Fermi Paradox

[KerikBalm]

To me the fermi paradox doesn't even need to bring up the communication difficulties.

The initial claims were that life would be all over... take a bacterial suspension culture and put in on an agar plate.... you get a "lawn" of confluent bacteria.

Dilute it several times, and you get just a few colonies that will slowly get bigger.... but they won't ever touch (the agar plate will dry out before they tough each other).

Having just a few civilizations in the galaxy already would mean that life is really really rare. Then we're only talking less than one order of magnitude away from being "alone", and orders of magnitude lower than the "classical" predictions of how many civilizations there may be.

If there were civilizationf just 100 LY away... communication wouldnt be such a problem... civilizations 20LY away... you could even have a conversation over the course of a lifetime.... if there aren't... Well having to reach out 10x farther to find an alien civ means there are 100x fewer on average - assuming the galaxy is a flat disk... which its not... its average thickness is about 10,000 LY... so having to reach out 10x farther means 1000 fewer civilizations.... one starts to realize that the "conservative estimates" for values in the drake equation have overestimated the numbers by orders of magnitudes... there are still some orders of magnitudes between being alone and those initial estimates... but it won't be like star trek or star wars where planets inhabited by sentient beings seem to be very common.

1 in the galaxy? 10? 100? 1000?... well its certainly not millions... certainly not capable of interstellar travel. a million civs that expand even in a 10 lightyear radius around their home is going to leave the galaxy teeming with life... which we don't see

[Bill Phil]

Absence of evidence is not evidence of absence.

We have very little idea as to why abiogenesis happens. The best answer we have is a cocktail of various elements and organic molecules, sufficient energy but not too much (it would destroy the bonds, or change them into something else), and a long amount of time.

[Green Baron]

Don't mix up life and civilizations. As has been stated elsewhere, there may be an abundance of (microbial) life, photosynthesis, whatever, even forms of plants or animals as has been on earth for 100s of my, but no civilizations.

 

[Bill Phil]

Just now, Green Baron said:

Don't mix up life and civilizations. As has been stated elsewhere, there may be an abundance of (microbial) life, photosynthesis, whatever, even forms of plants or animals as has been on earth for 100s of my, but no civilizations.

 

Civilization wouldn't exist without life. And it would only take a tiny bit of extra time to make one. Also, define 'civilization" in this context.

There's two questions here: How common is life in the universe, and how often does that life bring about civilization. We need to answer the one about life first.

[Green Baron]

19 minutes ago, Bill Phil said:

Civilization wouldn't exist without life. And it would only take a tiny bit of extra time to make one. Also, define 'civilization" in this context.

In this context ? Species capable to communicate over stellar distances. Or else it wasn't recognizable from the outside. So humankind is just starting to open the window.

And i'm of different opinion: the step from microbes to to a civilisation is a big one, bigger than the forming of microbes out of chemistry. On earth the latter happened in a few hundred million years but it took 2,8 billions of years for higher animals, another 300 my for plants and another 400my for us(tm). Under a sequence of events/incidents/conditions/changes that is probably not easy to replicate.

Though this is just an opinion and there are probably other sequences that can produce a similiar outcome, i do not know, can of course speculate.

Edit: sorry, i correct myself and change "capable to communicate" in "can be recognized as such" from the outside. Like em-emissions or ... well em-emissions. :-)

Editedit: i meant plant evolution on the landmasses. Sorry for being so fuzzy ....

Edited June 21, 2016 by Green Baron

[Bill Phil]

11 minutes ago, Green Baron said:

In this context ? Species capable to communicate over stellar distances. Or else it wasn't recognizable from the outside. So humankind is just starting to open the window.

And i'm of different opinion: the step from microbes to to a civilisation is a big one, bigger than the forming of microbes out of chemistry. On earth the latter happened in a few hundred million years but it took 2,8 billions of years for higher animals, another 300 my for plants and another 400my for us(tm). Under a sequence of events/incidents/conditions/changes that is probably not easy to replicate.

Though this is just an opinion and there are probably other sequences that can produce a similiar outcome, i do not know, can of course speculate.

Edit: sorry, i correct myself and change "capable to communicate" in "can be recognized as such" from the outside. Like em-emissions or ... well em-emissions. :-)

Editedit: i meant plant evolution on the landmasses. Sorry for being so fuzzy ....

After life discovered sexual reproduction (gene swapping), it took a few hundred million years to make civilization. Life just happened to be slow about getting to that point. That may not be true for all cases, however.

[Green Baron]

3 minutes ago, Bill Phil said:

After life discovered sexual reproduction (gene swapping), it took a few hundred million years to make civilization. Life just happened to be slow about getting to that point. That may not be true for all cases, however.

Yep. Sexual reproduction is one of the steps in the chain. Though it's not necessary, it just helps the evolutionary process to overcome challenges by adaptation more quickly. From an energetic viewpoint it's a disadvantage to feed more than one gender, hadn't there been times of abundance it might have never been developed and hadn't there been evolutionary challenges thereafter it might have been sorted out like so many other features :-).

This is part of the process i mean .... ready to be corrected by a biologist.

[PB666]

41 minutes ago, Green Baron said:

Yep. Sexual reproduction is one of the steps in the chain. Though it's not necessary, it just helps the evolutionary process to overcome challenges by adaptation more quickly. From an energetic viewpoint it's a disadvantage to feed more than one gender, hadn't there been times of abundance it might have never been developed and hadn't there been evolutionary challenges thereafter it might have been sorted out like so many other features :-).

This is part of the process i mean .... ready to be corrected by a biologist.

Yes but two genders generally afford specialization of labor, in birds it works to the advantages because it allows very fast griwth rates needed for flight animals that are nearly grown with the first few weeks of life. In humans it means there is a domestic/hunter division, which allows the expansion from a settlement tongather widely high energy resources.. In the case of some species the female eats the male gathering his resources. 

[KerikBalm]

Anyway, with regards to life, I don't think it will end up being soooo uncommon... I disagree with PB666 about titan... and Europa looks appealing... however... neither of those places is ever going to produce a civilization.

 

There may be some possible biochemistries based on something other than water as a solvent, much colder places, with smaller energy gradients, lower reaction rates...

Life doesn't have a tendency towards complexity per se. Most life on earth has genomes much smaller than ours. Rather what happens is that as the number of species goes up... as the variety goes up - then the "tails" of the graph contain more members... you find more outliers when you have more datapoints.

Places with abundant energy and nutrients drive high preproduction rates and high diversity. A large energy source support more links in the food chain. Thats why we've got a lot of biodiversity in the tropics. A frigid world with a low energy gradient (internal heating, or slow chemical reaction with the solar wind and upper atmosphere like on titan) is going to have a very basic food chain at best.

Now I'm not sure if there can be any possible biochemistry that works on Titan.

There's probably someway that life could survive under the ice of Europa... theres likely some areas where the energy gradient is large enough that something from Earth (or a community of somethings from Earth) could live.

That doesn't mean Europa has life.. the conditions at which life can exist aren't the same as those for which abiogenesis can occur.

As that is an unknown at this point... the existence of places like Europa makes me doubt that life is particularly rare... but I also know that places like Europa will never produce aliens that we can "talk" to.

We really need to pin down the prevalence of life in our own solar system though... I'm talking looking for subsurface life on Mars, and life in the oceans of Europa/Enceledus... Those 3 destinations would be the highest priority to me at this moment.

I'm already disappointed at the lack of fossil biofilms on Mars... particularly as it would seem unlikely that anything ever evolved to eat biofilms and make them recede as they did on Earth. I think abiogensis probably more difficult that we assume based on how "fast" earth got its life. If its hard... then I really doubt an even more difficult biochemistry would form on Titan (It may still be possible for one to exist, but its formation may require purposeful engineering, and there'd be no conditions where it spontaneously forms)

[Green Baron]

My hopes for solving the Fermi paradox in the future:

The discovery of some sort of basic metabolism (microbes or whatever) on one of the bodies in our solar system, i think mars is the only realistic chance in the near future (10-20 years). Or are there any plans for a rover or lander on one of the joolian errrr jupiterian moons ?

The discovery of earth-like planets (i mean *really* earth-like planets) with a new generation of instruments in 10-15 years. New telescopes are planned or work has begun, La Palma is still in the race for a new 30m-Telescope in the near future ;-)

I don't believe in a signal from elsewhere, the distances are too huge, even if other civs exist.

For me mars is not completely out of the race yet. Traces of biology are probably buried below the surface and maybe very old (i mean long gone ...), if they didn't form geological structures (like the banded iron formations in earth for example) than maybe only sophisticated instruments will be able to detect them.

Maybe we'll see, 20 years is not that long.

[Bill Phil]

22 hours ago, Green Baron said:

Yep. Sexual reproduction is one of the steps in the chain. Though it's not necessary, it just helps the evolutionary process to overcome challenges by adaptation more quickly. From an energetic viewpoint it's a disadvantage to feed more than one gender, hadn't there been times of abundance it might have never been developed and hadn't there been evolutionary challenges thereafter it might have been sorted out like so many other features :-).

This is part of the process i mean .... ready to be corrected by a biologist.

Life was in a general rut until sexual reproduction was evolved. It's possible that it was responsible for the "Cambrian Explosion" and within less than a billion years of having sexual reproduction, we evolved from tiny microbes to towering trees.

[KerikBalm]

unsupported assertions in the above post

[PB666]

14 minutes ago, KerikBalm said:

unsupported assertions in the above post

I support it. 

[KerikBalm]

http://paleobiol.geoscienceworld.org/content/26/3/386.abstract

Oh.... except that sexual reproduction predates the cabrian "explosion" by about half a billion years...

Yea, sure that's no reason not to support the assertion.

The presence of an "explosion" itself in the cabrian is debatable to begin with... when you start with a shaky argument built upon other shaky arguments... you end up with basically an unsupported assertion.

The ediacaran biota weren't nearly as simple as we first thought they were when the "cambrian explosion" first started to be talked about.

[PB666]

You simply want to be argumentative. The ediacran only lasted 40 million years, and there are no/few apparent extant representatives from ediacaran, mostly theses lineages went extinct. 

There are no exact dividing lines between various aspects of formalized sexual reproduction as to say it occurred 500 million years earlier. 

It certainly true that simpler forms of cambrian lifeforms existed in the ediocaran, but it is not certian that they existed 500 million years earlier or even 100 million years earlier, that is a reach. The evidence is based upon a red algae fossil that looks like a modern red algae. There is also the assumption that the the algae mated sexually.  In any case if life first firmed 3.8 to 4.2 billion years ago and sexually reproducing life appears 1.0 to 1.2 million years ago and the cambrian is closer 0.540 then the greatest growth of complexity is closer to the cambrian that to bioneogenesis. The basic statement that the cambrian explosion occurred as a result of complex sexual reproduction is true, but is also factored into a warming Earth with the ediacaran and other things. The proof of the pudding is in the eating. 

Thus here on Earth there was a three billion year hard period in the developemnet of sentiency. We don't know that other hard periods might exist as a common feature of evolution. With a sample of 1 the confidence range could be half a billion years to 100 billion years, and as such could greatly limit the emmergence of complexity under the best circumstances.  

There are other hard periods such as early star formation and the lack of metals for billions of years, because of these it is not plausible for sentient life to have existed in the early universe, and only credible within the last 5 billion years, so the basic notion that many/most sentients have existed and died out, the reason they do not contact us, is a fabrication. Life of our complexity is difficult to get going. Its the point. 

 

 

[Green Baron]

 

I see it in a similar way as @PB666. Moreover, as convenient as it might be, that sexual reproduction thing is only one step in a long row and maybe not even necessary (though ... well convenient). The geological processes that formed the biosphere over the last 700my (before is somewhat grey, only understood in principle, see "principle of uniformitarianism"), the evolutionary processes that brought species and discarded them (the ones we see in the fossil record are just the tip of an iceberg, the prosperous models that lived long enough and were buried under favorable conditions that their remains came upon us), the galactic environment, that all went hand in hand over a long period of time. Some processes are understood, but not enough to deduct any clue as to whether this can be repeated elsewhere.

And preliminary finally, about 7my ago, primates startet to develop a brain, something that costs A LOT of energy and is grossly oversized (for most i know, hehe). About 2,5my years ago we speak of humans (gender homo), and for 2.49my they lived out in the wild. Just with a period of favorable climate they startet to develop plant growing, animal domestication and domi to live in. And that independently in at least 3 regions of the world. Noone really knows "why" (it's probably not desirable for a hunter & gatherer to give up his lifestyle and start to ... work (uuuaaah !)). But that "snip" in time, these ~12.000yr or 500 generations are the reason why we have, after all, a civilization. And we do not know how the story continues. Will the brain degenrate ? Will we (we're doing good from what i hear) ? How long will it take until the species becomes extinct ? Or resets itself in war and patchwork states ? Will the window for communication be open long enough to make a contact ? Probably not ... since there must be a similar window on the other side.

To me all that seems very improbable, so improbably that the whole alien thing is a nice game (while hoping for a stable release). So, if something like this or with comparable output has happened somewhere else then it's probably far away, in space and time.

Happy to discuss further

Edited June 22, 2016 by Green Baron

[K^2]

When your statistics sample has a grand total of one datum, it's just stupid to argue about. We have one planet in this solar system that fully supports life we know, and it happens to be the one we live on. Given that probability of planet you're from being habitable is unity, this is useless information. Plus we have a few planets and moons that could have been habitable or might be partially habitable for life we know, plus another couple that might be habitable to life we hypothesize as potentially plausible. None of them have we confirmed or excluded possibility of life on. Even that would be a start. Knowing if Mars does or ever has harbored life would be something. But we don't know even that.

So again, we're back to having a single data point, which is useless for drawing even the loosest of conclusions on based on Anthropic Principle. Regardless of how likely or unlikely complex life is, here we are. Whether universe is filled with civilizations, or there is just one, we're guaranteed to be on such a planet, which means we can't use Earth's history or our particular evolution or environment as any sort of affirmation or rebuttal.

Which brings me back to my original thesis. What's the point of even arguing? If you're right, it's purely by chance. Might as well just pick a religion and stick to it at that point.

What we do know is what we should be doing to rectify this situation. We need to comb what little of space we have access to and either find other life or confirm its sterile. That means more sophisticated missions to Mars, and a fleet of probes to Europe and Titan as the first order of business. If we find life on other rocks, it's data. If we know whether it shares origin with terrestrial life or evolved independently, it's data. If we find bugger all, it's data. With this knowledge, we can start making some loose guesses as to what's happening in the rest of the universe, which might tell us a lot about dangers facing our civilization, be they from within or without. Either way, we'll be far better off than anything we could achieve with these, frankly, theological discussions.

[PB666]

5 minutes ago, K^2 said:

When your statistics sample has a grand total of one datum, it's just stupid to argue about. We have one planet in this solar system that fully supports life we know, and it happens to be the one we live on. Given that probability of planet you're from being habitable is unity, this is useless information. Plus we have a few planets and moons that could have been habitable or might be partially habitable for life we know, plus another couple that might be habitable to life we hypothesize as potentially plausible. None of them have we confirmed or excluded possibility of life on. Even that would be a start. Knowing if Mars does or ever has harbored life would be something. But we don't know even that.

So again, we're back to having a single data point, which is useless for drawing even the loosest of conclusions on based on Anthropic Principle. Regardless of how likely or unlikely complex life is, here we are. Whether universe is filled with civilizations, or there is just one, we're guaranteed to be on such a planet, which means we can't use Earth's history or our particular evolution or environment as any sort of affirmation or rebuttal.

Which brings me back to my original thesis. What's the point of even arguing? If you're right, it's purely by chance. Might as well just pick a religion and stick to it at that point.

What we do know is what we should be doing to rectify this situation. We need to comb what little of space we have access to and either find other life or confirm its sterile. That means more sophisticated missions to Mars, and a fleet of probes to Europe and Titan as the first order of business. If we find life on other rocks, it's data. If we know whether it shares origin with terrestrial life or evolved independently, it's data. If we find bugger all, it's data. With this knowledge, we can start making some loose guesses as to what's happening in the rest of the universe, which might tell us a lot about dangers facing our civilization, be they from within or without. Either way, we'll be far better off than anything we could achieve with these, frankly, theological discussions.

But you are not addressing the Fermi paradox at all, you are only addressing the issue of whether at some time in the long existence of some world, life arose, most likely like Mars got snuffed, or in the case of Titan, prolly is in such a restricted environment would hardly be recognizable here on Earth. The Fermi paradox basically is a refutation of a common misconception (Marvin the martian, war of the worlds, Venus needs men) etc. Which some sort of sentient life is at every turn of the stone. This can be basically and wholeheartedly refuted.

Quote

The Fermi paradox or Fermi's paradox, named after Enrico Fermi, is the apparent contradiction between the lack of evidence and high probability estimates, e.g. those given by the Drake equation, for the existence of extraterrestrial civilizations.^[1] The basic points of the argument, made by physicists Enrico Fermi (1901–1954) and Michael H. Hart (born 1932), are:

• There are billions of stars in the galaxy that are similar to the Sun,^[2][3] many of which are billions of years older than Earth.^[4][5]
• With high probability, some of these stars will have Earth-like planets,^[6][7] and if the Earth is typical, some might develop intelligent life.
• Some of these civilizations might develop interstellar travel, a step the Earth is investigating now.
• Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in about a million years. -wikipedia-Fermi paradox

Yes, Earth is 1, true, but where are the Earth comparables orbiting Sun comparables.

 

[Green Baron]

Your correct, K^2. I was just trying to explain why i see no paradox in the Fermi paradox and the connected assumption/implication that there might be "others", possibly similar to us, able to say "gimmy that towel i can't see the misery anymore" :-)

I too hope we find something in the future, but i doubt it will be intelligent and i highly doubt it has formed a communicative civilization.

 

[K^2]

@PB666 It's not a paradox. It's disagreement of extrapolation from a single data point onto a full set and then finding a contradiction. When you extrapolate like that, not finding a contradiction would have been more amazing. All that the Fermi "Paradox" really says is, "We know bugger all about what's out there, other than nobody informed us of their presence in a way we understood." And that can be pretty much just shortened to "We know bugger all." So what I've said up there aligns with Fermi Paradox pretty well.

Edited June 22, 2016 by K^2

[Green Baron]

4 minutes ago, K^2 said:

@PB666 It's not a paradox. It's disagreement of extrapolation from a single data point onto a full set and then finding a contradiction. When you extrapolate like that, not finding a contradiction would have been more amazing. All that the Fermi "Paradox" really says is, "We know bugger all about what's out there, other than nobody informed us of their presence in a way we understood." And that can be pretty much just shortened to "We know bugger all." So what I've said up there aligns with Fermi Paradox pretty well.

Hm, but that would imply that there is a dataset ? I'm not sure whether this is the case.

I am of course aware that earth's principles might not be valid elsewhere, but we have to start somewhere. Otherwise we only had questions, no answers.

Could a civilization form in a short period of time, like 500my from solidification of a planets crust to rockets into space ?

 

[magnemoe]

23 minutes ago, Green Baron said:

 

I see it in a similar way as @PB666. Moreover, as convenient as it might be, that sexual reproduction thing is only one step in a long row and maybe not even necessary (though ... well convenient). The geological processes that formed the biosphere over the last 700my (before is somewhat grey, only understood in principle, see "principle of uniformitarianism"), the evolutionary processes that brought species and discarded them (the ones we see in the fossil record are just the tip of an iceberg, the prosperous models that lived long enough and were buried under favorable conditions that their remains came upon us), the galactic environment, that all went hand in hand over a long period of time. Some processes are understood, but not enough to deduct any clue as to whether this can be repeated elsewhere.

And preliminary finally, about 7my ago, primates startet to develop a brain, something that costs A LOT of energy and is grossly oversized (for most i know, hehe). About 2,5my years ago we speak of humans (gender homo), and for 2.49my they lived out in the wild. Just with a period of favorable climate they startet to develop plant growing, animal domestication and domi to live in. And that independently in at least 3 regions of the world. Noone really knows "why" (it's probably not desirable for a hunter & gatherer to give up his lifestyle and start to ... work (uuuaaah !)). But that "snip" in time, these ~12.000yr or 500 generations are the reason why we have, after all, a civilization. And we do not know how the story continues. Will the brain degenrate ? Will we (we're doing good from what i hear) ? How long will it take until the species becomes extinct ? Or resets itself in war and patchwork states ? Will the window for communication be open long enough to make a contact ? Probably not ... since there must be a similar window on the other side.

To me all that seems very improbable, so improbably that the whole alien thing is a nice game (while hoping for a stable release). So, if something like this or with comparable output has happened somewhere else then it's probably far away, in space and time.

Happy to discuss further

Sexual reproduction give an selection of the fittest within an slow breeding long lived population with an far more effective mechanism than random mutations. I strongly doubt you will get something like fish and reptiles without it. Now imagine something with 20 years generations. Benefit will increase with life length. 
Yes hermaphrodites are more efficient, however its probably too complex, some animals are but its rare. 

Big brains on the other hand is likely to be random luck, we needed to be smart animals, homo habilis was an smart animal. 
Now you got an feedback effect in cooperation and communication within the pack, other humans was the far mos complex thing early humans ran into and nobody wanted to mate an moron.
Intelligence became an selection criteria same as tail on peacock, ability to make tools might also been one at times. 
During this time we also became peaceful, the brutes ate an stew of poison mushroom or got their trough cut by an flint blade during the night.  
We became smarter and more social than we needed, this did not pay off until way later 
We started farming because of population pressure, short term it was an bad deal however beer might have sweeten it, yes this is serious,  no bear no civilization. Native Americans in north america in large degree went back to being hunter gatherers as population crashed because of diseases from eurasia, its more cost effective and more fun, stone age farming is not fun, worse average height and life length dropped, overpopulation made it necessary and beer sweeten the deal. 

Now this is humans, an alien might well run into this totally different. you have my avatar and her people, pure predators, no easy species to domesticate, don't work well in large groups, 50 works well, more than 500 is an short time party, you don't know how everyone's smell. Worse they found it easy to control reproduction with some herbs so no run off population. 
Earth can support around 10 million humans, then we started farming. Now imagine an sentinel predator with no good hand, they might well be the dominate species and stop others from appearing but is an dead end. This is the good scenarios, you land on an planet with primitive but happy people. 

Now let go dystopian, that if average IQ leveled out at 60, enough for hunting or dirt farming, now you have to make an technological civilization, note that we are in an race condition, we can not use coal for all our energy needs of pollution reasons, oil and gas is limited and affected by pollution too. Fission is expensive if done safe. Perhaps too expensive. 
This is far from the first crisis, we started using coal then we started to run out of wood. 
Long term goats is probably the most environmental damaging thing we have created. They eat anything, any dirt farmer on bad soil will maximize on them. 
Now if you are stupid, do you manage to go nuclear or renewable fast enough, now add that you have serious problems keeping population growth down, "mote in the gods eye"
Now add aggression, you did not kill your brutes over an million year. you have no surrender reflex like humans first one who get nukes use them. you either get an constant nuclear war or an world government. Now if the world government think short term it might well end the civilization,  

 

 

[KerikBalm]

Quote

You simply want to be argumentative.

No, I want to avoid spreading of misinformation, where people present ideas as if it were scientifically established fact

Quote

The ediacran only lasted 40 million years

100 million, for which we have "megafossils" spanning 70 million years

Quote

it is not certian that they existed 500 million years earlier or even 100 million years earlier,

So if its not certain, you can't make an assertion one way or another... yet you are supporting just such an assertion in the face of this uncertainty.

Quote

The evidence is based upon a red algae fossil that looks like a modern red algae. There is also the assumption that the the algae mated sexually.

The assumption is based on the not just the fossil looking like modern red algae, but also the presence of spores which are produced sexually. Its more parsimonious to say that the spore formed by sexual reproduction, than an asexual origin that was then changed to sexual later. Your assertion (since you supported it) is less parsimonious with the evidence: sexual reproduction over half a billion years before the cambrian.

Quote

In any case if life first firmed 3.8 to 4.2 billion years ago and sexually reproducing life appears 1.0 to 1.2 million years ago and the cambrian is closer 0.540 then the greatest growth of complexity is closer to the cambrian that to bioneogenesis.

*billion, and if its 1.2 billion, then the start of the cambrian was closer to the modern day than the appearance of sexual reproduction. You're attempting to argue correlation is evidence for causation... when the correlation isn't even there...

I say again... unsupported assertion.

[magnemoe]

15 minutes ago, Green Baron said:

Hm, but that would imply that there is a dataset ? I'm not sure whether this is the case.

I am of course aware that earth's principles might not be valid elsewhere, but we have to start somewhere. Otherwise we only had questions, no answers.

Could a civilization form in a short period of time, like 500my from solidification of a planets crust to rockets into space ?

 

Main issue would be oxygen in atmosphere. On the other hand the early stuff on earth was not very efficient. 
On the gripping hand something good is probably part of somebody development project. 
Tips, signs and broadcasts demanding hard hats and protective boots indicate planet under construction 

[Green Baron]

39 minutes ago, magnemoe said:

Sexual reproduction give an selection of the fittest within an slow breeding long lived population with an far more effective mechanism than random mutations. I strongly doubt you will get something like fish and reptiles without it. Now imagine something with 20 years generations. Benefit will increase with life length. 
Yes hermaphrodites are more efficient, however its probably too complex, some animals are but its rare. 

Big brains on the other hand is likely to be random luck, we needed to be smart animals, homo habilis was an smart animal. 
Now you got an feedback effect in cooperation and communication within the pack, other humans was the far mos complex thing early humans ran into and nobody wanted to mate an moron.
Intelligence became an selection criteria same as tail on peacock, ability to make tools might also been one at times. 
During this time we also became peaceful, the brutes ate an stew of poison mushroom or got their trough cut by an flint blade during the night.  
We became smarter and more social than we needed, this did not pay off until way later 
We started farming because of population pressure, short term it was an bad deal however beer might have sweeten it, yes this is serious,  no bear no civilization. Native Americans in north america in large degree went back to being hunter gatherers as population crashed because of diseases from eurasia, its more cost effective and more fun, stone age farming is not fun, worse average height and life length dropped, overpopulation made it necessary and beer sweeten the deal. 

Now this is humans, an alien might well run into this totally different. you have my avatar and her people, pure predators, no easy species to domesticate, don't work well in large groups, 50 works well, more than 500 is an short time party, you don't know how everyone's smell. Worse they found it easy to control reproduction with some herbs so no run off population. 
Earth can support around 10 million humans, then we started farming. Now imagine an sentinel predator with no good hand, they might well be the dominate species and stop others from appearing but is an dead end. This is the good scenarios, you land on an planet with primitive but happy people. 

Now let go dystopian, that if average IQ leveled out at 60, enough for hunting or dirt farming, now you have to make an technological civilization, note that we are in an race condition, we can not use coal for all our energy needs of pollution reasons, oil and gas is limited and affected by pollution too. Fission is expensive if done safe. Perhaps too expensive. 
This is far from the first crisis, we started using coal then we started to run out of wood. 
Long term goats is probably the most environmental damaging thing we have created. They eat anything, any dirt farmer on bad soil will maximize on them. 
Now if you are stupid, do you manage to go nuclear or renewable fast enough, now add that you have serious problems keeping population growth down, "mote in the gods eye"
Now add aggression, you did not kill your brutes over an million year. you have no surrender reflex like humans first one who get nukes use them. you either get an constant nuclear war or an world government. Now if the world government think short term it might well end the civilization,  

 

 

Hi,

well, i must admit it's hard to imagine the diversity without sex. It's helpful :-)

I doubt whether sexual selection prefers the intelligent. It rather prefers the strong males and pretty female, things that today are highly influenced by cultural criteria. In times when population was thinner and people wandered in tribes it's more probabel that mixture between other groups was favored. The guys and gals of the other tribe must have been sexier than the ones they saw every day. It is assumed that in interglacials in the european ice age tribes met from to time to exchange their members and thus genome. In high glacial times they went through genetic bottlenecks. (Africa was different)

There is a misunderstanding: assuming that peace came with diversion and domestication came out of pressure. The contrary is the case: there are no (maybe one) hint of intraspecies violence in the lower stone age (until ~15.000 before now), but with the emergence of settlement there comes battle and killing. Pressure was not the reason of domestocation, it was the outcome. There was no reason for the start of plant growing and 1000yrs later domestication. It could as well have happened 110.000yrs earlier, in the OIS 5e, when climate was even better.

Edit: before someone else points out: i was very fuzzy with "lower stone age" and 15.000yrs. Don't nail me to the cross, there is no lower stone age in europe (let's say Palaeolithic) and the 15.000yrs are arbitrary, in fact the first known remains of battle are much younger. Will come up with sources if asked to.

Edited June 22, 2016 by Green Baron