Neoteny ( /niːˈɒtɨniː/), also called juvenilization, is one of the two ways by which pedomorphism can arise. Pedomorphism is the retention by adults of traits previously seen only in juveniles, 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. In contrast, in progenesis, sexual development occurs faster. Both processes result in pedomorphism. Ultimately this process results in the retention, in the adults of a species, of juvenile physical characteristics well into maturity and pedogenesis (paedogenesis), the reproduction in a neotenized state.

Neoteny is one of three dimensions of heterochrony, or the change in timing of developmental events: acceleration (faster) vs. neoteny (slower), hypermorphosis (further) vs. progenesis (not as far), and predisplacement (begins earlier) vs. postdisplacement (begins later).

The word neoteny is borrowed from the German Neotenie, the latter constructed from the Greek νέος (neos, young) and τείνειν (teínein, tend to). The adjective form of the word is either "neotenous" or "neotenic". The opposite of neoteny is either called "gerontomorphic" or "peramorphic".

Terence Kemp McKenna (November 16, 1946 – April 3, 2000) was an American philosopher, psychonaut, researcher, teacher, lecturer and writer on many subjects, such as human consciousness, language, psychedelic drugs, the evolution of civilizations, the origin and end of the universe, alchemy, and extraterrestrial beings.

Terence McKenna grew up in Paonia, Colorado. He was introduced to geology through his uncle and developed a hobby of solitary fossil hunting in the arroyos near his home. From this he developed a deep artistic and scientific appreciation of nature.

At age 16, McKenna moved to Los Altos, California to live with family friends for a year. He finished high school in Lancaster, CA. In 1963, McKenna was introduced to the literary world of psychedelics through The Doors of Perception and Heaven and Hell by Aldous Huxley and certain issues of The Village Voice that talked about psychedelics.

McKenna claimed that one of his early psychedelic experiences with morning glory seeds showed him "that there was something there worth pursuing." In an audio interview Terence Mckenna claims to have started smoking cannabis regularly during the summer following his 17th birthday.