Source: TW
Intelligence emergence on earth
The earth is 4.54 Billion years old. For most of that period, Earth had life on it. From at least around 4.1-4.2 Bya there was life on earth.
The neural foundations for high intelligence – say dog, cat or heron level – emerged only in the late Triassic 227 Million years ago. Thus, for around 4 billion years, earth had life, but not the foundation for higher intelligence.
Moreover, even after the foundation for that type of intelligence emerged in two lineages – the mammals and the dinosaurs – it did not evolve immediately:
-Something approximating cat-dog level intelligence emerged in carnivorans around: 42 Mya -Something nearing monkey-level intelligence probably emerged around 30 Mya -an intelligent whale emerged around 35 Mya -on the dinosaur side, parrot-level intelligence evolved 50-40 Mya. -Something approaching crow-level intelligence probably emerged around 30 Mya.
Thus, it took approximately 190 million years for a high intelligence but not human level to emerge after the basic platform was in place.
This suggests that there is likely quite a delay before the intelligence platform is reached from the time of seeding of life on a planet and even after that platform is reached it takes a while of high but not human intelligence to emerge. Of all those many lineages where this high intelligence emerged only one after 227 Mya reached the human level. So human level is not reached quickly by life unless that intelligence is under an arms race – essentially, to trivialize, some version of the killer ape hypothesis.
Prognosis
A corollary to that is instability of the species of where intelligence is ratchetting up. Hence, this species will not last too long due to conflict. Further, the downside of such intelligence is rapid discovery of “local minima” leading to deleterious solutions in the long run again favoring eventual extinction.
Finally, the human experience has taught us that such a species might also squelch intelligence from emerging elsewhere as it will denude other intelligent species, like whales and cousin apes.(4)
Hence, it would fall back into paradigm for other high conflict species with a life-span of around 1-5 Myrs max.
Elsewhere
Source: TW
There have probably been 100s of trillions of planets with current human or higher intelligent life in the visible universe as a lower bound. However, they probably lasted 1-5 million years before going extinct. We don’t think there are any intergalactic civilizations. We don’t think, for that matter, there are any truly inter-stellar civilizations. However, life with decent intelligence – say, a crow or a dolphin level – is way more abundant than that and quite stably around throughout the universe.
विश्वास-टिप्पनी
1B years for the planet to be uninhabitable.
If we say monkey level is stable, then 30 Mya for human like emergence - quite a few cycles left…