Man's Best Friend

Alex McDougall, Alexandra Pontefract, Bryan Izzard, Nicole Stula, and Jeffrey Wainberg
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© 2005 Nature Publishing Group

"The one absolutely unselfish friend that humans can have in this selfish world, the one that never deserts them, the one that never proves ungrateful or treacherous is their dog."

~George Graham Vest, Senator of Missouri, 1855

Table of Contents


Dogs. We all know what they are, and most people have lived with them as pets or seen them about in communities. But how much do we really know about them? The above quotation is believed to be the origin of the colloquial adage ‘Man’s Best Friend.’ The truth to the adage is recognized, as dogs remain among the most popular pets in the world. This treehouse provides information about many aspects of domestic dogs, to learn more about them, what they are capable of, and where they come from and to try to find an answer to the question ‘why are dogs man's best friends?’

Wild Dogs and Phylogeny

Domestic dogs, wild dogs, and wolves all belong to the Family Canidae, which also contains jackals, coyotes, and foxes. Canidae is contained within the group caniformia which is contained within the Order Carnivora, one of the eighteen current groups of Eutherians, or placental mammals. A full list of the groups contained in Canidae is provided below.

Within the Canidae are 14 groups, or genera. Contained within those 14 genera are at least 34 species and two subspecies (a chart showing all members in the Canidae is provided below). The genus Canis contains dogs, jackals, and wolves. The gray wolf, Canis lupus, is among 7 species of canids and also related to two subspecies, Canis lupus dingo and Canis lupus familiaris, which are known commonly as the dingo and the domestic dog, respectively.

Containing Groups for Canidae

Eutheria, Mammalia , Therapsida, Synapsida , Amniota, Terrestrial Vertebrates, Sarcopterygii, Gnathostomata, Vertebrata, Craniata, Chordata , Deuterostomia, Bilateria , Animals, Eukaryotes, Life on Earth








Arctic fox


Alopex lagopus Arctic fox


short-eared dog


Atelocynus microtis short-eared dog


dogs, jackals, and wolves
Canis adustus side-striped jackal
Canis aureus golden jackal
Canis latrans coyote
Canis lupus gray wolf
Canis mesomelas black-backed jackal
Canis rufus red wolf
Canis simensis Simian jackal

Canis lupus dingo dingo
Canis lupus familiaris dog

crab-eating fox
Cerdocyon thous crab-eating fox


maned wolf
Chrysocyon brachyurus maned wolf


Cuon alpinus dhole


Falkland Island wolf
Dusicyon australis Falkland Island wolf


African wild dog
Lycaon pictus African wild dog


raccoon dog
Nyctereutes procyonoides raccoon dog


bat-eared fox
Otocyon megalotis bat-eared fox


South American foxes


Pseudalopex culpaeus culpeo
Pseudalopex griseus Argentine gray fox
Pseudalopex gymnocercus pampas fox
Pseudalopex sechurae Sechura fox
Pseudalopex vetulus hoary fox


bush dog
Speothos venaticus bush dog


gray foxes
Urocyon cinereoargenteus gray fox
Urocyon littoralis island gray fox


Vulpes bengalensis Bengal fox
Vulpes cana Blandford's fox
Vulpes chama Cape fox
Vulpes corsac Corsac fox
Vulpes ferrilata Tibetan fox
Vulpes pallida pale fox
Vulpes rueppellii Rüppel's fox
Vulpes velox swift fox
Vulpes vulpes red fox
Vulpes zerda fennec

The Domestication of Dogs

One ancestor too many breeds

Breeds of Dogs

Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

Puppies of different dogs breeds. Pug © 2006 Evan Agee. Golden Retriever © 2006 Robert Dann. Boxer © 2007 Cynr. Dachshund © 2007 mms0131. German Shepherd © 2006 Joe Nicora.  Puppy images licensed under creative commons. Click on an image for license details.

Dog Diversity depends on three key factors

  • Systematic selection
  • involves carefully selecting certain dogs for inherited traits like body type, coat characteristics, speed, herding, hunting, endurance, and size
  • over time and from breeders’ choices, produce animals with distinctive looks and abilities
  • has yielded, for example, the saluki, basenji, and greyhound

Information on the Internet


A-Z Dog breed alphabet., 2005.

AHASS. (2005) Dogs are Truly Manís Best Friend. Internet Journal of Emerging Medical Technologies. [accessed 20 March 2006].

American Kennel Club., 2006.

Biology.About.Com. (1999) Truly Manís Best Friend. 11 November 1999. [accessed 15 March 2006].

Dog Breed Info Center., 1998-2006.

Ellegren, H. (2005) The dog has its day. Nature 438, 745-746.

Grabianowski, E (2006). How Police Dogs Work. How Stuff [accessed 20 March 2006].

Hare, Brian and Michael Tomasello. (2005). Human-like social skills in dogs? Trends in Cognitive Sciences 9(9): 439-444.

Horwitz, Debra F. (2001). Canine Communication. Atlantic Coast Veterinary Conference. Available: [online]

Proceedings/PR05000/PR00469.htm. [March 23, 2006].

Lanier, Jennifer L. (2000). A Review of Mammalian Scent Marking. Available: [online] [March 23, 2006].

Lindlad-Toh, K. et al. (2005) Genome sequence, comparative analysis and haplotype structure of the domestic dog. Nature. 438, 803-819.

Marinelli, L. Whitehead Genome Center Begins Sequencing Dog as Chimp Draft Nears Completion [WWW document] Broad Institute, 3 June 2003. [accessed 26 March 2006].

Miffline, K. (2006). Dogs In Space, Dogs.About.Com. [accessed 20 March 2006].

Natural History Museum of Los Angles. Dogs and Canines. 2004.

Nhuch, M. Turner, S. Dog Genome Assembled: Canine Genome Now Available to Reaseach Community World Wide. [WWW document] Broad Institute, 14 July 2004. [accessed 26 March 2006].

Pongcraz, Peter et al. (2005). Human Listeners Are Able to Classify Dog (Canis familiaris) Barks Recorded in Different Situations. Journal of Comparative Psychology 119(2): 136-144.

Reagan, R. (2005) Manís Best Friend., 13 May 2005. [accessed 15 March 2006].

Reide, Tobias and Tecumseth Fitch. (1999). Vocal tract length and acoustics of Vocalization in the domestic dog (Canis familiaris). The Journal of Experimental Biology 202: 2859-2867. (2006) About Us, The Seeing Eye. [accessed 20 March 2006].

Vergano, D. (2006) Ritual dog burials tell a story of man's best friend, and man., 22 January 2006. [accessed 20 March 2006].

Walton, B. (2002) 15,000 years with man's best friend., 22 November 2002. [accessed 21 March 2006].

Whole Genome Shotgun Sequencing (intermediate) [WWW document] Your Genome, 29 August 2001. [accessed 26 March 2006].

Learning Information

About This Page
This treehouse was created as partial fulfillment for credit in the course ORIGINS 2FF3, Origins and Evolution of Organisms, offered by Jon Stone, Associate Director, the Origins Institute at McMaster University.

Alex McDougall
McMaster University

Alexandra Pontefract
McMaster University

Bryan Izzard
McMaster University

Nicole Stula
McMaster University

Jeffrey Wainberg
McMaster University

Correspondence regarding this page should be directed to Alex McDougall at , Alexandra Pontefract at , Bryan Izzard at , Nicole Stula at , and Jeffrey Wainberg at

All Rights Reserved.

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