Genes associated with autism, anxiety, obsessive-compulsive disorder and other psychological problems have now been linked to human-directed social behaviors in dogs, suggesting that far more dogs than previously realized could suffer from these
mental disorders
.
The new research, published in Scientific Reports, reveals how malleable the identified gene regions are in dogs, since certain variations of them appear to explain the difference between a withdrawn dog and one that eagerly seeks human companionship.
The good news is, as with humans "there are cures which at least will decrease the problems," said senior author Per Jensen of the AVIAN Behavior Genomics and Physiology Group at Linköping University. "With respect to autism-like disorders, not much has been done, but OCD is a great problem in particular in some breeds of
dogs
. Dog psychologists usually have training programs that can alleviate some of these problems."
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Jensen and his team recorded the propensity of laboratory beagles (which they report were bred, kept and handled under standardized conditions) to initiate physical interactions with humans during an unsolvable-problem task.
For the task, the dogs had to slide three lids open in order to obtain treats in the containers underneath, but one of the lids was fixed in place and could not be opened. The researchers watched to see if the dogs engaged in human-directed behaviors, such as seeking eye contact.
WATCH VIDEO: When Did Dogs Become Man's Best Friend?
The genomes of 190 of the beagles were then analyzed. The scientists identified two genomic regions containing a total of five
genes
that are likely associated with the dogs' ability to connect with humans. In particular, a genetic marker within the gene
SEZ6L
was associated with time spent close to, and in physical contact with, humans. Two other markers located within the gene
ARVCF
were also associated with dogs seeking contact with people.
Jensen explained, "A genetic marker is simply a variation in the DNA sequence between different individuals. It could be a mutated gene, but in our case, the mutations are found in non-coding regions."
One of the beagles from the study works on the unsolvable task with researcher Mia Persson.
Mia Persson
While such variations have been tied to mental issues, genes often do not tell the whole story.
"For the particular behavior we have studied here, which is the propensity to seek proximity and cooperation with humans in difficult situations, the genes are responsible for about 30 percent of the variation seen in the population we have studied, so there is plenty of scope for improvement and modification through
training
."
The genes can also modify social behavior within "normal ranges," as well as be associated with pathological disorders, Jensen said.
Dogs could be especially prone to pathological disorders
since at least some of their genes, not to mention bodies, seem to be so malleable via breeding practices. Breeding of purebred
dogs
, for example, can affect both physical and behavioral traits in relatively few generations.
"We do not know why dogs are so extremely plastic," Jensen said. "In fact, the dog is the most variable species on the planet with respect to size, shape and behavior. Compare, for example, the size of a Chihuahua with a Great Dane, or the behavior of a terrier and a border collie."
Dogs representing different breeds ready for a walk in the Tribeca neighborhood of New York City.
Kristine Paulus, Flickr
He even said, "There is a possibility that breeds and individual dogs bred for high independence and endurance actually possess traits similar to those of autistic humans."
Because of the genetic connections to humans, dogs could serve "as a novel model system for human social disorders," the researchers believe. Adam Miklosi, director of the Family Dog Project and head of ethology at Eötvös Loránd University, told Discovery News that another canine expert, Karen Overall, raised a similar idea back in the year 2000.
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"The present results could be interesting as indicating a few new candidate genes regulating social behavior in dogs," Miklosi said, but he added that more work would have to be done to rule out alternative explanations for the recent findings, such as the possibility that "laboratory beagles may represent a specific population of dogs."
"Furthermore," he added, "researchers assume that the number of genes involved in both
schizophrenia
and autistic spectrum disorders could be more than 100," so it may not be very surprising that Jensen and his colleagues identified some of them in dogs.
Photo: Collected sample from prior research ready for DNA analysis. Credit: University of Michigan DNA Lab, Wikimedia Commons
Daniel Mills, a professor of veterinary behavioral medicine at the University of Lincoln, said, "There has been tremendous growth over the last 10–15 years in appreciation of the value of domestic dogs as models of human behavior, and their ability to help us answer questions that we simply can't do with other species."
At present, Jensen and his colleagues are studying
wolves
to see if they show the variations that dogs do within the same genetic markers. He suspects that they will, "since domestication is mostly caused by selection of already existing variation in the wild ancestors."
A future application of the research could be to allow owners and breeders to have their dogs' DNA tested to see whether the dogs have a genetic predisposition to be more or less interactive with humans.
Eventually, the genes associated with disorders could be
modified
to help eliminate many psychological problems in both humans and dogs.
SEE PHOTOS: The Earliest Dogs
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University of Manchester
A pointer named “Major” is identified as the first known example of a modern dog. A description of the dog was found in a now-obscure 1865 edition of a Victorian journal called The Field. It marks the earliest reported dog breed based on physical form and pedigree.
“The invention of ‘breed,’ physically and imaginatively, still shapes how we see and think about dogs today,” Michael Worboys, Director of the University of Manchester’s Centre for the History of Science, Technology and Medicine, told Discovery News.
Worboys and his team found the information concerning “Major” while preparing a new museum exhibit on dogs.
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Mietje Germonpré
The first domestication of dogs was thought to have taken place 31,680 years ago -- but new research suggests the skull in question likely belong to a wolf.
This particular specimen was found with a still-visible mammoth bone in its mouth.
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Jeffrey Beall/Flickr
The paleolithic dog remains resembled a modern Siberian husky, but suggest an animals that was significantly larger. Today, the Siberian husky, Samoyed and Alaskan malamute breeds are all closely related.
"The most remarkable difference between these dogs and recent dog breeds is the size of the teeth,” paleontologist Mietje Germonpré said.
Other early dog breeds, with a focus on the U.K., are featured in the museum exhibit curated by Worboys and his team. Entitled “Breed: The British and Their Dogs,” the exhibit runs at the University of Manchester museum through April 14.
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Bryan Ungard/Flickr
Another team of researchers, led by Heidi Parker of the National Human Genome Research Institute, used DNA analysis to determine the genetic relationships of numerous dog breeds. One such ancient breed is the Afghan hound. As its name suggests, it's native to the Middle East.
It’s one of the oldest dog breeds in existence, and was originally used for hunting hares and gazelles.
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Maja Dumat/Flickr
Parker and her team found that Akitas are yet another ancient breed. These dogs originated in Asia and are genetically similar to chow chows.
The breed was not included in the first dog show. “The first dog show was in 1859 when only two varieties were shown: pointers and setters,” Worboys said. It had nothing to do with the handsome Akita’s looks, as he explained that the first dog show was “for gun dogs only.”
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Renee Johnson/Flickr
The sleek-bodied saluki comes from Iran, where its distant ancestors might have once lived near the earliest farmers from the Fertile Crescent. Dogs in this region evolved the ability to eat a starch-rich diet around 12,000 years ago.
“Our findings show that it was crucial to early dogs to be able to thrive on a diet rich in starch,” Uppsala University’s Erik Axelsson, who led a related study, told Discovery News. “That indicates that dog domestication may be linked to the development of agriculture. It is possible that dogs may have been domesticated independently at locations where agriculture developed early, such as the Fertile Crescent and China.”
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Randi Hausken/Flickr
One of the most ancient dog breeds native to the United States is the Alaskan malamute. The DNA study found that they are genetically similar to Siberian huskies. This large, muscular dog was used -- and still is -- for pulling sleds, hauling freight by other means, and for additional work tasks.
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lindyi/Flickr
The basenji is “an ancient African breed,” according to Parker and her colleagues. While “Major” the pointer is the first documented modern breed of dog, the basenji is arguably the first dog to be heavily bred by humans. Although this dog hails from central Africa, paleontologists believe its wolf ancestors originally came from eastern Asia.
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Remigiusz Józefowicz/Wikimedia Commons
In China, the chow chow is affectionately referred to as Songshi Quan, meaning “puffy-lion dog.” It is genetically close to the Akita, also from Asia. It represents yet another early breed.
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canis-candie/Wikimedia Commons
Of the four most ancient known Asian dog breeds, the shar-pei was the first to diverge from a wolf ancestor, suggesting it is the oldest known Asian breed. This dog is famous for its deep wrinkles and blue-black tongue. Mutations of the same gene that causes wrinkles in these dogs can also cause wrinkling of human skin.