Neoteny is the retention, by adults in a species, of traits previously seen only in juveniles (pedomorphosis/paedomorphosis), and is a subject studied in the field of developmental biology. In neoteny, the physiological (or somatic) development of an animal or organism is slowed or delayed. Ultimately this process results in the retention, in the adults of a species, of juvenile physical characteristics well into maturity. In vertebrate biology, neoteny is most easily identified when sexually mature, completely viable juveniles or larva are found.