From Ferocious to Fido: The Complex and Elusive Pathways of Animal Domestication

It is an occurrence that many of us have experienced: the day that we come into contact with the questionable pet.  Perhaps we are at a someone's house who we do not know too well, and they decide to show us their boa constrictor.  Or, in the background of your boss's zoom screen, you see a large cage filled with colorful tropical birds.  Or maybe you are just scrolling through Instagram or Facebook, and you see a heartwarming video about a man and the raccoon that follows him around his farm.  You enjoy seeing the creature scurry, slither, or flutter but something scratches in the back of your mind.   Is it appropriate that this animal is kept as a pet?  The animal seems calm and at ease, but does that mean it is domesticated?  What exactly is a domesticated animal?  How do we separate them from wild animals?  The questionable pet brings up confusion about which animals are supposed to live with us or in our society, and which are better off being left in the wilds where we found them. 

Is this a domesticated animal?
Source: Wikipedia

How about this one?
Source: Flickr

These questions are all valid ones because domestication is not a simple concept to wrap your head around.  Determining exactly when a species becomes domesticated is a convoluted and difficult task.  This may give you pause; we cannot tell domesticated and wild animals apart?  You could glance at your dog, asleep in their fluffy bed after a difficult afternoon of eating kibble and barking at nothing, and you think, "Well, there would be no mistaking Harvey over there with a wolf.  Why is there any confusion?"  However, the dog has had thousands of years of change thanks to domestication, forming it's obvious differences from the wolf.  But when exactly did the dog stop being wild and start being domestic?  What exact traits had to change in order to precipitate this shift?  Do all domesticated animals share these traits?  These finer details are what this article hopes to explore.

How it all got started

Let's start with a look at how this phenomenon first came about.  The domestication of animals (and plants) represented, "a major shift in the influence of humanity over their life on earth and ultimately over humanity's future" (Cucchi & Arbuckle).  When we started to shape other lifeforms around us, humans showed the intelligence to direct the natural system of evolution in order to create forms that better suited our purposes.  These changes were quick (in an evolutionary timeframe) and widespread.  Two thirds of all current terrestrial vertebrate biomass is made up of domestic animals, while humans represent that other third. In contrast, wild vertebrate animals only account for 3-5% of terrestrial biomass (Cucchi & Arbuckle).   Yet that overwhelming majority of biomass encompasses only 30 species of domesticated animals (HK Talks).  Domesticated species are part of a large but not diverse group of animals.  The expansion of human beings has affected all living things on Earth, but only a select few have been chosen to live as part of our society.  

Animal domestication is a relatively new development; Homo sapiens first emerged about 300,000 years ago but the first domesticated animal, the dog, appeared approximately 17,000 years ago.  The oldest known dog fossil is from a burial site in Iraq dated at 14,000 years ago and it is known that dogs accompanied the first Native Americans who crossed the Bering land bridge beginning 18,000 years ago (Robinson).  About 14,000 years ago, the second animal species was domesticated, the reindeer.  This species emerged in northern Scandinavia and Russia and, although changed little morphologically, was used for clothing, shelter, tools, food, and transportation.  The Laplanders of Finland, Sweden, and Norway continue to use reindeer as their principal occupation and livelihood (Robinson).  These first converts helped early humans live more comfortably as hunters and gatherers. When human society shifted to incorporate new ways of living, more species of animals were needed.

A cave painting of a wolf-like Canid, circa 17,000 years ago
Source: Wikipedia

With the development of agriculture, humans began to create permanent settlements and larger social structures. Three independent cradles of civilization birthed the livestock animal species that became paramount to agriculture.  Sheep, goats, pigs, and cattle were domesticated in Southwest Asia (the Fertile Crescent) between 10,000 and 10,500 years ago.  China separately domesticated the pig at around the same time.  And in the Andes mountains, camelids, llamas, and alpacas were brought out of the wild between 8,000 and 9,000 years ago (Cucchi & Arbuckle).  The majority of domesticated animals were transformed in years described as Before the Common Era (BCE).  While there have been some domesticated creations in the modern era (the hedgehog, koi fish) the rate of domestication has greatly decreased since ancient times. 

Timeframe of Animal Domestication
Source: CompleteEdNY

Defining Animal Domestication

So how do we define the process of Animal Domestication?  Every species experiences domestication differently, so it is hard to button down the specifics. Domestication is not a single trait but a suite of traits, comprising elements affecting mood, emotion, agnostic and affiliative behavior, and social communication that have all been modified in some way (Driscoll, MacDonald, & O'Brien).   Darwin believed that domestication is the process through which "Man selects varying individuals, sows their seeds, and again selects their varying offspring" which represented "an experiment on a gigantic scale" (Decory).  While not incorrect, Darwin's definition is too vague and does not help us determine when a domesticated species successfully emerges.  Since Darwin's time, nations and governments have attempted to define domestication for the purpose of writing animal welfare laws.  For example, the United Nations' current definition reads: "Domesticated or cultivated species means species in which the evolutionary process has been influenced by humans to meet their needs".  While technically correct, this legal definition oversimplifies the process and, like Darwin's definition, does not provide specifics on how to distinguish a domesticated animal from a wild one.

In my own research, the best definition that I found was from Melinda Zeder.  Zeder's definition accounts for the complexity of domestication while being understandable to the layperson.  She defines Animal Domestication as: "A sustained, multigenerational, mutualistic relationship in which humans assume some significant level of control over the reproduction and care of an animal in order to secure a more predictable supply of a resource of interest and by which the animal is able to increase its reproductive success over individuals not participating in this relationship, thereby enhancing the fitness of both humans and target domesticates" (Zeder).  There are a few pieces of this definition that deserve to be highlighted.  The first is that the process is "multigenerational".  Domestication is not a process that can be completed on an individual.  If you take an animal into your home and train it to coexist in your environment, you end up with a tamed animal but not a domesticated one.  For domestication to occur, generations of animals must be subjected to artificial selection resulting in physical, genetic, and behavioral changes to the species.

Domestication takes multiple generations to show a visible effect, but how many? A famous study explored the multigenerational quality of domestication: Dmitry Belyaev's domesticated fox experiment.  The experiment took wild Eurasian red foxes and sought to create a docile and domesticated species through selective breeding, while documenting the process.  The experiment started in the 1950's and is still ongoing.  It has succeeded in creating friendlier and submissive foxes with droopy ears and juvenile features, very similar to changes observed in domesticated dogs.  However, the foxes still exhibit wild and uncontrollable tendencies, so the researchers have not yet declared that they have created a separate domestic species of fox.  Thanks to research like this, it is generally thought that at least 50 generations of selective breeding must occur before a species can be considered domesticated, but more time is needed to confirm this hypothesis.

Dmitry Belyaev and some Fox test subjects
Source: Etología Familiar 

The other term featured in Zeder's definition that should be highlighted is "mutualistic".  Domestication represents a mutually beneficial relationship between the humans and their selected species.  Although the quality of life of some domesticates is arguably poorer than that of their free-living progenitors (i.e. livestock in factory-farms), there can be no question that domestication has vastly enhanced the reproductive output of livestock and pets far beyond that of the wild ancestors (Zeder).  What makes animal domestication special, when compared to natural forms of mutualism, is that the process of forming these relationships is guided and purposeful on the side of the human beings.  While the human beings of 17,000 years ago were not aware of the overall impact of their actions, they were consciously selecting animals that would be better suited to live amongst our species.  Humans created the first domesticated animals so that they would have hunting partners, livestock, transportation, and easy sources of natural resources and in the process, they allowed the domesticated species to spread across the globe in numbers that few wild species have reached.  

Farm animals
Source: What's up! trouvaillesdujour

Factors for Domestication

Why are there not more domesticated species?  As mentioned before, there is only about 30 different domesticated species of animal.  If the mutualistic relationship between humans and domesticates is so beneficial, why haven't we performed this process more often?  The answer is simple; it takes too much effort and a ton of time to domesticate an animal species.  Once mankind had a couple domesticate species available, like the livestock that came out of the fertile crescent, it just did not make evolutionary sense to keep domesticating other species.  Once the early domestics filled the niche in our agricultural system, there was no need for additional species.  Plus, not all species are good candidates for domestication, so there is no guarantee that if the process was begun, it would be ultimately successful.

Generally, there are six characteristics that make a species a good candidate for domestication, although the scale and prevalence of each characteristic varies greatly from species to species.  These characteristics are:

• Hardiness, or the ability of the young to be removed from its mother and be around humans instead.  
• Dominance social behavior; important because humans co-opt the function of the leader and animals remain submissive even as adults.
• Herd behavior, which makes animals easier to manage.  Think of the herds of cattle and sheep that are managed and moved efficiently by farmers and ranchers.
• Utility to humans or the ability to be useful as food, fiber, work, companionship, or even worship.
• Facile reproduction, or a reproductive process that is easily conducted in a variety of environments.  Animals with finicky reproductive behaviors or elaborate courtship rituals would be poor candidates for domestication.
• Facile husbandry: domestic animals should have placid dispositions and versatility in terms of nutrition.  Koalas, for example, only eat leaves from a certain type of eucalyptus tree, and thus they would make poor domesticates because of the narrow food source.

There are many wild species that will never be able to adapt to a domesticated lifestyle due to traits given to them by natural evolution. As stated by Decory, "Some groups are programmed to being wild, meaning they are genetically highly precocious or 'hard-wired' to being wild. These hard-wired groups include the reptiles and other ectothermic animals such as invertebrates, fishes, and amphibians".  You may see these animals show up in aquariums or tanks, but it is highly unlikely that they will undergo the process of domestication and become new species.

This brings us back to the idea of unusual pets.  While things like boas, parakeets, and clownfish might be kept in people's homes, these are not domesticated animals but wild animals that have been tamed.  "Taming is conditioned behavioral modification of an individual; domestication is permanent genetic modification of a bred lineage that leads to, among other things, a heritable predistortion towards human association" (Driscoll, MacDonald, & O'Brien).  A wild animal could be quite tame and, conversely, domesticated animals can be aggressive.  Good examples of this phenomena are koalas and bulls.  Koala's would make terrible domesticated animals as previously mentioned, but they are quite tame and are often used in hands-on tourist attractions in zoos (ethics of such practices aside).  Bulls are within a firmly domesticated species but also not an animal that you would just approach and give scratches to.  

Pathways to Domestication

If a species is a good candidate for domestication, how does it occur?  There are multiple ways that domestication can proceed, called pathways.  Melinda Zeder identifies three pathways.  The first, and the most historically common, is referred to the Commensal Pathway and is described as such: "animals begin their journey into domestication by establishing a commensal relationship with humans - a relationship in which one partner (the animal) benefits and the other reaps little if any benefit or harm.  At some point in this association with humans and anthropogenic environments, these animals develop closer social or economic bonds with their human hosts, who begin to derive some tangible benefit from the association.  This new reciprocity sets the former commensal and its human host on a pathway to a domestic relationship" (Zeder).  Easy examples of this pathway are our favorite pets, cats and dogs.  Both cats and dogs started their domestic lifestyle by scrounging at the boundaries of human settlements for accessible sources of food.  As time went on, the species became more integrated into human society and began to serve in roles within the settlements.  Dogs became hunting partners and guards, while cats served as pest control and, eventually, both evolved into the additional role of companion animal or pet.

The Pug: Terrible Hunting Partner, Great Friend
Source: Cuteopolis

The second pathway is somewhat more intentional on the part of humans and is called the Prey Pathway; this pathway involves the changing of prey species into livestock animals so that there is easier access to their resources.  Basically, instead of relying on hunting to gather materials like meat or pelts, humans captured the animals and bred them in a captive environment.  Over time, the species were changed by selective breeding to be tamer and more productive and our modern livestock species were born (Zeder).  Examples include sheep, goats, cattle, and pigs.  The Prey Pathway shows the development of human civilization during this time when compared to the Commensal Pathway, as pre-existing agricultural systems must exist for the pathway to succeed.

The final pathway is the newest but is the also the most dominant in our modern times.  It is called the Directed Pathway and it refers to "a process initiated by humans with the goal of domesticating a free-living animal to obtain a specific resource or set of resources of interest... it probably only came into being once people were familiar with either commensal or prey-pathway domesticated animals" (Zeder).  In other words, this is the most deliberate procedure in which humans look at a wild animal, see a resource they would like to take advantage of, and set out to intentionally change the species to do so.  An example of this is horses, which were only domesticated about 5,000 years ago.  Horses appear suddenly in the historical record as means of transport and to aid armies, so it is inferred that their domestication was quick and deliberate in the scale of evolutionary and historical time.  This pathway is the culmination of progress from the Commensal and Prey Pathways, as it allows for any potential and viable species to be domesticated, instead of species that were prey or pre-existing partners.

While never completed, many tried to domesticate elephants through the directed pathway
Source: Macedonian Documents Blogspot

Throughout the discussion of domestication, it cannot be emphasized enough how much time domestication takes.  In an evolutionary scale, domestication can be considered a quick and recent development, but when we think of how we as individual human beings conceive of time, the reality is that we would perceive it as being slow and almost static.  No single human being has ever experienced the complete transition of a wild species to a domesticated species.  This is an important notion to consider, that the change from wild to domestic takes generations of time, especially when we live in a world with unprecedented interactions between the natural and the anthropogenic.  

Why does this matter?

Wild and domesticated animals have wildly different needs and attributes, and the gap between these two groups is generations of time.  We must take these disparate needs into account as we determine how best to address animal welfare in our world.  An understanding of animal domestication and the differences between wild, feral, and domestic animals is paramount to the ethical treatment of animals.  

Muddled definitions and poor understanding of differences between domesticated and wild animals allows for the mistreatment of animals within the confusion and "gray-space" that results.  There have been many widely publicized attempts to pass tame wild animals off as pets and companion animals, but these animals are not domesticated and are not built to thrive in a domestic lifestyle.  Inversely, it has become very popular to promote and sell products and practices for domesticated animals that are based around the preferences of their wild relatives (for example grain-fee diets or training regiments based on wild social behaviors).  The distinction between the two groups needs to be understood and respected.

Unfortunately, much of our existing legal framework for animal welfare does not have the detail to allow for these differences to be considered.  For example, the State of Michigan defines a domestic animal as "those species of animals that live under the husbandry of humans"; while the Federal US government along with 25 state governments does not have a legal definition of "domestic animal" at all.  As Molly Kordas describes: "What has resulted from the high variation among the several states is a complex, confusing patchwork of state laws and more frequently, regulations that proscribe some conduct in relation to possession of wildlife, but exempt other conduct, leaving gaps in the law" (Kordas).  Thus, in this legal mud, people are free to treat wild animals as if they were domestic and vice versa, which can have drastic effects on welfare.  Again, Molly Kordas explains:

"Domestication and welfare are tangled as domestication is the process through which a group adapts to captive conditions and to humans.  Domestication therefore testifies to the animals suitability to be in captivity while maintaining a good welfare.  Wild and tame animals did not go through domestication, their wild, innate behaviors have not been modified drastically, thus, one can wonder how a wild or tame animal, kept in captivity, could have a good welfare" (Kordas).

I would argue that no wild animal (except in cases of medical, conservation, or educational need) should be kept in captivity.  But without a clear legal distinction between wild and domestic, it would be an arduous task to implement such a ban.  Yet the reach of mankind continues to grow, and with every expansion it becomes easier and easier for people to capture wild animals and force them to exist in an environment for which they are not well suited.  You see it frequently with new pet fads (golden hamster, chinchillas, sugar-gliders, parakeets, etc.) and the globalization of our economy only provides economic incentive for these animals to be thrust unwillingly into living rooms and backyard pens.  These practices are dangerous for humans and animals alike.  

Tigers have large ranges in the wild, and do not do well confined to human domiciles
Source: Yahoo!

Incidents between wild animals and the humans who convinced themselves that these animals were pets are plentiful.  Molly Kordas, in her article "Don't Fence Me In: A Case Against the Taming and Domestication of Wild Animals", does a good job of providing examples, including: "A beloved chimpanzee named Travis, turned on his owner's close friend, mauling her and forcing his owner to stab him with a butcher knife to stop the chimp's attack.  A black bear cub named Little Bear almost died from malnutrition and multiple seizures.  A South African hippopotamus named Humphrey mauled and killed his owner, seemingly out of the blue.  Dog-wolf hybrids, which are illegal in some states, have maimed and sometimes killed children in recent years" (Kordas, see article for links).  What we do not realize when we see these news pieces, is that the animals are often owned legally, or at least in the legal "grey-area" we discussed earlier.  It should be clear to any reasonable person that a tiger, chimp, or hippopotamus should not be kept by humans, but unspecific legislature ensures that there will always be someone willing to take this chance.  

Animal domestication can be difficult to digest due to its broad timeline, large variations between species, and vague end goals of the process.  However, it is important that the general population has a good understanding of the concept for the purposes of improving welfare of both wild and domestic animal populations.  The lay person should know that domestic animals have generations of artificial selection separating them from their wild counterparts.  Species that have undergone this process have had their physical and behavioral characteristics slowly altered so that they may thrive in a human controlled environment.  This conceptualization would be a great start to resolving the issue of mistreatment of wild animals from being forced into human-centric environments.  A greater knowledge of this topic would also allow stronger legislature to be passed such that animal welfare is more completely protected. 

 

References Cited:

A History of Animal Domestication. (2012, March 11). Ukwildlife. https://ukwildlife.wordpress.com/2012/03/11/a-history-of-animal-domestication-3/

Carlos A. Driscoll, David W. Macdonald, & Stephen J. O’Brien. (2009). From Wild Animals to Domestic Pets, an Evolutionary View of Domestication. Proceedings of the National Academy of Sciences of the United States of America, 106, 9971–9978. https://doi.org/10.1073/pnas.0901586106

Cucchi, T., & Arbuckle, B. (2021). Animal domestication: From distant past to current development and issues Introduction. ANIMAL FRONTIERS, 11(3), 6–9. https://doi.org/10.1093/af/vfab013

Kordas, M. (2018). Don’t Fence Me in: A Case against the Taming and Domestication of Wild Animals. Chicago-Kent Journal of Environmental and Energy Law, 8(1), ii–43.

Margot Simone Marcelle Décory. (2019). A Universal Definition of ‘Domestication’ to Unleash Global Animal Welfare Progress. Derecho Animal, 10(2). https://doi.org/10.5565/rev/da.424

Melinda A. Zeder. (2012). The Domestication of Animals. Journal of Anthropological Research, 68(2), 161–190.

Robinson, J. L. (2021). Animal domestication. In Salem Press Encyclopedia of Science. SalemPress. https://proxy.library.cornell.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=ers&AN=88833125&site=eds-live&scope=site

Society, N. G. (2011, January 21). Domestication. National Geographic Society. http://www.nationalgeographic.org/encyclopedia/domestication/