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ETpro's avatar

Can we correctly assume that intelligence would eventually evolve on any planet that has life for a sufficient length of time?

Asked by ETpro (34472points) June 29th, 2010

We often think of evolution as a ladder leading from the simplest single-cell organism up, rung by rung, to humans and thus to intelligent life. This does not square at all with the real path of evolution, however. In fact, while life has increased in complexity it has done so not in the form of a long ladder, but in the form of a grassy meadow with shrubs and trees scattered here and there, each having many branches.

In truth, we have something like 50 million species on earth today and only one of them in the 3.5 billion year history of life has evolved into a sentient, intelligent being. Isn’t it possible—even likely—that there may be many planets supporting teaming life of diverse forms but with none of those life forms having followed the unlikely path to intelligence. Large brains demand a great deal of food. Pound for pound, they use far more energy than any other part of our bodies. So natural selection may not always push life toward relatively expensive large brains.

Could it be that there is a flaw in the SETI project’s assumption that life elsewhere in the Universe will inherently lead to intelligent beings? What do you think the odds might be that life on any given planet, if allowed billions of years to evolve, would culminate in an intelligent life form capable of interstellar communication?

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62 Answers

Qingu's avatar

It depends on what you mean by “intelligence.”

There are a bunch of different kinds of intelligence, which we’ve narrowed down through studies in artificial intelligence. The process of evolution is itself a form of intelligence. (Genetic algorithms)

Also, many other animal species are “intelligent”; humans aren’t the only ones. We’re not even the only ones with culture (chimps and other primates), or who mourn our dead (elephants).

I always wonder what certain phenomena in the universe would look if they were sped up, or slowed down. What we call intelligence is really a group of behaviors that occur at a certain rate, that seem to anticipate and react to external phenomena. What if storms on Jupiter exhibit this kind of intelligence at certain “rates” of observation?

dpworkin's avatar

No. Life stayed unicellular on earth for 5 billion years or so. There is no reason why it could not have stayed that way save for some stochastic process that may never repeat again in the universe.

wundayatta's avatar

No, I don’t think it would be a good idea to assume something like that. But I think that, if we have the resources, it is worth trying to detect life elsewhere. I don’t think we have any idea how to establish the odds that it exists, so I wouldn’t spend a lot of energy on the search, but a little is ok.

LuckyGuy's avatar

With the right molecular mix and the right environmental pressures it might even develop faster than here on earth. Intelligent life elsewhere might even communicate by some form of electromagnetic waves rather than the crude acoustic waves we use when we say, “Hey!”
Will SETI find it? Who knows?
The odds of us being alone are very small.

Qingu's avatar

@dpworkin, Earth hasn’t been around for 5 billion years. We don’t really know when the first multicellular life emerged, but it didn’t take 5 billion years, it may have only took 1 billion years after the first cell.

delirium's avatar

Humans aren’t the ideal “end” of things. I try to avoid that kind of anthropocentric thinking. A lot of this also depends on your definition of intelligence. Are cephalopods intelligent? Are dolphins? Whales? Bonobos? Chimps? Crows? Stomatopods?

Talking about “the most highly evolved” is equally wrought with potential error. We can be discussing it in different ways, from the most specialized animal (like flamingos) to the animal that can find a niche in most environments (like rattlesnakes). We could even discuss the synanthropic species as being highly evolved because they have been able to adapt so quickly to live with humans and their environmental degridation.

There are no fine lines when it comes to evolution. Every time you think you’ve found a hard line, an exception will appear. We thought nothing could live in places like hot springs and salt lakes but we eventually realized that there are extremophiles living there (archea, for example). We place these imaginary lines in this gigantic tree and only later realize that there are twigs and vines that cross it every which way. We thought the only venomous reptiles were snakes and gila monsters and realized a few years ago that almost every lizard and snake has some kind of venom, even if they cannot access it. We thought monitors were strict carnivores, and we’ve now just found frugivorous ones.

Intelligent is just another one of those lines.

dpworkin's avatar

@Qingu Thanks. As I typed that I remembered briefly that the last I heard the earth itself is only 5.4 billion years old. I’m sure 1 Billion years is a much better figure.

@delirium I absolutely agree. To believe otherwise is to commit a teleological error.

Dr_Lawrence's avatar

Giving our knowledge about life on planets is limited to a sample of one (1) out of billions of planets, I’d say we have insufficient information to make any reliable predictions.

I expect that natural selection applies as well on other planets as it does here.

Different environments will favour entirely different adaptations and will result in very different species at the top of the food chain.

Given billions of planets and some smaller number that may support some form of life, it seem reasonable that some will develop species characterized by what we understand as intelligence.

Val123's avatar

I’d say it’s sure possible. Not a given, but possible. But….what do I know!

Pandora's avatar

No, because intelligence hasn’t been proven on earth yet.

If we were intelligent we wouldn’t shit where we eat.

Qingu's avatar

Earth is 4.6 billion years old.

dpworkin's avatar

Hmm, Just a month ago a professor of mine provided me with a reference to a paper which suggested 5.4 billion. (I just looked it up.)

Val123's avatar

Guys! From Wiki : The age of the Earth is around 4.54 billion years.
@dpworkin Can you send us to the paper you referenced? It may be a theory that contradicts the “accepted” theory.

Ivan's avatar

Or he just accidentally switched the 4 and the 5.

dpworkin's avatar

I have a hard copy, but I’ll see if it has a DOI.

dpworkin's avatar

4.54 billion years old, and no sign of intelligent life anywhere near my keyboard.

Trance24's avatar

If a planet has life than yes I believe it is possible for intelligent life such as humans with the power of thought and choice, and the ability to change our environment.

Val123's avatar

@dpworkin Got ants? I got ants!

zophu's avatar

I’m not especially educated and I haven’t read any of the other answers yet, but here’s what I think about the subject:

Eventually, no matter how stable a life-supporting planet is, the climate’s going to change. (I guess.) Longterm survival would require advanced adaptation, meaning prediction, meaning intelligence. (Maybe.) And any intelligence would grow in complexity once it got started, because it would constantly challenge itself, because it would constantly be preparing for potential changes, because it would be constantly predicting things, because that’s what intelligence is. (I’m pretty sure.) So, if life is going to last indefinitely anywhere in existence, it’s going to need intelligence, and that intelligence is going to require growing complexity, which wold eventually lead to intergalactic communication/travel and the potential survival of major cosmic catastrophes and even uni-(multi?)-versal entropy itself!. . . (I guess.)

So, unless it’s going to die, life has to learn how to learn. Even non-intelligent life that’s supported by intelligent life for whatever reason has little hope for indefinite survival. It will eventually be replaced by something the intelligent life deems more useful, or the need for it will otherwise go away.

Ron_C's avatar

Even if the chance for intelligence is1 in 50 billion, there is still an excellent chance that there are intelligences out there. We may have a hard time recognizing them or finding them but chances are excellent that they are out there.

ETpro's avatar

Thanks to all who offered thoughts. Special thanks to @dpworkin for a good laugh on the Age of Earth issue.

@delirium Thanks for a thoughtful answer. Yes, I would allow that Stomatopods are relatively intelligent creatures. Anything smart enough to get called a Mantis Shrimp when it is neither a mantis or a shrimp must be clever. And their ability to learn and even adopt inter-species communication skills puts them in a league we would have to consider as intelligent compared to, say, snail darters.

Of course I think Cephalopods are extremely intelligent—but on that point, I may be a tad prejudiced.

But realistically, no other animal on earth has invested nearly as much in brain to body size as humans and the hominids that preceded us. Only humans have conquered all possible habitats, bending the environment to our needs when necessary. No others, at least as of today, have used increasing intelligence as one of their chief survival strategies. None other than homo sapiens are anywhere close to sending out messages across intergalactic space or listening for an answer.

zophu's avatar

@ETpro We probably killed off any other candidates for our level of intelligence, which probably wasn’t very intelligent.

ETpro's avatar

@zophu You are right about that. There is clear evidence we killed off Neanderthal. While it isn’t as clear what spelled the end of the other species from Australopithecines forward, it’s a pretty safe bet that more brains kept winning the war. But it was likely a case of kill or be killed, so I don’t know as great-great grandpa was stupid to have fought his way to the top. I, for one, and glad he made it.

zophu's avatar

@ETpro I guess it would be pretty weird having human-like people, less agile and less smart living alongside us. We would have made them slaves if we didn’t force them into extinction, so I guess it’s for the best. Still depressing to think about. Moreso than before, actually. :(

ETpro's avatar

@zophu This is what Australopithecus afarensis looked like.

dpworkin's avatar

Lucy! My darling!

ETpro's avatar

@dpworkin She was a hotie, all right. Too bad we weren’t around in her day.

dpworkin's avatar

Did you ever read Johanson on the subject of Lucy? She was his lil hottie, and he writes wonderfully about her.

ETpro's avatar

Ha! No, I haven’t read that. But can you blame him?

dpworkin's avatar

I think you can find it on Amazon. Johanson and Edy. The book is called Lucy something something something. Marvelous. Great treatment of A. robustus and how the dentition was misleading, etc.

ETpro's avatar

Here is is, for anyone interested. Johanson, Donald; Edey, Maitland (1981). Lucy, the Beginnings of Humankind. St Albans: Granada. ISBN 0–586-08437–1

dpworkin's avatar

It’s really quite an adventure story. The Leakeys were involved, too, in a competitive way.

ETpro's avatar

I added it to my “must read” list. Thanks for the tip.

Qingu's avatar

Important new information about the Neandartals!

“We” may have kiled them off, but we also sexed them up. Also, most of “us” aren’t just cro-magnons. Something like 75% of human beings have Neandartal DNA.

iirc, it’s not that the Neandartals were less intelligent or less agile (they were way stronger), it’s that their vocal chords weren’t as developed and they couldn’t use language effectively.

dpworkin's avatar

We think. They might have had a different sized pharynx, but many think they could speak. They were cold-adapted, and had a bigger cranial capacity than sapiens and they may not have invented throwable weapons, which would have put them at a disadvantage. Late Paleo flaked heads were notched by sapiens which might mean they were bound to a stick. The Neanderthal tools seem to have been hand tools.

ETpro's avatar

Neanderthal’s skeletal construction suggests their arms were not well adapted for throwing, so definitely throwable weapons were part of the toolkit modern man used to dislodge them in their cold habitats. But we definitely absorbed them to some degree, as well. I should know. I’ve been self employed for the last 25 years because I finally got fed up with working for an Neanderthal boss.

mattbrowne's avatar

The likelihood is 82.73 % in a 10 billion year time span. Okay, I made that up. But I believe our universe is bursting with evolutionary possibilities. Complex ecosystems will eventually offer niches for intelligent life.

ETpro's avatar

@mattbrowne Could be. But part of the reason we have the heated debate about human chauvanism and whether we are the only intelligence on earth or whether other life forms are intelligent is that there are perhaps a near infinite number of addaptations which give an organism an advantage in a given niche. Bats, for instance, devote nearly half their brain to hearing tuned to an ultrasonic frequency we can’t even hear. This lets them fly and locate prey in the dark. Likewise, great horned owls can soar in pitch blackness and hear a field mouse hundreds of feet down scurrying through grass in a field. Monkeys have relatively large brains for their body size. Not nearly as large as humans, pound for pound, but still large. But their brains are heavily devoted to visual processing so they can scurry over tree limbs up in a rain-forest canopy with no risk of falling, and can spot fruit among all that foliage with no difficulty. Beavers are incredibly adept at engineering and building dams. It is quite possible to develop a superior adaptation that provides a survival advantage, but has nothing to do with the ability to form a vast number of abstract associations, predict the future based on past events, and take action to shape the future to achieve desired goals.

dpworkin's avatar

There is quite a bit of ambiguity about the functional intelligence of Elephantidae, wouldn’t you agree?

ETpro's avatar

@dpworkin I would heartily agree. Why they might even be somewhere near the intelligence of Cephalopoda but I discount their achievement given the fact that they need hundreds of times the brain mass of a Chambered Nautilus or Squid in order to achieve their cleverness. But indeed, they communicate, they have fabulous long-term memory, they mourn their dead, and they have a rich emotional life that includes the ability to get annoyed with human intrusions in just the same way I would over a similar issue.

That said, I doubt that given another million years to evolve, Elephants will be starting their own SETI project. It appears there were a number of things that combined to cause selection to steer the sapiens branch of hominids toward intelligence as a survival strategy. We hunt, and we do so collectively. That gives us a source of protein sufficient to support large brains and lots of brain activity. Our hominid roots gave us the beginnings of a grasping hand and opposable thumb. We developed upright gait. Bipedalism left our hands free to wield weapons; transport goods or our young; fashion, carry and use tools… We mature slowly, giving us a long time to learn at our parent’s knees. Being social animals, and hunters as well as gatherers, we benefited greatly from the ability to communicate.

Evolutionary Anthropologists suggest that we might not have developed intelligence if even one of those factors had been absent on the path the hominid Eve took.

dpworkin's avatar

The altriciality you discuss is a byproduct of encephalization. If we had a long enough gestation period not to be as altricial, our heads wouldn’t fit through the vaginal barrel. It’s kind of a which-came-first proposition.

ETpro's avatar

That’s another of the specializations necessary for our particular survival gambit. Our brains grow for up to 15 years. No other animal has such a long time to mature its brain. In most, brain size plateaus very rapidly. And the fact we are bipedal and can carry and protect our young makes this long growth investment a workable survival strategy where it would doom an animal that was quadrupedal.

dpworkin's avatar

Although the Babinsky reflex suggests that we didn’t lose too many progeny when we were arboreal quadrupeds.

ETpro's avatar

Yeah, all hominids have got that going. One thing the hominids did to outstrip the cephalopods despite all the tentacles we could press into that service had we “thought” of it. :-)

delirium's avatar

Our brain growth can also be shown to be partly due to the fact that human primates are born comparatively prematurely because they have to be able to fit between our bipedal hips to be born. Not only do they require squishy heads with unsealed sutures, but they also are born at a time that they can’t even lift their own heads, where if you look at many other species, they’re capable of clinging to their mother/walking when born.

mattbrowne's avatar

@ETpro – But all your examples (bats, owls, beavers, monkeys…) occupy different niches in diverse ecosystems. And niches change becomes ecosystems change as well. For example triggered by climate change. A good example is the Pliocene closing of the Isthmus of Panama about three million years ago. All the niches in the rain forest were taken and the climate because very dry. Our human ancestors had to come down their trees.

One unique niche is only filled by human beings: environments that require years of planning ahead making complex deductions.

On exoplanets something similar might occur as well.

dpworkin's avatar

@delirium Human beings are indeed born with the ability to cling, especially to hair. That is the Babinsky effect of which we spoke earlier. You can see this most dramatically in premature infants who will cling upside down by the hands and feet to a rope suspended above their crib. It’s a rather astonishing sight, and speaks to the importance of not falling out of trees in one of our former lives. Oddly, the reflex diminishes with later perinatality, perhaps a case of ontogeny recapitulating phylogeny.

ETpro's avatar

@mattbrowne Great point. Certainly a possibility. But still, there is a huge congruence of selection pressures that coalesced to produce homo sapiens. It may not take the same presures in an ecosystem very different from ours, but it probably would require a substantial set of them.

Ron_C's avatar

@mattbrowne I was just reading about our evolution. It appears that we have a large bit of our DNA directly from neanderthals. There is also a theory that we overtook them by two methods, sex and murder. What that means is that, for a time, there were two sets of intelligent beings roaming the earth. Obviously the more prolific and violent won out.

It is also possible that in a more diverse environment more than one intelligent species could co-exist. After all, dolphins probably have intelligence and vocal abilities equal to ours. We co-exist as long as we stay out of each other’s environment.

My point is that man is not the only species that can inhabit this particular niche.

dpworkin's avatar

We have a trace of Neanderthal DNA suggesting that there was some limited interbreeding during the overlap period in Europe. We share more than 50% of our DNA with bananas, however, if you would like to draw some conclusions from that.

Ron_C's avatar

@dpworkin I say that we share DNA with all living things because we have the same predecessor from the primordial soup.

dpworkin's avatar

Good thinking, except we were created by God about 6K years ago.

Ron_C's avatar

@dpworkin oh yeah, I forgot.

mattbrowne's avatar

There’s still a good deal of speculation why homo sapiens survived and homo neanderthalensis didn’t. Comparative genomics has certainly got the potential to give researchers more clues. Many genes are common to all living things or at least very similar when we just look at what molecular cell biology has brought into light.

Dolphins probably don’t have intelligence and vocal abilities equal to ours. And they don’t have flexible human hands. They don’t plan three years ahead. They didn’t invent the wheel. They didn’t invent tools that allows them to explore the land outside the water while we are sending people into space. Still, they are amazing animals.

ETpro's avatar

@mattbrowne Sadly, dolphins don’t seem to be intelligent enough to discern the threat to life an oil spill poses and for ones already stressed or dying from the oil to use their vocalizations to warn others while there is still time for them to seek safer waters. I would gladly give up any human chauvinism I feel at our ability to do such if I could somehow confer that ability on the Dolphins and Whales in the Gulf of Mexico right nwo.

PattyAtHome's avatar

Wow the previous replies really left the original question behind for a bit huh. lol

The original question seems to be what are the odds that intelligent life elsewhere in the universe is likely to develop to a level that the SETI project might be able to find them.

First there’s been some discussion about what we mean by intelligence. Certainly there can be an argument made that most creatures with an advanced brain have some level of intelligence. I think mostly the idea is creatures that might have similar type of cognitive intelligence to ourselves.

What we’re really interested in finding is sentient beings that have intellectual abilities such as logic, reasoning, analyzing, prioritizing, abstract thought, etc. that are somewhat similar to our own. Further we need them to have developed some type of technology that might be discovered by SETI. This really narrows the scope down a lot.

The odds of finding beings of similar type intelligence as ourselves might be greater if we actually had the ability to visit other planets. Even if there are beings like that, not all of them will develop any type of advanced technology. They could have the greatest culture and philosophy in the universe, but no desire to look outward from their own world. Since we don’t have the technology ourselves to visit other worlds then we also need those beings to not just develop some type of civilization, but to develop a technological civilization advanced enough for interstellar communication themselves. This is where the challenge becomes even greater because not only does the civilization need to have the technology, it needs to have developed at the right time period for whatever signals it might have sent to arive at are SETI dishes in our lifetime. Unfortunately that means the other civilization would have to have existed long, long ago and may no longer be extant.

In order to find other sentient species that have a sufficiently similar type of intelligence and exist at the same time as us then both their species and ours will need to have a much more advanced technological abilities than we do now in order to find each other and develop communication.

The odds of the existence of extraterrestrial life somewhere in the universe may seem extremely high. Those odds become much less favorable as we start talking about other intelligent life forms that might exist at the same time as us, and that are sufficiently advanced to allow some form of contact or communication. As much as we’d like to think we aren’t alone in the universe it’s still possible that intelligent species haven’t yet ever existed at the same time in the universe. It’s kind of like an intergalactic lotto game. Maybe we’ll get lucky.

Oh yeah… There’s also the added condition that we want the species to be one that we actually want to find, or who we’d want to find us. Whenever thinking about this topic it’s a good idea to keep in mind the 1950 short story “To Serve Man” by Damon Knight. ;)

mattbrowne's avatar

@ETpro – Dolphins are less intelligent than humans but more in harmony with nature especially when you compare them to BP managers who are more in love with their shareholders and bonuses. Maybe it’s time to redefine intelligence.

ETpro's avatar

@mattbrowne No question that the intelligent ape can do some incredibly stupid things, like trashing the environment that supports all life on Earth.

@PattyAtHome Excellent answer. Thanks for getting us back to the topic of the question.

wundayatta's avatar

Let’s suppose we find a signal that seems to indicative of an intelligent source. Let’s suppose the signal comes from some 200 light years away. Will we try to communicate? Is it worth it? The soonest we could receive an answer would be 400 years later. Will our concerns then have any relationship to current concerns?

What if the signal is from 1000 light years away? 100,000? The more distance there is, the less likely the intelligence will still be there or still be intelligent or still be in and shape or have any interest in communicating. If it were 1000 light years away, what kind of confidence would we have that our civilization would be capable of handling an answer in 2000 years?

What if Kurzweil’s information singularity occurs? Surely it will occur within the next 1000 years; probably sooner. Wouldn’t the same thing happen to the other civilization? What does it mean when all matter in a solar system is turned over to computing power? What if we set up a Dyson sphere to capture as much of the sun’s energy as we can? Will we even be interested in what is out there any more? If we build a Dyson sphere, won’t it seem like our star just winks out?

Maybe we should be looking for stars that suddenly wink out. Whaddaya think about that?

ETpro's avatar

@wundayatta Remembering the fascination of Montgomery Scott upon seeing the Dyson Sphere. Unfortunately, even Freeman Dyson called the idea of actually constructing such a monster sphere “a joke” but regarding that episode of Star Trek he observed, “Actually it was sort of fun to watch it. It’s all nonsense, but it’s quite a good piece of cinema.”

wundayatta's avatar

Yah. Just like the information singularity.

Damn. I wish I could remember the name of the author who wrote a novel about the singularity. It started with lobsters or something.

Oh, It is Charles Stross. Accelerando. Should have trusted my instinct on that.

ETpro's avatar

@wundayatta Should I add it to my reading list.

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