Definition of knell. 1  transitive verb. : 2  to summon or announce by or as if by a knell. 3  intransitive verb. 4  1 : to ring especially for a death, funeral, or disaster : toll. 5  2 : to sound in an ominous manner or with an ominous effect.
For the journal, see Demography (journal) . Demography is the statistical study of populations, including of human beings. As a very general science, it can analyze any kind of dynamic living population, i.e., one that changes over time or space (see population dynamics).
Geneticists, specifically, study genes from plants, animals, and humans to determine how genes interact with each other, evolve, and duplicate. Developments in mapping the human genomeâthe set of all genes in human DNAâare taking biotechnology to a new level. Geneticists are gaining insight into ways of preventing a disease from even starting.