Neoteny describes a process by which paedomorphism is achieved, 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).

Specific individual traits that differ in descendant organisms, when compared to ancestors, are sometimes called neotenies; humans, for example, appear to have several neotenies in comparison to chimpanzees.

Neoteny in humans

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There is controversy over whether adult humans exhibit certain neotenous features, or juvenile characteristics, that are not evidenced in other great ape species. Stephen Jay Gould was an advocate of the view that humans are a neotenous species of chimpanzee; the argument being that juvenile chimpanzees have an almost-identical bone structure to humans, and that the chimpanzee’s ability to learn seems to be cut off upon reaching maturity.

While neoteny is not necessarily a physical state experienced by humans, paedomorphic characteristics in women are widely acknowledged as desirable by men (see Sexual attraction). Desmond Morris discusses the importance of neoteny in human sociobiology in The Naked Ape, The Human Animal, and The Human Zoo.

It is also worthy to note that paedomorphic variations not only exist between the sexes, but also between individuals, with some people displaying more characteristics of neoteny than others. This trend carries over to variations among ethnic groups as well.

Animal kingdom

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One example of a neotenic trait in vertebrates is the salamander species axolotl, which usually remains fully aquatic as it matures.

It is also theorized that the phylum Chordata first originated as a result of paedomorphism occurring in a highly primitive animal such as a sponge or coral.

Neoteny and progenesis

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Neoteny and progenesis are both mechanisms that result in paedomorphosis. Neoteny delays physiological and sexual maturity. Comparatively, progenesis halts development of the organism before achieving the adult maturity experienced by its ancestors. Progenetic organisms achieve sexual maturity in this juvenile state and is found among certain amphibians and insects.

Evolution

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Neoteny also plays a role in evolution, as a means by which, over generations, a species can undergo a significant physical change. In such cases, a species’ neotenous form becomes its “normal” mature form, no longer dependent upon environmental triggers to inhibit maturity. The mechanism for this could be a mutation in, or interactions between, genes involved in maturation, changing their function to impede this process.

Humans exhibit a number of prominent neotenies compared to the other great apes. Adulthood begins in chimps at about 2-3 years; in humans this occurs between the 14th and 17th year.

Neoteny is not the only contributing factor affecting maturation in species that may have undergone neotenous changes over the course of their evolution, and its actual involvement in the following examples is not well understood:

• flightless birds—physical proportions resemble those of the chicks of flighted birds;
• humans—with traits such as sparse body hair and enlarged heads reminiscent of baby primates.
• dogs—which share many physical features with the immature wolf

See also

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• Cuteness
• Heterochrony
• Paedogenesis

External links

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• DannyReviews.com—Ontogeny and Phylogeny, Stephen Jay Gould (book review), Danny Yee (October 16, 1992)
• DavidBrin.com—“Neoteny and Two-Way Sexual Selection in Human Evolution: A Paleo-Anthropological Speculation on the Origins of Secondary-Sexual Traits, Male Nurturing and the Child as a Sexual Image,” David Brin, PhD
• Neoteny.org—“Neoteny: The multidisciplinary implications of heterochronic theory”
• NIH.gov—“Ontogenetic study of the skull in modern humans and the common chimpanzees: neotenic hypothesis reconsidered with a tridimensional Procrustes analysis,” X. Penin, C. Berge, M. Baylac, American Journal of Physical Anthropology, vol 118, no 1, p 50-62 (May, 2002)
• NHM.org—“Neoteny/Juvenilization: Some dogs look and act forever young,” Natural History Museum of Los Angeles County

Developmental biology | Evolution | Evolutionary biology

Neotènia | Neotenie | Neotenia | Néoténie | Neotenie | ネオテニー | Neoteni | Neotenia | Неотения | Неотенія