Well, they certainly got there somehow. And like I said, I think it’s much more likely that the came from below than above. The exact mechanism of how they got there, I don’t know, but it doesn’t exactly break any fundamental laws.
Who knows that there wouldn’t be reptilian intelligence if they hadn’t gotten wiped out? I’ll grant that only one intelligent species will evolve on a planet, since this is such a specialized niche, but you can’t say that on other worlds it might have happened much more rapidly.
True, but even the impossibility of FTL travel doesn’t explain the Fermi paradox. It is possible that intelligent life existed eight billion years ago, or more, and if even one such species decided to expand at sublight speed, we should see evidence of it. No visitors - they don’t move fast enough to have gotten around to us in the past five thousand years, but radio at least. Maybe we’ll find evidence when we really start exploring the solar system. Maybe intelligence is an evolutionary dead end. But a quarantine is possible also.
I think we can conceive of living thousands of years without violating any laws, which makes the exploration of space a very different proposition. If we can send fairly autonomous robots to Mars less 65 years after the computer was invented, what will we be able to do in 200? I think that the probability that there are no star faring civilizations is less than that of an ftl drive.
Look, there’s no reason to suspect that “intelligence” is a likely outcome for any given biosphere. I suspect Peter Ward has it right…we’re likely to find that life of many various types is very common in the universe, but that most biospheres will consist of organisms at the prokaryotic grade.
Life on Earth began only a few million years after Earth formed liquid water. Either that life arose independently on Earth, or it came from outside the Earth, either way life arose on Earth astonishingly fast. Which argues that any place in the universe that has liquid water for several million years is also pretty likely to have life. If the origin of life were really unlikely it would seem like there should be billions of years where the conditions for life were present but it just didn’t happen. But that wasn’t the case. Very very soon after the conditions for life were present on Earth, we see life on Earth.
But for two billion years, life on Earth didn’t change very much. There were lots of bacteria, but nothing more complex. Think about that. Bacteria arose on Earth within a few million years, yet it took two BILLION years before the first eukaryotes show up. That’s pretty much contrary to our intuition about how life should behave…it seems like the creation of life itself should be the hard part, but once you’ve got living organisms they should start evolving and complexifying pretty rapidly. But that didn’t happen.
Well, eukaryotes finally arose on Earth. NOW the fun really starts, right? Except it didn’t. Now we have another billion and a half years of unicellular eukaryotic life staying pretty much the same. Life on Earth arose more than four billion years ago, yet stayed at the level of bacteria for half that period, and single cell protozoans for another billion.
It wasn’t until 650 million years ago that we see the first multicellular organisms. So multicellular life has existed on earth only ~1/6th as long as life itself. What this means to me is that something unusual has to happen for multicellular life to arise. Or it might be something different, which Sam Stone was alluding to. It might be that life on Earth could have evolved multicellularity earlier, but something kept happening that kept wiping out any nascent multicellular life.
We know mass extinctions happen periodically on our planet. Drop an asteroid on the Yucatan and blammo, no more dinosaurs. But what if the dinosaur killer were a bit larger? Instead of wiping out 70% of animal species like at the end of the Cretaceous, or 90% like the disaster at the end of the Permian (although that probably wasn’t an asteroid) you got hit with a disaster that kills 100%. Only survivors are bacteria and algae. And of course, just a bit larger than that and we get an impact that melts the crust and boils the oceans, and then we get something that not even bacteria can survive.
Maybe we’ve just got lucky that we haven’t been hit with a disaster like that for 650 million years, just tiny ones that allow SOME animals to survive. And the reason we don’t see any complex life for the first 3-4 billion years of Earth’s existance is that these disasters happen more frequently than we expect, and any trends toward more complex life were wiped out very quickly until we hit a lucky streak where they weren’t.
In other words, we don’t need Berserkers dropping asteroids on our heads, we’re probably overdue for a totally innocent natural biosphere-killer. Of course getting hit by a rock is like playing russian roulette, so just because we’ve missed getting one doesn’t mean we’re more likely to get one, but neither does it mean we’re less likely. We’ve spun the chamber and pulled the trigger and come up empty for the last 650 million years. So we’re probably not going to hit another global catastrophe any time soon, right?
Right, we needed some time without getting hit by those occasional killer asteroids. Which we did. There are billions of planets in our zone of the galaxy, so we can’t be the only planet that managed to not get continually hit back to the bacteria stage.
Once multicellular life gets going, it does head towards increasing complexity, doesn’t it? We ourselves are proof there is an intelligent tool-using niche, just like there is a fish niche and a bird niche and a giraffe niche.
I agree however, that intelligent doesn’t mean: build spaceships. If the unique circumstances leading up to Europe colonizing North America hadn’t developed, the native North Americans might have spent the rest of their species’ existence as hunter-gatherers. In other words, if we took Europe completely out of the equation, where would we be now?
My guess: any extraterrestrial race that learns how to coexist peacefully on their planet will never see any reason to move somewhere else. They’ll build defenses against asteroid impacts and just hang out where they are. Races who can’t peacefully coexist will destroy themselves long before achieving sustainable colonies.
The only exception I can imagine would be a hyperrational race who also achieved great technological reach, or a system of habitable worlds situated fairly close together.
The vast majority of people living in the Americas before 1492 were farmers, not hunter-gatherers, remember the story of the first Thanksgiving. And up until the late 1600s, China and India and the Ottoman Empire were more technically advanced and richer than Europe (the riches of the Orient!).
And I don’t think it’s quite accurate to say that life heads toward increasing complexity. It sure isn’t obvious that a wolf or a rat or a penguin is more “complex” than a Velociraptor or an Ichthyostega or an ammonite. It does make sense to argue that a Eukaryote is more complex than a prokaryote and a multicellular organism is more complex than a unicellular organism, or even that an Athropod or a Vertebrate is more complex than a jellyfish or a worm or a sponge. But is a Vertebrate more complex than an Arthropod? Is a human more complex than an Ichthyostega? Not really.
What Stephan J. Gould argued is that life doesn’t tend towards increasing complexity per se, but rather that there’s a limit to how simple life can be, any simpler and the organism isn’t capable of continuing to live. So you can’t get any simpler than a bacteria. You can get more complex than a bacteria and some species have evolved into things more complex than bacteria, but not because there’s some force that tends toward complexity but rather that sometimes there’s a space for more complex organisms. Complex organisms can either evolve to be more complex, stay the same, or become simpler. And they’re just as, or more, likely to become simpler than they are to become more complex.
And sure, the “rare earth” hypothesis doesn’t mean that there can be no other environments that support multicelluar life, just that perhaps Earth was pretty lucky to evolve multicellular life at all. How lucky we were is undetermined, but it seems pretty likely that we’ll find lots and lots more environments that support bacterial grade organisms than we will multicellular organisms.
And similarly, there’s not exactly a trend towards increased intelligence either. It’s just that a brain can only be so simple until it’s not really a brain anymore. Arthropods don’t show any trend toward more brains. But it is true that mammals tend to have larger brains than reptiles, and more recent mammals tend to have larger brains than early mammals. I think this is not because there’s a “trend” toward intelligence but rather because there’s unlimited space at the higher end of intelligence, but there’s a rock-hard floor at the low end.
There’s no reason to suppose that just because there’s a current niche for intelligent humans that if humans hadn’t evolved some other species would eventually evolve to fill that niche. There is such a thing as convergent evolution, where different evolutionary lineages find the same solutions to the same problems and so sharks and ichthyosaurs and dolphins ended up looking very similar. And so did thylacines and wolves, and thoatheres and horses, and creodonts and carnivores, and so on. But we also see that some continents have a particular kind of animal that could potentially exist on other continents but just doesn’t. There’s no ecological reason for hummingbirds to be confined to the Americas, but no old world species ever evolved to fill the same niche in the old world that hummingbirds do in the Americas. There are arctic puffins and auks that are convergent with Antarctic penguins, but nothing convergent with polar bears or muskox. The reason convergent evolution is so interesting is that it isn’t that common.
And even when convergent evolution happens, it often happens incompletely. Kangaroos in Australia fill the niche of antelope and deer, but are very different from them. They are convergent in diet and habits, but not in body plan.
So if humans went extinct or never evolved, there is absolutely no reason to suspect that racoons or monkeys or dolphins or elephants would suddenly start chipping stone axes and taming fire.
This argument is an example of the fallacy of data censoring. Since the only example we have has intelligence existing for a very brief period, we think that this is universally true. However we don’t know if intelligence in general lasts for millions of years or billions. If the former, Ward is right, if the latter then a good percent of planets with life will have intelligent life.
The longevity of intelligence is not in question here; it’s the likelihood of it arising in the first place. Two entirely separate issues.
But isn’t the longevity one of the Drake Equation factors?
It is. But, that’s as relevant to Lemur’s post as the mass of the tau neutrino.
Somewhere between 10[sup]-5[/sup] and 2 eV, last I saw.
I misinterpreted the argument as to be one saying there is a higher chance of finding primitive life because primitive life has been around so long.
The argument against the evolution of intelligence I don’t get. It is true that there is no drive to either intelligence or complexity, just random walks. However intelligence is certainly an asset to survival, at least in the short run. Thus, relatively more intelligent species should hold on in general. We ere lucky enough to get the mutation that allowed speech, while the chimps were not. But who knows what would have happened in another ten million years.
I think the probability of intelligence evolving is in the Drake equation also. The only numbers we are getting, the percentage of stars with earth-like planets, is looking a lot higher than their estimates.
Isn’t a part of the problem not really knowing how likely to occur abiogenesis might be? It seems to me that if life as we know it is a build-it-and-they-will-come deal, then you’d have to tag planetary systems like Sol-Terra as “very likely” to have intelligent life — assuming that natural selection and/or other mechanisms of evolution are universal. On the other hand, if there is no compelling reason that abiogenesis should occur even in the best of circumstances, then there is no compelling reason to believe that there is life of any kind — let alone intelligent life — anywhere else.
That said, I think that if there is intelligent life on earthlike planets, then its intellegence could be similar to human intelligence because basically the same skill sets would be required to adapt to the enviornment. Most of those skills, I think, would center around how to survive among predators. Our intelligence, it seems to me, is a part of our evolutionary adaptation. We used it to do things like escape predators, get food, protect ourselves against natural elements, and so forth. Life on planets like ours would have to do the same.
I think the same thing would hold even in an enviornment where predators don’t exist. If all animals were herbivores, for example, (assuming the planet had a similar or analogous biological model) then there would be no need to escape anyone trying to eat you. There still would be a need, though, to find food. And it’s possible that things could become very competitive in that regard. Intelligence would be a fine thing to help a creature survive and reproduce in such an environment.
But there’s still one more wrench to toss into the gearworks. If evolution is truly random in the sense of having no guiding hand — and there’s no reason to believe otherwise — then intelligence itself is not a necessary result of mechanisms like natural selection. Some other coping skill might work just as well to secure food and shelter as intelligence does. Brute force, for example. Or maybe even some sort of physical maleability. A relatively dumb shape-shifter might be able to adapt just as well as a really smart human.
Native Americans with out tech would have prolly lasted till a fairly complex society arose on the plains and Llamas or some domestic burden animal became available there. That’s about the only time and place it’d make sense to invent the wheel. Smooth ground to roll on and something to pull it. Anywhere else either has too many trees or too many hills and mountains.
Grassland has kind of been a catalyst in our history anyway. Didn’t our ancestors evolve bipedal walking, and tool use as a response to our loss of African forest? Had the ancestral forests remained would we have evolved as far as we did in our current direction? The other great apes of the forest seem to indicate no, but maybe that’s just because we killed off anything that competed with us in our intelligence niche.
But I believe this is backwards. As I said earlier, life on Earth arose in only a few million or tens of millions of years after the formation of liquid water. Life on Earth has existed for 4 billion years, yet we’ve only had multicellular life for 650 million years, genus Homo for two million years, *Homo sapiens sapiens *for 200,000 years, agriculture for 8,000 years, and the steam engine for 300 years.
It seems to me that the scale of time between when an advance shows up compared to how long the advance has existed shows that these advances are not inevitable. Each advance required the previous advance before it could occur, but were not an inevitable consequence of the previous advance.
If we define “intelligent life” on Earth as genus Homo, then life on Earth has existed for 4 billion years while intelligent life has only existed for 2 million. That means we’ve only had intelligent life on Earth for 1/2000th of the existance of life. If we define it as *Homo sapiens sapiens * then we’ve only had intelligent life for 1/20,000th of the existance of life. If we pretend that Earth is a typical planet, then it seems to me that we’d have to find 20,000 planets that could support life before we find one that has a species as intelligent as Homo sapiens sapiens.
Of course, we have no good reason to suppose Earth is typical, so that number is kind of meaningless. But it illustrates that intelligent life is far from typical, even on planet Earth. Life has existed on Earth for unimaginable eons, intelligent life for an eyeblink. If aliens visited Earth at random periods throughout Earth’s history, they’d have only a 1 in 20,000 chance of sampling Earth at a period when intelligent life existed. Those aren’t very good odds.
It did on earth, so we’ve got a single data point that says yes, this “trend” exists. As Lemur866 pointed out, there’s no real reason for multicellular life to evolve in the first place. The fact is that eukaryotic life, let alone multicellular life, appears to be a bizarre symbiont, possibly of multiple organisms. Getting past the bacteria “stage” requires a very specific sequence of steps. Let alone the subsequent formation of complex multicellular life.
Thinking of life in “stages” at all is a very outdated concept. Life doesn’t necessarily go from bacteria to eukaryote to sponge to worm to fish to reptile to bird. It could go in literally an infinite number of alternate pathways, or just stay put–with no selective pressure, why would a successful film of bacteria ever develop a nucleous? It didn’t happen on earth for over 2 billion years. The “niches” you’re talking about are specific to environments and ecosystems made up of other specific forms of life (trees, plankton, whatever). Assuming there would necessarily be a bird niche or an intelligent animal niche, or animal and plant niches at all, is completely unjustified given our current sample size of planets that have plants and animals. Finding intelligence elsewhere in the universe is sort of akin to finding a duck-billed platypus on another planet. Yes, it’s possible that in the vastness of space, that specific animal may have by chance evolved twice. But it’s silly to think it would be common.
And yet that bizarre symbiosis appears to have occurred at least twice independently in the history of evolution on this planet: Once with the mitochondria, and once with the chloroplasts. Something that happened once on Earth may well be a fluke, but when something’s happened twice on our planet, I don’t think it’s unreasonable to expect it to happen on other planets, too. Maybe not on all of them, but probably on a reasonable fraction of them.
Fair enough. Though the chloroplast lineage still hasn’t worked out how to make a spear 
I think the bottom line issues of Time Scale and Distance Scale are very good answers for this sort of thing. We’ve only been technological for a very brief period and here we’re acting like a bunch of teenagers who have just hit puberty and think they’re adults now. (Read: Ok, we’re here! Why won’t anyone take me seriously! I’m an adult now! I know everything! C’mon!)
If they were around, the answer comes down to WHY. Why bother making contact? What is to be gained? They don’t need our resources or our technology. They don’t NEED anything we have. Why bother making contact? Contact just gives away the only really valuable thing - Ideas.
If they were out there, they could gain anything they really need from us simply by observation. Ideas, new ways of doing things, new solutions to old problems. Just watch our TV shows, monitor our media, and they’ll know how we do things.
Because seriously, until we gain FTL travel - and they’d know about it well in advance by monitoring us - we pose no threat, offer nothing of value that they cannot gain without contact.