How do new characteristics arise in a population?
Populations always have a degree of variation within them – after all, not all organisms belonging to the same species are clones. These differences may be small but over many generations Natural Selection may favour some of these characteristics over others in rival organisms of the same species. Such minor advantages frequently become reinforced so that, with the benefit of many generations of hindsight it may appear that they have appeared from new. Both these effects mean that over time the “average” set of characteristics for a species gradually changes. There are also genetic mutations. The vast majority of mutations are actually neutral (they change nothing, for better or worse) but serve to prime the species for further variation as described above. Of the rest, most are detrimental and such mutants do not survive. The few beneficial mutations often rapidly exploit their new advantage – and again, the “average” set of characteristics for the species changes.
