Evolution, Psychology, Evolutionary

Psychology and Human Uniqueness

MSc Psychological Research Methods

PSYC073P

Epistemology and Philosophy of Science

December 12th 2006

Stephen Walker

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 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.

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.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.

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 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.

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 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.

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 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

Genomics and Bioinformatics

• DNA sequencing, inc human and chimpanzee

• Gene splicing and genetic engineering

• Gene expression data from ‘Microarrays’

The Darwinian Theory of Evolution −

“Descent with Modification”

� There are inherited differences between

individuals

� These include random variations

� Resources are not unlimited� 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

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 • 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

Almost all human

behaviour involves

cultural learning (Tomasello and Razoksky, 2003; Tomasello

et al., 2005)

Almost all animal

behaviour is genetically

pre-programmed (by

evolution) to fit an

ecological niche (Darwin, 1859;

Tinbergen, 1951; Manoli and Baker, 2004)

Human Uniqueness on behavioural grounds

et al., 2005)Tinbergen, 1951; Manoli and Baker, 2004)

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 • 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

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 based on spheres as in bumble bees, with S. American

stingless bees intermediate. NB thousands of solitary

bees which do not store honey

Another of Darwin’s examples:cuckoos

Another of Darwin’s examples:cuckoos

Darwin (1859) page 185 function and form

http://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.”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

Darwin (1859) page 185

http://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

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 • 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?

Evolution connects the human species with

the rest of the animal kingdom

Period, begins (Million Years)Era

Quaternary

Holocene 0,01

Pleistocene 1.6

Tertiary

Pliocene 5

Miocene 23

Oligocene 35

Eocene 56

Paleocene 65

Cenozoic Man

DinosaursCretaceous 145

Jura 210

Trias 250

Permian 290

Carboniferous 360

Devonian 410

Silurian 440

Ordovician 505

Cambrian 545

Proterozoic 2500

Archean 3800Precambrian

Paleozoic

Mesozoic

Oldest fossils of complex animals

Creation of extant phyla

Dinosaurs

Reptiles, birds, mammals

(Amniotes)

Primitive fish

First bacteria

First multicellular organisms

Lappin et al., 2006; standard texts

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

Bishop et al., 2002

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 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.”

Tinbergen

1951, title and frontispiece

Genome news network

Zig-zag dance

Experimental stimulus variation

A Study of Instinct

1951

• 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 • Tinbergen included some

ill-advised evolutionary

psychology

• But there is a case that

explanations for

stickleback and human

behaviour should be

fundamentally different.

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 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

E.g. Spiders

The orb web A first attempt

e.g. spiders 2

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. 213commenting on wolf and trapdoor spiders, p. 213

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 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).

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 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”

also vertbrates 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 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.”

Also birds

e.g. Dilger

(1961)

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 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.”

Slide 4 from the 2004 Nobel Lecture: Linda Buck

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 • 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)

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 written several more general books, most

recently “The Blank Slate” (2002) as well

as “The Language Instinct (1994)

Adaptations

• 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 • 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”.

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 tounwillingness to consider alternatives to

adaptive stories……..”

spandrels and

exaptations are

side effects of

natural selection

Evolutionary psychology, originally on the fringe of

academic psychology.., has gained respectability

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

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.

Tooby and Cosmides

• Cosmides, L. (1989). The logic of social

exchange: has natural selection shaped how

humans reason? Studies with the Wason

selection task. Cognition, 31: 187 - 276.

• Duchaine, B., Cosmides, L., & Tooby, J. • Duchaine, B., Cosmides, L., & Tooby, J.

(2001). Evolutionary psychology and the brain.

Current Opinion in Neurobiology, 11(2), 225-

230.

Swiss Army Knife

Cosmides: The Swiss Army knife is a flexible tool. Its

flexibility is not the result of having just one tool that is

applied to all problems. Instead, it is a bundle of tools,

each well-designed for solving a different problem –.

Similarly, the human mind does not have just one

blunt tool for solving all problems – and if it did, we blunt tool for solving all problems – and if it did, we

would be very limited indeed..

Cosmides (1989)

• Logic: If P then Q is only violated by P & ~Q

• Typically participants do not use this logic in the Wason 4 card test (if vowel, theneven number on back)

• A. if you have a bus pass, then you travel by bus• A. if you have a bus pass, then you travel by bus

• B. if you travel by bus, then you have a bus pass

• Cosmides used many more elaborate scenarios, and found a strong bias towards “detecting cheaters” in that participants get A wrong, but B right.

• But there is widespread disagreement, both

with the specific claims made about

reasoning and the Wason card-turning test,

• And with the general claims about highly • And with the general claims about highly

specialized mental tools for solving specific

problems

Examples• However, a few examples follow of papers

firmly in the field of evolutionary psychology in

recent issues of reputable journals.

• Catatonia, Anorexia Nervosa and depression are

proposed as adaptations,

• there is a fairly general theory about individual

decision rules interacting with group dynamics,decision rules interacting with group dynamics,

• a paper proposing an evolutionary account of

human facial expression of pain,

• and a paper arguing that a human “innate

releasing mechanism” for understanding agency

is a key feature of religious concepts of the

supernatural.

Moskowitz, A. K. (2004). “Scared stiff”:

Catatonia as an evolutionary-based fear

response. Psychological Review, 111(4), 984-

1002.

Guisinger, S. (2003). Adapted to flee famine: Adding an

evolutionary perspective on anorexia nervosa.

Psychological Review, 110(4), 745-761.

Anorexia nervosa (AN) is ..attributed to

psychological conflicts, attempts to be fashionably slender,

neuroendocrine dysfunction, ……. Considerable research

reveals these theories to be incomplete…..

This article presents evidence that AN's distinctive

symptoms of restricting food, denial of starvation, and symptoms of restricting food, denial of starvation, and

hyperactivity are likely to be evolved adaptive

mechanisms that facilitated ancestral nomadic foragers

leaving depleted environments; genetically susceptible

individuals who lose too much weight may trigger these

archaic adaptations. This hypothesis accounts for the

occurrence of AN- like syndromes in both humans and

animals and is consistent with changes observed in the

physiology, cognitions, and behavior of patients with AN.

Guisinger table

Depression

• Allen, N. B., & Badcock, P. B. T. (2006). Darwinian

models of depression: A review of evolutionary accounts of mood and

mood disorders. Progress in Neuro-Psychopharmacology & Biological Psychiatry, 30(5), 815-826.

• According to the social risk hypothesis, depression

represents an adaptive response to the threat of

exclusion from social relationships that, over the

course of evolution, have been critical to maintaining course of evolution, have been critical to maintaining

an individual's fitness prospects

• in the ancestral environment, depression induced: (i)

sensitivity to social risk/threat; (ii) signaling

behaviours that elicit social support; and (iii) a

reduction in risky behaviours

Kenrick, D. T., Li, N. P., & Butner, J. (2003). Dynamical evolutionary

psychology: Individual decision rules and emergent social norms.

Psychological Review, 110(1), 3-28.

• Following evolutionary models, psychological mechanisms are conceived as conditional decision rules designed to address fundamental problems confronted by human ancestors,

• A new theory integrating evolutionary and • A new theory integrating evolutionary and dynamical approaches is proposed.

• Three series of simulations examining trade-offs in cooperation and mating decisions illustrate how individual decision mechanisms and group dynamics mutually constrain one another, and offer insights about gene-culture interactions.

Kenrick and Butner, 2004

“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 “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 and Buttner wrong

• over a period of 35 years in Sweden (1965-

1999), there was no overall over-

representation of stepchildren as victims.

• Temrin, Nordlund, & Sterner, H. (2004)

• In families with both stepchildren and • In families with both stepchildren and

children genetically related to the offender,

genetic children tended to be more likely to

be victims.

Williams, A. C. D. (2002). Facial expression of pain: An evolutionary account. Behavioral and Brain Sciences, 25(4), 439-+.

• This paper proposes that human expression of pain ..,, arises from evolved propensities.

• The function of pain is to demand attention and prioritise escape, recovery, and healing; where others can help …, a distinct and specific facial expression of pain from infancy to old age, consistent across stimuli, and recognizable as pain by observers. and recognizable as pain by observers.

• ……..there has been skepticism about the presence or extent of pain, judgments of malingering, and sometimes the withholding of caregiving and help.

• … an evolutionary account can generate improved assessment of pain and reactions to it.

Darwin’s “The expression of the emotions in

man and animals” (1872)

Peleg et al. (2006). Hereditary family signature of

facial expression. PNAS 103(43), 15921-15926

• Correlated facial expressions in congenitally blind subjects and their seeing relatives, anticipates genes.

Further examples

• Rhodes, G. (2006). The evolutionary psychology

of facial beauty. Annual Review of Psychology, 57, 199-226.

• face preferences may be adaptations for mate

choice because attractive traits signal important

aspects of mate quality, such as health

• Averageness, symmetry, and sexual dimorphism

are good candidates for biologically based are good candidates for biologically based

standards of beauty

Atran, S., & Norenzayan, A. (2004). Religion's evolutionary landscape:

Counterintuition, commitment, compassion, communion. Behavioral and

Brain Sciences, 27(06), 713-730.

• Religion is not an evolutionary adaptation per se,

• but a recurring cultural by-product of the complex

evolutionary landscape

• A key feature of the supernatural agent concepts

common to all religions is the triggering of an

“Innate Releasing Mechanism,” or “agency “Innate Releasing Mechanism,” or “agency

detector,”

• whose proper (naturally selected) domain

encompasses objects relevant to hominid survival

– such as predators, – but which actually extends

to moving dots on computer screens, voices in

wind, and faces on clouds.

Domain General and Domain Specific

• The “Swiss army knife” idea is more formally

expressed in terms of domain specific or

modular capacities.

• The next paper argues that general intelligence • The next paper argues that general intelligence

is also domain-specific

• This is dangerous for Evolutionary Psychology,

since it opens the door to the idea that human

evolution ended up by providing us with very

open-ended and general purpose psychological

capacities.

Kanazawa, S. (2004). General intelligence as a domain-

specific adaptation. Psychological Review, 111(2), 512-523

• General intelligence (g) poses a problem for evolutionary psychology's modular view of the human brain. The author …. argues that general intelligence evolved as a domain-specific adaptation for the originally limited sphere of evolutionary novelty in the ancestral environment…environment…

• It has accidentally become universally important merely because we now live in an evolutionarily novel world

Kanisawa, Psych Review 2004

More Domain General ideas

Atkinson, A. P., & Wheeler, M. (2004). The grain of

domains: The evolutionary-psychological case against domain-general cognition. Mind & Language, 19(2), 147-176.

..evolutionary psychologists have argued that our innate psychological endowment consists of numerous domain- specific cognitive resources, rather than a few domain-general ones. … We rather than a few domain-general ones. … We conclude (a) that the fundamental logic of Darwinism,….. does not entail that the innate mind consists exclusively, or even massively, of domain-specific features, and (b) that a mixed innate cognitive economy of domain-specific and domain-general resources remains a genuine conceptual possibility.

Human Ancestors

• “psychological mechanisms are

conceived as conditional decision rules

designed to address fundamental

problems confronted by human

ancestors” (Kenrick and Butner, 2004)ancestors” (Kenrick and Butner, 2004)

• This is a typical claim in evolutionary

psychology, but there seems little

detailed interest in what human

ancestors might have done.

Human Evolution

• The epistemology of human evolution is

necessarily difficult, since it relies on

fossils, but fossil evidence has a

reasonable track record in other areas,

and human artefacts, in particular stone and human artefacts, in particular stone

tools, provide another source of

evidence

Human evolution, summarised on p. 6 of handout

Millions

top

Family Tree

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.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

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

• Suggests common ancestor ~450,000 yrs ago

Human uniqueness

• The human brain is uniquely large

• It is also functionally lateralized in a way which differs from chimpanzees

• It may be metabolically enhanced • It may be metabolically enhanced Cacares et al (2003)

• It may include different physiological components (Allman et al., 2005)

• It may be organized uniquely, e.g. large frontal lobes (Deacon, 1997)

Number of neurons in the nervous system

1,000,000,000,000

350,000,000,000

100,000,000,000

500,000,000

300,000,000

• Homo sapiens (maybe 1014)

• Chimpanzee

• Rhesus monkey

• Mouse

• Octopus300,000,000

50,000,000

850,000

250,000

20,000

381

302

• Octopus

• Stickleback

• Honey bee

• Fruitfly

• Sea slug

• Thread worm male

• Thread worm

In Striedter, G. F. (2006). Precis of Principles of brain evolution.

Striedter brain szie

Dorus, S., et al. (2004).

Accelerated evolution

of nervous system

genes in the origin of

Homo sapiens. Cell,

119(7), 1027-1040

Human, chimp, organg, Rhesus

primary microcephaly

Ponting and Jackson, 2005

• …….recent advances from the cloning of two human disease genes promise to make inroads in the area .. of brain size evolution.

• Microcephalin (MCPH1) and Abnormal spindle-like microcephaly associated (ASPM) are genes mutated in primary microcephaly.

• In this, the brain is of a size comparable with that of early hominids. hominids.

• It has been proposed that these genes evolved adaptively with increasing primate brain size. ….both genes have undergone positive selection during great ape evolution.

• the evolutionary patterns of all four presently known primary microcephaly genes are consistent with the hypothesis that genes regulating brain size during development might also play a role in brain evolution in primates and especially humans (Evans, 2006)

More on brain size genes

• Evans et al., (2005) claim the microcephalin

has continued to evolve adaptively in

modern humans

• They say one genetic variant of

microcephalin appeared as recently as microcephalin appeared as recently as

37,000 years ago.

• The same team (Merkel-Bobrov et al, 2005)

say that APSM, another gene regulating

brain size, had a new variant only 5,800

years ago

Huxley’s

comparisons

“So far as cerebral structure goes

therefore, it is clear that man differs less

from the Chimpanzee or the Orang, than

these do even from the monkeys, and that

the difference between the brains of the

Chimpanzee and of Man is almost

insignificant, when compared with that

between the Chimpanzee brain and that of

a Lemur. “(Darwin, 1874/1901, p. 312)

semendeferi1

The Semendeferi et al., (2002) table Semendeferi table

• Schoenemann et al.(2005) recently suggested

that prefrontal white matter is

disproportionately larger in humans than in

other primates

• but Sherwood et al. (2005) countered that a)

Brain re-organization: expansion of the

frontal lobesThe sherwood 2005

• but Sherwood et al. (2005) countered that a)

the boundary between prefrontal and other

cortex is not well defined; and b) that in any

case, although the data showed humans having

more white matter than the average primate,

they did not show a difference between humans

and great apes.

Allman et al 2005

• Von Economo neurons (VENs) are a

recently evolved cell type which may be

involved in the fast intuitive assessment of

complex situations.

• As such, they could be part of the circuitry

supporting human social networks.supporting human social networks.

• We propose that the VENs relay an output

of fronto-insular and anterior cingulate

cortex to the parts of frontal and temporal

cortex associated with theory-of-mind

• We propose that in autism spectrum

disorders the VENs fail to develop normally

Allman et

al., 2005

Hutsler, 2003

7 autopsies:

50-97 yrs of

age.

Human Brain Asymmetries

age.

No

chimpanzees

Sun, T., & Walsh, C. A. (2006). Molecular approaches to brain asymmetry and handedness. Nature Reviews Neuroscience, 7(8), 655-662

Sun, T., & Walsh, C. A. (2006). Molecular approaches to brain asymmetry and handedness.

Elevated neuronal activity?

• Caceres et al. (2003) applied a variety of genetic techniques to the cortical tissue (removed post-mortem) of humans, chimpanzees and rhesus macaques.

• These suggested that humans and chimpanzees are more similar to each other than to the macaques, which is as expected,

• but also that there were dozens of genes that were • but also that there were dozens of genes that were expressed very differently in human and chimpanzee cortex, with 90% of these being expressed more actively in humans than in chimpanzees, which suggested that

• The human is brain is characterized by “elevated levels of neuronal activity”.

• As a contrast, comparing gene expressing in the human and chimpanzee heart and liver revealed very little difference of this kind.

• the human glia-neuron ratio in the prefrontal region did not differ significantly from predictions based on brain size.

• Further analyses of glia-neuron ratios across frontal areas in a humans, chimpanzees, and macaque monkeys showed that regions involved in specialized human cognitive functions, such as "theory of mind" (area 32) and language (area 44) have not evolved differentially higher requirements for metabolic support.

• …greater metabolic consumption of human neocortical

neurons relates to the energetic costs of maintaining

Sherwood, C. C., et al. (2006). Evolution of increased glia-neuron ratios in the human

frontal cortex. PNAS, 103(37), 13606-13611.

neurons relates to the energetic costs of maintaining

expansive dendritic arbors and long-range projecting

axons in the context of an enlarged brain.

• “Sherwood et al. (1) provide support for the

idea that the human brain is more or less

a large hominoid (ape) brain and can be understood in that context.”

• Enard et al., (2002) did cross-species comparisons of the DNA for FoxP2, which when mutated gives rise to articulatory disorders in humans. Although it is “highly conserved” their data suggested that “this gene has been the target of selection during recent human evolution.

• Watakabe et al., (2006) review gene expression profiling of postnatal rhesus neocortex. Although profiling of postnatal rhesus neocortex. Although there is overall homogeneity of gene expression across different cortical areas, a few genes show marked area-specific patterns, e.g. genes specific to visual cortex and to association cortex.

More genetic suggestions for human uniqueness

• Prabhakar et al, (2006) found many human-specific changes in regulatory sequences of DNA with almost no overlap with chimpanzee equivalents and suggest that these may have contributed to uniquely human features of brain development.

• Pollard et al., (2006) found a particular regulatory gene expressed especially in certain neurons in human neocortex from 7 to 9 gestational weeks and say that this and similar “human accelerated regions provide new candidates in the search for uniquely human biology”

Paleontological evidence from human

evolution

• Stone tools provide the main currently

available clues to human evolution

• But partly because they survive only

periods of geological time

• Other artifacts made from wood and

bone may have been important, even if

nothing now survives

Psychologist

cover

Oldowan tools >2m years

Acheulian

tools

1,4 m – 0.5 m

yrs, mainly

Homo erectus

Size of Handaxes

Neanderthal

tools, 400k yrs

ago – 100k

(Mousterian)

Approx 25 k

years ago,

modern homo

sapiens

Delagnes & Roche (2005)

• Even 2.34m years ago there was a highly

controlled technology for producing stone flakes

following constant technical rules and resulting in

high productivity.

• Their data consists of reconstructions of cobble

reduction sequences --- putting the flakes back reduction sequences --- putting the flakes back

together, e.g.

Delagnes & Roche (2005) 2.34m years ago

The hand and tools

The hand and tools

• Some apes from around the time of the last common ancestor seemed to have hands like early hominids (Moya-Sola et al, 2005; Alba et al., 2003)Alba et al., 2003)

• Since modern apes show some evidence of tool use it is likely that the hands became adaptively useful from the very earliest stages of bipedalism.

Chimpanzee tools

The hand and tools: Castiello 2005

Findings from patients

with brain damage who

have difficulty in

grasping objects are

difficult to reconcile with

neurophysiological neurophysiological

findings, ……….

……as the patients' lesions are confined to regions that,

in monkeys, do not seem to be involved in grasping-

related visuomotor transformations ---

Napier (1980)

Napier infants

Napier, ape

hands

Napier, power

and precision

grips

Napier – Screwtop

The hand and tools: conclusion

• The consequence of evolution is that

humans have domain-general potential for

manual skill

• The hands can be used for anything

anatomically possibleanatomically possible

• There is no evidence for completely

steretotyped movements, even for the

precision grip (Wong and Whishaw, 2004)

Wong, Y. J., & Whishaw, I. Q. (2004). Precision grasps of children and young

and old adults: individual differences in digit contact strategy, purchase pattern,

and digit posture. Behavioural Brain Research, 154(1), 113-123.

The grasping patterns of male and female young

adults, older adults and children were examined as

they reached (with both left and right hand) for five they reached (with both left and right hand) for five

small beads (3-16 mm diameter).

Frame-by-frame analysis of grasping indicated a high

degree of variability in digit contact strategies,

purchase patterns and digit posture both within and

between subjects.

Other technologies: Neanderthal hut

Mammoth remains

Other technologies: Cave

paintings, Southern France

and Spain, 31,000 to 8,000

year before present

Chauvet (31k) bison with active legs

Detail of horses at Chauvet (31k)

Hand at Chauvet (31k)

Lamp at Lascaux

(13k)

Bull at Lascaux

(13k)

Functional differences: cultural learning

and invention• Tomasello & Rakoczy (2003) have argued that there are

two (initial) stages of uniquely human social cognition.

• The first stage is observable in one year olds, who have

an understanding of other persons as intentional agents,

• This enables them to take part in pretend play, and is

important as a prerequisite for shared attention and early

social and linguistic learning.

• The second stage is the “Theory of Mind” belief-desire • The second stage is the “Theory of Mind” belief-desire

psychology which normally starts around 4 years of age,

but which is dependent on several years of linguistic

communication.

• These early stages of uniquely human social cognition

enable the cultural “ratchet” of social and

technological innovation (Tomasello et al., 2005)

“And so if we imagine a human child born onto a

desert island, somehow magically kept alive by

itself until adulthood, it is possible that this itself until adulthood, it is possible that this

adult’s cognitive skills would not differ very

much – perhaps a little – but not very much, from

those of other great apes.” (121) T and rakoczy

Understanding and sharing intentions

Tomasello et al., 2005

• a species-unique motivation to share

emotions, experience, and activities with

other persons.. Leading to ..

• “species-unique forms of cultural cognition

and evolution”and evolution”

Almost all human

behaviour involves

cultural learning (Tomasello and Razoksky, 2003; Tomasello

et al., 2005)

Almost all animal

behaviour is genetically

pre-programmed (by

evolution) to fit an

ecological niche (Darwin, 1859;

Tinbergen, 1951)

Human Uniqueness on behavioural grounds

et al., 2005)Tinbergen, 1951)

Reading

• As last week for nature/nurture

• Any of the papers quoted.

• Or a debate initiated by Lickliter, R., &

Honeycutt, H. (2003). Developmental

dynamics: Toward a biologically plausible dynamics: Toward a biologically plausible

evolutionary psychology. Psychological

Bulletin, 129(6), 819-835.

• Or take a brief look at one of the books on

human evolution listed in the handout.

Books on Human Evolution (alternatives)

Bradshaw, J. L. (1997). Human Evolution: A

Neuropsychological Perspective. Hove: Psychology

Press. BK lib 599.935BRA.

Johanson, Donald C., and Edgar, Blake (2001) From

Lucy to Language. London: Cassell paperbacks. 2 Lucy to Language. London: Cassell paperbacks. 2

copies in Main Birkbeck Library, classmark=599.938

JOH

Jones, S., Martin, R. D., & Pilbeam, D. R. (1992). The

Cambridge encyclopedia of human evolution. Cambridge

[England] ; New York, NY, USA: Cambridge University

Press, BK lib 599.9 CAM, 3 copies

Richards, G. (1987) Human Evolution. Routledge:

London. (Bk Lib GYW, N [Ric])

Conclusions

• Evolutionary theory is essential for many areas

of animal behaviour, and rapid advances in

molecular genetics may impinge on

knowledge of the physiological underpinnings

of human capacities

• But a crucial outcome of human evolution was • But a crucial outcome of human evolution was

a fairly open aptitude for cultural and

technological invention

• The human brain may not be equivalent to a

blank slate, but it has large areas of free space

for cultural and historical changes — the blank

parts may be the most important.