Originally Posted by TimWalker

And one can't expect a high tech civilization to arise in the ocean - how could you even reach the stage of using fire?

You obviously don't know about the aquatic Xindi species.

James50

The latest (or by now, second to latest?) Scientific American had an article about another bottleneck caused by extremely nasty weather about 100,000 years ago that made a lot of Africa uninhabitable except in small pockets. One of those pockets was along the southernmost shore, where sea food abounded and there were lots and lots of plants, especially root vegetables of different kinds. Sea food, sea weed, and root vegetables sounds like a pretty nutritious diet to me.

And lots and lots of caves. Now being excavated, and guess what? Modern human brains and culture may have started 40,000 years ago in Europe (ah, these European barbarians, always behind the curve), but the South African enclave was there first and a lot earlier.

I read that and found it very interesting. It seems to dissolve the difference posited between anatomically modern humans and behaviorally modern humans. IIRC, behaviorally modern humans were thought to begin @ 40-75 thousand years ago. The art displayed by these south Africans 200,000 years ago seems to push these dates back quite a bit. Totally interesting!

Originally Posted by The Grey Badger

The idea that the aliens would have to be more morally advanced than us because they're, well, they're more advanced, does not make sense to me. Indigenous people all over this planet could give you chapter and verse on why not.

Aliens do not have to be more morally advanced than us because they're more advanced. They have to be more morally advanced than us because otherwise they will be extinct, and thus never get here. We have to become more morally advanced than we are, in the specific senses of giving up war and becoming environmentally responsible, because if we don't we will become extinct (or at least destroy our civilization). Same logic applies to other species. Having that kind of technology means you have to learn how to behave.

There may indeed be no way around Einstein's limits. If there is a way, though:

The second - pity we couldn't have multiple choices here - is that planets may be common, but life may be rare. Life may be common, but complex life may be rare. Complex life may be common, but intelligent life may be rare.

The first is possible. The second two are not. I went into this in detail a few years ago when this thread was more active.

Then, postulating intelligent life, there are several booby traps our own species has narrowly avoided --

We domesticated plants and animals and started the agricultural age. Most civilizations dead-ended there, with huge masses of subsistence-level peasants, a steep social pyramid, and very little innovation.

Ah, now this brings up social/cultural/technological evolution rather than biological. A very interesting observation, Pat. However --

In our past, we have two major jump points. The first was the development of agriculture, cities, written language, the basics of classical/agrarian civilization. The second was the development of the printing press, the scientific method, and the industrial revolution. The first happened independently in various places. The second happened only once, but since the civilization that did it quickly explored and dominated the whole world, there was no opportunity for it to happen independently anywhere else.

In social as in biological evolution, the prerequisites have to be met before it can happen. The development of civilization couldn't happen until there were enough people that feeding them by foraging and hunting became impractical. Why do I say this? Because human beings are inquisitive and curious, and the propagation of plants from seed is an easy and obvious thing to observe happening and making this happen deliberately an easy and obvious technology. That our ancestors depended on foraging and hunting for over a hundred thousand years because they were too stupid to figure out how to farm completely defies belief. The only reasonable explanation for why they didn't farm is not that they didn't know how, but because they didn't see any need, and farming is a lot of work and not much fun.

So -- no civilization until it has to happen, until population reaches a certain density. Then it happens inevitably, given conditions that make farming with primitive technology even possible.

Are there similar prerequisites for the jump to industrial civilization? Since it's only happened once this is a lot more speculative, but I'm going to say that there are several possible key factors. One is the invention of movable type. This made reading material cheap enough that most town-dwellers could afford it, and so promoted widespread literacy and a revolution in politics and religion through the printed tract or pamphlet. This in turn made the scientific revolution possible. Without this basic invention, it would not have been possible for Europe to develop modern science and industrial methods. It's also arguable that it was not just the printing press but the combination of printing press and alphabet that facilitated this.

With somewhat less confidence, I can also point to Europe's division and lack of a central authority. This set the nations of Europe in competition with each other and placed a premium on military technology, which spilled over into other areas and encouraged the advance of science and technology generally.

I can say with confidence, then, that there is no way any civilization prior to the invention of movable type could have made the jump, because the prerequisite invention did not exist. One reason that Western Europe did so and not China, where movable type was actually invented, may be that China did not also have the alphabet; another possibility is that China had a strong central authority and was not divided into competing polities. This made it a more conservative society with less incentive to innovate.

Suppose Europe had also suffered under the same handicap. Imagine that the Roman Empire had never fallen, or that the Church was strong enough to suppress nationalism. Printing and literacy might have been suppressed in the interest of public order, and the scientific and industrial revolutions might not have happened there. But the technology of printing would have spread to Islamic civilization and to India. Islam was no more unified than Europe and the revolution could have happened there instead, or in India, which was divided into multiple kingdoms just as Europe was. So it could well be that it did not happen in other places for no other reason than because it DID happen in Europe and so Europeans jumped into a massive lead.

Before the printing press it couldn't happen. After the printing press it was not guaranteed to happen in any one place (China proves this), but was certain to happen sooner or later somewhere.

There is another theory, BTW. It's "Somebody has to be the first. Why not us?"

That's also possible. All of the speculation involves assuming that it's not true, though, and also that there's some way around Einstein's speed limit.

Originally Posted by Brian Rush

I'm pretty sure it did emerge in some of the smaller dinosaurs during the Cretaceous only to be wiped out by the K/T extinction. I don't know of any fossil evidence of creatures that might have been following an intelligence strategy from the Permian. If there were any, though, the end-Permian extinction, which was the worst in geologic history, would probably have done them in. I'm a little fuzzier on the Triassic and Jurassic.

Intelligence pretty quickly emerged in the Tertiary and in multiple species. Rats and squirrels appeared within 5 million years after the extinction, monkeys in 15 million years, parrots and chimpanzees in 35 million. A lot of these intelligent species aren't even related to each other except to the extent that they're all either mammals or birds, so clearly we have multipe emergences, not a single emergence that branches.

/Troodon and dinosauroid

Tim:

Yes, that's pretty much what I had in mind. Once evolution produces certain advances in the construction of brains and nervous systems that make it possible, the evolution of pre-human (or "candidate") intelligence becomes very likely. It's happened independently in several different geni of dinosaur, mammal, and bird. Once candidate species begin to emerge, the emergence of human-scale intelligence is only a matter of time, given an open niche.

I think a lot of the belief that intelligent life is unlikely comes from anthropomorphism. People confuse that question with the question of how likely the specific evolution of our own species, H. sapiens, was. Human evolution specifically was unlikely in the extreme, but human beings are not the only intelligent life-form that this planetary biosphere could have tossed up. That one or another of the candidate species would have gained abilities comparable to ours is, I think, a very high-probability prospect. We just happened to be the one to get there.

This is also an argument against the extreme environmentalist position that humans ought to become extinct as a danger to the biosphere. If we did, that would open the niche we currently occupy, and there are many many candidate species now alive. One or another of those would evolve to fill our niche in a comparatively short time, probably less than a hundred million years. Sooner or later, some civilized species must make the transition to becoming caretakers rather than rapists of the biosphere. If we become extinct, that simply delays the process.

Originally Posted by Brian Rush

... Once evolution produces certain advances in the construction of brains and nervous systems that make it possible, the evolution of pre-human (or "candidate") intelligence becomes very likely. It's happened independently in several different geni of dinosaur, mammal, and bird. Once candidate species begin to emerge, the emergence of human-scale intelligence is only a matter of time, given an open niche...

Yes, but intelligence is not the only factor in why we are who we are. A hugely intelligent dog will still have no east way to achieve what we have achieved. We have opposable thumbs and arms intended for working rather than climbing. We're bipedal, so we always have our hands ready for use and we are weak, making the use of tools mandatory for survival. We were forced to use our intelligence or die.

Sometimes, even weakness is strength.

The second - pity we couldn't have multiple choices here - is that planets may be common, but life may be rare. Life may be common, but complex life may be rare. Complex life may be common, but intelligent life may be rare.

Originally Posted by Brian Rush

The first is possible. The second two are not. I went into this in detail a few years ago when this thread was more active.

Actually the second option seems increasingly likely.

Extremophiles can potentially live in a very large number of planetary environments.

"Extremophile Hunt Begins"

"One thing we've learned in recent years," notes Hoover, "is that you don't have to have a 'Goldilocks' zone with perfect temperature, a certain pH level, and so forth, for life to thrive." Researchers have found microbes living in ice, in boiling water, in nuclear reactors. These "strange" extremophiles may in fact be the norm for life elsewhere in the cosmos.

Originally Posted by Marx & Lennon

Yes, but intelligence is not the only factor in why we are who we are. A hugely intelligent dog will still have no east way to achieve what we have achieved.

I used "intelligence" as a shorthand. I meant by "candidate" a species whose survival strategy involves intelligent manipulation of the environment combined with social activity. Dogs are not candidate species, and neither are whales or pigs despite their intelligence, but apes, raccoons, crows, ravens, and parrots all are. Maybe even bears, although that's more of a stretch.

Tone70: that would mean there's a lot more life out there than conventional assumptions would estimate, but that a larger percentage of it is to be found in environments not conducive to the development of complex life. The net effect on frequency of complex life is nil, because the only difference is that we would expect to find non-complex life where otherwise we would expect to find none.

Originally Posted by Brian Rush

Tone70: that would mean there's a lot more life out there than conventional assumptions would estimate, but that a larger percentage of it is to be found in environments not conducive to the development of complex life. The net effect on frequency of complex life is nil, because the only difference is that we would expect to find non-complex life where otherwise we would expect to find none.

Okay, which means...

The second - pity we couldn't have multiple choices here - is that (1)planets may be common, but life may be rare.(2) Life may be common, but complex life may be rare. Complex life may be common, but intelligent life may be rare.

Originally Posted by Brian Rush

The first is possible. The second two are not. I went into this in detail a few years ago when this thread was more active.

that the first and second options are possible with decent odds available on the likelihood of number two, yes?

Tone 70:

What I meant was that the possibility of "extremophile" life doesn't change the equation in any significant way. All speculation up to now has been based on the idea that no life could exist except in relatively friendly environments, which would also be friendly to the development of complex life.

If we now believe that life (but not complex life) could emerge in more hostile environments, that doesn't make the occurrence of complex life any less likely. It makes the occurrence of life more likely, that's all. And so it impacts possibility #1, not #2.

On any planet that was conventionally believed to have the possibility of life, it could be that life will be rare. (Although the rapidity with which life developed on earth after the condensation of liquid-water oceans suggests to the contrary.) On any planet that does have life, though (setting aside extremophiles as extraneous to the whole speculation, which they are), the likelihood of complex life is very high indeed.

Of the eight steps I listed way back when, I would say the only likely bottlenecks are #1 and #8, and maybe #6 although I doubt it. We don't understand the process by which life emerged really, so it's hard to say how likely it would be. And we have no certain examples of any intelligent species that has survived the challenge we face today, so we don't even know for certain that it's possible; we might be doomed. Our understanding of how human-level intelligence emerged from the candidate intelligence of the earlier primates is also not that great, so conceivably it would be a rare thing. But I would tend to doubt it simply because it's normal for a species' survival strategy to be intensified and improved on over time, especially under survival pressure. But the other steps we know a lot more about, and they look very likely indeed given the prerequisites.

David Brin came up with another theory.

The aliens get FTL and decide "Wa-hoo! Let's go fill up the Galaxy!" and after several thousand years their Galactic Empire has filled up, strip-mined, and exhausted the soil, water, and resources of every planet in it, and dies. Rinse and repeat.

I believe he got this theory by reading the history of Earth.

Originally Posted by TimWalker

Extremophiles notwithstanding, I imagine a combination of Rare Earth and a modified Naked Ape choice. Rare Earth for creatures with complex nervous systems. Modified naked ape: 1) mass extinction that wipes out a promising root stock (Troodon?) and 2) possible extinction of a candidate species.

All this before we get to the civilizational stage, which includes potential pitfalls such as WMD (weapons of mass destruction) and climatic disaster.

I already explained why I don't think Rare Earth is a likely possibility. Let me go over it again.

The argument is that the development of intelligent life on Earth took such a long time (3.5 billion years) that it argues that the probability is very low. There's also an argument that there is no "arrow" to evolution, so no tendency of biospheres to evolve intelligent life. Each of these arguments is fallacious. The first is fallacious because each step in the progress towards spacefaring intelligence (which, by the way, we have NOT completed here) has prerequisites, and once the prerequisites were achieved getting to the next step never took long. The second is fallacious because evolution having an "arrow" is not a logical requirement for there being a tendency to evolve intelligent life. Evolution has not one arrow but a lot of them (one for every potential survival strategy), and it goes in all of those directions at the same time. One of those is towards intelligent life, which is certainly not the only viable survival strategy, but it is one, and therefore it WILL be pursued.

On the first, to reiterate what I said earlier regarding some of the key steps of the process:

1) Life could not begin until we had liquid-water oceans. Once we did, life emerged within 300 million years. That this was 4.1 billion years after the planet was formed is irrelevant. It was impossible for 3.8 billion of those years. Once it became possible, it happened quickly, arguing that once the conditions are right, the emergence of life is a high-probability event, not a low-probability one.

2) What I've called "candidate" intelligence, on the order of today's apes, crows, and parrots, cannot emerge until there is sufficient differentiation of brains and nervous systems to make it possible. Candidate intelligence first emerged in the Cretaceous (that we know of for certain) about 400 to 500 million years after the first emergence of differentiated nervous systems capable of evolving into it -- but we must also recognize that this first development of simple brains was followed by no less than four mass extinction events before the first fossil record of candidate intelligence that we have uncovered. Of course, the further back we go, the more incomplete the fossil record becomes, so there could have been candidate intelligence as far back as the Ordovician era although that's highly unlikely (and it would have been a marine organism, which represents a dead end, as does the intelligence of whales). Certainly there were primitive amphibians, reptiles, and proto-dinosaurs in the Permian era and there could have been candidate species, but if there were they perished in the Permian/Triassic extinction event.

Another extinction event occurred between the Triassic and the Jurassic, so the first real chance for candidate intelligence to emerge was in the Jurassic and Cretaceous eras. We find it in the latter. It went extinct, though, without evolving full sapience.

After the K/T extinction, it took only about 65 million years for the mammals that survived the event to evolve candidate intelligence and then full sapience -- two major evolutionary steps requiring only an eyblink of geological time.

Do you see what I'm saying? Once the preconditions for each of these to take place had been reached, they occurred rapidly. This suggests that, given the necessary preconditions, the likelihood of each taking place is high, not low.

Development of civilization is likewise a high-probability event, given full sapience. Humans did this in many placed independently all over the world, once the population had reached a point where farming needed to replace foraging and hunting.

We're left really with only one possible bottleneck, and that's self-destruction (as you say) through environmental collapse and/or nuclear war. On this, we have no data, but at least many human beings are aware of the challenge and that at least gives us a possibility of successfully navigating the troubled waters. We've changed in many ways over the centuries. We're an adaptable species. It could be that this, too, is a high-probability event, and even if it's not, the fact that the others leading up to it are suggest that there will be many rolls of the dice, resulting in a fair number of successes as long as success isn't completely impossible.

It seems to me that Rare Earth is just about the least likely explanation on the list. Slow Boat is (I'm afraid) the most likely. But if Slow Boat isn't true, then the most likely explanation is some variation on Prime Directive.

Originally Posted by Brian Rush

1) Life could not begin until we had liquid-water oceans. Once we did, life emerged within 300 million years. That this was 4.1 billion years after the planet was formed is irrelevant. It was impossible for 3.8 billion of those years. Once it became possible, it happened quickly, arguing that once the conditions are right, the emergence of life is a high-probability event, not a low-probability one.

Just to correct your timeline without trying to alter your basic point:

The basic timeline is a 4.5 billion year old Earth, with (very approximate) dates:

• 3.8 billion years of simple cells (prokaryotes),
• 3 billion years of photosynthesis,
• 2 billion years of complex cells (eukaryotes),
• 1 billion years of multicellular life,
• 600 million years of simple animals,
• 570 million years of arthropods (ancestors of insects, arachnids and crustaceans),
• 550 million years of complex animals,
• 500 million years of fish and proto-amphibians,
• 475 million years of land plants,
• 400 million years of insects and seeds,
• 360 million years of amphibians,
• 300 million years of reptiles,
• 200 million years of mammals,
• 150 million years of birds,
• 130 million years of flowers,
• 65 million years since the non-avian dinosaurs died out,
• 2.5 million years since the appearance of the genus Homo,
• 200,000 years since humans started looking like they do today,
• 25,000 years since Neanderthals died out.

http://bit.ly/c62vD

It seems to me that Rare Earth is just about the least likely explanation on the list. Slow Boat is (I'm afraid) the most likely. But if Slow Boat isn't true, then the most likely explanation is some variation on Prime Directive.

Slow boat is indeed the mostly likely. Without Warp drive, there is not enough time for anyone to get here. Also, the radiation levels in transit are not good for living things. Humans may not even make it to Mars without cooking themselves in the radiation and its not practical to make lead shielded space capsules.

James50

Nitpick: there is chemical evidence for photosynthetic life in 3.95bya sedimentary rocks in Greenland's Isua Formation, which fits the Last Universal Common Ancestor of all living organisms to be something like modern Green Non-Sulfur Bacteria such as Cloroflexus.

Originally Posted by Brian Rush

I already explained why I don't think Rare Earth is a likely possibility. Let me go over it again.

The argument is that the development of intelligent life on Earth took such a long time (3.5 billion years) that it argues that the probability is very low. There's also an argument that there is no "arrow" to evolution, so no tendency of biospheres to evolve intelligent life. Each of these arguments is fallacious. The first is fallacious because each step in the progress towards spacefaring intelligence (which, by the way, we have NOT completed here) has prerequisites, and once the prerequisites were achieved getting to the next step never took long. The second is fallacious because evolution having an "arrow" is not a logical requirement for there being a tendency to evolve intelligent life. Evolution has not one arrow but a lot of them (one for every potential survival strategy), and it goes in all of those directions at the same time. One of those is towards intelligent life, which is certainly not the only viable survival strategy, but it is one, and therefore it WILL be pursued.

On the first, to reiterate what I said earlier regarding some of the key steps of the process:

1) Life could not begin until we had liquid-water oceans. Once we did, life emerged within 300 million years. That this was 4.1 billion years after the planet was formed is irrelevant. It was impossible for 3.8 billion of those years. Once it became possible, it happened quickly, arguing that once the conditions are right, the emergence of life is a high-probability event, not a low-probability one.

2) What I've called "candidate" intelligence, on the order of today's apes, crows, and parrots, cannot emerge until there is sufficient differentiation of brains and nervous systems to make it possible. Candidate intelligence first emerged in the Cretaceous (that we know of for certain) about 400 to 500 million years after the first emergence of differentiated nervous systems capable of evolving into it -- but we must also recognize that this first development of simple brains was followed by no less than four mass extinction events before the first fossil record of candidate intelligence that we have uncovered. Of course, the further back we go, the more incomplete the fossil record becomes, so there could have been candidate intelligence as far back as the Ordovician era although that's highly unlikely (and it would have been a marine organism, which represents a dead end, as does the intelligence of whales). Certainly there were primitive amphibians, reptiles, and proto-dinosaurs in the Permian era and there could have been candidate species, but if there were they perished in the Permian/Triassic extinction event.

Another extinction event occurred between the Triassic and the Jurassic, so the first real chance for candidate intelligence to emerge was in the Jurassic and Cretaceous eras. We find it in the latter. It went extinct, though, without evolving full sapience.

After the K/T extinction, it took only about 65 million years for the mammals that survived the event to evolve candidate intelligence and then full sapience -- two major evolutionary steps requiring only an eyblink of geological time.

Do you see what I'm saying? Once the preconditions for each of these to take place had been reached, they occurred rapidly. This suggests that, given the necessary preconditions, the likelihood of each taking place is high, not low.

Development of civilization is likewise a high-probability event, given full sapience. Humans did this in many placed independently all over the world, once the population had reached a point where farming needed to replace foraging and hunting.

We're left really with only one possible bottleneck, and that's self-destruction (as you say) through environmental collapse and/or nuclear war. On this, we have no data, but at least many human beings are aware of the challenge and that at least gives us a possibility of successfully navigating the troubled waters. We've changed in many ways over the centuries. We're an adaptable species. It could be that this, too, is a high-probability event, and even if it's not, the fact that the others leading up to it are suggest that there will be many rolls of the dice, resulting in a fair number of successes as long as success isn't completely impossible.

It seems to me that Rare Earth is just about the least likely explanation on the list. Slow Boat is (I'm afraid) the most likely. But if Slow Boat isn't true, then the most likely explanation is some variation on Prime Directive.

I have read a hypothesis saying that our huge brains are an adaptation to an extremely flexible hyper-generalist lifestyle imposed by the incredible amount of climatic variation on the scale of a few decades during the Ice Ages. Our current Interglacial is a rare period of climatic stability, a "long summer" to quote the title of a book by Brian Fagan, that allowed agriculture to take hold, the climate was too variable and unpredictable during the Last Ice Age for true agriculture to take hold. Our huge brains allow us to adapt to such extremes though culture and learning, we are not locked in to a single definite "human nature".

The current interglacial is not yet unusually long. It's lasted for about 10,000 years, which was the normal duration of interglacials during the Pleistocene. That is of course for major interglacials, not the briefer warming periods that occurred during ice ages. This is definitely a major interglacial. We should be coming to the end of it, although due to global warming it's possible we won't. Even if we are, 10,000 years is a long time on a human scale and we shouldn't expect a sudden return of the glaciers.

Was climate unstable during the ice age, or was it just colder? In the latter case, there should be large areas of the globe where agriculture is possible.

Originally Posted by Brian Rush

The current interglacial is not yet unusually long. It's lasted for about 10,000 years, which was the normal duration of interglacials during the Pleistocene. That is of course for major interglacials, not the briefer warming periods that occurred during ice ages. This is definitely a major interglacial. We should be coming to the end of it, although due to global warming it's possible we won't. Even if we are, 10,000 years is a long time on a human scale and we shouldn't expect a sudden return of the glaciers.

Was climate unstable during the ice age, or was it just colder? In the latter case, there should be large areas of the globe where agriculture is possible.

It was both colder AND far more unstable and irregular. As I posted above, climatic variation on the scale of decades was MUCH higher than now and on the scare of hundreds to a couple thousand years one sees enormous swings between extreme cold and near-interglacial warmth, especially in the northern hemisphere. It was the extreme variability, not the cold, that made true agriculture impossible. There is strong evidence of extensive land management just short of agriculture, but there was not the needed stability to make true agriculture viable.

If climate instability is on the scale of decades, it should still be possible to practice agriculture using modern methods. I can see where that would present a problem to primitive agriculture, though.

That's an interesting alternative theory as to why it took humans so long to take up farming. I had been assuming it was because farming isn't fun and nobody would want to do it if you can go hunt and forage for your food.

... they're here!

Or at least there in Mono Lake.

This is big. Until now it was believed that there were six elements essential to life namely carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Well now it appears that there may be some substitutions allowed. To explain with a littl emore detail:

Originally Posted by TheAge.com

MOST people find it hard to get enthusiastic about bacteria. Except when the medical tests come back clearing them of an STD. But on Friday, scientists at a NASA news conference were positively ecstatic about bacterial test results. Remarkably, a US laboratory confirmed the researchers had found a little critter that wasn't made from the conventional building blocks of life....


...The fact that arsenic-based life exists even though this element is highly toxic to most of Earth's creatures is a remarkable discovery. But the real reason for the scientific exuberance is that this has opened a great big door: life may come in more colours than scientists had imagined.

Maybe there are Martian bugs, but we haven't found them so far because we've been looking for the wrong kind of life. And if two radically different forms of life have evolved on Earth, how many other possibilities are there out there? Life may be able to thrive in the most extreme of galactic environments: the entire cosmos could be alive...

...nature's love of a broad range of possibilities has been the central message for astronomers searching for other living worlds. Over the past 15 years they've found more than 500 planets orbiting other star systems, and what a wacky collection of unpredicted lands nature has thrown up.

There are lava-lands, where the daily top temperature is high enough to melt gold. And giant lumbering planets as big as Jupiter that whiz around their suns, not every 12 years like our Jupiter, but in four days! Astronomers didn't expect this variety: their theories predicted alien solar systems would be, by and large, like ours.

If you're fascinated by the possibility of life elsewhere in the galaxy, you could be in for some extraterrestrial thrills. Astronomers have just developed the ability to not only find planets around other stars, but to actually learn something about these alien worlds' atmospheres.

Just last week, the atmosphere of a planet only a few times bigger than the Earth, orbiting a small star about 40 light years away, was studied. Frustratingly, it possibly has a high cloud layer blocking detailed chemical analysis of its atmosphere. But the atmospheres of other planets have revealed chemical elements like sodium and hydrogen.

The search is only beginning. What if we find that one of these distant atmospheres is rich in oxygen? The 21 per cent oxygen in our skies wasn't created when our planet formed; rather, it has been pumped up there by living creatures. If another world were discovered to have similar oxygen and ozone concentrations to us, it would be powerful evidence that the planet is also home to living creatures.

And what about this: we detect a distant planetary atmosphere that has artificial chemicals in it, that could not be created naturally, chemicals such as CFCs. That would, at long last, be good evidence that we have galactic neighbours, perhaps with big hair and fridges full of beer.

Does anyone remember the Horta from the Star Trek episode The Devil in the Dark ?
It was a silicon based life form that kept killing miners and was not detectable at first because the Federation was only used to dealing with carbon based life forms.
Well now we've found that arsenic can replace phosphorous as a building block of life!
Wow!

A 4T does turn a culture back towards a rational, outer world focus as opposed to the more emotional inner based focus of an awakening. Could it be that what we learn from this and other discoveries during this 4T could lead to a new golden period for science as the 1T approaches?

Originally Posted by herbal tee

.
Does anyone remember the Horta from the Star Trek episode The Devil in the Dark ?
It was a silicon based life form that kept killing miners and was not detectable at first because the Federation was only used to dealing with carbon based life forms.

It looked like a wad of carpet remnants on wheels.

Well now we've found that arsenic can replace phosphorous as a building block of life!
Wow!

A 4T does turn a culture back towards a rational, outer world focus as opposed to the more emotional inner based focus of an awakening. Could it be that what we learn from this and other discoveries during this 4T could lead to a new golden period for science as the 1T approaches?

I like the way you think here. Humans get so puffed up at times with all we know, and yet probably we have hardly scratched the surface of what is out there.

James50

Originally Posted by herbal tee

... they're here!

Or at least there in Mono Lake.

This is big. Until now it was believed that there were six elements essential to life namely carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Well now it appears that there may be some substitutions allowed. To explain with a littl emore detail:



Does anyone remember the Horta from the Star Trek episode The Devil in the Dark ?
It was a silicon based life form that kept killing miners and was not detectable at first because the Federation was only used to dealing with carbon based life forms.
Well now we've found that arsenic can replace phosphorous as a building block of life!
Wow!

A 4T does turn a culture back towards a rational, outer world focus as opposed to the more emotional inner based focus of an awakening. Could it be that what we learn from this and other discoveries during this 4T could lead to a new golden period for science as the 1T approaches?

That's actually the first thing I thought of when I heard this story on NPR. Mr. Spock mindmelding with the creature, revealing that people were minning its children.

~Chas'88

Originally Posted by herbal tee

... they're here!

Or at least there in Mono Lake.

This is big. Until now it was believed that there were six elements essential to life namely carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Well now it appears that there may be some substitutions allowed. To explain with a littl emore detail:



Does anyone remember the Horta from the Star Trek episode The Devil in the Dark ?
It was a silicon based life form that kept killing miners and was not detectable at first because the Federation was only used to dealing with carbon based life forms.
Well now we've found that arsenic can replace phosphorous as a building block of life!
Wow!

A 4T does turn a culture back towards a rational, outer world focus as opposed to the more emotional inner based focus of an awakening. Could it be that what we learn from this and other discoveries during this 4T could lead to a new golden period for science as the 1T approaches?

...and I called arsenic God's greatest mistake. Well, after making carbon monoxide impossible to detect by smell, color, or taste.

Someone suggested to me another roadblock on the way to post-stone-age civilization that might make that rare, even if intelligent life isn't. The Earth has a lot of plate tectonics and volcanic activity that brings metallic ores to the surface. No one knows exactly why (it could have something to do with having such a huge moon). Without this geological factor, metals tend to get buried deep underground because their weight drags them down near the planet core. So most planets might not have metal ores easily available, and civilization would be limited to a stone-age technology.

Unless there could be a substitute for bronze and iron?

Originally Posted by Brian Rush

Someone suggested to me another roadblock on the way to post-stone-age civilization that might make that rare, even if intelligent life isn't. The Earth has a lot of plate tectonics and volcanic activity that brings metallic ores to the surface. No one knows exactly why (it could have something to do with having such a huge moon). Without this geological factor, metals tend to get buried deep underground because their weight drags them down near the planet core. So most planets might not have metal ores easily available, and civilization would be limited to a stone-age technology.

Unless there could be a substitute for bronze and iron?

Aluminum is the most abundant metal in the earth's crust and the third most abundant element. Unfortunately it is never found free in nature. We had a bronze and iron age. We are now in something of an aluminum age. I am not sure whether you need to go in that order.

James50