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The myth that a year in a dog's life is equivalent to seven years in humans has been dispelled.

What is the reality

By Grecu Daniel CristianPublished 2 years ago 3 min read
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Scientists have dispelled the myth that one year of a dog's life would be equivalent to seven years of a man's life and found that young specimens are "older" than previously thought.

The findings, published in the journal Cell Systems on Thursday, suggest that a one-year-old dog is actually about 30 years old in "human years."

A team of researchers at the University of California, San Diego School of Medicine has studied epigenetic changes in DNA - which do not affect the DNA sequence, but can activate or deactivate genes.

The team compared how certain molecules, called methyl groups, have accumulated over time in certain regions of the human genome with how these molecules have accumulated in similar areas of the dog's genome.

The results, based on genetic data from about a hundred Labrador Retriever specimens, from chickens to older dogs, revealed that one year in humans is not the equivalent of seven years in dogs.

Dog aging slows down over time

In the first year of life, dogs show much faster accumulation of methyl groups in the genome compared to humans, suggesting that they age at a much faster rate.

However, the rate of aging in dogs, compared to that of humans, slows down over time.

"It makes sense if you think about it - a nine-month-old dog can have puppies after all, so I already knew that the 1: 7 ratio isn't the right way to estimate age," said Trey Ideker, a researcher at San Diego School of Medicine, quoted by phys.org.

The findings suggest that a one-year-old dog would have a "human age" of about 30 years, while a four-year-old would be about 54 years old in a "human year," and a 14-year-old would be equivalent to a man of about 70 years.

The formula, according to the team, is: human age = 16 ln (dog age) + 31. In mathematics, ln refers to the natural logarithm of a number.

According to the research team, in the case of young and old dogs, the relationship seems to reflect the ages at which humans and dogs reach certain benchmarks.

"For example, the epigenome translated seven weeks into dogs in nine months in humans, which corresponds to the infant stage, when permanent teeth appear in both puppies and babies," the team noted in a study presentation.

"In the case of seniors, the life expectancy of the 12-year-old Labrador Retriever has been translated correctly into the 70-year-old human life expectancy," according to the researchers.

However, scientists have noted that the association is less accurate when it comes to benchmarks in adolescence and the second half of life.

The team added that this study suggests that both humans and dogs accumulate methyl groups on some of the same genes as they age.

These, the team noted, are involved in a variety of development-related functions.

The researchers noted that the study will need to be repeated on other dog breeds.

How long does a dog live?

The life expectancy of dogs varies depending on the breed. Here are some key elements that can guide you, some things being easy to do when we want our pet to live longer. The average lifespan of dogs, including all breeds, is between 10-13 years, with plus and minus variants that cannot be taken as a benchmark. Think that we humans live in fairly wide intervals, which would be to consider that we will all live as the oldest on the planet. A sensitive subject, painful but necessary. Here are the facts:

If we evaluate the situation according to breeds, a life expectancy below average, of 8-9 years, would have the dogs belonging to the breeds: Bull terrier, Bulldog, Newfoundland, German Dog, Bloodhound, Bordeaux Dog, etc.

On the other hand, the longest-lived breeds, with a lifespan of 14-15 years, are the dwarf kennel, the Dachshund, the Chihuahua, the dwarf Schnauzer, the small terrier dogs.

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Grecu Daniel Cristian

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