Pierrick Bourrat

Altruism is one of the most studied topics in theoretical evolutionary biology. The debate surrounding the evolution of altruism has generally focused on the conditions under which altruism can evolve and whether it is better explained by kin selection or multilevel selection. This debate has occupied the forefront of the stage and left behind a number of equally important questions. One of them, which is the subject of this article, is whether the word “selection” in “kin selection” and “multilevel selection” necessarily refers to “evolution by natural selection.” I show, using a simple individual-centered model, that once clear conditions for natural selection and altruism are specified, one can distinguish two kinds of evolution of altruism, only one of which corresponds to the evolution of altruism by natural selection, the other resulting from other evolutionary processes

In this paper I argue against the claim, recently put forward by some philosophers of biology and evolutionary biologists, that there can be two or more ontologically distinct levels of selection. I show by comparing the fitness of individuals with that of collectives of individuals in the same environment and over the same period of time – as required to decide if one or more levels of selection is acting in a population – that the selection of collectives is a by-product of selection at the individual level; thus, talking about two or more levels of selection represents merely a different perspective on one and the same process

For evolution by natural selection to occur it is classically admitted that the three ingredients of variation, difference in fitness and heredity are necessary and sufficient. In this paper, I show using simple individual-based models, that evolution by natural selection can occur in populations of entities in which neither heredity nor reproduction are present. Furthermore, I demonstrate by complexifying these models that both reproduction and heredity are predictable Darwinian products (i.e. complex adaptations) of populations initially lacking these two properties but in which new variation is introduced via mutations. Later on, I show that replicators are not necessary for evolution by natural selection, but rather the ultimate product of such processes of adaptation. Finally, I assess the value of these models in three relevant domains for Darwinian evolution