired into the fly’s nervous system”

41. also vertebrates e.g. zebrafish Gahtan, E., Tanger, P., & Baier, H. (2005). Visual prey capture in larval zebrafish is controlled by identified (four of them) reticulospinal neurons downstream of the tectum. Journal of Neuroscience, 25(40), 9294-9303. “Many vertebrates are efficient hunters and recognize their prey by innate neural mechanisms. During prey capture, the internal representation of the prey's location must be constantly updated and made available to premotor neurons that convey the information to spinal motor circuits.” “Seven-day-old zebrafish oriented toward, chased, and consumed paramecia with high accuracy.”

42. Also birds e.g. Dilger (1961)

43. Also for mammals Choi et al. (2005) Lhx6 delineates a pathway mediating innate reproductive behaviors from the amygdala to the hypothalamus, Neuron, 46(4), 647-660 (in embryonic and adult mice) “Virtually all metazoan organisms exhibit innate reproductive and defensive behaviors that are triggered by signals sensed from conspecifics or predators. …. The stereotypical nature of these behaviors suggests that their underlying neural circuits are likely to be genetically ‘hard-wired’.” “In mammals, innate reproductive and defensive behaviors are mediated by anatomically segregated connections between the amygdala and hypothalamus.”

44. Slide 4 from the 2004 Nobel Lecture: Linda Buck

46. Contrasts • there remain very contrasting positions within contemporary psychology particularly relating to how much emphasis is given to broadly biological as opposed to psychosocial evidence and theory. • The contrasts are less stark if we use “horses for courses”: explaining how the olfactory system works in mice is different from theorising about voting intentions in the Ukraine (2004) or the Tory leadership election (2005) or political events in Lebanon (2006)

47. Evolutionary Psychology • Attempts to explain human psychology as a series of specialized adaptations • Driven in part by Chomskyan linguistics (see last week’s lectures): Pinker has written several more general books, most recently “The Blank Slate” (2002) as well as “The Language Instinct (1994)

48. Williams (1966) defined an adaptation as “a characteristic that has arisen through and been shaped by natural and/or sexual selection. It regularly develops in members of the same species because it helped to solve problems of survival and reproduction in the evolutionary ancestry of the organism. Consequently it can be expected to have a genetic basis ensuring that the adaptation is passed through the generations”. Adaptations

49. Spandrels Gould and Lewontin, 1979; Gould, 1997 “An adaptationist programme has dominated evolutionary thought in England and the United States during the past forty years. It is based on faith in the power of natural selection as an optimizing agent.” We fault the adaptationist programme for its unwillingness to consider alternatives to adaptive stories……..” spandrels and exaptations are side effects of natural selection

50. Evolutionary Psychology Bjorklund, D. F., & Smith, P. K. (2003). Evolutionary developmental psychology: Introduction to the special issue. Journal of Experimental Child Psychology, 85(3), 195-198 • Evolutionary psychology, originally on the fringe of academic psychology.., has gained respectability within the last decade. Articles written from an evolutionary psychological perspective are found in the field’s most prestigious outlets; it has professional societies and journals of its own; college courses and textbooks are devoted to it; and there are academic positions specifically designated for evolutionary psychologists.