How Many Organisms during a Pregnancy?

Abstract

Mammalian placental pregnancy is a neglected problem case for theories of organismality. This example is closer to home than those typically discussed within philosophy of biology. I apply evolutionary and immunological accounts of organismality to the “counting question”: How many organisms are present during a placental pregnancy? I conclude that an evolutionary approach yields the answer two, because of bottlenecking, germ-soma sequestration, and sexual recombination. By contrast, an immunological approach answers one, because of pervasive interactions across the placenta. This analysis expands and refines recent work on a biologically informed metaphysics of pregnancy, an undertheorized area of philosophy of science.

Topics & Concepts