 Undoubtedly, the growth and development of molecular biology over the past half century has made reductionism in biology a central issue (and DNA a household word). However, it would be wrong to assume that different aspects of reductionism only gain traction in the wake of the molecularization of biology juxtaposed with discussions of reduction from a logical empiricist perspective (see  Section 3.1).  Besides a perennial concern with what makes  life  distinctive, we can distinguish at least two reductionist themes throughout history relevant to the life sciences and its philosophy: (1) the relation among different branches or domains of knowledge and (2) the relation between  parts and wholes  (Grene and Depew 2004, Magner 1994). These two themes link up in a complex fashion with both epistemic and ontological reduction. (Questions about methodological reduction tend to coalesce around new technologies that open up the possibility of pursuing reductionist research methods, such as making observations at a lower level with microscopy.) Additionally, these themes arise in the context of specific domains of enduring interest: (a) the complex relations among different animals and plants in natural environments, i.e., “ecology”, (b) the integrated relations among the parts and whole of an organism, i.e., “physiology/functional anatomy”, and (c) the dynamic relations among the homogeneous components in the early stages of an embryo that eventually beget a unified whole organism containing heterogeneous parts in appropriate arrangement and connection, i.e., “development/reproduction”.