  Mayr claims that his Biological Species Concept (BSC) is an advance on both; individual species members are objectively related to one another not by a shared relation to a type but by causal and historical relationships to one another. He can thus be understood as arguing for a new, objective way of understanding the epistemological grounds for grouping individuals into species. This new way of grouping stresses historical, genetic and various ecological relationships among the individuals as the grounds for determining species membership. His claim is that this is more reliable and objective than similarities of phenotypic characteristics. This makes sense of the importance he eventually places on the fact the BSC defines species relationally: