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Anonymous
Why do animals age at such different rates?
>> Yiffdog !!gE/Npivj/5x
Hang on, I heard that the small, rat-like breeds of dogs outlive big breeds.
And they have FAST heartbeats, no?
>> Anonymous
>>203179
I think that's because big dog's hearts need to work harder to get blood going through their bodies? ...wait. That contradicts everything else.

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>> Anonymous
>>203180

The only explanation I can think of is that given the huge variation of size we've created among domestic dogs, there's obviously an 'ideal size' for the basic canine design. You'd think it would be medium/largish dogs i.e wolf or wild dog size, but apparently by creating small dogs we've created the ideal canine size!

Also keep in mind that dogs can be TOO small - very tiny ones like teacup chihuahuas tend to have a myriad health problems that shorten their lifespan. They're not supposed to be THAT small.

Here's a theory of mine: Great Danes may have a body mass ten times that of a Jack Russell, but their hearts are certainly not ten times as big - they're maybe two or three times as big! Ergo, large breeds simply do not have large enough hearts to support their size for any length of time; they're bound to fail a lot sooner.
>> Anonymous
>>203195

Also, dogs are freaks of nature, really. In the animal kingdom, usually things that are larger live longer!
>> Anonymous
>>203198
Makes sense, since humans made dogs and nature made most other things.
>> Anonymous
Cells reproduce through a process called mitosis (splitting in half). An embryo starts out as a single cell, then rapidly divides until there are enough cells to form a whole body. Unfortunately, most cells are hard coded to divide a certain amount of times before they begin breaking down (notice that humans usually start getting sick at around 40 or older).

That's why small dogs live longer. Because their cells don't have to reproduce that much during the growing process, which adds extra years to their life. On the other hand, big dogs have to grow more mass (bigger organs, bones, etc) so their cells have to divide more often than a smaller dog.
>> Anonymous
Hm what about goldfish ? they can live up to 20 years + and grow to about 8 inches
>> Anonymous
>>203324
What about Blue Whales? They live for around 80 years and grow from 7 m to 30 m.
Wouldn't most creatures have evolved to age slowly and keep fertile for a long period of time and thus make more babies?
>> Anonymous
The average lifespan of an animal is usually determined by its lifestyle. Animals that have a lot of offspring and are likely to get killed young tend to have short rapid lifespans so that they have time to breed before something eats them. Animals that have few offspring and have few or no natural enemies tend to live more slowly and have longer lifespans. So the lifespan of a hare is about 4 years but an elephant may live to be 60. Similarily a weasel is lucky to live more than 3 years while a lion may live 16 years and a polar bear for 30.

In nature, very few animals get to grow old. They are usually species that are on top of their food chain or don't have natural enemies when fully mature. They are usually either among the largest or most formidable species in their ecosystem, and they utilize a reliable food source (plants, plankton).