  This result also has important implications for the interpretation of the theory of natural selection as one wholly about populations, and not also about individual fitness differences, discussed above (individual versus trait fitness). Note that the problem of distinguishing drift from selection in ensembles—i.e., large populations—has the same character, and is in principle susceptible to the same solution as the problem of drift makes for evolution among lineages with small numbers of individual members. We can distinguish drift from selection in ensembles as well, if we accept that there is such epistemic access to ecological fitness differences and to the initial conditions of births, deaths and reproductions, taken one at a time, and we accept that these individual-differences aggregate into ensemble-differences.