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Study Shows Small Dogs Evolved in Middle East

aschae — Thu, 25 Feb 2010 20:11:52 +0000

Source: Sciencemag.org, Feb 24, 2010

Mexico may claim the Chihuahua, and Tibet the shih tzu. But a new genetic study indicates that all small dogs have their origins in the Middle East.

The origin of the domestic dog is a hot topic in evolutionary biology. Scientists agree that today’s Fidos came from the domestication of the gray wolf, but they are at odds over where this took place. Previous genetic studies focusing on mitochondrial DNA—inherited only from the mother—have suggested that modern domestic dogs are descended from animals that lived in East Asia between 5000 and 16,000 years ago. But archaeological excavations in Europe and the Middle East have found remains of what appear to be domestic dogs dating back as far as 31,000 years.

Now, a team led by evolutionary geneticist Melissa Gray of the University of California, Los Angeles, has examined nuclear DNA to fill in a crucial piece of the puzzle. The researchers took samples of blood, tissue, or saliva from three populations: large domestic dogs (those weighing more than 30 kilograms), small dogs (weighing less than 9 kilograms), and wild wolves, foxes, and coyotes from around the world. They then looked at a gene called insulin-like growth factor 1 (IGF1). All canines, wild or domestic, have some form of this gene—precisely which form is strongly associated with the size of an animal’s skeleton.

The team found that the version of IGF1 carried by all small dogs is found in very few large dogs and no wild canines. But a very similar form of the gene is found in gray wolves from the Middle East. That means that this region is probably the birthplace of the common ancestor of all the world’s small dogs. Because they all carry the same variant, it is extremely unlikely that small body size evolved more than once. And for the gene to have had time to spread all over the world, it must have evolved shortly after dogs were first domesticated.

Gray emphasizes that the study, published today in BMC Biology, doesn’t necessarily mean that dogs were first domesticated in the Middle East. But it’s a “strong indication” that that region “has played a significant role in the early history of domestic dogs.” The authors note that archaeologists have found remains of small dogs dating to 12,000 years ago in the area. There are older sites in Europe and Russia, but they contain larger dogs. She says humans living in small agricultural communities may have deliberately bred small dogs because they ate less and could be kept in small spaces.

Adam Boyko, a geneticist at Stanford University in Palo Alto, California, who specializes in the evolution of the domestic dog, is impressed by the study. “This really pokes a hole in the argument of this relatively simple domestication in East Asia, … which is what people have been arguing based on mitochondrial DNA,” he says.

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Study: Wolves beat dogs when it comes to logic

aschae — Tue, 08 Sep 2009 18:12:26 +0000

Source: MSNBC.com, September 3, 2009

In experiments, dogs followed human clues despite seeing better solutions

Wolves do better on some tests of logic than dogs, a new study found, revealing differences between the animals that scientists suspect result from dogs’ domestication.

In experiments, dogs followed human cues to perform certain tasks despite evidence they could see suggesting a different strategy would be smarter, while wolves made the more logical choice based on their observations.

In fact, dogs’ responses were similar to human infants, who also prioritize following the example of adult humans.

During the tests, a researcher would repeatedly place an object in Box A and allow the subjects to find it. When the experimenter then switched and put the object in Box B, human babies and dogs were confused and continued to search for it in the first box. Wolves, however, easily followed the evidence of their eyes and located the object in Box B.

The finding could help scientists learn more about the evolution of social behavior, not just in dogs but in humans as well.

Human cues
The differences reflect an emphasis on different learning styles, scientists say.

“I wouldn’t say one species is smarter,” said Adam Miklosi of Eötvös University in Hungary, co-author of a paper describing the results in the Sept. 4 issue of the journal Science. “If you assume an animal has to survive without human presence, then wolves are smarter. But if you are thinking that dogs have to survive in a human environment where it’s very important to follow the communications of humans, then in this aspect, dogs are smarter.”

The researchers think the differences between the dog and wolf subjects — both of which had been raised in human captivity in these experiments — arises from genetic traits that have been bred into dogs over 10,000 years of domestication by humans. Wolves and dogs diverged from a common ancestor at least 15,000 years ago, scientists think.

“This finding provides strong support for the domestication hypothesis, by again showing striking dog-wolf differences, and striking dog-human convergences — in this case, in a task with which most dogs have no previous experience,” Michael Tomasello and Juliane Kaminski, scientists from the Max Planck Institute for Evolutionary Anthropology in Germany who did not work on the new study, wrote in an accompanying essay in the same issue of Science.

Other experiments have noted that dogs are more attentive to the human voice and subtle vocal changes than wolves — another trait that likely results from domestication.

Dog-human connections
In some ways, domesticated animals resemble human infants because both learn primarily by following and listening to adult humans, rather than judging all new situations for themselves.

“When babies are young they are exposed to a relatively complex environment which is full of very complicated situations,” Miklosi told LiveScience. “Children are programmed to learn from the adult humans, especially when they can’t understand the logic behind the situation — like learning a language. What they have to do is go along with what adults are saying.”

Children are programmed to learn from their elders when it comes to crossing the street and other dangerous situations in which following their own curiosity and instincts are not the best learning mechanisms.

It is similar for domesticated dogs, which are bred to be able to follow human cues when it comes to situations like not eating food off the table, rather than following their own instincts to go for the chicken. This ability makes dogs easier to train — a key requirement for a domesticated species.

Even though the wolves used in the experiment were raised in captivity, their parents or their parents’ parents were wild, so the test wolves are not domesticated creatures with traits hard-wired into their genes over thousands of generations.

Social evolution
The point of the research is not just to learn about the domestication of dogs, but to use dogs and wolves as a test case for studying how social behavior can evolve, and especially how it may have evolved in humans.

“We see dog behavior and human behavior as a convergence,” Miklosi said. “Dogs became similar to humans because they had to live in a human social environment. This will tell us quite a lot about human social evolution.”

By studying how dogs learned to socialize with humans, scientists hope to understand more about how humans came to socialize with humans.

Interestingly, dogs and babies did react differently to one aspect of the experiment: When the human researcher was replaced by a new person, dogs forgot their lesson about Box A and followed their eyes instead. Infants, however, responded the same with multiple human teachers, continuing to trust the human over the visual evidence.

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Babies understand dog-speak, new study finds

aschae — Tue, 28 Jul 2009 19:47:43 +0000

Research from Brigham Young University (BYU) gives new meaning to the expression “babes in the woods.” It turn out, babies may not be as naive as we once thought — especially where their canine counterparts are concerned.

A new study shows that babies can “speak dog” (or at least comprehend it), even with little or no previous exposure to dogs. Infants just six months old matched the sounds of an angry bark and a friendly yap to photos of dogs displaying threatening or welcoming body language, respectively.

While paring babies and dogs might seem like a zany idea, according to BYU, experiments of this kind help us understand how babies learn. Long before they master speech, babies astutely recognize and respond to external stimuli.

These findings come on the heels of a study from the same Brigham Young University lab showing that infants can also detect mood swings in Beethoven’s music.

“Emotion is one of the first things babies pick up on in their social world,” said BYU psychology professor Ross Flom, lead author of the study. “We chose dogs because they are highly communicative creatures both in their posture and the nature of their bark,” Flom said.

In the experiment, the babies were shown two different pictures of the same dog, one in an aggressive posture and the other in a friendly stance. Then the researchers played — in random order — sound clips of a friendly and an aggressive dog bark.

While the recordings played, the six-month-old babies spent most of their time staring at the appropriate picture. Older babies usually made the connection instantly with their very first glance.

Study co-authors Dan Hyde and Heather Whipple Stephenson conducted the experiments as undergrads and don’t recall any babies getting upset. “Infants are pretty cooperative subjects,” Stephenson said.

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