The border between these two categories, however, can be hard to discern. Steven Frank (2012) has developed a detailed mapping between equations describing change due to natural selection and equations used in information theory. Change across generations can be seen as the accumulation of information by a population about its environment. So far, there is no claim that populations use this information in any way, and the situation is akin to that found in tree rings: a tree accumulates, in its rings, information about climatic conditions in its past, though the tree does nothing with that information. Frank may view the role of information acquired by evolution in a more substantive way: “selection causes populations to accumulate information about the fit of characters to the environment” (2012: 2391). But it is doubtful that anything more than an inferential role has yet been shown for this kind of information.