Session: Conceptual Challenges for Human Microbiome Research: Speakers: Mark Borrello; John Huss; Mark Sagoff (organizer); Commentator: Chris Diteresi; Chair: Lindley Darden

The investigation of the nature of biological individuality has a long and interesting history. Biologists have been fascinated by the wide range of biological entities that might count as individuals. Perhaps not surprisingly, humans have generally been perceived to be among the most coherent kinds of individuals. In this paper, I will examine the ways in which concepts of individuality have developed in biology since the mid-19th century with a particular focus on humans. I will then use this history to illuminate the role of the microbiome in changing concepts of human organismality and individuality. I will suggest some ways that the discussion of the human microbiome might contribute to the long standing, and ongoing discussion on the levels of biological organization and the processes of selection.