Study of especially the , , and age structures of populations.

Demography as typically defined is in terms of the study of this factors among ourselves. Ecologically, however, there is no reason to limit our interests and thus demography, though originally a study of humanity, in fact can be applied to any species.

Demography is, however, limited to the study of individual species and therefore falls under the heading of population ecology. See also such concepts as reproductive rates, reproductive tables, life tables, cohorts, , and survivorship curves.