Evolutionary theory of human warfare: genes, individuals, groups
Date
26/06/2019Metadata
Show full item recordAbstract
Recent years have seen an explosion of multidisciplinary interest in coalitionary intergroup
aggression – i.e. warfare – in human societies, and considerable advances in our
understanding of its origins and evolutionary-ecological drivers. However, the study of
human warfare has largely neglected the possibility that different parties – e.g. men versus
women, younger versus older generations, or attacking versus defending groups – might have
different incentives to influence the expression of warfare-related behaviours, which may
result in conflicts of interest within and between groups and sex differences in behaviour. In
this thesis, I develop a mathematical evolutionary framework, based on kin-selection theory,
to investigate such differences in incentives, with special attention to sex-specific
demography as a potential driver of conflicts of interest at multiple levels of the biological
organisation. I find that: (a) the ecology of warfare can drive the evolution of sex-biased
dispersal, which in turn modulates intrafamily and intragenomic conflicts over warfarerelated
behaviours, with the latter leading to parent-of-origin-specific gene expression
(genomic imprinting) and maladaptive behavioural disorders; (b) almost-exclusively male
warfare can be driven by an evolutionary feedback between male and female participation in
battle, rather than fundamental differences between the sexes; (c) sex is a fundamental
modulator of altruism in the context of the demography of warfare, with the sex that
competes more globally and/or is more philopatric being favoured to behave more
altruistically towards same-sex groupmates than opposite-sex ones; (d) conflicts of interest
within and between attacking and defending groups inhibit the formation of military alliances
and the shift to large-scale human societies more generally. Taken together, these results
suggest that differences in incentives for different parties in the context of warfare – often
driven by sex-biases in demographic parameters – result in behavioural sex differences and
conflicts of interest within and between different organisational levels.
Type
Thesis, PhD Doctor of Philosophy
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http://creativecommons.org/licenses/by-nc-nd/4.0/
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