system
Given the following post, respond as if you're commenting on Reddit:
human
Why do most animals on earth live “roughly” the same time frame?

Most animals survive between like 5 years and 100 years. I know some outliers like turtles end up living to like 150 but what’s stopping things from living to 1000, 10’000?
 
I’m guessing there’s some smaller beings or 1/not-very-many celled organisms that last a long time but I’m not aware of anything that’s not microscopic that lasts ages. How come?
gpt
There is an evolutionary downside to living a very long time. Climate and habitats can change pretty drastically and if you evolved to live in one, the new version may not suit you well. It helps the species to be able to evolve quickly enough to continue. If a species is over populated by 1,000 year old individuals who haven't changed their DNA over generations then they can't generically respond to the new habitat's needs. You have to pump out babies that are changing over generations in order for the species to survive by adapting over time.