Population Thinking and the Uniqueness of Biological Entities.

The concept of ‘population thinking’ was introduced by Ernst Mayr in the mid-twentieth century and it has since become one of the most pervasive notions in the philosophy of biology. Despite its influence, however, the term has been widely misunderstood, even by those who have done the most to champion it. Population thinking today is often confused with population-level thinking (i.e., the idea of treating populations as units of analysis), which, ironically, is the opposite of what Mayr intended to convey when he coined the term. For Mayr, population thinking was a way of emphasizing the variation among individuals in a population, as well as the importance of recognizing their differences and uniqueness. In this paper, I recover the original meaning of ‘population thinking’ and elucidate its central role in evolutionary theory. I also demonstrate its surprising relevance to many other areas of contemporary biology. In particular, I show how the recent introduction of novel methodologies in molecular biology has led to a number of unexpected discoveries that are best understood through the lens of population thinking. Finally, I examine the historical origins and philosophical foundations of population thinking, and I show how it lies at the heart of what makes biology different from physics.