Immortal animals would have a better chance of longterm survival, or to survive as a species, so why do animals grow old and die? Bill Nye the Science Guy explains a hard fact of evolution.

Jaco: Hi there Bill. My name is Jaco. I'd like to know what the evolutionary advantage is in growing old and dieing. They are biologically immortal animals on this planet so what is the evolutionary advantage for us to grow old and die? Surely immortal animals should have a better shot or a better chance at survival long-term or to survive as a species.

Bill Nye: Jeffrey, it would be great maybe to be immortal but nobody seems to be. I don't know if you're familiar with this, I'm of a certain age I pay taxes. You can't get away from having to pay taxes. The other thing that is clearly true and inescapable is you're going to die. I'm the first to admit it kind of sucks, first to admit. But the reason we all got this far is our ancestors had kids, had you, for example. And this just seems to be the way of the world. The thing about evolution that is so wonderful and so troubling is you don't have to be extraordinary, you do not have to be this super organism, this Superman, Superwoman, super mushroom, super palm tree, all you have to be is good enough. You have to be good enough to pass your genes on. And there is no reason, as far as anybody can tell, there's no reason in nature for natural systems to produce something that's better than good enough. If it happens it happens, but there's no reason. If you're not good enough you get eliminated, your genes don't show up in the future, but if you're good enough they do. Just think of all the troubling people you meet, all the people who think wow wouldn't it be better if they weren't around? I'm sorry man they were good enough, as are you and I. That's a great question.

So what it does for me is this knowledge that we're going to die, you just try to make the best of every day. I mean there's going to be hard times; there's going to be difficult times; almost certainly you're going to get sick from time to time because the germs and the viruses and parasites the bacteria are out to get you man. But with all of that you just try to make the best of every day because you only get to so many.