Origin of Life

Three Possible End-Member Scenarios for the Origin of Life

1) The origin of life may have been a miracle.
2) The origin of life was an event fully consistent with chemistry and physics, but one that was almost infinitely unlikely and required an improbable sequence of numerous steps.
3) The universe is organized in such a way that life is an inevitable consequence of chemistry, given an appropriate environment and sufficient time.
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T. A. Gardner said:
4. The origin of life was consistent with chemistry and physics and helped by an outside intelligent agent acting to move it along.

This variant is equally plausible simply because we have not found proof that it cannot have happened, at least as it applies to life on this planet. Now, maybe that doesn't apply to the origin of the first lifeform, but the entire universe is rather a large place so...
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^ I include that under category 1).
To me, life evolving through an intelligent agency, versus life evolving by miraculous intervention is a distinction without a difference.
 
Cypress said:
The lesson from Earth at least seems to be that the evolution of intelligent, technologically-capable life is exceedingly rare. Earth itself is almost one quarter the age of the universe, and in all that time only one species evolved capable of technology. And it took 4 billion years just to get there.

If humans (or alien civilizations) self-annihilate or go extinct, the odds of another technologically-capable civilization evolving on the same planet seems slim to none. That does not rule out that non-sentient, lower life would continue to thrive.

That is my read on the hypothesis anyway
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It's not a certainty that we're the only one. Multiple ice ages would have scourged any signs of civilization not to mention the lowering of the oceans inversely to the ice age. 75% of the planet is water and we've barely begun to explore it. Earthquakes and volcanoes add to the problem along with impact events every 60 million years or so. <--- we're overdue. ;)

Heck, we can't even find an intact Boeing 777 airliner underwater even with clues on where to look.

https://en.wikipedia.org/wiki/Impact_event
Asteroids with a 1 km (0.62 mi) diameter strike Earth every 500,000 years on average.[16][17] Large collisions – with 5 km (3 mi) objects – happen approximately once every twenty million years.[18] The last known impact of an object of 10 km (6 mi) or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago.[19]

Impact event map: https://upload.wikimedia.org/wikipedia/commons/c/cc/Earth_Impact_Database_world_map.svg

There's good news to the numbers, though. :thup:
 
Cypress said:
^ I include that under category 1).
To me, life evolving through an intelligent agency, versus life evolving by miraculous intervention is a distinction without a difference.
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We really don't know if it is miraculous. For all we know, some intelligent species has done this in a whole bunch of places for whatever reason. We also don't know how we'd stack up with other intelligent species elsewhere in the universe since we have yet to meet any.
 
T. A. Gardner said:
We really don't know if it is miraculous. For all we know, some intelligent species has done this in a whole bunch of places for whatever reason. We also don't know how we'd stack up with other intelligent species elsewhere in the universe since we have yet to meet any.
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Or we're just a thought in the mind of God.
 
NiftyNiblick said:
If your theory were true, that somebody did a horribly poor job, especially in consideration of his/her alleged omnipotence and omniscient awareness.
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Who mentioned "omnipotence or omniscience?" I certainly didn't.

I'd rather take a secular approach than believe in an adversarial and spiteful supreme being, particularly with no real evidence to suggest that the latter exists.

But that's me. Each to his/her own, but don't inject your religious superstitions into the laws of the land.
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Okay, take a secular approach. That denies that there could be the possibility of something or someone else in the universe that's intelligent and capable of travelling to Earth. It doesn't require anything approaching religious belief to accept that as a possibility.
 
T. A. Gardner said:
Who mentioned "omnipotence or omniscience?" I certainly didn't.



Okay, take a secular approach. That denies that there could be the possibility of something or someone else in the universe that's intelligent and capable of travelling to Earth. It doesn't require anything approaching religious belief to accept that as a possibility.
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Secularism doesn't deny the plausibility of space travel. The concept of infinity strongly suggests other life forms somewhere.
While we cannot presently imagine the technology required to transport the life forms from one life supporting place to another many light years away,
all taking place during the finite lifetime of the traveler,
nor the willingness of any sentient being to live it's entire life traveling on a spacecraft so that a further generation could explore something,
there are many things existing today that once could not have been imagined.
 
T. A. Gardner said:
Okay, you want to believe that it all happened by random chance on the basis of known chemistry, biology, and physics. I added in the possibility that someone deliberately stirred the witch's caldron to make it happen. It's certainly possible there is other intelligent life in the universe. I'm not counting that out as a possibility, no "hocus pocus" involved.
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I was being facetious when I posted that hocus pocus remark, and I really didn't think that you would take it seriously; like I said, your opinion is as good as anybody else's.
 
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T. A. Gardner said:
We really don't know if it is miraculous. For all we know, some intelligent species has done this in a whole bunch of places for whatever reason. We also don't know how we'd stack up with other intelligent species elsewhere in the universe since we have yet to meet any.
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Okay, but that sounds more like a mechanism than a cause. If our planet were seeded by aliens, that is a mechanism for the delivery of life to earth. Presumably, biomolecules, aka life, itself in such a scenario still simply requires the laws of chemistry and physics for its emergence.
 
Dutch Uncle said:
I used to during the Von Daniken craze.

Although there's scant evidence of either, I'm more inclined to believe in ancient civilizations than ancient aliens.
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There's also the possibility that ancient civilizations had technology that was buried.
 
AProudLefty said:
There's also the possibility that ancient civilizations had technology that was buried.
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Agreed. Anything on the level of the bronze or iron age would be extremely significant.

Mankind have been around for over 200,000 years, up to 300,000. That's a lot of time for even modest civilizations with domesticated animals, crops and metal working several times over. Say 10,000 years each.

Famine, pestilence and war could easily destroy an entire civilization. Did anyone ever figure out what happened with the Anasazi?

https://www.smithsonianmag.com/history/riddles-of-the-anasazi-85274508/
The airy settlement that we explored had been built by the Anasazi, a civilization that arose as early as 1500 B.C. Their descendants are today’s Pueblo Indians, such as the Hopi and the Zuni, who live in 20 communities along the Rio Grande, in New Mexico, and in northern Arizona. During the 10th and 11th centuries, ChacoCanyon, in western New Mexico, was the cultural center of the Anasazi homeland, an area roughly corresponding to the Four Corners region where Utah, Colorado, Arizona and New Mexico meet. This 30,000-square-mile landscape of sandstone canyons, buttes and mesas was populated by as many as 30,000 people. The Anasazi built magnificent villages such as ChacoCanyon’s Pueblo Bonito, a tenth-century complex that was as many as five stories tall and contained about 800 rooms. The people laid a 400-mile network of roads, some of them 30 feet wide, across deserts and canyons. And into their architecture they built sophisticated astronomical observatories.


For most of the long span of time the Anasazi occupied the region now known as the Four Corners, they lived in the open or in easily accessible sites within canyons. But about 1250, many of the people began constructing settlements high in the cliffs—settlements that offered defense and protection. These villages, well preserved by the dry climate and by stone overhangs, led the Anglo explorers who found them in the 1880s to name the absent builders the Cliff Dwellers.


Toward the end of the 13th century, some cataclysmic event forced the Anasazi to flee those cliff houses and their homeland and to move south and east toward the Rio Grande and the Little Colorado River. Just what happened has been the greatest puzzle facing archaeologists who study the ancient culture. Today’s Pueblo Indians have oral histories about their peoples’ migration, but the details of these stories remain closely guarded secrets. Within the past decade, however, archaeologists have wrung from the pristine ruins new understandings about why the Anasazi left, and the picture that emerges is dark. It includes violence and warfare—even cannibalism—among the Anasazi themselves. “After about A.D. 1200, something very unpleasant happens,” says University of Colorado archaeologist Stephen Lekson. “The wheels come off.”

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ThatOwlWoman said:
I'm taking Physical Anthropology this semester
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Cypress said:
I currently lean towards number two, but keep an open mind.
It would be nice if we had more intel on emergence: the transition from non-life to life. There is zero chance something as mind boggling complex as even a single eukaryotic cell just appeared on the scene without an incredible sequence of interim events. Unless we were seeded from another planetary body.
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I would be inclined to go with #3. Not in my lifetime, nor even in the next few generations, but at some point, I believe we will discover that the universe is teeming with life.
 
Cypress said:
great points

What is weird to me is that even after 4 billion years, life apparently only evolved once on earth. Every living thing today is a genetic descendent of those first microbes from 3.8 billion years ago.

I just wonder why life did not evolve more than once on earth? If life is so resilient, why didn't different genetic strains of life evolve, or why didn't entirely different life forms evolve here?
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Conditions were conducive only for one?
 
Yeah. There is no reason why various origins couldn't have arisen. There were probably hundreds of thousands of soups.
 
domer76 said:
Conditions were conducive only for one?
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For sure.

Maybe DNA-based life is the only plausible form of life for Earth's environment.

But four billion years is a long time, and if the laws of chemistry and physics are so conducive to the emergence of life, it just seems a little weird that in all that vast depth of time life only evolved once, and it evolved based on deoxyribonucleic acid.

If I were working in the fields of abiogenesis and astrobiology, these would be my working hypotheses:


In four billion years, life only evolved once on earth, suggesting that the evolution of life is rare and requires a series of highly unlikely chemical and physical reactions.

Maybe DNA-based life is the only plausible form of life (this seems a little weird given how complex and versatile carbon chemistry is).

Maybe environmental conditions on earth for some reason inevitably lead to DNA-based life.

Maybe life evolved more than once on earth, but we just have not seen, or looked for the evidence.
 
Cypress said:
For sure.

Maybe DNA-based life is the only plausible form of life for Earth's environment.

But four billion years is a long time, and if the laws of chemistry and physics are so conducive to the emergence of life, it just seems a little weird that in all that vast depth of time life only evolved once, and it evolved based on deoxyribonucleic acid.

If I were working in the fields of abiogenesis and astrobiology, these would be my working hypotheses:


In four billion years, life only evolved once on earth, suggesting that the evolution of life is rare and requires a series of highly unlikely chemical and physical reactions.

Maybe DNA-based life is the only plausible form of life (this seems a little weird given how complex and versatile carbon chemistry is).

Maybe environmental conditions on earth for some reason inevitably lead to DNA-based life.

Maybe life evolved more than once on earth, but we just have not seen, or looked for the evidence.
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Evidence currently states life only evolved on Earth.
 
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