Evolution occurs due to changes in the environment such as the introduction of new species of organisms or the development of a relationship between two species which could lead to a symbiotic relationship where both species evolve together. This is called co-evolution or in other words, as one species changes, the other species will also in order to adapt. There are a diverse amount of examples of co-evolution between many different species; however, the most interesting, in my opinion, and well known co-evolutionary affiliation is through the relationship between dogs and humans. Australian Aborigines once said “dogs make us human” which could be literally true, and vice versa. An argument backed by Edward R.B. McCabe in his 2009 presidential address for the Evolution, Co-evolution, and the American Society of Human Genetics summarizes “that dogs and humans coevolved. As dogs evolved from wolves, they changed genetically. Humans showed changes at approximately the same time that are similar to those seen in domesticated animals.” Briefly, as Mark Derr, a popular American author and journalist noted for his books on dogs, likes to say, when dogs and humans met, they immediately began walking down the same path. Although it is true that the coevolution of dogs and humans involved more the dogs evolving genetically and phenotypically, over a course of centuries humans have deeply interwove dogs into their culture and economy. During his recent lecture during the UCLA Center for Society and Genetics: Dog + Human Co-Evolution program, Derr retold an old Native American folktale of the “dog children”. To paraphrase the story, there had once a dog who could turn into a man. One night, he lay with a girl and months later she gave birth to eleven pups, five male and six female. Now, these pups akin to their father could change into human children also. One night when they had removed their canine skins and were dancing and singing around the fire, their mother tossed all of their skins into the fire save for one. Thus, ten of the pups remained human children and one remained as a dog. Even though this would be an interesting explanation for the co-evolution between humans and dogs, in reality, this partnership probably has been evolving over millions of years. An example of one of the co-evolutionary benefits dogs provide humans is a more distinguished sense of smell, which the Dog Nose Knows project allowed humans to experience via a clever card game.
The Umwelt of Dogs:
On February 2011, UCLA’s Institue for Society and Genetics held a workshop beautifully demonstrating the different perceptual worlds (or umwelt) of dogs and humans. The Dog Nose Knows (DKN) project was conceptualized by the UCLA Design│Media Arts Professor Victoria Vesna and Columbia neuroscientist Siddharth Ramakrishnan and was designed by Adeline Said Drucker. Drucker created a “sniffing booth” game that allowed players to become canine as they experienced real aspects of a dog’s life (i.e. obedience, territorialism, and social hierarchy) by using their “nose” to sniff out hazardous scents, urinate on spots to mark them as territory, and challenge other players to “duels”, also known as rock-paper-scissor mini-matches. The DKN project creates the scent-based world of a dog for humans to experience. Close your eyes and “imagine,” said Columbia University, New York dog-cognition researcher, Alexandra Horowitz, “imagine the scent-based world of a dog…look around and imagine that everything you see has its own individual scent. And not just each object – different parts of the same object may hold different types of information.” (Reference). For instance, picture a flower, where each petal has a different scent. Each scent tells the dog which insects it has been visited by, which individuals have touched it, and so on. The dog’s nose even allows for the dog to understand the passage of time by the change in strength and character of the scent. One recent study, from 2005, showed that dogs may be able to detect subtle differences in odor from one footstep to the next as they follow a human’s scent trail (Hepper & Wells). The DKN project offers humans a glimpse into the highly detailed world of a dog, revealing the dog’s acute sense of smell that benefits humans in the human-canine co-evolutionary relationship.
Dog’s Primary Sense:
“They haven’t got no noses,
The fallen sons of Eve;
Even the smell of roses
Is not what they supposes;
But more than mind discloses
And more than men believe.”
-- from “The Song of the Quoodle,” G.K. Chesterton
Humans are predominantly visual creatures with their short noses, the cone and rod receptors in the retina of their eyes that allow them to see in both color and black/white vision, and the highly developed complexity of their brains that allow them to analyze distance, depth, shape, texture, etc. Dogs, on the other hand, experience much of their world through their nose. Although we are still not able to fully understand exactly how they experience the world around us (Ramakrishnan), examination of the large surface area of the canine nasal passages lends higher efficacy in heat, moisture, and odor transfer, allowing for higher sensitivity to smell compared to humans. In addition, accordion-like passages inside the dog’s head provides more time for the odor to be computed (identified); note that this phenomenon also allows for some dogs to track or find objects or people. In a task called the ageing crime scene identification (Ramakrishnan), dogs were asked to identify certain people after varying lengths of time. Correct identification occurred in up to sixty percent success rates for eight-week-old scents. In some cases, researchers even used seven-year-old scents that also lead to positive identification. Dogs have 220 million olfactory receptors in their nose versus the five million in humans; thus, making their smell about a thousand times better than humans. Also, dog’s noses function quite differently from our own. When we inhale, we smell and breath through the same airways within our nose, however when dogs inhale, a fold of tissue just inside their nostril helps to separate their olfaction and respiration leading to a higher concentration of odor in the nasal passages. Since dogs can wiggle their noses independently and that the reach of each of their nostrils is smaller than the distance between the nostrils they can decide which nostril an odor arrived in. This then allows them to locate the source of the smell.
In conjunction to the above, dogs also have a secondary olfactory capability made possible by their vomeronasal organ, Jacobson’s organ, is located in the bottom of a dog’s nasal passage. This particular organ picks up pheromones, the chemical unique to each animal species that advertises mating readiness and other sex-related details, and other scents. Scents are a very integral piece of information in memories, relationships (such as our human-dog co-evolution), and life in general. For instance:
“Smell and memory have a strong link. In two synapses, one triggers a memory that was stored in the subconscious. We breath up to 24,000 times per day; we move 12.7 meters of air. With every breath, we inhale smell molecules – information about our surroundings. Even when we sleep, we smell. Our kidneys smell, our skin smells” (Tolaas).
Obviously, the sense of smell is an important part of our daily lives. Sissel Tolaas, scent curator, researcher, and “professional provocateur” (NOWNESS) currently explores the aromatic potential of bacteria in her ongoing investigation into the most mysterious and evocative of our senses. She believes in both enhancing and manipulating our personal perfumes and that the scents of the future will evolve from present scents which are too much caught up in a perfume craze. Since she became immersed in the study and research of scents, Tolaas has created an archive of over 7,000 smells including the smell of her daughter at different ages, animal feces, aromatic socks, and so on. Using her discoveries and knowledge on the complexities of smells, she has worked on projects such as educating children about pollution, a conceptual fragrance project with leading fashion photographer Nick Knight, and using scent aides in the recollection of traumatic memories in patients undergoing therapy. Tolaas is trying to create awareness about the essential part scents play in our livelihoods.
The Working Dog:
Through their highly evolved sense of smell, dogs have helped humans with hunting, keeping vermin and pests away, serving the military and police, assisting the disabled, finding injured people in natural accidents, and provided companionship. Dogs and humans have partnered in order to achieve harrowing feats. “Dogs are used to detect landmines in war zones, truffles, track game and criminals…find humans trapped under snow or landslides and cadavers buried below the surface” (Dog Nose Knows). One such dog-human partnership occurred between former Secret Service agent Ed Hawkinson and his explosive-sniffing dogs. Hawkinson trained his dogs to protect the President and presently he trains Labradors to detect weapons in schools. Search and rescue (SAR) dogs have been widely used and even written about as in Nora Roberts’ lovely novel called “The Search”. Search and rescue dogs are trained to search out the odor given off by humans trapped beneath collapsed structures of natural debris. The dog barks at the site to alert their handlers where the victim lies and, depending on the reaction of the dogs, handlers can understand even from a distance whether the victim is alive or dead, or even whether the victim is uninjured or severely injured. The hours of training that dedicated handlers and hardworking dogs undergo when becoming a SAR team creates an extremely close bond between handler and dog, a unique and powerful example of co-evolution.
The co-evolution between dogs and humans provide for both the comfort and prosperity of each. While dogs provide humans with an exceptional sense of smell for rescue endeavors, pest control, safety, and companionship, humans have enhanced the social support, communication, and socialization skills of dogs. So far, both seem to have benefited from their mutual relationship and both have changed genetically, phenotipically, and culturally to accommodate and advance the survival of the other species. As it is often said, dogs can be a human’s best friend. Hopefully humans are also dog’s faithful allies.
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