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Discussion Starter #1
A "new study by researchers at University of California San Diego School of Medicine" has "created a formula that more accurately compares the ages of humans and dogs. The formula is based on the changing patterns of methyl groups in dog and human genomes—how many of these chemical tags and where they're located—as they age."


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"Especially when dogs are young, they age rapidly compared to humans. A one-year-old dog is similar to a 30-year-old human. A four-year-old dog is similar to a 52-year-old human. Then by seven years old, dog aging slows."

The researchers "Ideker and Wang collaborated with dog genetics experts Danika Bannasch, DVM, Ph.D., professor of population health and reproduction at UC Davis School of Veterinary Medicine, and Elaine Ostrander, Ph.D., chief of the Cancer Genetics and Comparative Genomics Branch at the National Human Genome Research Institute, part of the National Institutes of Health. Bannasch provided blood samples from 105 Labrador retrievers. As the first to sequence the dog genome, Ostrander provided valuable input on analyzing it."

This study was done with Labs but they plan to test other breeds to see if the results hold up.

If they test poodles and the results do hold up, I've got two 40 year olds on my hands.
 

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I have heard similar things about wolves in terms of when their physical prime is. It's interesting because when dogs are in their physical prime we view them as immature. I do not think dogs reach mental maturity until they are two, but I hope people reach it a bit earlier than 40!
 

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I'm not believing the conclusions of this study. Here's why:

"The formula provides a new "epigenetic clock," a method for determining the age of a cell, tissue or organism based on... chemical modifications like methylation, which influence which genes are "off" or "on"...

Okay, so far, I'm listening, but the two Ph.D's conclude:

"What emerged from the study is a graph that can be used to match up the age of your dog with the comparable human age..."This makes sense when you think about it—after all, a nine-month-old dog can have puppies, so we already knew that the 1:7 ratio wasn't an accurate measure of age," Ideker said.

Their graph doesn't add up to me. A 15 year old girl can give birth, but the graph places an equivalent dog at 5 to 6 months of age. At this age, a female is unlikely to go into heat, or for the males, to have sufficient quality semen to impregnate.

By the time a woman is 40, her fertility has dropped radically; the age-equivalent dog on their chart appears to be only around 20 months old.

The chart shows a 52 year old woman and a 4 year old dog are equivalent in age. From the standpoint of energy and reproduction, no comparison. Or their 60 y/o human being age-equivalent to a 6 y/o dog, the latter which can still have puppies and has a lot of run and play left in it for most breeds.

I think the flaw is they tried to match up this cellular process (of "methylation, which influence which genes are "off" or "on") with how it affects the aging process of both dogs and humans. But the chart doesn't line up with reality from a reproduction standpoint.

Perhaps they tried to compare apples to oranges where the same biological rules do not apply? It's an interesting start but I think they have more work to do.
 

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Medium/big dogs age more rapidly than small dogs and even with this method, it doesn’t take that into account. I don’t think a 6 year old toy poodle is equivalent to a 60 year old human. A small dog starts showing age around 10.
 

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Dechi, I agree with you 100%. There is a huge difference in the development timeline when comparing small breeds to large ones.
 

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Discussion Starter #8 (Edited)
I'll be interested to see if they continue testing breeds. This was for Labs only, so this study is just the opening shot.

This study is showing measurable comparable biological changes for development and aging in all mammals and then correlating to expected lifespans. That's why I really hope the keep the testing going.

I think it's safe to say that those of us raising our dogs from pups can attest that the rate of their early development to physiological maturity is definitely not at the 1 human year to 7 dog year ratio of conventional wisdom.

I'll drop in the link to the paper.

"Introduction

The wisdom that every year in a dog’s life equates to seven human years reflects our deep intuition that development and aging are conserved processes that occur at different rates in different species. All mammals, whether dog, human, or other creature, pass through similar life stages of embryogenesis, birth, infancy, youth, adolescence, maturity, and senescence. Although embryonic developmental programs have been relatively well studied, many of the molecular events governing postnatal life stages, including those tied to aging, are still unresolved. Over the past decade, it has become clear that a prominent molecular alteration during aging is remodeling of the DNA methylome, the pattern of epigenetic modifications whereby methyl groups are present at some cytosine-guanine dinucleotides (methyl-CpGs) but absent from others.The methylation states of tens of thousands of CpGs have been found to change predictably over time, enabling the construction of mathematical models, known as “epigenetic clocks,” that use these shifting patterns to accurately measure the age of an individual."


This excerpt addresses some of Vita's comments.

" We found that this function showed strong agreement between the approximate times at which dogs and humans experience common physiological milestones during both development and lifetime aging, i.e., infant, juvenile, adolescent, mature, and senior.
The observed agreement between epigenetics and physiology was particularly close for infant/juvenile and senior stages. For instance, the epigenome translated approximately 8 weeks in dogs (0.15 years) to approximately 9 months in humans (0.78 years), corresponding to the infant stage when deciduous teeth develop in both puppies and babies In seniors, the expected lifespan of Labrador retrievers, 12 years, correctly translated to the worldwide lifetime expectancy of humans, 70 years.
For adolescent and mature stages, the correspondence was more approximate, with the epigenome showing faster changes for dogs, relative to humans, than expected by physiological tables.
Thus, the canine epigenome progresses through a series of conserved biological states that align with major physiological changes in humans, occurring in the same sequence but at different chronological timepoints during each species’ lifespan."
 
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