07/24/2003
Capable Canines
Yesterday a mini tornado swept through our area, downing trees and power lines. As a result we have had no power for almost a full day now and I am working on the remaining battery power on my laptop. The following column is a first draft, unpolished and unedited but I will try to post it before the battery dies. Please forgive any errors and lack of coherence.
I was taking my morning walk one day last week, thinking about what subject to discuss in this week’s column and also keeping an eye out for the black bears which had been spotted in the neighborhood. As I looked for the bears, a big deer sauntered across my path. Not too long ago, my only concern would have been hostile dogs. Near the end of my walk I saw a passing van with the words “Canine Coach” on the side. When I got home and turned on the TV news, Warren Eckstein, our local pet guru, was saying that neutering and spaying of dogs not only prevent unwanted offspring but also lessen the chances of dogs getting various diseases such as prostate and breast cancer. It was clear that my subject had to be dogs since the day before I had clipped an article by Elizabeth Pennisi titled “A Shaggy Dog History” from the November 22, 2002 issue of Science.
I’ve known three dogs intimately in my life, the first being a childhood pet, a Boston terrier named Runtsy, given to us by my Aunt Edna as I recall. I was devastated when someone poisoned her. Then there was Ralph, a mixed breed we got for our youngest son when he broke his arm defending the goal in a soccer game. Ralph was not only a great pet but also a wise investment in that our son learned to be responsible for Ralph’s morning walks and his care. But poor Ralph - we confined him to the breakfast room, kitchen and porch of our house for the eleven years he was with us.
Some years later, our oldest son acquired Rosie, another mixed breed, while living in Greenwich Village in New York. After he married and moved to New Jersey, we agreed to dog sit Rosie on occasion. We stipulated, however, that Rosie would also be confined to the quarters that Ralph had once occupied. But Rosie, named after Roseland, where she was found as a stray, was a charmer. Before an hour had passed on her first visit, she had seduced us into granting her the run of the house. Soon she was spending her nights curled up in my favorite chair in our bedroom. One could not have asked for a more congenial companion.
When and how did the dog evolve into man’s best friend? Our 1962 World Book Encyclopedia states that dogs, jackals, wolves, coyotes and foxes all stemmed from a critter named Tomarctus that lived around 15 million years ago. Tomarctus is described as a sort of wolf-like creature. The dog seems to be of much more recent vintage and most experts agree that dogs trace their origin to the wolf, although some think it more likely that the jackal is the dog’s predecessor. Pennisi’s article talks about the dog’s heritage and three other papers in the same issue of Science on that subject and on the intimate relationship of man and dog.
When did the dog originate? In 1997, Robert Wayne and Carlos Vila of UCLA performed an extensive genetic study of some 300 individual dogs, wolves, coyotes and jackals of different breeds and lineages. They concluded that the dog is related to the wolf and comes from several different lineages of wolves. They also estimated that the dog first appeared about 135,000 years ago. While their wolf relationship was pretty much accepted, their date proved highly controversial, with many arguing for a more recent 14-15,000 years ago or even later. The first fossil evidence dates from the more recent time.
Peter Savolainen of the Royal Institute of Technology in Stockholm and his colleagues took on the job of actually pinpointing the place of origin of the dog. They did DNA studies on over 400 dogs from all over the world and on nearly 40 wolves from Europe and Asia and report their results in the same issue of Science. Combining their results with Chinese workers’ studies they conclude that man’s best friend arose in East Asia from several different lineages of the wolf in East Asia about 15,000 (40,000 years ago is not out of the question). In another paper in that issue, Jennifer Leonard and colleagues from UCLA conclude from their work that at least five lineages of dogs traveled along with the human settlers of North America who came across from Siberia roughly 12-14,000 years ago.
How did the wolf become tamed and branch off from the main wolf species? One theory is that humans took wolf puppies and raised them either as pets or as assistants in the job of hunting for food. Others believe that wolves scavenged food from the human discard piles and that over time became less and less afraid of the humans. This theory postulates that evolution favored the wolves that were bolder in approaching the humans and that eventually the dog was the result.
Another paper in the same issue of Science was the most interesting to me and prompted a visit to the Web site of Harvard Magazine. Brian Hare, a graduate student at Harvard started a series of studies that seem to show how closely the dog has learned to adapt to man’s needs and desires. He and his colleagues carried out very simple experiments in which he compares the behavior of dogs with that of wolves and chimpanzees. The simple experiment is to take two boxes, put food in one box and see whether the subject chooses the correct box to get the food. The hook is that the researcher will look at the box with the food or even point to it, mark it or tap on it.
Let’s try the chimp, our close relative. Out of 11 chimps, only two seemed to get the message that the human was cluing them to the source of gratification. On the other hand, out of 11 dogs, nine caught the clues to choosing the right box. Controls were run to assure that odor was not a factor. If dogs come from the wolf, you might expect the wolf to also catch on quickly. It turns out that seven wolves did no better than chance in choosing boxes while seven dogs did much better, no matter which clue was given. Conclusion – in the process of becoming tame and adapted to coexistence with humans the dog has learned to recognize these cognitive signals employed by humans.
Now the question is does the dog learn this response or is it ingrained. Bring in the puppies, some raised in close contact with humans, others kept in more isolated circumstances. Both sets of puppies perform better than the wolves or the chimps. So one concludes that this skill of cognitive recognition is now embedded in the dog’s genes.
Possibly as you read this, Brian Hare is in Siberia carrying out similar experiments with a group of silver foxes. These aren’t ordinary silver foxes by any means. Workers at the Institute of Cytology and Genetics at Novosibirsk have been selectively breeding these foxes for 45 years, following the work of the late Dimitry Belyaev. The approach has been to deliberately breed the foxes to obtain tamer and tamer foxes. The method they used has been to wait until the fox kits were four weeks old, stand in front of the cages and see which kits came towards the researcher and which went the other direction. The ones that came towards the workers were then bred to produce another generation of foxes. The Web site genomenewsnetwork.org indicates that 30 generations of Belyaev silver foxes have now passed.
Over those 45 years the foxes indeed have become tame enough to be house pets. Not only that but their physical appearance has changed. Their fur is a different color and they’ve become more gracefully slender. I was somewhat surprised to read that their brains have become smaller. Could it be that they no longer have to fend for themselves but can count on their human associates to provide their needs? Hence they don’t need as many neurons? The Harvard magazine Web site quotes Darwin as saying that there isn’t a single domestic animal that doesn’t have drooping ears, at least somewhere in the world. Sure enough, the Belyaev foxes have developed floppy ears!
Will they also have developed the dog’s ability to interpret our not so subtle cues? Brian Hare may already be finding the answer. Stay tuned.
Allen F. Bortrum
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