The Domestication of Man: What the Silver Fox and Aurochs Tell Us About Our Own Evolution


"Domesticate (verb): to adapt (an animal or plant) to life in intimate association with and to the advantage of humans"

-Merriam Webster Dictionary

Part I - We Domesticate Them: The Silver Fox Experiment

In 1959, Soviet scientist Dmitri Belyaev began an extraordinary experiment.  He had hypothesized that the grey wolf had become the modern dog through the selection for a single trait, tameness.  To test his theory, Belyaev chose the wild silver fox and, for over 50 years, researchers selectively bred only the tamest fox cubs.

As the experiment progressed, startling traits started to emerge.  Not only were the foxes becoming tamer (based on "low flight distance", the distance one can approach the animal before it runs away) but they also began to show features such as raised tails, mottled coloration, and curly hair.  The speed with which these changes occurred was also unexpected.  Within just three generations, the foxes acted friendly towards their human caregivers, and after only 35 generations, they were tail-wagging, finger-licking, cuddle muffins.

The changes were not just superficial either. The tame foxes' skulls were also broader with shorter snouts and smaller teeth.  The foxes also retained into adulthood juvenile behaviors such as increased submissiveness and barking.  This process, alternately referred to as neoteny (from the Greek "neos"/"young" and "teinein"/"tend to") or pedomorphism, has been carried to an extreme degree in the development of "toy" and "teacup" breeds of dogs.

The results, therefore, backed up Belyaev's original hypothesis.  The ancestors of wolves had been solitary hunters.  By the time wolves were taken into human company, they had already developed a daytime hunting, pack structure that could have primed them for domestication by our daytime hunting ancestors.

Once a particularly "tame" wild wolf came into contact with ancestral humans, it would have been a rather natural decision to keep only the tamest cubs.  The usefulness of dogs then led to their near universal adoption by all human populations.  By replicating this process under the scrutiny of modern scientific observation, Belyaev demonstrated the likelihood of this chain of events.  His tame silver foxes are actually sold as pets to help fund the now struggling project.

However, the implications of Belyaev's study go beyond simply explaining the origin of dogs. Thanks to his research, we now know that an entire suite of pedamorphic physical, behavioral, and hormonal changes can result from the selection for tame behavior.

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Part II - We Domesticate Them and They Change Us: From Aurochsen to Holsteins

Milk, the ubiquitous white liquid that "does a body good". Most of us don't really think about milk all that much. It's just there; assumed even. Look at the new USDA "Food Plate", and you'll see milk, low-fat of course, positioned conveniently to the upper right of the plate, waiting for your hand and, later, gullet.

The awkward truth, however, is that milk is coaxed from the teat of a large ruminant animal. How this came to be is somewhat mysterious, and even more unlikely, considering that what we call "cows" used to be "aurochsen", a much larger, meaner animal that likely discouraged the theft of its precious milk by way of extremely long, sharp, horns.

As we learned earlier, from the example of the silver fox, there was probably a very strange aurochs, the result of genetic happenstance, that didn't run, or gore, when humans approached.  Over a short amount of time, this relatively tame beast beget more tame calves, which would start to display pedamorphic characteristics (brown spots, curly hair, placid demeanor, etc.) that would, thousands of years later, result in the doe-eyed Elsie.

Why the first cattlemen decided to take on the process of domesticating the aurochsen, is still unclear.  Perhaps aurochsen were kept as "portable meet lockers".  Cows could convert indigestible plants into food, but that first warm glass of aurochsen milk wouldn't have gone down so smooth.

Prior to the domestication of cattle, humans, like every other mammal species (thus defined by milk-producing "mammary glands"), drank milk, but it was from their own mother.  After a few years, babies would grow into children, and would then be weaned onto an adult diet of plants, animals, insects, etc.  Efficient as always, the body would then cease producing lactase (the enzyme that allows for the digestion of the milk sugar lactose).  The bottom line is (or was), adult mammals don't drink milk.

Well, rules are meant to be broken, and, after some award fumbling, we started to at least try drinking milk.  Most experienced terrible stomach upset, gas, and all the other symptoms of what we now call "lactose intolerance", but some special person didn't.  Instead of running off to the bathroom (or, more likely, a "latrine" or "shit pile").  This person, went on to sire children with the same genetic mutation for adult lactase production.  So great was benefit conferred by lactose tolerance that the trait emerged both in Eurasia (~10,000 BC) and later in several groups of African pastoralists (~6,000 BC).  Now, a full 75% of the human population has some capacity for digesting lactose beyond childhood.

By yielding to the human hand, cows ensured their survival (they number 1.5 billion), but pedamorphism has rendered them susceptible to predation (their natural aggression has given way to lackadaisical alarm) and dependent on human caregivers.  We willingly provide them with grazing land, burning forests and clearing trees in the process, and accept their noxious emissions (cattle account for almost 18% of greenhouse gasses) as their milk and meat sustains millions, if not billions of our kind.  Yet, in marrying the cow, we too were forever changed.

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Part III - We Domesticate Ourselves: Docile, Gracile, and Nearly Naked

When considering our own kind, we tend to exhibit a predictable bias. Uniquely human traits are situated atop the evolutionary pedestal and all other forms of life are so many steps along the way. Gazing into the mirror, we see our clothed bodies as a sign of having shed, both literally and figuratively, the hairy wildness of our ancestors. We brush our canineless teeth with clawless hands and accept that they must be the outcome of evolved "brains" triumphing over primitive "brawn".

What if, perhaps, there was something else at work? Numerous theories have been presented for curious, uniquely human, traits such as hairlessness (the "aquatic ape" theory for example), yet Occam's razor urges us to "tend towards simpler theories" and to select "the one that makes the fewest new assumptions."

So what, then, is already assumed?

Humans share a common ancestor with the modern chimpanzee, and, having changed little since our paths diverged, chimps can show us what we may have once been like.  Similarities between humans and chimps that are not found in any other mammals include the use of tools and the practice of war ("raiding" in evolutionary parlance). Yet, despite the fact that 96% of our DNA is identical, there are vast differences between us.

For one, chimpanzee society is divided into separate male and female hierarchies.  In practical terms, this means that guy chimps do guy chimp things with other guy chimps, with female chimps spending more time alone, typically gathering food for themselves and their young.  Within the male chimp hierarchy, there is typically an "alpha" male backed up by "lieutenants" (often related to the alpha male) and it is these dominant males who tend to have the greatest "fitness" in the Darwinian sense (i.e. the most chimp "baby mommas".)

Humans, on the other hand, form a pair bond, where each male is essentially guaranteed reproductive access to one or more females.  A side effect of the pair bond system is that human males have a reduced need for competition with other males and an increased opportunity to cooperate in activities such as raiding and complaining about their wives.

Additional traits that humans possess that chimps lack include our capacity for language, our spiritual and religious beliefs, and, after adopting sedentarism and agriculture, a stratified social structure with separate classes of warriors, priests, craftsmen,  politicians, farmers. etc.

What we see, then, is a gradual increase cooperation, that then enabled technological innovation and the emergence of new behaviors.  These new behaviors and technologies required further increases in cooperation, that then required even more innovation, and so on.  As human society transitioned away from  chimpanzee-like dominance hierarchies, and even from egalitarian hunter-gatherer social structures, we, like the cow and the dog, became more and more dependent on each other, and our new culture for survival.  (Note: Cooperation within a group does not imply or assume cooperation between groups.)

It doesn't take a great intellectual leap to see how the greater and greater "cooperation" assumed by nearly all anthropologists, evolutionary biologists, and sociologists could be another way of saying "tameness".  And, as we know from the previous examples of the wild fox and aurochs, we would then expect to see pedamorphism in humans; which is exactly what we do see.

When comparing infant chimpanzees and infant humans, both exhibit broad, flat features, small teeth, large eyes, and rounded skulls.  Both, too, have hair only on their head and back. As a chimpanzee matures, however, it's teeth become enlarged, it becomes more aggressive (greater levels of adrenaline), less playful and affectionate, a full coat of body hair develops, and its skull ridges become accentuated.  A human adult, on the other hand, reaches sexual maturity while retaining most of it's juvenile physical and behavioral characteristics.  It is possible, therefore, to look at certain human "advances" such as the adoption of clothing and the use of weaponry as necessary compensations for our truncated physical maturation.

Human neoteny has continued unabated and is well documented in the fossil record.  Gracilization, a term referring to the "refinement" of human features (less robust skeletons, smaller skull and brain size, flattened brow ridges, etc.), is pronounced not only when anatomically modern humans are compared to other human species like the Neanderthal and Cromagnon, but when comparing anatomically modern humans and even medieval skeletons to contemporary humans.  Inadequate diets, a reduced need for physicality in securing resources, and other environmental changes have been given as explanations for gracilization, but it is likely that these changes simply exacerbated the pedamorphic process already taking place.

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Part IV - Final Thoughts

Erwan Le Corre, founder of MovNat often refers to modern humans as "zoo humans", but this definition is not completely accurate.  Animals in zoos are still wild.  They are put on display so that we may be reminded, in some small way, of our own long lost wildness.  We are simply domesticated.  

The idea of human domestication may be distasteful to some, but this is likely due to our own perception of being "outside" of the natural world.  Many of us would like to believe that we are somehow insulated from the changes environment and evolution have wrought in other animal species.  Charles Darwin himself excluded human beings from his seminal work, "On the Origin of Species", anticipating the controversy such an idea would engender. (It would be more than a decade before he applied his theories to human beings in "The Descent of Man".)

In many real ways, domestication defines us.  With greater cooperation, docility, and curiosity, we have gone on to construct cities with millions of individuals living together in relative safety and enjoy passions such as art, fashion, and literature.  We now speak of "one human family" and hope for "world peace", yet, as much as we have been brought together, we are also split apart.  The eternal struggle of the "haves" vs the "have-nots" has echoed throughout recorded history and remains just as relevant today.

Yet, many of us still feel a yearning for a life uncertain, essential, and lived fully by tooth and claw.  We may have gone, unconsciously, like the dog and cow, into domestication, but unlike them, the leash and the tether rest in our own fleshy hand.  Like dogs howling at the moon, we occasionally cry out for the wild, dangerous places of our ancestors.  We bristle at the trappings of our self-made world, struggle against the yoke we placed on our own shoulders, and dream of sleeping under a sky carpeted with infinite stars.

It may be wise to honor our latent, "wild" genes, the vestiges of our ancient past, for the world of today is not guaranteed to be the world of tomorrow.


Resources:

"Domesticated Silver Fox" Wikipedia.org, http://en.wikipedia.org/wiki/Domesticated_silver_fox

"The Wild Life of our Bodies" by Rob Dunn, pg 119-29

"Cow 'emissions' more damaging to planet than CO2 from cars" By Geoffrey Lean, Environment Editor, Independant.co.uk, http://www.independent.co.uk/environment/climate-change/cow-emissions-more-damaging-to-planet-than-cosub2sub-from-cars-427843.html

"Occam's Razor" Wikipedia.org, http://en.wikipedia.org/wiki/Occam's_razor

"New Genome Comparison Finds Chimps, Humans Very Similar at the DNA Level" http://www.genome.gov/15515096

"Neoteny" Wikepedia.org, http://en.wikipedia.org/wiki/Neoteny

"Gracilization of the Modern Human Skeleton" by Christopher B. Ruff http://seattlecentral.edu/faculty/jwhorley/Gracilization.pdf

"Temporal Trends in Vertebral Size and Shape from Medieval to Modern-Day"
Juho-Antti Junno, Markku Niskanen, Miika T. Nieminen, Heli Maijanen, Jaakko Niinimäki, Risto Bloigu, and Juha Tuukkanen http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2652716/

"Charles Darwin" Wikipedia.org, http://en.wikipedia.org/wiki/Charles_Darwin
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About Tony Fed

Tony is the host of the Paleo Magazine Radio podcast, author of "Paleo Grilling: A Modern Caveman's Guide to Cooking with Fire", and Cofounder of Powerful PT, an innovative information resource for Fitness Professionals. He has appeared on numerous local and national television and radio broadcasts and regularly hosts healthy cooking workshops and informational lectures. He is also a full-time Personal Trainer and Wellness Consultant who lives in Jacksonville Florida with his wife Jamie.
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1 comments:

  1. Perhaps history does not agree? Neoteny yes, but not self administered. I suspect radiative stress diminishing intellectual capacity.

    ReplyDelete