Topaz Halperin

In the past two decades there has been a high-profile debate between two frameworks for exploring biodiversity in ecology: the niche-based framework and the neutral framework. This paper discusses contrasting approaches to forge a causal relationship between the niche theory and the neutral theory. The first approach suggests that evolution for niche _differentiation_ may lead to neutrality, and the second suggests that evolution for niche _convergence_ may do so. Although counterintuitive and rarely considered, here I argue that the differentiation hypothesis is more promising. As will be demonstrated, adopting this hypothesis has notable implications for how the neutral theory is received.

The study of biological altruism is a cornerstone of modern evolutionary biology. Associated with foundational issues about natural selection, it is often supposed that explaining altruism is key to understanding social behavior more generally. Typically, biological altruism is defined in purely effects-based, behavioral terms – as an interaction in which one organism contributes fitness to another, at its own expense. Crucially, such a definition isn’t meant to rest on psychological or intentional assumptions. We show that, appearances and official definitions notwithstanding, the notion biological altruism carries a vestige of the psychological, intentional concept familiar to us from the human domain. In particular, definitions of altruism from Hamilton onwards presuppose an actor\recipient distinction – a distinction, so we argue, that has questionable biological grounding. We arrive at this conclusion step-by-step, first looking at several simple, “austere” definitions and their problems, and then critiquing the actor\recipient distinction directly. If successful, our arguments suggest that the category of biological altruism requires a significant rethink.