[_8j50]

Except natural selection can't start over. It onlu works if there are always a high rate of survivors and even if that was not an issue consider 4 billion years and a generous generation life of one year (natural selection cycle), 4 billion isn't a whole lot even for small features when you don't have an enormous population and birth rate. Let's say there were 100000 humans at some point and only a 1000 fatal features (being generous) it's not just the replacement rate of defective humans that needs to exceed the elimination rate, a certain percent of replacements must be free of all fatal defects and survive. Also, consider how there should be many failed species that attempted to evolve into a human like species or a primate. You can't always luck out, at some point the entire branch has to fail, requiring subsequent attmepts meanwhile the fatal conditions that required the evolution will not go away.

[KingMob]

> It onlu works if there are always a high rate of survivors

There doesn't have to be a high rate of survival if the reproductive rate compensates for losses.

E.g., if 80% of wild rabbits are eaten, but the remaining 20% can give birth to 5 bunnies per parent per lifetime, the population will be stable.

I have no idea where you're getting your beliefs, but most of it is wrong in both the math and biology.

[_8j50]

What I am saying is that rate needs to continue to be positive and out of 20% survivors many will not carry the survival gene. And on top of that, it isn't just one thing that kills a rabbit in your example, the climate, not finding mates, predators, disease and more all must be overcome at once. Survivors must overcome a wide array of adversity and succesfully pass on that combination of abilities and this needs to happen every generation.

Look at it in bits and bytes. For each adversity overcoming feature that a species has inherited, let that a be a bit set to 1. With 2 adversaries you have only two bits where only need one out of 4 individuals that has both bits on. For a realistic adversity of 32, you need 4billion bits all set to one. And this is without considering how a survival trait against one adversity can be a fatal trait against another. Now these bits need to be passed on, if one of them is missing then the only chance that individual has to survive is by pure chance they avoid that adversary.

Think of the endless adversities we face and overcome, you are saying for millions of generations, there has been an unbroken chain of survivors that kept overcoming a geometrically expanding adversity. Just a degree increasing in the global temperature causes entire ecosystems to collapse.

Survival is the exception, not the default.

[wruza]

Yet creatures survive and reproduce, the fact that you can observe, analyze and even control.

I think you’re ignoring a bunch of dynamics by trying to model it with binary.

Prey population going down means a predator population also going down and a competitor population going up. It’s not an endgame, it’s just an “ear” of a very complex attractor, which with time only sharpens it ability to have as little escape points as possible.

1°C fluctuation by itself does nothing, because life usually has much wider tolerance due to long seasonal fluctuations. A global +-degree means there will be a tipping point somewhere which would bring a local drastic change. Locally life may suffer, but it counteracts with migration and preexisting diversity. It simply suffers everywhere, always. It’s a modus operandi. A little bit more is barely fatal.

So yes, survival is the default because life naturally specializes in it.