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Human Domestication

May 25, 2012

Philosophers have long been plagued with the question of man’s place in nature.


Jean-Jacques Rousseau (1755), for instance, had argued that “civilised” living conditions would have negative consequences, labeled under the term “degeneration” (Rousseau JJ: Discours sur l’origine et les fondemons de l’egalité parmis les hommes. Amsterdam: Marc Michele Rey; 1755.)


In the 1940s, the German philosopher Arnold Gehlen proposed a self-domestication theory of homo sapiens, according to which domestication would, on one hand, induce biological maladaptedness through abandoning natural selection, but, on the other hand, open new prospects for cultural development.(Gehlen A: Der Mensch. Seine Natur und seine Stellung in der Welt. 3rd edition. Berlin: Junker und Dünnhaupt; 1944.)

In regards to the discussion of human biological changes resulting from domestication, psychiatrist Martin Brune reminds and warns us,

Albeit modern human biology may be largely free of moral allegations, there seems to be a need for discussing the possible impact of biological findings and hypotheses on contemporary conceptualisations of mental health and treatment options of psychiatric disorders. This premise is based on the fact that biological ideas have always been at risk of socio-political misuse, and on the concern that the advent of new genetic techniques may be tempting to “improve” human genetic material and eliminate unwanted traits, part of which could erroneously be attributed to human self-domestication.  (Brune, Martin: On human self-domestication, psychiatry, and eugenics, in Philosophy, Ethics, and Humanities in Medicine 2007, 2:21 doi:10.1186/1747-5341-2-21)

Brune is obviously referring to eugenics, theories of ‘master races’, etc. That is not what this paper will focus on. The purpose of this paper is to make the argument that ‘civilized’ humans are domesticated animals, regardless of genetic background. Furthermore, I propose that domestication is physically, mentally, emotionally and spiritually detrimental to any human being.


Charles Darwin emphasized (1) that the domestication of animals is more than taming, (2) that it represents a goal-oriented process for human purposes, (3) that the variability of physical and ‘mental’ characteristics is greater in domesticated species than in their wild ancestors, including the occurrence of dwarfism and gigantism, (4) that the behavioral plasticity and educability of domesticated species is greater, and (5) that the brain size of domesticated animals is smaller than that of their wild ancestors’.  (Darwin C: Variation of animals and plants under domestication. Volume 2. London: Murray; 1868.)

Darwin points out that, “man differs widely from any strictly domesticated animal; for his breeding has never long been controlled, either by methodical or unconscious selection.”(Darwin 1868: 29) However, I wish to point out that domestic humans are condemned to reproduce only with other domesticated humans, this, enhanced by socio-economic class systems, is a form of selective breeding. The overwhelming majority of civilized humans do not interbreed with the remaining hunter-gatherers of the world.

With respect to brain size, Darwin argued that in contrast to domesticated animals the human brain and skull has increased over time. This is simply incorrect.

University of Wisconsin Anthropologist John Hawks is quoted in a Discover Magazine article titled “If Modern Humans Are So Smart, Why Are Our Brains Shrinking?” :

“Over the past 20,000 years, the average volume of the human male brain has decreased from 1,500 cubic centimeters to 1,350 cc, losing a chunk the size of a tennis ball. The female brain has shrunk by about the same proportion. “I’d call that major downsizing in an evolutionary eyeblink,” he says. “This happened in China, Europe, Africa—everywhere we look.” If our brain keeps dwindling at that rate over the next 20,000 years, it will start to approach the size of that found in Homo erectus, a relative that lived half a million years ago and had a brain volume of only 1,100 cc.”  (McAuliffe, Kathleen “If Modern Humans Are So Smart, Why Are Our Brains Shrinking?” Discover Magazine Jan. 20, 2011)

So why is this happening? The article continues:

“Which brings us to an unpleasant possibility. ‘You may not want to hear this,’ says cognitive scientist David Geary of the University of Missouri, ‘but I think the best explanation for the decline in our brain size is the idiocracy theory.’ Geary is referring to the eponymous 2006 film by Mike Judge about an ordinary guy who becomes involved in a hibernation experiment at the dawn of the 21st century. When he wakes up 500 years later, he is easily the smartest person on the dumbed-down planet. ‘I think something a little bit like that happened to us,’ Geary says. In other words, idiocracy is where we are now… A recent study he conducted with a colleague, Drew Bailey led Geary to this epiphany. The aim of their investigation was to explore how cranial size changed as our species adapted to an increasingly complex social environment between 1.9 million and 10,00 years ago. Bailey and Geary found population density did indeed track closely with brain size, but in a surprising way. When population numbers were low, as was the case for most of our evolution, the cranium kept getting bigger. But as population went from sparse to dense in a given area, cranial size declined, highlighted by a sudden 3 to 4 percent drop in EQ starting around 15,000 to 10,000 years ago. ‘We saw that trend in Europe, China, Africa, Malaysia—everywhere we looked,’ Geary says. The observation led the researchers to a radical conclusion: As complex societies emerged, the brain became smaller because people did not have to be as smart to stay alive. As Geary explains, individuals who would not have been able to survive by their wits alone could scrape by with the help of others—supported, as it were, by the first social safety nets.”

Geary is saying that civilization(dense, settled populations) makes us idiots!

From a biological perspective the greatest dispute with regard to physical changes in anatomically modern humans akin to domestication pertains to the decline of brain volume from around 1,500 cm3 to roughly 1,350 cm3, which could be interpreted in further support of the human self-domestication hypothesis. However, an argument has been made that the decline in stature was accompanied by a reduction in body size such that the allometric brain-body relation remains unchanged.(Ruff CB, Trinkaus E, Holliday TW: Body mass and encephalization in Pleistocene Homo. Nature 1997, 387:173-176)

But the more current research of John Hawks points out that, in civilized peoples, brain size has decreased more than the body:

“Hawks spent last summer measuring skulls of Europeans dating from the Bronze Age, 4,000 years ago, to medieval times. Over that period the land became even more densely packed with people and, just as the Missouri team’s model predicts, the brain shrank more quickly than did overall body size, causing EQ values to fall. In short, Hawks documented the same trend as Geary and Bailey did in their older sample of fossils; in fact, the pattern he detected is even more pronounced. Since the Bronze Age, the brain shrank a lot more than you would expect based on the decrease in body size,” Hawks reports. “For a brain as small as that found in the average European male today, the body would have to shrink to the size of a pygmy” to maintain proportional scaling.” (McAuliffe, Kathleen: If Modern Humans Are So Smart, Why Are Our Brains Shrinking? Discover Magazine Jan. 20, 2011)

So as we see, since the beginning of the Neolithic Revolution; not only has the human brain shrunk relative to the whole body, it’s size reduction is even more prominent for those humans living in civilization (post Bronze Age populations of high density).

Volume 5 of Grzimek’s Encyclopedia of Mammals shows a decrease in brain size for domestic animals species:

There is a close correlation between brain changes and behavioral changes in domestic animals. It has been primarily gregarious wild species that have been domesticated. In captivity, social behavior patterns changed. Many social structures that have the effect of preserving the species in the wild lose their purpose in captivity. Indeed, in view of high-density living conditions, social structures are disadvantageous for contact of domestic animals among themselves and with humans. (Grizimek’s Encyclopedia of Mammals)


In the 1940s Nobel laureate Konrad Lorenz speculated on the relation of human psychological capacities to the process of domestication. In his article Durch Domestikation verursachte Störungen arteigenen Verhaltens (“Domestication-induced disorders of species-typical behaviour”, published in 1940) Lorenz reiterated parallels between the living conditions of civilized inhabitants of metropolitan areas with domesticated animals, which he thought indicated signs of degeneration. (Lorenz, K: Durch Domestikation verursachte Störungen arteigenen Verhaltens Z Angw Psychol Charakterk 1940, 59:2-81.)

In the biological literature following Darwin, the term “domestication” became increasingly poorly defined. The criterion of intentional and goal-directed selection, which according to Darwin’s definition was critical for domestication, was largely replaced, at least with respect to humans, by the equation of culture and civilization with domestication.

To more fully understand human domestication, we must delve into the theory of psychological neoteny.

Psychological neoteny is a theory proposed by psychiatrist Bruce Charlton, in which ever-more people retain for ever-longer the characteristic behaviors and attitudes of earlier developmental stages. He used the term neoteny in reference to biological neoteny. To understand psychological neoteny, lets first discuss biological neoteny.

In developmental biology, neoteny is one of the two ways by which paedomorphism can arise. Paedomorphism is the retention by adults of traits previously seen only in juveniles.

Physical, behavioral and neurological features “prolong” over generations, manifesting later and later in ontogeny until specific characteristics of embryos, babies and toddlers emerge as full-blown adult characteristics.


Domestication has involved selection for behavioral characteristics that characterize young animals so, since “behavior is rooted in biology”, domestication has resulted in an array of similar neotenous physical traits having arisen in various domesticated animals.(Trut, L. N. (1999). Early Canid Domestication: The Farm-Fox Experiment American Scientist. 87(2), 160-169.)

Comparative studies on dog and wolf behavior and anatomy have shown that dog physiology and most dog behaviors are comparable to those of young wolves, an example of neoteny and pedomorphism.

Neotenous Wolf

Psychological neoteny is a theory proposed by psychiatrist Bruce Charlton, in which ever-more people retain for ever-longer the characteristic behaviors and attitudes of earlier developmental stages.

Bruce Charlton is a doctor and psychology professor at Newcastle University in Britain. His paper The rise of the boy-genius: psychological neoteny, science and modern life introduced the theory of “psychological neoteny”. The following is the abstract from his paper:

“The mid-twentieth century saw the rise of the boy-genius, probably because a personality type characterized by prolonged youthfulness is advantageous both in science and modern life generally. This is the evolution of ‘psychological-neoteny’, in which ever-more people retain for ever-longer the characteristic behaviours and attitudes of earlier developmental stages. Whereas traditional societies are characterized by initiation ceremonies marking the advent of adulthood, these have now dwindled and disappeared. In a psychological sense, some contemporary individuals never actually become adults. A child-like flexibility of attitudes, behaviours and knowledge is probably adaptive in modern society because people need repeatedly to change jobs, learn new skills, move to new places and make new friends. It seems that this adaptation is achieved by the expedient of postponing cognitive maturation – a process that could be termed psychological neoteny. (‘Neoteny’ refers to the biological phenomenon whereby development is delayed such that juvenile characteristics are retained into maturity.) Psychological neoteny is probably caused by the prolonged average duration of formal education, since students’ minds are in a significant sense ‘unfinished’. Since modern cultures favour cognitive flexibility, ‘immature’ people tend to thrive and succeed, and have set the tone of contemporary life: the greatest praise of an elderly person is to state that they retain the characteristics of youth. But the faults of youth are retained with well as its virtues: short attention span, sensation- and novelty-seeking, short cycles of arbitrary fashion and a sense of cultural shallowness. Nonetheless, as health gets better and cosmetic technologies improve, future humans may become somewhat like an axolotl – the cave-dwelling salamander which retains its larval form until death.”  (Charlton BG. The rise of the boy-genius: psychological neoteny, science and modern life. Medical Hypotheses. 2006; 67: 679-81)

Traditional tribal and agricultural societies are characterized by ‘initiation ceremonies’ marking very clear-cut transitions between the stages of life: especially the advent of formal adulthood.(Campbell Joseph, The masks of god: primitive mythology, Penguin: New York, USA, 1991.)

Xhosa male initiation

Initiation ceremonies have been completely wiped away by modern industrial society:

“Indeed, some traditional societies are ‘gerontocracies’ in which age accumulates prestige. But over recent decades in liberal democracies, these transitional ceremonies have dwindled in importance, and often disappeared altogether. The ‘coming of age’ now serves only as an excuse for a party. The reason is that, in an important psychological sense, some modern people never actually become adults – or, if they do, the process is delayed into late middle age when loss of youthful appearance and vitality becomes impossible to deny. The timing of significant marker points of maturity – such as graduation from college, marriage, first child – which used-to occur at almost fixed ages, are in modern cultures stretched across a much larger time span than in the past, mainly by increasing delays in some individuals… With such a chronological spread of events, each individual’s experience is now probably unique in its specific combination and timing of such significant events – which further erodes the predictable progress through formal stages of maturity characteristic of traditional societies. The gradual diminution of initiation ceremonies and indefinite postponement of adopting a stable, integrated adult personality is no accident: these facts recognize that modern societies are characterized by a continual requirement, throughout life, for a child-like flexibility of attitudes, behaviours and knowledge [2, 4]. People need repeatedly to change jobs, to learn new skills and information, to move to new places and cultures, to make new friends – all of these are a cultural novelty for human animals evolved to cope with small hunter gatherer societies of just a few hundred people[1, 4]. Since mature adults have not evolved to manage these challenges, it seems that people have adapted by postponing their psychological maturation – a process that could be termed psychological neoteny.”  (Charlton, B.G. 2006)

But of course there is a downside to psychological neoteny, in that the faults of youth are retained as well as its virtues. Modern society is characterized by a short attention span, frenetic sensation- and novelty-seeking, ever-shorter cycles of arbitrary fashion, and (so cultural intellectuals would argue) a pervasive emotional and spiritual shallowness. There are a lot of divorces and broken families. Modern people – it seems fair to say – also lack a profundity of character which seemed commoner in the past.(Charlton B.G. 2006)

The gist of Charlton’s hypothesis is that ‘psychological neoteny’ is an adaptation to domestication, that results in emotional and spiritual shallownesss. What I am contending is that the traits of psychological neoteny are not necessarily beneficial, as proponents of modern society and it’s “boy geniuses” would claim. Psychological neoteny is only necessary for survival in an industrialist culture.

In science, medicine, and most of modern life there has been a powerful and progressive trend toward specialization with less competency in general survival abilities.(Charlton B, Andras P. The modernization imperative. Imprint Academic: Exeter, UK, 2003.)

Psychological neoteny is the response of the human psyche to the trauma of domestication. Consequently, this adaptation to modern society is not necessarily healthy for a human being.

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  1. I’m not sure if you still operate this website, but I just want to let you know the following: today i started a research in order to understand if I could raise a wolf instead of a dog because i thought they are more “whole” beings. and after a couple of articles i came across this one and now my picture of the situation in which we are right now in the world made SENSE for the first time. Thank you for that.

    (By the way I’m not getting a wolf ;))

  2. I’m not sure if you still operate this website, but I just want to let you know the following: today i started a research in order to understand if I could raise a wolf instead of a dog because i thought they are more “whole” beings. and after a couple of articles i came across this one and now my picture of the situation in which we are right now in the world made SENSE for the first time. Thank you for that.

    (By the way I’m not getting a wolf ;))

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