neoteny

n. ability to reach sexual maturity during the larval stage (Zoology)

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. The English word neoteny is borrowed from the German Neotenie, the latter constructed from the Greek νέος (young) and τείνειν (to extend). The standard adjectival form is "neotenous", although "neotenic" is often used.
See more at Wikipedia.org...

Ne·ot·e·ny n. The attainment of sexual maturity by an organism still in its larval stage. neoteny prolongation of the larval form in a sexually [more]Neoteny - Community and Resources

Noun
1. an evolutionary trend to be born earlier so that development is cut off at an earlier stage and juvenile characteristics are retained in adults of the species
(hypernym) evolutionary trend

Retention of juvenile features in sexually mature adult animals. Neoteny frequently correlates with recent evolution of the species (like Homo sapiens).