I like to think the great filter was the evolution of mitochondria - as far as we know, this only happened once in billions of years of life on our planet, and

I like to think the great filter was the evolution of mitochondria - as far as we know, this only happened once in billions of years of life on our planet, and it seems to have paved the way for the complex life we have. But more likely there are many filters, and maybe technology destroying the ecosystem we depend on is one of them.