Special Seminar - Pierrick Bourrat: Transitions in Evolution: A Formal Analysis
- Date: Jun 4, 2019
- Time: 10:00 AM - 11:00 AM (Local Time Germany)
- Speaker: Pierrick Bourrat from Macquarie University, Sydney, Australia
- Please find more information on the speaker here: https://researchers.mq.edu.au/en/persons/pierrick-bourrat
- Location: MPI Plön
- Room: Lecture hall
- Host: Paul Rainey
Abstract:
Evolutionary transitions in individuality (ETIs) are
events during which individuals at a given level of
organization (particles) interact to form higher-level
entities (collectives) which are then recognized as new
individuals at that level. ETIs are intimately related to
the literature on levels of selection. Yet, levels of
selection can be approached from two different perspectives
following Okasha (2006). One, referred to as 'synchronic',
asks whether selection occurs at the collective level while
the partitioning of particles into collectives is taken for
granted. The other, referred to as 'diachronic', asks the
origins of the partitioning of particles into collectives.
After having presented the two perspectives and a classical
formalism used to deal with the levels of selection question
in the literature, namely the multilevel version of the
Price equation, I show that because this formalism treats
the levels of selection question from a synchronic
perspective, it is inadequate to explain ETIs. This is
because a fundamental aspect of ETIs is the origins of
collectives. From there, I develop a framework on levels of
selection compatible with the diachronic perspective. This
framework relies on the distinction between what I call, on
the one hand, a 'functional aggregative collective trait',
and on the other hand, a 'functional non-aggregative
collective trait'. After having presented this distinction,
I implement it in the Price equation, leading to a new
statistical partitioning of this equation and which, I
argue, represents a causal decomposition more relevant for
ETIs. Finally, I exploit this partitioning to explain the
critical stages of an ETI. In addition to its explanatory
power, a experimental measure of the degree of functional
non-aggregativity could be used as a proxy for the degree of
individuality of a collective.