I have broad interests in behavioural and evolutionary biology, but my current research centres on four main topics:
1. Evolution of decision mechanisms
Animals, including humans, do not always behave in the ways
predicted by simple optimality models: sometimes they appear to do
'irrational' things. To understand this better, we need to develop a
more comprehensive theory of decision making which takes into account
the evolved mechanisms underlying behaviour. In a new ERC-funded project
at Bristol, we are using novel theoretical approaches to try to explain
puzzling features of behaviour such as impulsiveness, intransitivity
and state-dependent valuation and understand the evolutionary basis of psychological states.
Collaborators: Luc-Alain Giraldeau, Steven Hamblin, Andy Higginson, Alasdair Houston, Dave Mallpress, John McNamara, Pete Trimmer
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2. Flexible mate choice
Sexual selection
is a potent
evolutionary force, generating an incredible diversity of
courtship
displays which serve to attract the opposite sex. According
to standard 'textbook'
theory, all individuals should
strongly prefer
mates offering high-quality genes or plentiful resources, because this
gives them the greatest fitness. This view is at odds with the
considerable variation in mate preferences we see in real animals: some
individuals have strong preferences, some have weak preferences, and
some prefer a different type of mate altogether. We have been building
evolutionary models to try and understand why such differences exist.
Rather than fixed, uniform preferences, our work suggests that mate
preferences should be flexible, with individuals adjusting their
choosiness according to their current condition and circumstances
relative to others in the population. We have been testing the specific
predictions of our models by studying humans taking part in a
'speed-dating' event.
Collaborators: Colin Bleay, Bram Buunk, Rufus Johnstone, Ani Kazem, Jessica Pass, Katharina Riebel |

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3. Flexible aggression
Just as for mate preferences (see above), there are good reasons why
individuals should adjust their levels of aggression depending on their
current state. We have been building evolutionary models of flexible
aggression in which individuals learn about their fighting strength
from the outcomes of previous contests. This has interesting
consequences for the way that aggressive behaviour should change with
age, and in response to previous experiences of victory and defeat. In
parallel work, we have been examining developmental trajectories of
aggression in boys growing up in the Canadian province of Quebec, and winner and loser effects in fallow deer during the annual rut.
Collaborators: Dómhnall Jennings, Rufus Johnstone, Richard Tremblay
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4. Sex ratios and sexual selection
It is often argued that attractive males should produce more sons,
because these sons will inherit their father’s attractiveness. Numerous
field and laboratory studies have addressed this hypothesis, but the
results are mixed. We have been developing new theory to understand the
evolution of sex-ratio adjustment and how this might interact with
processes of sexual selection. Alongside, we have been conducting
large-scale aviary experiments on zebra finches
to determine how sex ratios and maternal investment are affected by the
relative attractiveness of the parents, and analysing large datasets of
humans in Rwanda to investigate patterns of sex-ratio bias in relation
to wife rank.
Collaborators: Bram Kuijper, Ido Pen, Thomas Pollet, Nikolaus von Engelhardt, Franjo Weissing, Klaudia Witte, Richard Zann
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