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Researchers Develop New Formula to Calculate Your Dog’s Human Age

The new technique is based on changes in DNA over time

California, November 18, 2019: No one knows how it started, or where it came from, but the idea that you can convert your dog’s age to human years by multiplying by seven? Total myth. But we like to contextualise our animal companions’ ageing against our own lives; if nothing else, it helps us to relate to them.

As reported by Sciencealert, finding an accurate way to do so isn’t easy, but a team of researchers has developed a formula. And it’s based not on some arbitrary metric, but on changes to DNA over time; they’ve described it in a paper published on the pre-print resource bioRxiv ahead of peer review.

The team’s method is based on an epigenetic mechanism called methylation. As both humans and domestic dogs (Canis lupus familiaris) age, methyl groups are added to our DNA molecules, which can change the activity of a DNA segment without altering the DNA itself.

This obviously has its own function, but one corollary is that DNA methylation can be used to measure age in humans. This is called the epigenetic clock. So, led by geneticists Tina Wang and Trey Ideker of the University of California San Diego, the researchers set out to compare the epigenetic clock of humans to the epigenetic clock of dogs. Dog lifespans can vary wildly: from 6-7 years for some large breeds such as mastiffs to as many as 17-18 years for dogs such as chihuahuas. Despite this variation, all dogs exhibit a similar developmental, physiological, and pathological trajectory.

A single breed offers strong genome homogeneity, which increases the chance of identifying genetic factors associated with complex traits including ageing, the team said. So they used Labrador retriever dogs for this study. They then compared their dog data to the published methylation profiles from the blood of 320 humans, aged between one and 103 years, and those of 133 mice. “Using targeted sequencing, we characterise the methylomes of 104 Labrador retrievers spanning a 16 year age range, achieving >150X coverage within mammalian syntenic blocks,” they wrote in their paper.

“Comparison with human methylomes reveals a nonlinear relationship which translates dog to human years, aligns the timing of major physiological milestones between the two species, and extends to mice.” The similarities were the greatest when comparing young dogs to young humans, and elderly dogs to elderly humans.This matching of the epigenetic clocks allowed the team to derive a formula for calculating the ‘human’ age of dogs: human_age = 16ln(dog_age) + 31.

So, multiply the natural logarithm of your dog’s age in years (here’s a calculator you can use) by 16, then add 31. That will give you the dog’s age in ‘human years’.Using this formula, certain milestones matched up really well. Seven weeks in dogs was found to correspond with nine months in humans – the time when baby teeth are erupting in puppies and infants. The two species’ average lifespans also matched up – 12 years for the Labradors, and 70 for humans.

That said, other milestones didn’t match up quite so well. Dogs, for instance, go through puberty and reach sexual maturity faster than humans, so the period between adolescence and middle age doesn’t match up – a five-year-old Labrador is calculated at around 56 in human years. But dog methylation slows down as they age, so humans can catch up.

And, of course, there’s that pesky problem with different breeds ageing differently. So we’ll probably never have a one-size-fits-all approach – but a formula based on the epigenetic clock is considerably more useful than simply multiplying by seven. The team’s research has been published on bioRxiv.

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Books Reveal Why Dog and Humans are So Close

Relationship between Man and his best friend decoded

New York, October 18, 2019: Dogs have been jubilantly kicking their legs in the air for at least 14,000 years, and during that time they became our devoted companions. Two new books offer different takes on this interspecies bond. The first makes a compelling case that dogs do far more than just obey us — they love us. The other book offers a broader look at all the complexities and contradictions of the human-dog relationship.

According to ScienceNews Clive Wynne, a canine behaviorist and founding director of the Canine Science Collaboratory at Arizona State University in Tempe, has always loved dogs, but it took him many years to become convinced that the feeling is reciprocated. In Dog Is Love, readers accompany Wynne on his scientific journey from skeptic to believer. Not only do dogs love us, he argues, but it is their capacity and desire to connect with humans that makes dogs unique.

Many scientists are loath to talk about the emotional lives of animals, love in particular (SN: 3/2/19, p. 28). The concept “seems too soppy and imprecise,” Wynne writes, and we risk anthropomorphizing dogs. But acknowledging their capacity for love is the only way to make sense of why dogs are so devoted to us and thrive in our company, he argues. Dog Is Love takes readers all the way from theories about how dogs became domesticated to recent behavioral, biological and genetics research that provides convincing evidence that our canine companions feel affection. Dogs’ genetic makeup predisposes them to be loving (SN: 8/19/17, p. 8), Wynne argues, and early exposure to humans (or even other animals) solidifies the connection.

Our Dogs, Ourselves offers a more comprehensive exploration of the human-dog relationship. Alexandra Horowitz, head of Barnard College’s Dog Cognition Lab in New York City and author of the 2009 New York Times bestseller Inside of a Dog, gives an overview of the culture of dogdom — the way people acquire, name, train, raise, treat, talk to and see dogs. She explores the lighter side of this culture, including our fixation with dog accessories — everything from dog bathrobes and canine body sprays to fake testicles.

But Horowitz also tackles the darker side and poses some thought-provoking ethical questions: Should we view dogs as property? Is spaying and neutering dogs the right way to deal with overpopulation? Should dogs be used in research?
Both books address a particularly thorny problem: dog breeds. Initially, dogs were bred for specific purposes — hunting or providing comfort, for example. But in the late 1800s, the emphasis became purity, Horowitz writes. Today, purebred dogs are descended from a relatively small pool of founders and inbreeding is rampant. A purebred’s family tree might reveal that “his father is also his grandfather and his mother’s uncle to boot,” Wynne writes. Because the gene pool for each breed is closed, genetic defects crop up. Dalmatians are predisposed to deafness and a heritable urinary tract disorder. German shepherds are prone to hip problems.

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That Old Adage About Dogs Resembling Their Owners? New Research Suggests It’s True

Dog personality may share similar characteristics to that of human personality.

It’s well known that human personalities change as we age. Now a detailed study of dog personalities indicates that our canine companions often go through remarkably similar changes during their lives—and our own personalities may be a key factor.

Psychologists at Michigan State University published a paper this month in the Journal of Research in Personality that examined dog personalities and found some evidence to support the old adage that dogs resemble their owners. “Dog personality may share similar characteristics to that of human personality,” the study said in summarizing its findings.

“When humans go through big changes in life, their personality traits can change. We found that this also happens with dogs—and to a surprisingly large degree,” William Chopik, a Michigan State professor of psychology and the study’s lead author spoke to Sciencedaily

“We expected the dogs’ personalities to be fairly stable because they don’t have wild lifestyle changes humans do, but they actually change a lot,” Chopik said. “We uncovered similarities to their owners, the optimal time for training, and even a time in their lives that they can get more aggressive toward other animals.”

As reported by Fortune.com, the study surveyed people who owned 1,681 dogs belonging to 50 breeds and aged between a few months and 15 years. The owners were asked to evaluate their dogs’ personalities and behavioral history, along with their own personalities.

Chopik found that the “sweet spot” for obedience training came well beyond puppihood, at around six years old, when dogs have outgrown their excitable puppy ways but before old habits settle in. That’s also the age when dogs are most likely to show aggressiveness to humans or other animals.

The study also indicated that personality traits that can emerge in dogs over time—excitation, aggression, fear, and anxiety—can be amplified by the behavior of their human companions. Overall, the people who were most satisfied with their dogs were the ones who invested in obedience training and who offered their dogs an active and playful life.

 

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