Avoid Table Scraps in Your Dog’s Diet
November 28, 2015
Show all

Dog evolution and domestication

Contents

  • Introduction 3
  • Evolution and domestication  4
    • The likely ancestor of the dog 4
    • The two main theories of domestication 8
    • How the dog developed into early breed types 9
    • Hierarchy systems 10
  • Conclusion 13
  • References 14

List of tables

Table 1: Canid species, their distribution and chromosome number      6

List of figures

Figure 1: Relationship tree of carnivores based on differences in single-copy DNA sequences5 (DTmR) (Wayne, no date).                                  7

 

  • Introduction

It is widely believed that every canine today can be traced back to the origins of Miacis, a small weasel type animal that existed around 55 million years ago (Strauss, no date). There are two main theories of how the dog became domesticated, both beginning with wild wolves. The first theory argues that humans took young wolf cubs out of the wild, reared and tamed them, over time selectively breeding them for help in tasks such as herding, hunting and livestock guarding. According to the second theory, adult wolves themselves joined the humans as settlements were established, thus benefitting from food and shelter, and in time being welcomed, bred from, and employed in these tasks (PBS, no date). As new breeds developed, their qualities and characteristics could be divided into groups, such as herding, guarding and hunting (Wayne, 2014).

Hierarchies have become a problem over the years, as early research into captive wolves and their social structure has been applied to domestic dog behaviour (sharing a common ancestor and being similar in body language and development). This has led to people assuming their pet dog is being dominant or pulling rank, when in fact it has not been trained what to do. A lot of people still believe if the dog is aggressive towards the human then that person has to fight back harder, to show they are alpha (Miller, 2011).

2.0 Evolution and domestication

2.1 The likely ancestor of the dog

Jenson (2007) stated that skeletal remains of early dogs were found in Mesolithic sites (culture sites) in Europe, Asia and America, the earliest dating back to 14,000 BP (before present). This evidence supports the theory that the dog was the first domesticated animal, thousands of years before farming stock. The first remains of the domestic dog, found in central and Eastern Europe and in the Middle East, are difficult to analyse as the differences between species (wolves and dogs) are not obvious. It is more than likely that every dog today can be followed back to its weasel-like ancestor Miacis, living 55 million years ago (Strauss, no date). There were a large number of predators, preceding the Canids, and overlapping their time line, for instance Amphicyon (‘bear dogs’), which more closely resembled bears than dogs.

The earliest Canids, and the bone crushing, Hesperocyaninae were the direct forerunners of all later Canids. These were around the size of a small fox and many of their remains have been found in North America (Strauss, no date). There appears to have been three main subgroups. The first Hesperocyon evolved in North America and became extinct 15 million years ago. Their appearance was that of cross between a weasel and a fox. The second group, the Borophaginae, increased in number around 3.4 million years ago. They were more like hyenas in appearance and had large powerful jaws. The Boraphagines eventually became extinct around 2.5 million years ago. .

The third group, the Caninae also included the dire wolf (Canis dirus), now extinct. This group seem to have been confined to North America until about 7 million years ago when some of the species crossed the land bridge into Asia (Anon ‘Wolf to Woof’, no date).

In more recent times), it has been suggested that jackals were partially domesticated and purposely bred with dogs during Egyptian times (Bradshaw 2012). However, evidence suggests that these either died out or eventually returned to the wild. This theory supports Lorenz’s idea of jackal domestication (Serpell, 2002). Further studies only provide limited evidence that all Canis species can produce fertile offspring and interbreed (Mikloski, 2012).

Up-to-date genome sequencing suggests wolf-dog diversification occurred between 11-16,000 years ago in South East Asia, the Middle East and Europe, which is supported by fossil findings. However, there is a discrepancy within genome dating due to current uncertainty about mutation rates (Freedman et al., 2014). This recent research questions previous hypotheses of one wolf group lineage, as there is no evidence to support the belief that modern dogs were related to modern wolves (Freedman et al., 2014). The study further highlights the complexity of dog domestication, suggesting the genetic overlap found in wolves and dogs could be as a result of interbreeding following domestication, and that the ancestral lineage of the dogs tested might have died out (Freedman et al, 2014). Bradshaw (2012) further supports this by suggesting there are coyote genes present in some modern dog breeds in North America.

Table 1. Canid species, their distribution and chromosome number

Species Wolf-like canids

Small (5 — 10 kg)

Common name        Geographic range    2na

 

Canis aureus Golden jackal Old World                     78
Canis adustus
Side-striped jackal Subsaharan Africa
Canis mesomelas Black-backed jackal
Subsaharan Africa 78
Large (12-30 kg)
Canis simensis Simien jackal
Ethiopia 78
Canis lupus Gray wolf
Holarctic 78
Canis latrans Coyote
North America 78
Canis rufus Red wolf
Southern US 78
Cuon alpinus Dhole
Asia 78
Lycaon pictus African wild dog
Subsaharan Africa 78
South American canids
Speothos venaticus Bushdog
Northeast S. America 74
Lycalopex uetulus Hoary fox
Northeast S. America 74
Cerdocyon thous
Crab-eating fox
Northeast S. America 74
Chrysocyon brachyurus Maned wolf
Northeast S. America 76
Red fox-like canids
Vulpes aelox Kit fox
Western US 50
Vulpes vulpes Red fox
Old and New World 36
Vulpes chama Cape fox
Southern Africa
Alopex lagopus Arctic fox
Holarctic 50
Fennecus zerda Fennec fox Sahara                          64
Other canids
Otocyon megalotis Bat-eared fox
Subsaharan Africa 72
Urocyon cinereoargenteus Gray fox
North America 66
Nycteruetes procyonoides Raccoon dog Japan, China               42b

 

 

  • a Diploid chromosome number. b variable number of B-chromosomes
  • present (Wayne, no date)

The domestic dog’s closest relative is the gray wolf (Canis Lupus)

(Jensen, 2007). Evidence since investigations into evolution strongly suggests the wolf to be the ancestor of the domestic dog. However, it has also been asserted that other canids have played a part, for instance the coyote or the jackal, which would help to explain morphological and behavioural differences within breeds of domestic dogs. Whilst this has been neither proven nor disproven, evidence such as nuclear markers and mitochondrial DNA (MDNA) point strongly towards the wolf being the sole ancestor. Researchers into MDNA tested over 1000 dogs and the results indicated MDNA more closely matched to wolves than to the other wild canids. The results only consider female lineage due to MDNA solely being passed on maternally (Jensen, 2007).

2.2 The two main theories of domestication

The first theory is that of domestication. Amos (2013) states that wolves started to become enticed by food cooking at glacial sites 14,000 years BP (Before present). Groups of humans would have produced food waste that some wolves then scavenged from perimeter dumps. Only the most confident of the wolves (with a greater tolerance to humans and less flight distance) would take advantage of this new environmental niche. Coppinger (2000) believes the reduction of flight distance was a crucial development that played a major roll in the transformation of the wolf to the dog today. Wolves with a shorter flight distance would allow humans or novel (normally fearful) stimuli closer, before running, as well as eating in their presence. This trait would have been passed on through breeding (wolves able to live close to the settlements would likely mate with each other), which would make it stronger; a natural selection for the ability to live with humans (PBS, no date). Cubs would be more likely to thrive in the village dump environment, with readily available food and being farther from predators (with greater flight distance) (Coppinger, 2000). It is also possible that there was just one domestication event and that the domestic dog evolved from an ancestral wolf-dog. This was suggested by a 2009 study by the Royal Institute of Technology (Melina, 2010).

The second theory argues that humans (Mesolithic hunters) took very young wild wolf cubs from the den before their eyes had even opened (day 10), hand rearing, adequately taming, socialising and habituating them to village life. By preventing dispersal at maturity, selectively and repeatedly breeding the tamer wolves, whilst destroying any showing aggression, they were then, over generations, able to produce domesticated wolves, which they trained for hunting and protection. Over thousands of years of partly natural but mostly purposeful selection, a new population of dogs emerged (Training Behaviour, 2005). Coppinger (2000) argues that this would be an impossible undertaking for early humans, who would not have the resources, time or foresight needed.

2.3 How the dog developed into early breed types

Wayne (2014) suggests that over the past two centuries there has been an explosion of different breeds within the domestic dog. These fall within such categories as herding, guarding and hunting. The evolutionary hierarchy shows that genetically, based on results of studies and grouping work by DNA technologies, dog breeds fall into these groups. However, in the 1700s dogs were classified by Linnaeus according to morphological characteristics (Science Learning, 2009).

Dogs today evolved from a line of mammals called Canids. This is widely believed as they both have similarly shaped teeth. All 400 domestic dog breeds belong to one species Canis familiaris and many specialists believe that all breeds originated from one species, the Gray wolf (Canis lupus) (Melina,2010). DNA (energy making structures within cells) indicates that domestication is likely to have occurred in only one region, otherwise one would expect to find more than one lineage within modern dogs. Most breeds were bred by humans only a couple of centuries ago, selecting for traits according to the tasks they would undertake: louder barks for protection, for example, and good temperament. One of the earliest breeds to be selected was the greyhound, which is still present today. Cross breeding really became popular around the nineteenth century. As Irvine from University of Colorado explains, because of natural mutation, environment and human preference, breeds became more specialised and greater numbers were bred (Melina,2010). Foxes in Belyaev’s study gained more dog-like characteristics when selected for tameness, such as floppy ears, curly tails and pie bald coats, along with yipping and barking. Also their reproductive cycle became longer and more frequent (Coren, 2006; Trut, 1999).

2.4 Hierarchy systems

 2.4.1 Captive wolf packs

Stillwell’s (2013) research on captive wolf packs and hierarchy systems in the 1970s revealed that these wolves had a fixed hierarchy in which the alpha male and female dominated. The alpha pair took control of the food and always ate first, along with controlling others in the pack through the use of aggression. Older wolves dominated over younger wolves. Traditionally this concept has been mistakenly applied to domestic dogs, as they are borne from wolves (APDT, 2014), presuming they also have a rigid hierarchy structure, centering on dominance, and basing training methods on this premise. Dr David Mech, an expert in wolves, has asserted that because captive wolves are forced to live in a confined environment; never being allowed to leave and form new packs (as the adolescent males would in the wild), aggression will naturally occur more in this environment. In a captive situation older wolves tend to dominate the pack and compete amongst each other for food and other valued resources as they do not need to work together as a pack to hunt and kill (large) prey.

2.4.2 Wild wolf packs
In the wild wolves exist in packs consisting of mothers and fathers, plus offspring that have not yet left the pack. They work hard together to find and kill sizeable prey and to care for and protect their young. Fights over resources are rare and as offspring usually disperse before the age of three (to start new packs and find mates) battles for dominance do not occur, unless initiated by a different pack over territory. The mating pairs command a natural respect from the youngsters; consequently serious conflict is rare. Working together as a pack far outweighs any desire for fighting within the pack (USGS, 2013).

2.4.3 Feral dog packs

Wild packs are usually domesticated dogs that are either strays that have originally lived in a home or have been born on the streets to tame mothers. Shelter is usually found in derelict areas or buildings. Unlike wolves they are promiscuous, with fathers taking little part in rearing (though more so in the East) (Pal, 1998). Western feral dogs tend to be unrelated and uncoordinated groups, which are actively discouraged by humans, and so never really settle, with no social structures established (Boitani,1995). More aggression is seen in these groups than in Eastern feral dog groups, which tend to be mainly familial, with some recruited strays. Eastern feral dogs are generally better tolerated by humans (considering them as mutually beneficial), and often form a hierarchy relating to food and shelter (Pal, 1998). In the 1980s, a problem arose with these dogs and they were captured and used for dog fighting. This meant they were being selectively bred for aggression, which led to a loss in their control and also made them more of a threat to livestock and humans (Mott, 2013).

2.4.4 Owned dog groups

Miller (2011) states that observations on captive wolves by Schenke created the theory that as dogs came from wolves their interactions with other dogs and humans were similar, and that training methods (often harsh) should centre on being the dominant Alpha. This concept became very popular and often any unwelcome behaviour was labelled ‘dominant’, when actually the dogs just needed to be trained what to do. Dogs in the home tend to have been placed together by humans and would typically not naturally form a social pack. They have to learn to get along, but issues with aggression can arise due to the fear of losing possessions or access to a valued resource such as food shelter or affection, and not a vying for status. Unfortunately, views on how people should treat dogs are heavily influenced by the media, and the dominance model continues to be peddled by some. Humans are not dogs and dogs know this. Humans need to understand that a good group of dogs will work together due to voluntary differences and incredible communication which helps them to avoid conflict (Miller, 2012).

According to Bradshaw (2012) dominance describes a relationship between individuals, regarding a resource in a specific situation, but the term is often used incorrectly to describe a trait or characteristic, where actions are motivated by higher social status. Some trainers would say that if a dog rushes out of a door, pushing past the owner, jumps up, steals food and has confident body language, he is ‘dominant’ and trying to be the leader of the pack. They might recommend imitating the ‘behaviour’ of the alpha wolf, to remedy this, for instance by rolling the dog, pinning it or scruff shaking, in conjunction with a rank reduction programme. However, these methods are punishing and often trigger defensive aggression in response to human threat. Unfortunately these methods (random bullying) invariably worsen behaviours, and can shut the dog down emotionally and make them scared to try anything or give the owner attention (learned helplessness). This is extremely detrimental to the human-dog bond (ASPCA, 2014).

3.0 Conclusion

It appears that when considering the different theories as to how the domestic dog came about there are valid arguments for both views. There are predominantly two main theories as to how the wolf was domesticated, one being that of Mesolithic hunters rearing wild wolf puppies and selectively breeding the tamest and most useful, in time training them to hunt. The other argument is that wolves basically domesticated themselves, being as scavengers of food waste from village dumps. It is likely that every carnivore alive today traces back to Miacis which existed around 55 million years ago. It is widely agreed that dogs today evolved from a line of mammals called Canids. All 400 domestic dog breeds belong to one species, Canis familiaris, which in turn most specialists believe originated from one species, the Gray wolf (C. Lupus).

Hierarchy systems are very different between captive wolves, wild wolves, feral and domesticated dogs. In the wild, all young wolves are potential breeders (alphas) and so there is no evidence of a hierarchy due to age, more on an accepted ranking amongst individuals, demonstrated through posturing. The natural pack behaviour of feral dogs is very weak, unstructured and disorganized, the opposite of that of wild wolves. Domestic dogs, although ancestors of wolves (with very similar body language and stages of development) are now far removed from wolves and training methods based on wolf research are at best unhelpful and at worst potentially damaging.

 

4.0 References

APDT [Association of Professional Dog Trainers] (2014) Dominance and dog training [online] Available at: <http://www.apdt.com/petowners/choose/dominance.aspx> [Accessed 27 April 2014]

Amos, J. (2013) Dog evolved on waste dump [online] Available at: <http://www.bbc.co.uk/news/science-environment-21142870 > [Accessed 27 April 2014]

ASPCA (2014) Is your dog dominant? [online] Available at: <http://www.aspca.org/pet-care/virtual-pet-behaviorist/dog-behavior/your-dog-dominant> [Accessed 07 May 2014]

Bradshaw, J. (2012) In Defence of Dogs. London: Penguin Books

Coren, S. (2006) The Intelligence of Dogs. New York: Free Press

Freedman, A.H., Gronau, I., Schweizer, R.M., Ortega-Del Vecchyo, D., Han, E., Silva, P.M., Galaverni, M., Fan, Z., Marx, P., Lorente-Galdos, B., Beale, H., Ramirez, O., Hormozdiari, F.,Alkan, C., Vilà, C., Squire, K., Geffen, E., Kusak, J., Boyko, A.R., Parker, H.G., Lee, C., Tadigotla, V., Siepel, A., Bustamante, C. D.,Harkins, T. T., Nelson, S. F., Ostrander, E.A., Marques-Bonet, T., Wayne. R. K., Novembre, J. (2014) Genome Sequencing Highlights the Dynamic Early History of Dogs [online] Available at: <http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1004016> [Accessed on 4 May 2014].

Jenson.P, (2007) The Behavioural Biology of Dogs [Online] Available at: <http://books.google.co.uk/books?hl=en&lr=&id=SpkSd__EdKYC&oi=fnd&pg=PA3&dq=evolution+of+the+canids&ots=4m-y_QLQZ6&sig=cD7SKTlHWdMvJEM_Pn1ygpJ2F_o#v=onepage&q=evolution%20of%20the%20canids&f=false> [Accessed 27 April 2014]

Miklosi, A. (2012) Dog Behaviour, Evolution, and Cognition. Oxford: Oxford University Press

 Melina, (2010) The Incredible Explosion of Dog Breeds [online] Available at: <http://www.livescience.com/8420-incredible-explosion-dog-breeds.html> [Accessed 5 May 2014]

Mott, (2013) U.S Facing Feral-Dog Crisis [online] Available at: <http://news.nationalgeographic.com/news/2003/08/0821_030821_straydogs.html>[Accessed 5 May 2014]

Miller, (2011) De-Bunking the “Alpha Dog” Theory [online] Available at: <http://www.whole-dog-journal.com/issues/14_12/features/Alpha-Dogs_20416-1.html> [Accessed 5 May 2014]

Pal, S. K., Gosh, B. and Roy, S. (1998) ‘Agonistic Behaviour of Free-ranging Dogs (Canis familiaris) in Relation to Season, Sex and Age’ Applied Animal Behaviour Science 59(4) pp.331–348

PBS (no date) Dogs that Changed the World [online] Available at: <http://www.pbs.org/wnet/nature/episodes/dogs-that-changed-the-world/what-caused-the-domestication-of-wolves/1276/ > [Accessed 5 May 2014]

Science Learning (2009) Constant Evolution [online] Available at: <http://www.sciencelearn.org.nz/Contexts/Hidden-Taonga/Science-Ideas-and-Concepts/Classification-system> [Accessed 27 April 2014]

Serpell J, (2002) The Domestic Dog: its evolution, behaviour and interaction with people [online] Pg 8 Available at <https://books.google.co.uk/books?id=I8HU_3ycrrEC&pg=PA8&lpg=PA8&dq=Lorenz’s+idea+of+jackal+domestication&source=bl&ots=BcarYyi7u5&sig=0ymGOzKG4P2-mgI_Xt-pAzwbhHk&hl=en&sa=X&ei=-AJKVb__FIX1UPS9gMAK&ved=0CC0Q6AEwAg#v=onepage&q=Lorenz’s%20idea%20of%20jackal%20domestication&f=false > (Accessed 06/05/15).

Stilwell S, (2013) Train your dog positively

Strauss, B. (no date) Prehistoric Dogs [online] Available at: <http://dinosaurs.about.com/od/otherprehistoriclife/a/Prehistoric-Dogs-The-Story-Of-Dog-Evolution.htm> [Accessed 3 May 2014]

Trut, L. N. (1999) ‘Early Canid Domestication: the farm-fox experiment’, American Scientist, 87, pp 160-168

Training and behaviour (2005) [online] Available at: <http://www.responsibledog.net/evolution_domestication.html> [Accessed 5 May 2014]

USGS, 2013 Alpha status, Dominance, and Division of Labor in Wolf Packs [Online] Available at:

<http://www.npwrc.usgs.gov/resource/mammals/alstat/intro.htm> [Accessed 5 May 2014]

Wayne, R. (no date) [Online] Available at:

<http://wooferhouse.net/Links/MolecularEvolutionOfTheDogFamily/MolecularEvolutionOfTheDogFamily.htm> [Accessed 6 May 2014]

Wayne,.R. (2014) The Canine Genome [online] Available at: <http://genome.cshlp.org/content/15/12/1706.full#sec-6> [Accessed 27 April 2014]

Wolf to Woof (no date) Evolution from Early Canids to Today’s Dogs [online] Available at: <http://www.wolf2woof.com/EVOLUTIO/EVOLUTIO.HTM> [Accessed 3 May 2014]

No votes yet.
Please wait...
Voting is currently disabled, data maintenance in progress.

Leave a Reply