 This should occasion no surprise, since, as  section 1  indicated, historically organisms have been regarded as prominent examples of biological individuals and organism and biological individual have often been used interchangeably. But the short quotation drawn from Maynard Smith and Szathmáry also helps to explain why simply equating biological individuals with organisms would be a mistake. The parts that compose organisms in all their complexity are, often enough, themselves biological individuals. Even if some of those parts are also organisms (e.g., the microbes that live on and in macrobes), many are not. Precisely the same is true of the populations and lineages that individual organisms in turn constitute. These may occasionally be organisms (e.g., eusocial insect colonies as “superorganisms”), but typically populations and lineages are biological individuals that are not organisms. If either this internal compositional complexity to organisms or their formation into populations and lineages are necessary features of organisms (which many philosophers and biologists at least tend to think they are; see Lidgard &amp; Nyhart 2017a: 18–23), then this would prove a stronger conclusion: given that there are organisms, there must be some biological individuals that are not organisms.