The Evolution of Mind and
Society
Dr Andy Wells
ISP Flagship Lecture
Series
16th November 2010
Universal Declaration of
Human Rights
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Article 1.
All human beings are born free and equal
in dignity and rights.They are endowed
with reason and conscience and should
act towards one another in a spirit of
brotherhood.
Conflict and co-operation
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Conflict and co-operation are the two most
fundamental concepts in human social
psychology.
To begin to understand human social relations
and social institutions we need to consider how
and why the capacities for conflict and cooperation are deeply embedded in the human
psyche.
That consideration is best undertaken from the
standpoint of evolutionary theory.
Human sociality is part of our evolved biological
heritage, extended and amplified by culture.
Human behaviour.

Consider the following scenario:
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John and Tom meet in the street and get into
an argument. Tom pulls out a knife and stabs
John who subsequently dies of his injuries.
Tom is arrested and charged with murder.
Here’s another scenario:

Jane and Teresa meet in the street and get
into an argument. Teresa pulls out a knife and
stabs Jane who subsequently dies of her
injuries. Teresa is arrested and charged with
murder.
Sex Differences.
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Sex differences in physique, behaviour
and achievements of many kinds are
normal rather than exceptional.
The data are not in question.
Explanations are contested.
Evolutionary explanations are an essential
part of a proper understanding of sex
differences and of a broad range of other
socially significant phenomena.
Estimated UK population
age distribution 1999
7000
6000
5000
4000
3000
2000
1000
0
1
15 20 30 45 60 65 75 8
1
5
5
nd to to 0
t
t
t
t
t
t
t
t
+
er
4
9 o1 o1 o2 o4 o5 o6 o7 o8
1
4
9
9
4
9
4
4
4
U
Males
Females
UK Crime Statistics:
Indictable Offences.
300
250
200
Male
Female
150
100
50
0
1996
1997
1998
1999
Nobel Prize Winners
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813 individuals have been awarded a
Nobel Prize. 773 of them were men.
The Nobel Prize has been awarded to 40
women since 1901. One woman, Marie
Curie, has been awarded the Nobel Prize
twice, in 1903 (Physics) and in 1911
(Chemistry).
40/813 = 0.049
In 2009 the prize for economics was
awarded to a woman for the first time.
Evolutionary explanation.
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Evolutionary theory explains species typical
behaviours and sex differences in behaviour.
Evolutionary analysis grounds and illuminates
other types of explanation.
Evolutionary theory provides powerful analytical
tools for social psychologists with many different
interests.
The capacities for conflict and co-operation,
modulated by systematic sex differences in
behaviour, form the macro-structure within
which the micro-structures of individual and
group social relations can best be understood.
Human evolution: the big
picture.
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Humans are the product of a lengthy
process of evolution.
Like every other species on the planet we
are descended from single celled animals
that existed billions of years ago.
We belong to the class of mammals.
As such we are relative newcomers.
The last ones standing…
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Humans supplanted the Neanderthals, either by
killing them or by displacing them into marginal
habitats where they were unable to survive.
We have also caused the extinction of most of
the large, land animals which existed when we
came on the scene.
This has happened because Homo sapiens is a
relatively large and powerful species with highly
developed predatory instincts and exceptionally
flexible social organisation.
Darwin’s two theories.
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Our current understanding of evolutionary
processes rests on two fundamental theories
originally developed by Charles Darwin.
 The theory of natural selection.
 The theory of sexual selection.
Both theories are needed to explain human
evolution and contemporary social behaviour.
Natural Selection 1.
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Life is a competitive, often bitter, struggle to
survive and to leave offspring.
Individuals differ in their characteristics.
Some of these differences contribute to
success in the struggle.
Differences can be mental as well as physical.
Genetic uniqueness implies that social
behaviour is shaped primarily for individual
interests and secondarily for group interests.
Natural selection 2.
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The (heritable) characteristics of successful
individuals spread through a population via their
descendants.
The characteristics of unsuccessful individuals
are lost.
Evolution has shaped humans physically and
mentally for conflict and co-operation.
Inequality of opportunities and outcomes is a
feature of the evolutionary process which has
left its mark on the contemporary world.
Inequality
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All living humans are the descendents of
successful competitors in the struggle for
resources.
In the contemporary world access to resources is
grossly unequal.
Most of us, for most of the time, find it easy to
live with fundamental inequality.
Indifference to absolute inequality is a signature
of the evolutionary process.
Inequality relative to social reference groups is
much more important for most people.
Inequalities of wealth and
income.
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Pogge (2010) cites data which show that
the poorer 50% of the global population
have 1.1% of global private wealth and
3% of global household income.
By comparison, the richest 10% have
85.1% of global private wealth and
71.1% of global household income.
Inequalities exist both between and
within countries.
Social and societal psychologists should
be aware of these huge disparities.
Sexual selection 1.

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Many creatures have characteristics that
imperil their survival. The enormous tail
of the peacock is a classic example.
The theory of sexual selection explains
how these characteristics can undergo
positive selection if their mating benefits
outweigh their survival costs.
Sexual selection involves both
competition and choice.
Sexual selection 2.
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Darwin observed that competition for
mates typically occurs more strongly
among males than among females and
that females are typically more choosy
than males about their choice of mate.
Darwin was unable to find a satisfactory
explanation for this pattern.
Robert Trivers explained competitiveness
and female choosiness in terms of
differential parental investment.
Reproductive success.
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The currency of evolution is reproductive
success.
Each of us is the product of an unbroken
chain of ancestors.
Conflict, co-operation and systematic sex
differences are explained by
understanding their links to reproduction.
None of this implies that our ancestors
understood evolution or were immediately
motivated by the desire for children.
It takes two to tango.
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Differential parental investment is one of
the key foundations of social relations.
In sexually reproducing species the
female sex is defined as the one with
larger gametes.
Anisogamy is the rule rather than the
exception.
Differential investment.
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Human females invest much more heavily
than males in the early stages of
parenting.
Because of this, access to females is the
limiting factor on male reproductive
success.
As a consequence males compete among
themselves for access to females and for
status and resources.
Sexual dimorphism.
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Dimorphism is an indication of a history of
sexual competitiveness.
Humans are modestly dimorphic.
Human males, on average, are taller, heavier
and more muscular than females indicating a
greater degree of intra-sexual competition.
Sexual dimorphism underpins some notable
behavioural differences between men and
women such as the propensity for violence.
1999 UK prisoners: violent
crimes.
3500
3000
2500
2000
Male
Female
1500
1000
500
0
15- 18- 21- 25- 30- 40- 50- 60+
17 20 24 29 39 49 59
Variance in reproductive
success.
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Every human child has two parents, therefore,
on average, human females and males have
equal numbers of children.
However, there is greater variance in
reproductive success among males than among
females.
This promotes more intense intra-sexual
competition among males and strategies to
promote exclusive access to females.
Males are also more interested, on average, than
females in extra-pair copulations.
UK Divorce statistics:
decrees granted by sex.
120000
100000
80000
Wife
Husband
Both
60000
40000
20000
0
1995
1996
1997
1998
1999
1999 UK prisoners: sexual
offences.
1600
1400
1200
1000
800
Male
Female
600
400
200
0
15- 18- 21- 25- 30- 40- 50- 60+
17 20 24 29 39 49 59
Social relations preagriculture.
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Prior to the development of agriculture,
humans lived in small, nomadic bands.
Competition was limited by scarcity of
resources and storage capacity.
Co-operation was promoted by multiple
needs for social cohesion.
Privacy was virtually non-existent.
Individuals’ lives were open to public
scrutiny.
Social relations postagriculture.
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Agriculture made settled living possible and
offered new arenas for competition and
dominance.
Institutionalised social strata arose for the first
time.
Armies became possible.
Technological change was accelerated by a social
class freed from the constraints of daily food
production.
Conflict became amplified by weapons
technology and the raised stakes of the game.
Contemporary social
relations.
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Contemporary social relations result from
interactions between individuals whose
psychology has been shaped by multiple
influences:
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The mammalian heritage.
The primate heritage.
The hominid heritage.
Species specificity of Homo sapiens.
Agriculture and writing.
Contemporary environments.
Knowledge of evolution.
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Evolution is an inescapable force in human affairs.
An understanding of the evolutionary processes that have
shaped human psychology leads to two related insights:
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Fundamental aspects of human social behaviour have deep
phylogenetic roots and are hard to change.
Evolved human dispositions can be managed through the
construction of appropriate social institutions.
Social engineering via the construction of institutions such
as political parties, legislatures and education systems
must be informed by knowledge of the deep history of our
species as well as by more recent events.