Many birds live in jungles, and have smart brains. So clearly jungles is far from enough.

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It's difficult to imagine getting to technological civ being a really hard step. It's true that being smart isn't enough; you need a big brain + dexterity + language (which is initially dependent on a big brain but also specific genes). You need to be smart enough to solve natural puzzles and use tools, be precise enough to make tools better efficiently, and then pass on the knowledge. Then give it a few hundred thousand years and a few ups and downs in civ and you've random walked to explosive tech take off as we did.

Now, birds like corvids can understand water displacement puzzles instantly, and can use tools but will probably not easily evolve the dexterity required to optimize them, so not every path leads to all the required abilities. Dolphins have it even worse; smart and social but in a highly limited environment for tool use. It seems that the viable evolutionary path for all three factors on a planet is an arboreal lifestyle where you develop not just intelligence and sociality/language, but also the prerequisite for hyper-dextrous hands. Even then you may need to be forced to move away from the jungle to grasslands for grasping hands to evolve human level dexterity; other great apes remain stuck at a level of dexterity that is high enough to use tools but not easily optimize them.

All that said, the social part probably evolves easily, leading to complex brains, and then once you have a sufficient level, perhaps all you need is for jungles to exist for long periods and then give way to grasslands periodically due to climate change. If that's a reasonably full description of the relevant pressures, then tech can't be a very hard step from complex brains, unless for some reason jungles are the rarest thing in the universe.

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“The four most common chemically active elements in the universe—hydrogen, oxygen, carbon, and nitrogen—are the four most common elements of life on Earth.“ - Neil deGrasse Tyson

The abundance of those elements in the universe makes me think life is widespread (at least in the extremophile form which Hanson’s talked about.)

“In November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way, 11 billion of which may be orbiting Sun-like stars” -Wikipedia (I know, I’m quoting Wikipedia, forgive me)

As far as panspermia, there have been a number of experiments that demonstrated a favorable outcome for abiogenesis. The most famous was the Miller–Urey experiment in which they tried to mimic the chemical environment of primordial earth in the lab and added sparks of electricity. They were able to produce amino acids. That was in 1952. I’m sure there’s been more experiments since.

I know evolution by natural selection doesn’t always mean increases in complexity, it simply means organisms change genetically due to environmental pressures. But, it seems to me more complex organisms would be able to outcompete those of lesser complexity in many circumstances. For instance, the first light sensitive organism would have a huge advantage in spotting predators and food over one without vision. One could see how eyes and other senses would rapidly evolve in acuteness. The same goes for intelligence. Here we are all 7.8 billion of us, and precisely zero Neanderthal left. So my guess is abiogenesis and even the evolution of complexity may be common in the universe.

The Filters we face now and in the future may include: mutually assured destruction from nuclear weapons, environmental degradation, Pandemics like the Black Plague and even COVID, EM and the Technological Singularity, rapidly replicating Nanobots and who knows what kinds of Death Star-type weaponry the future holds, natural disasters like a massive volcano erupting or a comet smashing into earth have always been an issue.

Any of those could cause mass extinction and then life would have to evolve for billions of years into the future for human-like intelligence to appear again and the cycle may repeat itself until the sun exhausts it’s hydrogen and envelopes the earth...

...Or we could progress, surpass those obstacles, and colonize a portion of the galaxy.

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For every Great Filter there is an equal and opposite Possibility that Earth is an under-performer.

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Fixed; thanks.

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2106 journal articleI assume you meant to write "2016".

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