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Dogs and People: Evolution of a Special Relationship

Our evolutionary connection involves a form of mutual dependency.

Dogs are very useful to people. Service dogs devote themselves to caring for the disabled. Sled dogs pull great weights over the ice. Dogs rescue people who are drowning, or trapped in avalanches.

A lesser-told story is the great reliance of dogs on people for their food, for shelter, and for protection from larger predators.

Mutual Dependency (Inquilinism)

There are many examples in nature of different species who rely on each other for survival. Slave-making ants raid the nests of another species and carry off their young who grow up to do all of the work in the colony. If the slave-makers did not have their captives, who become imprinted on the nest through olfactory signals emitted by the queen, they would be incapable of feeding themselves or raising their own young.

This is an extreme case of one species being completely dependent on the services of another. The human-dog relationship is not quite so extreme but there are several intriguing suggestions of mutual dependency.

What do humans get out of the relationship? We can train dogs to do almost anything they are capable of, in our service, including cadaver dogs and those that may diagnose cancer. In the early days of our association, the greatest service of dogs may have been detecting game animals at a distance.

Sensory Systems

Dogs were domesticated by 35,000 years ago, a time when human activity was crashing the populations of large grazing animals (1).

Early dog owners relied heavily on the sensory capacities of their canine partners. We know this because human sensory capacity declined rather markedly with reliance on the tracking assistance of dogs (2).

Of course, dogs benefited from the relationship as well, becoming dependent on humans for their food, shelter, and protection from large predators. Domestic dogs can digest grain-based foods, implying that their digestive system evolved to cope with foods that are not a normal component of the diet of wild dogs. Feral dogs, such as dingoes, do not establish dietary independence from food produced by humans and rely on scraps obtained from garbage dumps (3).

Dogs were used to hunt smaller animals rather than large grazing animals, as illustrated by the practices of Aborigines. Men hunted large animals, such as kangaroos, wallabies, and ostrich and left dogs behind to avoid scaring off the prey. Aboriginal women used dogs to hunt small animals (4). The canine helpers improve their hunting success. This conclusion was drawn from archaeological research on sites such as Tunnel Cove in South West Australia. The introduction of dogs four thousand years ago is associated with a reduction in the populations of small game animals.

Dogs are widely used by indigenous hunters particularly in forested locations where game is difficult to track. Examples of such societies include the Shuar and Quichua of Peru, Ecuador, and Colombia (5). Dogs have a special status and are treated much like people in some respects. Bizarrely, dogs were given psychedelic drugs that people used to make connections in the spirit world (6). The thinking was that such experiences would enhance the dogs' capacity to find prey.

The Special Relationship

Dog-human cooperation brought tight emotional bonding on both sides. The majority of dog owners have no trouble describing the pet as a family member, complete with ritual burials and periods of mourning.

This inter-species closeness is illustrated by a site at Lake Baikal, Siberia, that dates between 7,000 and 8,000 years ago (1). Dogs were buried with valuable items, such as knives and necklaces and were sometimes buried alongside their masters. This suggests that dogs were considered spiritual beings deserving of the same consideration as humans. Remarkably, the Baikal people lived mainly on fish and seals, forms of subsistence where dogs were of no help. Dogs were treasured as social companions rather than purely for their utility.

The emotional closeness of dogs and humans suggests that we have been extremely successful at tapping into the social systems of wolves and using the devotion of the dog to our advantage. In wolf society, every individual serves the alpha pair. Humans assume the alpha role in our relationship with dogs. Dogs who do not accept a lower status can be aggressive rather than compliant.

Even more important, perhaps, was the remarkable capacity of dogs to fit in with human social systems. In some ways, this is a unique narrative within the domestication of animals. Dogs were not simply selected for being tamer and more manageable, as is true of other domestics. They also underwent many other changes—to their digestive systems, their reproduction, and their communication skills (1,3).

References

1 Dugatkin, L. A., and Trut, L. (2017). How to tame a fox (and build a dog). Chicago, IL: University of Chicago Press.

2 Stephan, H., Frahm, H, & Baron, G. (1981). New and revised data on the volume of brain structures in Insectivores and Primates. Folia Primatologica, 35, 1-29.

3 Newsome, T. M., Ballard, G-A., Crowther, M. S., Fleming, P. J., and Dickman, C. R., (2014). Dietary niche overlap of free-roaming dingoes and domestic dogs: the role of human-provided food, Journal of Mammalogy, 95, 392–403 DOI:/10.1644/13-MAMM-A-145.1

4 Balme, J., and O'Connor, S. (2016). Dingoes and Aboriginal social organization in Holocene Australia, Journal of Archaeological Science: Reports, 7, 775-781. doi: 10.1016/j.jasrep.2015.08.015.

5 Koster, J. (2008). Hunting with dogs in Nicaragua: An Optimal Foraging approach. Current Anthropology. 49. doi: 10.1086/592021.

6 Bennett, B. C,, and Alarcón, R. (2015). Hunting and hallucinogens: The use psychoactive and other plants to improve the hunting ability of dogs. Journal of Ethnopharmacology, 171,171-83. doi: 10.1016/j.jep.2015.05.035. Epub 2015 May 28. PMID: 26027755.

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