Why do squirrels live for 25 years and rats only 3 years?

Why are closely-related species so variant in longevity?Why do squirrels live for 25 years and rats only 3 years?
A 25 year old squirrel would be pretty ancient. They actually live more like 10 to 15 years, but they do live several times longer than rats.


Generally a species life span is determined by how long it takes to reproduce enough young to ensure continuation of the population.


Rats are much faster breeders. A female rat can produce 40 baby rats a year, while a squirrel only has 7 or 8 babies per year. So it takes five times as long to produce the same number of new additions to the species. In the wild, most rodents become food for some other animal before they can reproduce, so only a couple of those 40 are likely to survive and produce 40 more.





So the next question would be why do rats breed so much faster? That may have something to do with lifestyle and diet. Squirrels are vegetarians. In general, vegetarian species grow slower, reproduce less and live longer. Most squirrels are cold climate species, which hibernate or reduce their activity greatly in winter. Rats are always active. They are not adapted to cold weather, and only survive in Northern climates by living in houses or other manmade structures. Basically, through evolution rats have developed a live fast, die young strategy of survival.Why do squirrels live for 25 years and rats only 3 years?
A rat's heart will beat faster than a squirrle so thats why.