8 ms·

The Mythology of Dog Years

simonsquiff 12y ago
Can anyone explain why dogs (amongst others) age so much faster than humans? A 10 year old dog will be grey and have other visible aging signs, whilst we're still youthful. What is the difference? Are dogs cells dividing at a faster rate than ours, and if so why are they doing that? Presumably the answer gives us insight into the aging process, but I've not been able to find answers in some casual browsing.
- johnchristopher 12y ago
  Enquiry into the evolution of aging aims to explain why almost all living things weaken and die with age. There is not yet agreement in the scientific community on a single answer. The evolutionary origin of senescence remains a fundamental unsolved problem in biology. http://en.wikipedia.org/wiki/Evolution_of_ageing http://en.wikipedia.org/wiki/Evolution_of_ageing The biological mechanisms which regulate lifespan evolved several hundred million years ago. edit: Regarding dogs: http://www.insidescience.org/content/large-dogs-age-faster-die-younger/953 http://www.insidescience.org/content/large-dogs-age-faster-d...
- danieltillett 12y ago
  The why is easy - like everything it is because dogs that age any slower than the average dog did not have any more offspring. The difficult question is the how question - how do humans and dogs differ in their ageing process. Anyone who can answer this will be more famous than Einstein. A more interesting question is how do humans manage to age so much slower than chimps. This has occurred so recently in evolutionary history that it must involve only a few genes. Any process that is controlled by a few genes can, in theory at least, be a pharmaceutical target.
  - mrfusion 12y ago
    Are you sure humans age more slowly than chimps? I thought they basically live to the same age?
dvirsky 12y ago
Oh man, that just made me realize my 9 year old dog doesn't have a lot of time left probably. It's weird, she doesn't seem to behave any differently than say 4-5 years ago, and still has lots of energy and zero health issues. So I just don't think of her as being old. According to these charts she's 55-60 in human years.
- jedberg 12y ago
  It's only a rule of thumb. Our Huskies (large dog) generally lived to be 15 to 17 years old. That's about 100 in human years according to the chart at the bottom of the article.
- electromagnetic 12y ago
  Depends on the dog, depends on the breed, depends on their health. The problem with average life expectancy is that most dogs don't die of natural causes, they get put down. We would have a shorter average life span if we allowed people assisted suicide for those with terminal conditions, especially ones that drag on for years or decades. Think ALS, Alzheimers and Parkinson's, they can last twenty or thirty years. Often long past when a person would want to die for the benefit of themselves but also everyone around them. We make that choice for our dogs. My in-laws put their dog down, he likely could have got another year but he was suffering and you don't torture things you love with forcing them to stay alive.
guard-of-terra 12y ago
We humans are very badly designed. A dog probably gets around eight active years or more, but we humans only have like three. When we are mature, fertile, energetic, without building up health problems. And then we have six more dog years of being old.
- Udo 12y ago
  Are you by chance in your early twenties? The core message is that animal years map very badly to human years. During the first twenty years, we are busy with development. The fertility part is gender specific, and lasts about 25 to 30 years in women and much longer in men. Conflating active years with fertility is a problematic idea. Maturity is a very fuzzy concept, but cortical development is commonly not considered complete until the mid-twenties. The variance in energy is probably higher compared across different individuals than across different age groups. Health problems also vary greatly from person to person, but it's fair to say that crossing 40 risk factors for everything go up dramatically. How many active years humans get out of their life is subject to great individual variation. Some get zero. Others are highly productive for 60+ years. But I agree it's not enough - that's why we need transhuman advances in science. Less than a Guard of Terra, maybe more like a Space Marine ;)
  - guard-of-terra 12y ago
    I'm in late twenties. The idea that I have to make all the important choices in the first half (second quarter even) of my life which is almost over saddens me. Short fertility in women (which we cut in half with our clumsy society) is THE problem. With the exclusion of mismatches, which I shun, male fertility is effectively limited to the same age range too.
    - Udo 12y ago
      It depends a lot on attitude. If you consider procreation and family a big goal in your life, then you're right: the clock is always ticking. I'm almost 40 now, that ship has thoroughly sailed. I don't agree that all the important choices happen during the first half though. Consider that for the first 1.5 decades you hardly make any of your own choices at all. So while the procreation thing is about halfway over at your age, in a lot of other ways you're just getting started.
jedberg 12y ago
My vet actually had the 15, 10, 4, 4... etc chart on the wall. I think 7 came because at the end of the dog's natural life you could get a rough estimate using the rule of 7 because it averaged out.
V-2 12y ago
OK, a long read, but at the end it seems that she was actually even older than the equivalent of 200 human years? :)
TomNomNom 12y ago
The concept of 'dog years' has always interested me. I recently quipped to some friends that if there's 7 dog years in a human year, there's 2^y computer years in a human year; so a 6 year old computer is 64 in computer years.
dneronique 12y ago
> Puberty range in most women and bitches At first I was offended and then I was 'Oohh...'

Can anyone explain why dogs (amongst others) age so much faster than humans? A 10 year old dog will be grey and have other visible aging signs, whilst we're still youthful. What is the difference? Are dogs cells dividing at a faster rate than ours, and if so why are they doing that? Presumably the answer gives us insight into the aging process, but I've not been able to find answers in some casual browsing.

johnchristopher 12y ago
Enquiry into the evolution of aging aims to explain why almost all living things weaken and die with age. There is not yet agreement in the scientific community on a single answer. The evolutionary origin of senescence remains a fundamental unsolved problem in biology. http://en.wikipedia.org/wiki/Evolution_of_ageing http://en.wikipedia.org/wiki/Evolution_of_ageing The biological mechanisms which regulate lifespan evolved several hundred million years ago. edit: Regarding dogs: http://www.insidescience.org/content/large-dogs-age-faster-die-younger/953 http://www.insidescience.org/content/large-dogs-age-faster-d...
danieltillett 12y ago
The why is easy - like everything it is because dogs that age any slower than the average dog did not have any more offspring. The difficult question is the how question - how do humans and dogs differ in their ageing process. Anyone who can answer this will be more famous than Einstein. A more interesting question is how do humans manage to age so much slower than chimps. This has occurred so recently in evolutionary history that it must involve only a few genes. Any process that is controlled by a few genes can, in theory at least, be a pharmaceutical target.
- mrfusion 12y ago
  Are you sure humans age more slowly than chimps? I thought they basically live to the same age?

dvirsky 12y ago

Oh man, that just made me realize my 9 year old dog doesn't have a lot of time left probably. It's weird, she doesn't seem to behave any differently than say 4-5 years ago, and still has lots of energy and zero health issues. So I just don't think of her as being old. According to these charts she's 55-60 in human years.

jedberg 12y ago
It's only a rule of thumb. Our Huskies (large dog) generally lived to be 15 to 17 years old. That's about 100 in human years according to the chart at the bottom of the article.
electromagnetic 12y ago
Depends on the dog, depends on the breed, depends on their health. The problem with average life expectancy is that most dogs don't die of natural causes, they get put down. We would have a shorter average life span if we allowed people assisted suicide for those with terminal conditions, especially ones that drag on for years or decades. Think ALS, Alzheimers and Parkinson's, they can last twenty or thirty years. Often long past when a person would want to die for the benefit of themselves but also everyone around them. We make that choice for our dogs. My in-laws put their dog down, he likely could have got another year but he was suffering and you don't torture things you love with forcing them to stay alive.

guard-of-terra 12y ago

We humans are very badly designed. A dog probably gets around eight active years or more, but we humans only have like three. When we are mature, fertile, energetic, without building up health problems. And then we have six more dog years of being old.

Udo 12y ago
Are you by chance in your early twenties? The core message is that animal years map very badly to human years. During the first twenty years, we are busy with development. The fertility part is gender specific, and lasts about 25 to 30 years in women and much longer in men. Conflating active years with fertility is a problematic idea. Maturity is a very fuzzy concept, but cortical development is commonly not considered complete until the mid-twenties. The variance in energy is probably higher compared across different individuals than across different age groups. Health problems also vary greatly from person to person, but it's fair to say that crossing 40 risk factors for everything go up dramatically. How many active years humans get out of their life is subject to great individual variation. Some get zero. Others are highly productive for 60+ years. But I agree it's not enough - that's why we need transhuman advances in science. Less than a Guard of Terra, maybe more like a Space Marine ;)
- guard-of-terra 12y ago
  I'm in late twenties. The idea that I have to make all the important choices in the first half (second quarter even) of my life which is almost over saddens me. Short fertility in women (which we cut in half with our clumsy society) is THE problem. With the exclusion of mismatches, which I shun, male fertility is effectively limited to the same age range too.
  - Udo 12y ago
    It depends a lot on attitude. If you consider procreation and family a big goal in your life, then you're right: the clock is always ticking. I'm almost 40 now, that ship has thoroughly sailed. I don't agree that all the important choices happen during the first half though. Consider that for the first 1.5 decades you hardly make any of your own choices at all. So while the procreation thing is about halfway over at your age, in a lot of other ways you're just getting started.

jedberg 12y ago

My vet actually had the 15, 10, 4, 4... etc chart on the wall. I think 7 came because at the end of the dog's natural life you could get a rough estimate using the rule of 7 because it averaged out.

V-2 12y ago

OK, a long read, but at the end it seems that she was actually even older than the equivalent of 200 human years? :)

TomNomNom 12y ago

The concept of 'dog years' has always interested me. I recently quipped to some friends that if there's 7 dog years in a human year, there's 2^y computer years in a human year; so a 6 year old computer is 64 in computer years.

dneronique 12y ago

> Puberty range in most women and bitches At first I was offended and then I was 'Oohh...'