How come smaller dogs generally havw longer life spans than larger dogs, but larger animals, like horses, have an even longer lifespan?
In: Biology
It’s the same with humans. Taller people are expected to have shorter lifespans than short people. Simply put, because there is more of them to go wrong. Think how many cells there are in a person. A tall person obviously has more cells. More cells = more chance of something going wrong within one of them to cause diseases like cancer and the more of you there is, the more your heart has to work to get blood everywhere, more blood is required to fill your body, your lungs work harder to oxygenate all that blood, you kidneys and liver work more filtering it.
The more of you there is, the more strain you put on your body, which is also why obese people have shorter life spanss.
Same thing applies to dogs. Even though they’re different breeds, they’re the same species. So, within their species, big dogs are more likely to die sooner than small dogs.
Remember though, that only applies within a species.
Outside of species, when comparing different species, it’s actually larger animals that tend to live longer. This is due to a lot of factors, but one main one being, the smaller an animal is, the more likely it is to be prey. Which means they need to breed fast before being eaten. The result of breeding fast, is they don’t need to live long, just long enough to reproduce. On the reverse, the bigger an animal is, the less likely it is to be prey.
So a general rule is, smaller animals evolved to have short lives and breed quickly, where as bigger animals evolved to live longer and therefore can breed more slowly.
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