Why do cats have short lives – much shorter than the lives of humans? I briefly did some reading about this. I had to, although I did have some ideas, rather vague ideas, before trying to answer the question. It’s obviously very complicated and it seems that we are not sure why cats have shorter lives than humans. However, I will deliver a theory. Note: It may be incorrect to presume that cats have short lives in an absolute sense. Their lifespans are average in length. The better question might be: Why do humans have long lives?
The heavier that animals are (i.e. the bigger they are) the smaller surface area to volume ratio they have. This helps to reduce heat loss. Domestic cats are much smaller than humans. Their bodies have to work harder. Their heart rate (normal resting pulse) is about 140 bpm compared to the human’s 80 bpm. A cat has to maintain a normal body temperature between 100.5 to 102.5°F. Humans have a body temperature of 98.6°F.
Body Works Harder
The cat’s heart and metabolism therefore works harder. Perhaps it is simplistic to say that as the body is working harder the lifespan is going to be shorter. Why didn’t the cat evolve to extend its lifespan by lowering its body temperature? Evolution is about survival. It’s about natural selection improving the chances of survival. Survival also includes survival of the species as well as the survival of individuals.
The domestic cat breeds (proliferates) very efficiently. Therefore there is no need for an extended lifespan in order to ensure the survival of the species. As a cat is smaller than the human and works harder than the human and as there is no need to extend the lifespan because of efficient breeding, the domestic cat ages seven times faster than the human.
Reddit.com – answers why do cats have short lives?
The experts on Reddit.com have come up with some fancy answers. One says that natural selection (remember Darwin’s theory?) picks out the optimum lifespan for an individual when taking into account its long-term survival and proliferation. Like I said, the domestic cat is a very good survivor if left intact. There is no need for a long life to preserve species and to proliferate successfully.
Another person says that an animal’s size and life expectancy is tied together. I’ve already mentioned that. Species of mammal which are 30 times heavier than another species will live twice as long. This person says that humans should live around 28 years but because we are so well looked after and mollycoddled we live to 80. Do we live too long as a consequence? This reflects the difference between feral cats and domestic cats. People say that feral cats live for about three or four years and we know that domestic cats live around 18 years normally. However, this is a discussion about lifestyle rather than lifespan.
Lifespan vs Lifestyle
It is perhaps useful to distinguish between an animal’s natural lifespan and its lifestyle which can extend or reduce the lifespan. The domestic cat in the wild has a much shorter lifespan than the domestic cat in a nice home where he is well looked after. It could be argued that the domestic cat’s lifespan is extended because of domestication. It is perhaps unnaturally extended and should be shorter.
To return to the beginning, we don’t know for sure why cats have shorter lives. However a combination of metabolism, breeding success, evolution, size, heart rate, genetics etc. dictates the answer.
If you have a theory on: why do cats have short lives, please tell me.
P.S. Small dogs live longer than large ones I am told. This may be because due to inbreeding large dogs have more health issues.
P.P.S. Lions are much larger than domestic cats. Why don’t they live longer? The answer is probably because their lifestyle in either captivity or the wild works against longevity.