title: Being human is a gut feeling.
abstract: Some metagenomic studies have suggested that less than 10% of the cells that comprise our bodies are Homo sapiens cells. The remaining 90% are bacterial cells. The description of this so-called human microbiome is of great interest and importance for several reasons. For one, it helps us redefine what a biological individual is. We suggest that a human individual is now best described as a super-individual in which a large number of different species (including Homo sapiens) coexist. New concepts of biological individuality must extend beyond the traditional limitations of our own skin to include our resident microbes. Besides its important contributions to science, microbiome research raises philosophical questions that strike close to home. What is left of Homo sapiens? If most of our cells are not Homo sapiens cells, what does it mean to be an individual human being? In this paper, we argue that the biological individual is determined by the amount of functional integration among its constitutive parts, a definition that applies perfectly to Homo sapiens and its microbiome.
authors.affiliation: Département de philosophie, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada.
authors.forename: Thiago
authors.initials: T
authors.lastname: Hutter
authors.affiliation: Département de sciences biologiques, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada ; Institut national des sciences appliquées de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne CEDEX, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Gimbert
authors.affiliation: Département de philosophie, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bouchard
authors.affiliation: Département de sciences biologiques, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada.
authors.forename: François-Joseph
authors.initials: FJ
authors.lastname: Lapointe
keywords: Biological individuality; Functional integration; Homo sapiens; Super-individual