What is Neoteny?

February 24, 2010 | 19 Comments

While reading Still Life with Woodpecker by Tom Robbins in the early 1980s, for the first time I came across the word “neoteny.”  Robbins may have been familiar with Stephen J. Gould’s work, Ontogeny and Phylogeny, published in 1977.  Ontogeny and Phylogeny is considered the most important modern exploration of neoteny.  Gould believed neoteny explained how human beings evolved.

Gould described the dynamics of heterochronic theory.  Neoteny is one of the six processes of heterochrony.  Here we’ll mostly talk about neoteny and neoteny’s opposite, acceleration.  Both describe how changing the rate of maturation can result in lightning-fast evolution.  Changing the timing of maturation also affects evolution.

When describing neoteny, Gould and others have found it convenient to consider the chimpanzee as representative of a human-like forebear perhaps five million years old.  If you note a chimpanzee infant’s relatively small chin, large head relative to body size, large eyes relative to face and upright positioning of the head on the neck, you get the idea that a chimpanzee infant exhibits features much like a contemporary human adult.  There are a number of features retained by a chimpanzee infant, and the infant of what would be our ancient ancestor, which over a period of thousands of generations grew slowly to appear in the features of descendant adults, moving upwards through toddlers to preteens to adolescents.  That is the basic principle of neoteny.  Ancestor infant features prolong or extend themselves over the course of evolution into later and later maturational phases until infant traits appear in the adults of descendants.  Not just physical features are affected.  Ancient chimpanzee infant or human forebear child personality characteristics such as curiosity, playfulness, displays of affection and social behavior all prolong themselves, through neoteny, to appear in the features of adult descendants, modern humans.

Acceleration is the opposite of neoteny.  Imagine an animal, over time, condensing or withdrawing adult features backward, or earlier, over generations.  Ancestor adult features appear earlier and earlier with successive generations until the traits of adult ancestors appear in the children of their descendants.  For example, if a relatively hairless elephant forebear had evolved into the mammoth when an ice age came, the hairy aspect of an adult may have resulted, over time, in hairy babies.  Evolution would in this case encourage the acceleration of maturation so that adult features appear in the very young, with the adults becoming even hairier over time.

Prolonging maturation results in neoteny.  Neoteny is when ancestor infant features appear in descendant adults.  Withdrawing or condensing maturation creates acceleration, or the moving backward through ontogeny, or development, so that adult characteristics emerge in the young of descendants.

By adjusting only the rates and timing of maturation over generations, evolution can be dramatically sped up.  Mutation is not required.  Evidence suggests that a host of environmental influences in addition to sexual selection can directly influence the rate and timing of maturation, resulting in neoteny and its opposite.

Foxes have been observed to evidence dramatic changes in look and behavior in as few as 20 years of targeted breeding.  Individuals were selected to breed that exhibited “tame” behavior, or the neotenous features of cooperation, playfulness and displays of affection.  Coats changed, ears flopped down, barking emerged and even estrus varied, prolonging reproduction periods.  This happened in less than a dozen generations.  When humans selected cooperative individuals to mate, cooperation became a feature of descendants.  Physical changes accompanied selection for behavior.

In perhaps the most unique exhibition of neoteny and acceleration, in Mexico there is a salamander-like creature called an axolotl.  It has external gills and spends its whole life in the water.  Change the axolotl environment and remove the water, and the axolotl, over a generation, will adjust to become a creature virtually identical to the North American salamander.  The North American salamander lives on land and uses lungs.

The axolotl is the larval or embryonic stage of the salamander.  This creature can evolve or adjust maturation to offer descendants a choice of a larval version (living in the water) or an adult version (living on the land).  Both forms reproduce.  The axolotl features neotenous characteristics of the salamander.  Or, you might say that the salamander exhibits acceleration regarding axolotl features.

The absence or presence of water determines which form this axolotl/salamander takes, an environmental effect.  With wolves or foxes, generations change according to which features humans select when assigning mates.  Humans also change, exhibiting neoteny or acceleration, based upon environmental influences or features selected when mates are chosen.  With humans, I hypothesize that those environmental features that influence levels of testosterone and estrogen affect the rate and timing of maturation.  In addition, how humans select each other as mates, their sexual selection behavior from within social structures, also determines the speed and intensity of maturation-rate-and-timing-determined evolution.

Testosterone controls the rate of maturation.  Estrogen controls the timing.  Human evolution is controlled by these two hormones.

Specific environmental variables influence the levels of testosterone and estrogen in males and females.  Light, diet, stress, exercise, drugs, alcohol, tobacco use and touch all influence testosterone and often estrogen.  Sometimes they affect males and females in opposite directions.

I hypothesize that if a mother with an embryo behaves in ways or is exposed to factors that increases or decreases these hormone levels in her womb, the maturation rates and timing of her children will be affected.  I posit that a result can be the prolongation or acceleration of maturation, accompanied by changes in the timing of maturational events.  For example, increasing a mother’s testosterone and estrogen levels will decrease her son’s testosterone and estrogen levels.  A lower rate of testosterone slows maturation.  A lower level of estrogen delays the timing of specific maturational events.  A net result may not only be a slower maturing son, but a son with less synapse pruning of the right cerebral hemisphere when very young.  A hallmark of facile language use is a smaller right cerebral hemisphere.  If this pruning is diminished or delayed, the son may be challenged in the use of language.  Adjusting the timing of maturation can result in differences in adult predilections or behaviors. This is how I connect neoteny with autism.

If an aboriginal society is introduced to high-fat diets, the age of puberty drops.  If high-fat diets continue, the age of puberty drops further with successive generations.  The timing of maturation has been affected with elevated estrogen levels causing an earlier surge in pubertal synapse-pruning testosterone.  Puberty comes earlier.  In the West, with several generations of increased fat, the age of puberty has dropped three to four years.

If an infant has testosterone and fat or estrogen levels that are too low, language-encouraging testosterone surges may be delayed.  Children emerge from their parents with hormonal constellations based upon their parents’ testosterone/estrogen balance and changes that may have occurred while in the womb.  Testosterone and estrogen naturally ally themselves to specific social structures, patrifocal or matrifocal.  The mating of a high-testosterone woman with a low-testosterone man constitutes a central core of matrifocal social structure.  The mating of a high-testosterone man with a low-testosterone woman is central to patrifocal social structure.  Varying levels of estrogen impact social structure, compelling additional variations.  The net result is that how people select mates leads to the promotion of specific characteristics that can change over time as the environment adjusts levels of testosterone and estrogen.

For example, let’s say a patrifocal aboriginal society experiences climatic change.  Increases in rainfall result in the blossoming of high-fat foods.  Putting on bulk, females experience increases in both testosterone and estrogen.  Male testosterone diminishes.  The age of puberty drops.  Females with a more authoritative hormone distribution begin to pick males that behave cooperatively.  Domineering men grow less common.  Over generations, birth rates increase, accompanied by a shift in social structure and sexual selection.  Commanding woman and cooperative man become the new convention.

The females exhibit an acceleration of characteristics that exhibit authority at younger and younger ages.  The males feature more and more neoteny over generations as they prolong the trait of childlike cooperation into the behavior of adults.  Evolution in humans features a balance of both neoteny and acceleration as sexual selection within social structure in combination with environmental influences compel a balanced transformation.

Bands of proto humans over time drift in neotenous and accelerated directions, transforming quickly in just the way that we breed dogs.  Still, there is an overall trend in a neotenous direction.  Playful, curious, creative, social and affectionate adults become more and more highly valued over time.

Lightning-fast human evolution is a direct result of sexual selection and environmental effects influencing testosterone and estrogen to adjust maturation rate and timing to speed up physical and behavioral transformation.  Wolves, foxes and salamanders evolve in just this way.  So do humans.


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19 Comments so far

  1. James Strawbridge on October 15, 2009 9:07 am

    I really enjoyed finding your thoughts on neoteny. I first came across it some years ago in ‘Still life with woodpecker’ and combined with the phrase ‘the young will grow’ (mentioned in a short story by Nigerian writer Ben Okri) it has determined much of my thoughts on life and even business. In fact I named my company ‘neoternal’ as a result. I think it’s a great name but causes huge marketing problems because everyone goes: “what?” and I usually have to spell it letter by letter. Anyway, thank you for a very insightful and informed post on the subject.

  2. Andrew on October 15, 2009 10:06 am

    Thank you, James, for your comment. Neoteny seems to be a sleeper concept, occasionally referred to, but usually unclear when it come up. I’m hoping the additional conjectures I’m assigning to the concept doesn’t make things even cloudier.

  3. Jon Gluckman on October 19, 2009 1:43 pm

    Very good capsule version of your ideas, suitable for framing. Thanks again for being “out there.” How and why “cosmic” events should partake of timing/maturation heterochrony in ways analogous to biological processes eludes me. Maybe you’ll come up something Jungian next, a la synchronicity. Of course, you would avoid veering into mysticism!

  4. Andrew on October 19, 2009 1:55 pm

    I keep thinking of cosmic events as regards these theories because physicists naturally use natural selection to explain cosmic events. If natural selection does not satisfactorily explain evolution, and dynamics involving maturation does, then the question is, does any dynamic that unfolds across time also experience the prolongation of early era features into later stages, and visa versa.

    An answer may come in S. J. Gould’s discussion of how an understanding of the means vs. the averages of systems comes with any system for which boundaries exist. If there is a boundary, as there is in any process that unfolds across time, the boundaries being birth and death, then there is a natural compelling of information to congregate at some distance from the walls.

    I have no experience with laws of averages, means, and statistical patterns. Perhaps someone with some experience can jump in.

  5. Neoteny - ForumGarden on November 25, 2009 7:38 am

    […] process of animal species such as humans. I’d like to know your thoughts. Thanks for your time. Neoteny, testosterone, estrogen and the rate and timing of maturation. | Neoteny, sexual selection, … __________________ Feeling strange – like you’re different – as if you’re on the wrong planet? […]

  6. Troy Camplin on February 9, 2010 5:12 pm

    I go so far in my dissertation “Evolutionary Aesthetics” to argue that neoteny was what was responsible for the evolution of language as well. It may also be why pedophilia exists — which may also go a long way to explaining why pedophiles have proven notoriously incurable. It seems, in evolution as in much of our behaviors, we are a deeply tragic species.

  7. Andrew on February 9, 2010 10:36 pm

    Indeed, I believe there is a powerful bond between neoteny and language, and perhaps between neoteny and speech. Regarding pedophilia, I never gave it thought in connection to neoteny. What you say makes sense. Bonobo are neotenous chimpanzees and engage occasionally in child sensuality.

  8. Jon Gluckman on February 10, 2010 1:37 pm

    Something is not reconciled in my mind. I started long ago with Weston LaBarre’s “Shadow of Childhood” as an introduction to neoteny (I haven’t read Gould et al). In that book neoteny is presented as the source of human error in judgment and rationality; that is, prolonged infant dependency leaves the child “believing” in authority figures and in constant need as an adult for such irrational allegiances, regardless of those leaders’ patent intellectual dishonesty and moral turpitude. Yet it is a child who sees the emperor’s lack of clothing and magicians despair of misdirecting the attention of an audience of children. And you present the human products of increased neoteny as “playful, curious, creative, social and affectionate,” with linguistic superiority as well as liable to support matriarchy. I find this, if not a paradox to tickle your fancy, then an enrichment of whatever irony can be derived from our situation. At least in this country neoteny is a fatal flaw, and the reaction away from the brief 1960s flourishing of neoteny has left us in a greater slough of closed-mindedness than existed before. The corporate military-industrial-medical-media-agribusiness complex runs on treating the public like neotenized herd animals. Where is the optimism? Spengler said optimism is cowardice, but you don’t strike me as unwilling to consider the darker side of things. How to resolve my quandary?

  9. Troy Camplin on February 10, 2010 6:17 pm

    Humans are all those things (though I don’t thin neoteny makes us “herd animals” — as that is a very mature-animal behavior). We both believe in the magician and see right through him. We are playful, inventive, creative, etc. But we are also prone to accepting authority and beleiving in magical castles in the sky — the source of our love of utopian visions of all sorts. And at the same time, we are childishly rebellious. Neoteny makes humans more paradoxical and, thus, more complex. Both visions are correct simultaneously. We are a tragic animal.

  10. Andrew on February 10, 2010 9:07 pm

    Hey Jon and Troy,

    Jon, your focusing on both the dark and light sides of what we carry into adulthood offers a balance that I don’t personally usually run with. I talked about this a little in the posting here http://bit.ly/5V1uu6. What I think you’re doing is confusing natural childhood states with traumatized or unnatural childhood experiences. Hrdy’s Mothers and Others offers insight into this area by suggesting matrilineal/matrilocal hunter gatherer societies display a unique, compassionate, egalitarian world view.

    Troy, I believe the tragedy is our interpretation of experiences from a split consciousness point of view, without a developed intuition for what bridges the split. Both visions may be correct simultaneously, yet, I believe, what makes them both correct is less paradoxical than our not yet identifying with both sides.

  11. Thomas McVeigh on April 15, 2010 10:03 am

    Hi – loving the concept of neoteny, and how it shaped human evolution; and within this article the ideas about high-fat diets resulting in societies composed of earlier sexual maturity, dominant females and cooperative males is very interesting.

    Perhaps most interesting is the axolotl. There is a theory called the Aquatic Ape hypothesis. Born of the idea that modern man evolved distinct form our ape cousins because we lived in a water dominated environment (leading to our hairless bodies, “hooded” noses, larger brains?, etc) – this theory fits well with neoteny as it suggests we may have needed adolescent traits (perhaps going as far back as taking some of the traits of our amphibian-like foetus) to survive in a significantly different environment.

  12. Brian on November 16, 2010 3:57 pm

    I see the same problem that Troy does. Animal infants are all “playful,” but human infants are not “curious, creative, social and affectionate,”, and have no respect for authority. They are very egotistical and dependent. They must be taught affection, co-operation, and herd mentality, to survive the modern jungle, or they perish.

    But I do hope that this will also end “common sense” concept that war was a male invention: We as homo sapiens, probably killed off the other homo erectus rivals like Neanderthals, which ended-up as “dead-ends”. It could have been females who encouraged, striking the “next-tribe-over”, for security reasons. The females had the co-operation of the brute force needed, just like today.

    But in public this idea is seen as ridiculous by both women & men. Why? “Male pride”

  13. Brian on November 16, 2010 4:06 pm

    Compassion-of-the-other (someone or something different from our own family unit) is the thing which is NOT being taught to children at any stage of development, and is a key to our survival.

  14. Troy Camplin on November 16, 2010 4:09 pm

    Indeed. A great deal of recent research shows that such compassion only comes about through trade. It is the great civilizer

  15. Anna on February 22, 2011 6:18 am

    @ Brian,

    Compassion-of-the-other (someone or something different from our own family unit) is the thing which is NOT being taught to children at any stage of development, and is a key to our survival.

    Don’t all parents teach their kids to be good citizens and behave compassionate to others whether they know them or not?

    I agree with your earlier statement that infants are egoistical and dependant and must be taught affection for others, co-operation and so on (all though there are of course individual differences – not all kids are the same). I think the same applies to altruistic traits – the compassion for strangers. Infants don’t have it and they don’t grow it by themselves… they learn it.

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