Neoteny: the neural development that certain species, notably humans, continue to experience after birth. Man is born immature and helpless. He is not capable of locomotion or of any of the directed, volitional behavior indispensable for self-preservation. The survival of the neonate is predicated on devoted parental care. 

Freud thought of the neonate as a pyschologically undifferentiated organism, born with a congenital equipment and certain Anlagen (hereditary predispositions) This organism still lacks consciousness, perception, sensation (as an awareness), and all other psychological functions, be they conscioius or unconscious. (See René Spitz, The First Year of Life.) 

René Spitz distinguishes two processes that initiate differentiation: Maturation, which is the unfolding of phylogenetically evolved and therefore inborn functions of the species -- these emerge in the course of embryonic development or are carred forward after birth as Anlage -- and development-- the emergence of forms, functions, and behaviour which are the outcome of exchanges between the organism and the inner and outer environment. (this distinction functions like that between preformation and epigenesis.) 

The biological theory of neoteny is that there is a trend in evolution to be born earlier, cutting off development at an earlier stage in the ancestral developmental sequence. Thus, for example, the adult human resembles the fetal ape more than it resembles the adult ape.