Methane-Based Life Possible On Titan

ratamacue0 sent me this interesting Slashdot post: Methane-Based Life Possible On Titan – Slashdot.

Randym writes:

With the simultaneous announcement of a possible nitrogen-based, cell-like structure allowing life outside the “liquid water zone” (but within a methane atmosphere) announced by researchers at Cornell (academic paper) and the mystery of fluctuating methane levels on Marsraising the possibility of methane-respiring life, there now exists the possibility of a whole new branch of the tree of life that does not rely on either carbon or oxygen for respiration. We may find evidence of such life here on Earth down in the mantle where “traditional” life cannot survive, but where bacteria has evolved to live off hydrocarbons like methane and benzene.

There’s a lot in this post, all relating to life and methane.  The first is about a study of possible life that might exist in liquid methane (instead of water), which is a possibility in the outer solar system, notably on Titan, a moon of Saturn and the largest one in the solar system.  The average temperature on Titan is about -179 ºC, below the boiling point of methane.  On Titan, methane may flow like water does on Earth, in rivers and lakes.

The idea that there may be methane life in the universe has been around for a while.  The new model seems to lend some support to the idea, but I think it’s important to understand that this is only a hypothetical model.  If methane based life does exist on Titan, I wonder at what stage it would be in its evolution, since life is chemistry, and chemistry at -179 °C (94K) seems like it’s going to flow a lot slower than chemistry at 15 °C (288K).  If there is life on Titan, I think it’s likely still in the relatively early stages.

Mars is cold by our standards, but it’s not far enough from the sun to be cold enough for liquid methane.  Methane is a gas there, just like it is here.  My understanding is that the significance of methane there may be as a possible waste or by-product from some kind of life, much as it is from some life on Earth.  The methane on Mars may still be from non-living natural processes, like volcanoes.  Only time will tell.

The article on life in the lower levels of Earth’s crust is interesting.  I think it got included here because that life may feed on chemicals like methane.  Again, this is different than what’s being envisioned as a possibility for life on Titan, but still pretty fascinating, particularly the possibility that life may permeate down into Earth’s upper mantle.

I think all of this goes to show that we have reasons to believe that life can exist in a wide variety of environments, and that only looking for it in narrow habitat zones may be too limiting.  Personally, given the wide variety of what we call “life” here on Earth, I suspect that when we do find the first extraterrestrial life, it may well challenge our very conception of what life is.  We may end up debating whether or not it actually is life, or just some kind of previously unknown complex chemical processes.

Complex life in the universe may be much rarer than previously thought

At least, according to a couple of astrophysicists: Complex life may be possible in only 10% of all galaxies | Science/AAAS | News.

The universe may be a lonelier place than previously thought. Of the estimated 100 billion galaxies in the observable universe, only one in 10 can support complex life like that on Earth, a pair of astrophysicists argues. Everywhere else, stellar explosions known as gamma ray bursts would regularly wipe out any life forms more elaborate than microbes. The detonations also kept the universe lifeless for billions of years after the big bang, the researchers say.

…The sheer density of stars in the middle of the galaxy ensures that planets within about 6500 light-years of the galactic center have a greater than 95% chance of having suffered a lethal gamma ray blast in the last billion years, they find. Generally, they conclude, life is possible only in the outer regions of large galaxies. (Our own solar system is about 27,000 light-years from the center.)

Things are even bleaker in other galaxies, the researchers report. Compared with the Milky Way, most galaxies are small and low in metallicity. As a result, 90% of them should have too many long gamma ray bursts to sustain life, they argue. What’s more, for about 5 billion years after the big bang, all galaxies were like that, so long gamma ray bursts would have made life impossible anywhere.

This is sobering when considering how much life might be in the visible universe.  It doesn’t really change the possibility of life on the exoplanets in our neighborhood of the galaxy.  I still tend to think we’ll find evidence of life in the light spectrum reflected off one of those exoplanets within a few decades.  And there’s this caveat in the article:

But are 90% of the galaxies barren? That may be going too far, Thomas says. The radiation exposures Piran and Jimenez talk about would do great damage, but they likely wouldn’t snuff out every microbe, he contends. “Completely wiping out life?” he says. “Maybe not.”  But Piran says the real issue is the existence of life with the potential for intelligence. “It’s almost certain that bacteria and lower forms of life could survive such an event,” he acknowledges. “But [for more complex life] it would be like hitting a reset button. You’d have to start over from scratch.

Most of my regular readers will know that I already tend to think that microbial life is the most prevalent in the universe, that complex life is rare, and that, due to the Fermi Paradox, intelligent life is profoundly rare.  Having biospheres periodically purged every few hundred million years throughout most of the universe probably just makes complex and intelligent life orders of magnitude rarer yet.

I usually say that our closest neighboring civilization may be in another galaxy.  If these findings stand, it might be more likely that they’re hundreds of millions, if not billions, of light years away.  Of course, it’s also possible that civilizations arise more often than I’m thinking, but that virtually all of them get wiped out from a gamma ray burst before they get a chance to spread.

Either way, the chances of us ever meeting any of them appear to be increasingly unlikely.

The article finishes with some possible advice for SETI:

The analysis could have practical implications for the search for life on other planets, Piran says. For decades, scientists with the SETI Institute in Mountain View, California, have used radio telescopes to search for signals from intelligent life on planets around distant stars. But SETI researchers are looking mostly toward the center of the Milky Way, where the stars are more abundant, Piran says. That’s precisely where gamma ray bursts may make intelligent life impossible, he says: “We are saying maybe you should look in the exact opposite direction.”

Eavesdropping on E.T. and the possibility of interstellar travel

Gabriel Popkin as an article at Inside Science about a study that looks at the possibility of intercepting communications between other alien civilizations.  The idea is that communicating across interstellar distances is best done with lasers.

So far, the optical search for extraterrestrial intelligence has focused mainly on the hope of receiving—and recognizing—an intentional, laser-encoded message. Researchers use dedicated telescopes or mine astronomical data collected for other purposes, like the Sloan Digital Sky Survey, to search for light pulses that could not be produced by any known object like a star. So far, no one has reported a light pattern that suggests an extraterrestrial intelligence.

But rather than look for light beamed directly at us, astronomers could also try to intercept signals sent between two distant civilizations. If advanced beings have existed for millions of years, they may well have found each other and started talking. Eventually many light beams would penetrate the intergalactic darkness, creating a criss-crossing network of communication beacons. As our solar system revolves around the galactic center, could we meander into the path of one of these beams?

While an interesting idea, the study largely concluded that this is unlikely to happen.

Unsurprisingly, he found that the chance of intercepting another civilization’s messages increased as more civilizations joined the communications network. He also found that the interception probability increased dramatically as the angle through which the beams spread out increased.

But the probability of accidentally wandering through a beam remained small as long as the beams were narrow, or collimated, like a typical laser. The beams would have to spread out about 1,000 times more widely than a standard laser pointer—in other words, more like a flashlight beam—before we have a decent chance of intercepting them, Forgan says. Sending out such a wide beam would require far more energy than emitting a tightly collimated one.

This isn’t too surprising.  Interstellar space is vast, and solar systems are (relatively) tiny.  As the article discusses, the aliens would have to go expensively out of their way to increase the odds of being detected by a third party.

One thing I find interesting about these studies, is that they have an implicit assumption: that interstellar travel or exploration is impossible, even robotically.  Because if it is possible and there are indeed hundreds of civilizations in the galaxy, then there would likely already be a communication relay in every solar system, and a vast interstellar communication web network.  If so, then our system would almost certainly have multiple beams interacting with other nearby stars.

If the aliens don’t want to be detected, it is possible that they could keep their relay stations in the Oort cloud, the region of comets and other icy bodies extending for a couple of light years out from the sun.  Of course, avoiding detection would have to be a major priority for them to keep their facilities so far away from the free solar energy of the sun.  But they could have decided to do so as soon as they noticed a tool using species developing on the third planet.  And if staying  hidden is a priority, we’re unlikely to find them for a while.

But, is the assumption that interstellar travel is impossible a valid one?  Or are SETI and other astronomers being overly pessimistic?  Most people are aware of the speed of light limitation, that nothing can travel faster than light.  But lamenting that issue is actually a bit of sour grapes, since we don’t even have the foreseeable technology to get to a significant percentage of the speed of light.  Just getting to 10% of c (the speed of light) will require astounding amounts of energy.

But it’s hard to imagine that in the centuries and millennia ahead, that we won’t be able to cobble together some method of getting to at least 1% of c.  There have been designs around for decades, such as the Orion Project, which would use nuclear explosions to propel a craft up to a high speed.  And there are many more speculative designs out there that could conceivably improve on that.

The problem is that Orion would still take centuries to reach the nearest star.  It’s easy enough for science fiction writers to wave their hands and imagine robotic probe machinery working that long, but engineering it is a different matter.  Still, Voyager 1 is four decades out and is expected to work at least another decade, albeit in a very low power mode.  Building a probe that could work for centuries would be difficult, but it remains an engineering challenge, not a fundamental limitation of physics.

And I think that’s why I remain optimistic that interstellar exploration will ultimately be possible, at least with robots.  Because the issues to be overcome are engineering ones, not fundamental scientific ones.  It’s hard to say whether those engineering challenges will be overcome in a century, a millennia, or farther out, but insisting that they never will seems unnecessarily pessimistic.

But as soon as we reach that conclusion, we’re back to wondering where everyone is (the Fermi Paradox).  Either they (or more likely their robotic representatives) are already here in the solar system, and hiding, as described above or in some other way, or they’re simply not there.  Or perhaps more accurately, the nearest neighboring civilization is millions of light years away in another galaxy, far enough away that they haven’t had time to reach us yet, if they ever will.

How should we communicate with aliens? Should we communicate?

The array of telescopes atop Mauna Kea (Hawaii)
The array of telescopes atop Mauna Kea (Hawaii) (Photo credit: Wikipedia)

Seth Shostak has a post up at HuffPost asking what we should say if we ever find ourselves in conversation with aliens.  Apparently this was the topic of a recent conference at the SETI institute.

Before commenting on Shostak’s main thesis, I think he makes an assertion that deserves scrutiny.

A decade of research by astronomers now suggests that a trillion planets dot the Milky Way. It takes a real Debbie Downer to believe that they’re all as dead as the Equal Rights Amendment.  Unless Earth is special beyond reason, you can confidently assume there are plenty of societies out there.

I’ve got no problem with this statement, until the last sentence, where Shostak takes a logical leap.  (Albeit an understandable one being he’s a member of SETI.)  Certainly, unless Earth is “special beyond reason”, we can expect plenty of worlds with life out there.  Given the history of life on Earth, I think we can expect most extraterrestrial life to be simple microscopic organisms.  Complex life (plants and animals) will likely only be on a minority of worlds.

And given that the Earth was 99.995% of its current age before an intelligent species arose, and also given the Fermi Paradox (if there are plenty of civilizations out there, where is everyone?), I think we should expect intelligent life to be exceedingly rare.  Rare enough that our closest intelligent neighbor may be millions of light years away in another galaxy.

Of course, it’s always possible that interstellar travel is impossible and that the only way civilizations could ever interact with each other is by signaling across the void.  And that gets to Shostak’s main topic.

A leitmotiv of the conference — one thing that just about everyone felt they could agree on — was to beware of anthropocentrism. Don’t assume that the way we think or describe things will be the same for the extraterrestrials. Context and local knowledge are the frameworks of our daily lives, and it’s easy to forget that these are peculiar to us, both in place and in time. The aliens will not get our jokes, our literature, or our reality TV. Their minds, presumably vast and deep, could be as different from ours as those of bats and beetles.

The problem isn’t even anthropocentrism, it’s terracentrism (don’t know if that’s a word, but I’m making it one).  We might have some hope of rising above anthropocentrism by comparing ourselves to non-human animals, but aliens that evolved in a radically different environment may think so differently that even communications like pictures or mathematics may simply be assuming too much.

The fact is, we probably have little hope of figuring out, a priori, how we need to communicate with extraterrestrials.  With that in mind, I agree with Shostak that, if we choose to communicate (more on that in a bit), we should do so liberally.

It’s a tough problem, and my own contribution was to opine that — rather than wrestle endlessly with what we should say — we send it all. Or at least send a lot. I suggested that we transmit the contents of the Internet, or some large subset thereof, rather than offering up more “greeting cards” similar to those that have been bolted onto some of our spacecraft. Sure, there’s a lot of silly stuff on the web — it’s not curated, to use the language of museums. But it’s wide-ranging, covers a lot of human activity, and is highly redundant. For example, the concept of “automobile” is present in descriptions, photos, and videos. That redundancy will help them — assuming they have the processing power — to figure out a lot of what we’ve sent.

In other words, give them enough so that they have a chance of piecing together our concepts.  If you think about it, if we were receiving communication from an extraterrestrial civilization, that’s probably how we would prefer to receive it.  Inundate us, and let us figure it out, particularly since interactive communication is probably going to be impossible, with replies likely to take centuries, if not millennia.

But this raises the question of whether we really should communicate.  Any other civilization that we’re likely to contact would almost certainly be far more advanced than ours, and by “far more”, think millions of years more advanced.  The probability of us connecting with another civilization that just happened to emerge within a few thousand years like we did, is infinitesimal.

Even if they’re 500 light years away, and the soonest they could conceivably affect us would be over a thousand years from now, that’s likely not nearly enough time for us to catch up technologically and be on anything like the same level as they would be.  Communicating with them may simply be the mouse summoning the cat.

Of course, it’s hard to see why an advanced civilization would bother conquering us.  Any desirable natural resources we might have would be much easier to obtain in the Kuiper belt, or on other planets without the bothersome resistance of the inhabitants.  And our biologies aren’t likely to be compatible enough for them to eat us.  (In any case, it would be easier to synthesize the food rather than travel interstellar distances to obtain it.)

But we should consider that it likely wouldn’t even amount to conquest for them.  Their attitude toward us might be the same as that of a scientist studying mice, and experimenting on them.

I suspect that it we ever did receive a signal, we’d get a lot of clues from what was in it.  If there was extensive information about themselves, including information that helped us solve many technological problems, then we might be able to assume they were benign.  On the other hand, if all we received was the interstellar equivalent of a dial tone, we would probably want to carefully consider our next move.

Blindsight by Peter Watts, a review


I recently read Peter Watts’s book, ‘Blindsight‘, a hard(ish) science fiction novel about first contact with extraterrestrials.  This is a book that’s been out for several years, and was a Hugo Award nominee in 2006, so I’m a bit late to the party.  Indeed, since I started this blog in November, a number of people have recommended this book to me as an interesting commentary on the human mind and consciousness.

On balance, I enjoyed the book, but I found it required a lot of work to read.  The problem was that I find Watts’s style of writing, at least in this book, to be confusing.  He seems to delight in finding unusual ways to describe things, often obliquely referring to scientific concepts to give insights into a situation.  This was fine for those scientific concepts that I already understood, but it often left me out in the cold if I wasn’t familiar with them.  (I’m pretty scientifically literate, so if I struggled, I think a typical lay reader would also.)

Watts also has a frustrating habit of referring to the same character with several different names or labels, often leaving me confused about who exactly was saying or doing things.  This was particularly confusing early in the book since one of the characters has multiple personalities, and I wasn’t always sure whether a name or description applied to one of those personalities, or was just another label for one of the other characters.

And Watts often likes to describe things indirectly, giving you sensory impressions of the narrator without coming out and just saying what’s going on, counting on the reader to put the picture together.  Often though, I didn’t find that enough information had been given for me to do that, that he often depended a little too much on my ability to read between the lines.

Of course, lots of authors do these things, but I found having all of them together left me in an ongoing cloud of confusion as to exactly what was going on.  Because of these difficulties, I almost stopped reading the book at around the hundred page mark.  I ultimately soldiered on because of the many recommendations, and because, in spite of the confusing writing style, I still found the story and characters interesting.

As the story begins, tens of thousands of alien probes fall into Earth’s atmosphere, scanning and transmitting information to an extraterrestrial location before they burn up.  Naturally this causes great alarm.  A quick analysis shows that the transmissions went to an object in the Kuiper belt.  A team is quickly thrown together to go out and investigate.  The Kuiper belt object turns out to be a decoy, leading the team to a rogue planet, a gas giant, about half a light year from the solar system, with alien machines in orbit, including what appears to be a controlling structure that quickly becomes the focus of the team’s efforts.

The story is told in the first person.  The narrator, due to severe epilepsy, had half his brain removed as a child.  This has left him a very strange person, supposedly missing huge amounts of the cognitive attributes of humanity.  He has learned to cope, essentially faking his humanity to get along with everyone else.  The result is that he is often described as, and thinks of himself as, a human Chinese Room.  Ironically, his name is Siri, the same as Apple’s iOS digital assistant service.  (Although this was written years before Apple developed it.)

The crew also includes a scientist who is apparently heavily cyborged, a linguist who has divided her brain into several personalities, a soldier who controls an army of battle robots, and a vampire, who is in charge.  Yes, a vampire.

Initially, the idea of vampires existing in what was otherwise a straight science fiction tale threw me out of the story.  But Watts does a good job of naturalizing them.  In this story, they aren’t supernatural, just an extinct offshoot of humanity, through technology recently brought back from extinction,  with a mutation that turned them into predator cannibals.  One traditional aspect of vampires is retained: their fear of crosses.  (Caused by an aspect of their mutation that causes them to go into convulsions when they see perpendicular shapes.)

The title of the book, “blindsight,” refers to a condition where someone’s eyes are functional, in the sense that they receive light and transmit it on to the brain, but some problem in the brain prevents the person from actually being conscious of what they’re seeing.  They can see, but they’re still blind.  It’s a type of blindness sometimes seen in patients with certain types of brain damage.  The phenomenon becomes a plot point in the story.

The narrator, and all of the other characters, serve as vessels to explore the nature of the human mind, and of consciousness.  Each of the characters ends up serving as a contrast to normal humans.  A contrast that sheds light on how the minds of regular humans work.  And at a certain point in the story, the central AI of the team’s ship, ominously called “Captain,” itself becomes an important player, providing an additional contrast.

And when we’ve explored those human variations to some extent, the aliens are introduced and we’re treated to a comparison between how they and humans think.  In the end, there turns out to be an astonishing difference, a difference that, in the story, has profound, disturbing implications for the future of humanity.

It’s difficult to say much more without getting into spoilers.  The book was a hard slog, but I found the payoff to be worth it.  If you like science fiction, and are  interested in the human mind, in consciousness, its evolutionary purposes, and how an alien mind might be different than ours, then I recommend it.

One thing that spurred me to read this book was that Watts has just come out with a sequel, ‘Echopraxia‘, which I may get around to reading at some point, and possibly reviewing here.

Find alien civilizations by their pollution?

Rainbow pollution
Rainbow pollution (Photo credit: gambier20)

There’s been speculation that advanced telescopes may be able to find hallmarks of alien life by looking for oxygen in the spectrum of light reflected off of exoplanets, but this article suggests using the James Web Space Telescope to look for pollution: Pollution on other worlds may show advanced alien life – space – 27 June 2014 – New Scientist.

Life is messy. So to find aliens, why not look for their pollution?

As part of its mission, NASA’s upcoming James Webb Space Telescope (JWST) will be able to look at starlight filtered through the atmospheres of Earth-sized planets and search for signs of life. Most proposed plans involve hunting for highly reactive gases such as oxygen that usually need a living source to replenish them. But these methods might only hint at relatively simple life such as plants and microbes.

Henry Lin at Harvard University thinks we could find more advanced civilisations if we look instead for industrial pollution. His team calculates that JWST should be able to spot two kinds of chlorofluorocarbons (CFCs), complex carbon-based gases used in solvents and aerosols.

“Their production requires a network of chemical reactions that are only known to be produced artificially on Earth,” says team member Avi Loeb at the Harvard-Smithsonian Center for Astrophysics.

My initial reaction to this is that we don’t know how long the polluting phase really lasts for a civilization.  It might only last a century or two before a typical civilization switches completely to renewable or non-emitting energy sources.  And an advanced civilization may be eons past their polluting phase.  Then I read this part.

JWST would only be able to filter out signs of CFCs from highly polluted atmospheres, the team found, but still within levels that humans could tolerate. In addition, the telescope could in principle detect the remnants of civilisations that annihilated themselves, since some CFC molecules survive for up to 100,000 years and could outlast their sources, says Loeb.

100,000 years is still a pretty brief period in astronomical and geological scales, but if the great filter is that most civilizations destroy themselves, then we might be lucky enough to spot a remnant or two this way.  I can’t say the prospect of finding something like this would be enticing, since it would indicate that our long term outlook is bleak.  Still, if it happens to be reality, I would want to know it.

Did a cosmic fluke make life on land possible?

When pondering how likely life is to develop on other worlds, or what types of life might develop, we always have to always bear in mind that we currently only have one example to work with.  And that example has one extremely unusual attribute, a large moon, at least large in relation to the size of Earth.

There have been speculations over the years about how Earth’s moon may have played a unique role in helping life to develop on this planet, from stabilizing and slowing the Earth’s rotation, giving it a much calmer and more stable climate than it otherwise would have had, to the effects of tidal forces on life’s rhythms.

This article highlights a paper that looks at the moon and its tidal forces possible role in helping life to colonize land:  Did A Cosmic Fluke Make Life On Land Possible? | Inside Science.

Terrestrial animals may owe a special debt to the sun and the moon. It may have been their combined pull on ancient Earth’s oceans that helped primitive air-breathing fish gain a toehold on land, new research suggests.

In a new study, published in the journal Proceedings of the Royal Society A, physicist Steven Balbus argues that the gravitational forces generated by the sun and moon would have been conducive to the formation of a vast network of isolated tidal pools during the Devonian Period, between 420 to 360 million years ago, when fish-like vertebrates first clambered out of the sea.

If this theory is true, then terrestrial life might be as rare as a large moon.

Balbus said that developing his theory has made him skeptical of the notion that complex terrestrial life might be common in the universe. “A lot of things had to come together in a strange way on the Earth,” he added.

Maybe the great filter is the absence of a large moon around most rocky planets.


If evolution started over, how similar would its results be?

Zach Zorich has an interesting piece at Nautilus asking if the world began again, would life as we know it exist?

In less than five milliseconds, a Hydromantes salamander can launch its tongue—including the muscles, cartilage, and part of its skeleton—out of its mouth to snag a hapless insect mid-flight. Among amphibians, it is the quick draw champ. Frogs and chameleons are comparative slowpokes when it comes to their ballistic anatomies. “I’ve spent maybe 50 years studying the evolution of tongues in salamanders,” says David Wake, an evolutionary biologist at the University of California, Berkeley, “this is a particularly interesting case because salamanders, who don’t do anything fast, have the fastest vertebrate movement I’m aware of.” Within their lineage, evolution found a better way to accomplish tongue-hunting. Their seemingly unique adaptation appears to have evolved independently in three other unrelated salamander species. It is a case of convergent evolution—where different species separately developed similar biological adaptations when faced with the same environmental pressures. Salamanders are Wake’s go-to example when asked a decades-old question in evolutionary biology: If you could replay the “tape of life” would evolution repeat itself? In the salamanders, it appears it has: In other organisms, it may not have.

Zorich’s piece describes some fascinating experiments testing this question, and is well worth reading in full.

My own view is that this is really two separate questions.  The first is how likely is the rate of evolutionary “progress”, or increases in complexity and capabilities?  The second is, if those increases in complexity and capability did happen again at a similar rate, how similar would the results be to the ones we observe today?

On the first question, I can’t see that it is at all guaranteed.  There’s nothing to make us believe that the development of complex life was inevitable.  It took billions of years on Earth.  Viewed on geological timescales, complex life is a recent innovation.  The Earth was 87% of its current age before the Cambrian Explosion took place.  Complex life does predate the Cambrian, but 75-80% of the Earth’s age had elapsed before it developed.

Earth probably only has another 500 million to 1 billion years before the sun’s growing heat makes life impossible.  In other words, it took life most of the time it’s going to have (4 billion years out of a likely 5 billion year window) to evolve complex life.  If we started over, it’s very possible that life would never get out of the microscopic phase in time.  Of course, it’s also possible complex life might have developed earlier; we just don’t know.

But if complex life did develop, and if the environment were the same, how similar would the results be to today’s life?  I’m tempted to think that we’d see very similar ecological niches to the ones we have now.  The many examples of convergent evolution would seem to bear something like this out.

However, we have to remember that a large part of the environment is caused by life itself.  The oxygen in the atmosphere first came about from early life, and the continued oxygen levels are maintained by life that outputs it as a waste product.  Many of the optimal shapes for land animals are related to trees, grasslands, and similar life that they have to navigate through and around.  Much of life lives in an environment generated by life itself, in the biosphere.  If life started over, that biosphere would almost certainly be radically different.

Still, broadly speaking, I would expect some functional similarities.  For example, you’d still have life living in the water, and the same fish shapes that are conducive to moving through the water would be conducive again if life started over.  Many of the same shapes that are optimal for moving over land surfaces would be optimal again.  It would still be productive for species to eat other species in a food chain.  It would still be optimal for sense organs to be in the front and highest part of an animal’s body.

But within those broad functional niches, there would almost certainly be differences that we would find radical.  For example, I see no guarantee that sexual reproduction would exist, or if it did that it would resemble anything we’re familiar with.  While creatures that can regulate their own body temperature might exist, something like mammalian glands might never develop.

Of course, all of this is speculation on my or anyone else’s part.  As Zorich describes in his article, evolutionary experts are divided about it.  Unless and until we have access to life that evolved independently in its own environment, in other words, until we have access to an extraterrestrial biosphere, we won’t really know.

One point that I do think we can assess with high probability: if life started over, humans wouldn’t exist.  Turn back the clock by 1% of Earth’s age (45 million years), and nothing resembling humans had evolved yet.  Humanity’s existence is a very recent phenomenon, and civilization is a blink of the eye in geological time.

Would some intelligence capable of a technological civilization eventually develop?  Given the time constraints on complex life I mentioned above, and the amount of time it took a technology using intelligence to develop on Earth, it’s hard to say that it’s likely.

Many people point to the other intelligent species out there, such as crows, dolphins, elephants, octopuses, and so on.  With all those other intelligent species, wouldn’t it be likely that one or more of them would eventually evolve into a technology using species?  And if so many intelligent species developed this time around, wouldn’t that make it likely that a technology using species would develop in a rewound world?

The problem is that developing a technological civilization requires more than just brain power, it requires a body plan with enough dexterity to manipulate the environment.  So far, primates are one of the few species groups, perhaps the only one, that has managed to develop this type of body plan, and only great apes (including humans) managed to pair this body plan with high intelligence, and only very recently in evolutionary time.

I think the probability of life producing a technological civilization is very low.  Given the existence of the Fermi Paradox, it seems reasonable to conclude that it is profoundly rare event.

So, to summarize, if life started over, I think there’s a good chance complex life wouldn’t develop, but if it did, we’d see a lot of creatures that, from a distance, looked similar to the creatures alive today, but that would likely still be different in many ways hard to imagine.  I think the probability of human level intelligence developing would be profoundly low.

The Fermi Paradox – Wait But Why

The “Wait But Why” blog takes an in depth look at something some of us were discussing on another thread: the Fermi Paradox.

Everyone feels something when they’re in a really good starry place on a really good starry night and they look up and see this:

Some people stick with the traditional, feeling struck by the epic beauty or blown away by the insane scale of the universe. Personally, I go for the old “existential meltdown followed by acting weird for the next half hour.”

But everyone feels something.Physicist Enrico Fermi felt something too—”Where is everybody?”

full article at The Fermi Paradox – Wait But Why.

I’ve written myself about the Fermi Paradox, and my belief that the simplest explanation is that intelligent life is very rare.  But I’ll fully admit that this is an area where there’s still lots of rooms for possibilities.  That said, I think we can be pretty confident from the paradox that the Star Trek version of reality, with scores of alien civilizations within a few dozen light years of Earth flying around faster than light, doesn’t exist.

Life on the Billionth Rock From the Sun | Seth Shostak

Seth Shostak has an article at HuffPost on asteroids.  Not the usual we-need-to-prepare-for-incoming, but discussing something I’ve noted before that the space age needs: an economic incentive.  As some of us have discussed, mining asteroids looks like it might be an excellent candidate.

These rocks are a resource. The fact that they’re in small chunks makes mining them as appealing as cat videos. And at least two companies are considering doing just that. The consequences could be mind-boggling. According to John Lewis, chief scientist for Deep Space Industries, if humanity can improve its recycling efforts, then ores smelted out of just the nearest asteroids will supply the needs of 80 billion of us until that distant day on which the sun dies.

That sure beats the slow and inevitable impoverishment that will be our fate if we confine mining to our own back yards (or preferably someone else’s back yard). The asteroids aren’t so much a renewable resource as an endless one.

via Life on the Billionth Rock From the Sun | Seth Shostak.

Shostak also discusses the possibility of us living on asteroids, and on the rocks further out from the sun in the Kuiper belt and scattered disk.

The only issue with these far out locations is their distance from the sun and the inability to use solar energy.  Shostak talks about Freeman Dyson’s idea of using mirrors near the sun to beam energy out to specific colonies.  But that seems like it would quickly grow cumbersome with large numbers of such colonies.  To be economically feasible, those outer colonies would probably eventually need to figure out a way to use the materials on hand to generate energy.

I suspect any such colonies would be “manned” by robots, or post-humans.  Maintaining natural humans that far out from the sun would probably be too energetically expensive.