Evolution and humans: only us in the universe (Evolution)

by David Turell @, Wednesday, October 23, 2019, 05:41 (52 days ago) @ David Turell

A well reasoned article:

https://www.livescience.com/evolution-says-humans-only-intelligent-life.html?utm_source...

"Are we alone in the universe? It comes down to whether intelligence is a probable outcome of natural selection, or an improbable fluke. By definition, probable events occur frequently, improbable events occur rarely — or once. Our evolutionary history shows that many key adaptations — not just intelligence, but complex animals, complex cells, photosynthesis, and life itself — were unique, one-off events, and therefore highly improbable. Our evolution may have been like winning the lottery … only far less likely.

***

" All convergence happened within one lineage, the Eumetazoa. Eumetazoans are complex animals with symmetry, mouths, guts, muscles, a nervous system. Different eumetazoans evolved similar solutions to similar problems, but the complex body plan that made it all possible is unique. Complex animals evolved once in life's history, suggesting they're improbable.
(my bold)

***

"There are places where evolution repeats, and places where it doesn't. If we only look for convergence, it creates confirmation bias. Convergence seems to be the rule, and our evolution looks probable. But when you look for non-convergence, it's everywhere, and critical, complex adaptations seem to be the least repeatable, and therefore improbable.

***

"All organisms come from a single ancestor; as far as we can tell, life only happened once.

***

"These one-off innovations, critical flukes, may create a chain of evolutionary bottlenecks or filters. If so, our evolution wasn't like winning the lottery. It was like winning the lottery again, and again, and again. On other worlds, these critical adaptations might have evolved too late for intelligence to emerge before their suns went nova, or not at all.

"Imagine that intelligence depends on a chain of seven unlikely innovations — the origin of life, photosynthesis, complex cells, sex, complex animals, skeletons and intelligence itself — each with a 10% chance of evolving. The odds of evolving intelligence become one in 10 million.

"But complex adaptations might be even less likely. Photosynthesis required a series of adaptations in proteins, pigments and membranes. Eumetazoan animals required multiple anatomical innovations (nerves, muscles, mouths and so on). So maybe each of these seven key innovations evolve just 1% of the time. If so, intelligence will evolve on just 1 in 100 trillion habitable worlds. If habitable worlds are rare, then we might be the only intelligent life in the galaxy, or even the visible universe.

"And yet, we're here. That must count for something, right? If evolution gets lucky one in 100 trillion times, what are the odds we happen to be on a planet where it happened? Actually, the odds of being on that improbable world are 100%, because we couldn't have this conversation on a world where photosynthesis, complex cells, or animals didn't evolve. That's the anthropic principle: Earth's history must have allowed intelligent life to evolve, or we wouldn't be here to ponder it.

"Intelligence seems to depend on a chain of improbable events. But given the vast number of planets, then like an infinite number of monkeys pounding on an infinite number of typewriters to write Hamlet, it's bound to evolve somewhere. The improbable result was us."

Comment: And add to that our human form of consciousness, the most improbable result of all,
Adler's key point. Against all odds, especially if the result of natural materialism. Note the one complex invention which is the source of our bush of life is from the Cambrian Explosion, with no precursors! See my bold above.


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