A gene acquires a meaning only via its history of dynamic interaction with its niche. That niche consists not only of the physical environment outside the organism’s body, but also of the body itself, other genes in that body, and all the other genes within the population of conspecifics—including any variants of the gene in question. All the interactions between the gene and its niche are physical events, yet they can be expressed purely in terms of information acting on other information—all the properties of a niche can always be rendered abstractly as a dynamic set of constraints that guide the evolution of the genes that it affects. Hence, the meaning of a specific gene (e.g., a gene encoding the instruction to “dilate both pupils as the sun sets”) depends intrinsically on that gene’s history of interaction with its niche, but not on the niche’s physical character. Indeed, recall that many components of the gene’s niche are abstractions: namely, all the other genes in the host organism and in the conspecific population. So, critical rationalism explains in exactly the same terms the meanings of genes and of human ideas. Both genes and ideas are abstract entities that acquire their distinctive meanings via their histories of dynamic interaction with their respective niches, which are corresponding sets of abstract constraints that affect the evolution of all the genes or ideas they interact with. What physical system instantiates the abstract constraints that constitute a niche, be it a regional biome on Earth or a skull-encased network of neurons, is immaterial for critical rationalism vis-à-vis how the information adapted to that system acquired its meaning.