Our Place in the Universe

universe

 

What are the odds that humankind will survive long enough to colonize the Universe?

Katja Grace argues that the odds are low. Stripped of some nuance, her argument comes down to this:

  1. The fact that we’re around suggests that intelligent life is likely to be common.
  2. No other intelligent life appears to have colonized the Universe.
  3. If they haven’t succeeded, why should we?

By coincidence number one, I discovered Katja’s post (via a ringing endorsement from Robin Hanson) just hours after I’d posted yesterday’s entry here on The Big Questions disputing point 1). Of course, if point 1) fails then so does the entire argument.

So in response to Katja’s and Robin’s posts, I think it’s worth quoting a book review from the astrobiologist Charley Lineweaver, who I also quoted yesterday. Here is Lineweaver commenting on the “convergentist hypothesis”—that is, the hypothesis that evolution tends to converge on something like human intelligence:

[The convergentist hypothesis] is an appealing idea, but it has failed a series of exhaustive tests. It disagrees with the best data we have. A series of long-duration, independent and thorough experiments in evolution were set up and left to run. The most straightforward interpretation of the results is that human-like intelligence is not a convergent feature of evolution. There is no “intelligence niche” toward which animal species have a penchant to approach. In the absence of humans, other species do not converge on human-like intelligence as a generic solution, or even a specific solution to life’s challenges. These tests have been universally ignored.

The names of these tests are South America, Australia, North America, Madagascar, and India…For landlocked species, these continents that drifted independently of each other for between 50 and 200 million years were crucial experiments for evolution.

The time scale for tripling the size of the human brain in Africa was about 2-3 million years, while the time scale of the experiments was 50-200 million years. Thus, the experimenters were conservative and ran the tests 10-100 times longer than was necessary.

Five continents and millions of species evolving over tens or hundreds of millions of years are yelling at us upwind against our vanity: “…Human intelligence is not a convergent feature of evolution.” Rather, it is a species-specific trait—like the beautiful yellow crest of a sulfur-crested cockatoo.

Now, by coincidence number two, I happen to have had lunch with Robin Hanson yesterday, and I ran this argument by him. Robin is unimpressed. He doubts that five experiments are enough to tell us very much about what might happen on 1022 planets. In Robin’s words, “all this shows us is that the likelihood of evolving intelligence is less than about one in six”. He’s willing to take those odds.

I am sympathetic to Lineweaver’s view that we should no more expect to find extraterrestrial intelligence than extraterrestrial basketball. I am extremely sympathetic to his view that after six experiments, we essentially know for sure that evolution has no tendency to produce intelligence consistently. But I’m also sympathetic to Robin’s view that in the vastness of the Universe, six experiments can’t tell us much about what we might find. What else am I missing?

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22 Responses to “Our Place in the Universe”


  1. 1 1 Fenn

    I’d also factor in the likelihood of panspermia (http://en.wikipedia.org/wiki/Panspermia) something Hanson believes confirmed. http://www.overcomingbias.com/2009/11/pamspermia-confirmed.html

  2. 2 2 Bennett Haselton

    I would disagree with point 1:

    “1.The fact that we’re around suggests that intelligent life is likely to be common.”

    According to the anthropic principle, even if you could somehow determine that the odds of intelligent life evolving on a given planet, were 1 in 10^10, it would *still* not be an impressive coincidence that we happen to find ourselves on a planet with intelligent life, because if we hadn’t been born on a planet with intelligent life, we wouldn’t be here thinking about it.

    And then you have the multi-universe version (related in detail by Richard Dawkins in _The God Delusion_): Suppose you calculate the odds of intelligent life on a given planet to be 1 in 10^30. Is it then an impressive coincidence that life evolved on at least one of a group of only 10^22 planets in our universe? No, because there could be many universes, and by necessity, we had to find ourselves in one of the universes where intelligent life did evolve, however small a minority that might be.

    Here’s an interesting twist that I haven’t seen spelled out before as part of this argument. Suppose you had extremely reliable calculations showing that the odds of intelligent life evolving on a given planet, were 1 in 10^30. If ours were the only universe, it really would be too much of a coincidence to find ourselves here — so the calculation would actually prove, to an extremely high probability, that there must be *other universes*. That’s rather eerie — to be able to prove, using nothing more than math and science, that other universes do exist, even if completely inaccessible from this one.

    (Those other universes could still be predecessors or successors to ours — for example, if our universe is part of an endless sequence of universes that each explode in a Big Bang, expand, start to contract again, and collapse into a Big Crunch, and then explode in a new Big Bang to birth the next universe — that would still be enough to satisfy the many-universes requirement above. But the other universes would have to exist *somewhere*. The argument would prove that time can’t simply begin at the Big Bang and end at the Big Crunch, with nothing before or after and no other universes to be found anywhere else.)

  3. 3 3 Max Marty

    Darn it Haselton, you beat me to that one!

    I’m somewhat surprised that you didn’t mention that this argument sounds a lot like Fermi’s paradox, particularly point 2. As such, I think Seth Shostak from the SETI institute wrote up a good summary of some of the responses to point 2 in a series of 3 articles on the paradox. As I’d summarize it, it could be that:

    1) They ARE there, we just don’t see them. We’re not technologically advanced enough to notice them yet.

    2) They ARE there, but they’ve decided to keep us in a sort of “human zoo”. A no-fly-zone of sorts.

    3) Related to idea 2, we’re actually sitting on a giant space petri-dish, being carefully studied while being left to not contaminate the experiment.

    Here is a good link, his articles are towards the top of the page http://www.ufoevidence.org/topics/fermi.htm

  4. 4 4 Snorri Godhi

    The quoted passage troubles me. Here is my understanding of it:

    [1] human intelligence has appeared a few million years ago in Africa;
    [2] before then, no other species on Earth developed human-level intelligence, in spite of hundreds of millions of years of evolution;
    [3] in 5 other continents, human-level intelligence did not develop.

    And from this, Lineweaver concludes that the probability of human-level intelligence developing is … much less than 1/6 ??

    Also note that he did not pick a random point in time: if he had looked at Earth 5 million years ago, he might have concluded that human-level intelligence never evolves — and he would have had 6 independent experiments to prove it!

    Also, does he actually name people who subscribe to the “convergentist hypothesis” or is he setting up a strawman?

  5. 5 5 Ross Parker

    Don’t worry about those people on the shore, Columbus. They can’t really exist, or they would have sent boats to us first.

  6. 6 6 Bennett Haselton

    It reminds me of a thought that popped into my head when I was about 10: Will humans ever invent time travel? Impossible, because if someone in the future invented time travel, then by now someone would have come back in time to tell us about it!

    Unless, of course, we’re in a case of Marty’s point 2 above: Time travelers are observing us, but invisibly. (This is plausibly if they want to avoid creating paradoxes.)

    Or, maybe, before time travel is invented for the first time, we have to travel forward on a normal timeline to arrive at the point when time travel is invented. Then, when it’s invented and a time traveler goes back in time, either (a) he’ll travel to a parallel world separate from ours, where earlier humans are fascinated to meet a time traveler, or (b) the events we’re living now will simply “unravel” as the traveler goes back in time, and time will re-weave itself with a different version of events. Either interpretation could allow time travel to be invented at some point in the future, without us being aware of it.

  7. 7 7 Harold

    Or possibly you can only travel back in the time machine to the point where it was created. It hasn’t been invented yet, so no time travellers

  8. 8 8 Noah Yetter

    Point #2 is highly unconvincing. Our ability to observe the distant universe is extremely limited, and looks far back in time. There is no reason to believe that if intelligent life was common in the universe that we would be able to observe that fact.

  9. 9 9 Harold

    Perhaps we could say it hasn’t been seen to colonise our bit of the universe.

  10. 10 10 Harold

    This is very similar to the “simulated universe” I mentioned in another post. Basically, if it postulates that given the increasing pace of computer technology, ore descendents will one day be able to run a detailed computer simulation of their ancestors, in which the simulatees are not aware of their status. If it is possible, then it is highly unlikely that we are in the one real universe, among countless simulated ones. We are probably in a simulation within a simulation! The only way for us to be “real” is for it not to be possible to achieve, or possibly for no-one ever to want to run such a simulation. Nick Bostrom puts it fully here (even with some math in it!):
    http://www.simulation-argument.com/simulation.html

  11. 11 11 Bob

    Steve: I’m on the run, so briefly: This is precisely why some people hope that we won’t find primitive life in our solar system, see “The Great Filter.”

    I enjoyed that last Lineweaver paragraph. We try to deny that our species is special (so to speak), and we end up glorifying a species-specific trait. Vanitas vanitatum. Subtle is the Devil. :-)

    Bennett: So some will choose to believe in completely inaccessible other universes, and some will choose to believe in the ancient unfalsifiable “God” hypothesis. Po-tae-to, po-tah-to.

  12. 12 12 mcp

    Bennett explained exactly why premise 1 is ridiculous.

    How has the sleeping beauty problem not been mentioned?

    From Wikipedia:

    The paradox imagines that Sleeping Beauty volunteers to undergo the following experiment. On Sunday she is given a drug that sends her to sleep. A fair coin is then tossed just once in the course of the experiment to determine which experimental procedure is undertaken. If the coin comes up heads, Beauty is awakened and interviewed on Monday, and then the experiment ends. If the coin comes up tails, she is awakened and interviewed on Monday, given a second dose of the sleeping drug, and awakened and interviewed again on Tuesday. The experiment then ends on Tuesday, without flipping the coin again. The sleeping drug induces a mild amnesia, so that she cannot remember any previous awakenings during the course of the experiment (if any). During the experiment, she has no access to anything that would give a clue as to the day of the week. However, she knows all the details of the experiment.

    Each interview consists of one question, “What is your credence now for the proposition that our coin landed heads?”

    The answer of course is 1/3.

  13. 13 13 Biopolitical

    Convergence is the evolution of similar traits under similar environmental conditions. For example, fish, marine mammals, diving birds and many invertebrates have independently evolved similar body shapes; and flying insects, birds and bats have all evolved wings. I wouldn’t say that animals have a “penchant” for fins or for wings. But it seems that under certain conditions fins and wings evolve more easily than, say, jet propellers.

    Under certain environmental conditions (for example, when resources are highly clumped in space) different lineages have independently evolved sociality. There are other “solutions” to clumped resource distributions but it seems that living in groups is one that evolves quite easily.

    Increased intelligence has repeatedly evolved among social animals. Examples are elephants, crows, parrots, dolphins and primates. When living in groups, individual organisms that are able to play relatively complex strategic games often have an advantage in mating. Intelligence is a common “solution” to the problem of reproduction when living in groups.

    So, it seems that when you have certain environmental circumstances sociality and intelligence evolve relatively easily. Judging from what has happened on Earth we can imagine that some planets have organisms with fins, some have organisms with wings and some have organisms with intelligence. How large the fins, the wings and the intelligence is harder to say.

  14. 14 14 Steve Landsburg

    Biopolitical:

    I wouldn’t say that animals have a “penchant” for fins or for wings. But it seems that under certain conditions fins and wings evolve more easily than, say, jet propellers.

    I don’t think we can say this (at least not without referring to something other than biological history). Insects, birds and bats all evolved wings rather than jet propellers, but
    insects, birds and bats all started with an enormous shared genetic heritage. All we know is that animals with that particular heritage evolve fins and wings more easily than, say, jet propellers. Without more argument, this tells us nothing about what animals with a different genetic heritage might develop.

    Ditto, of course, for intelligence.

  15. 15 15 Biopolitical

    You first argued that animal evolution on Earth lacked a “penchant” for intelligence and that knowing this fact made intelligence in other planets less plausible. Now you say that animal evolution on Earth does have an idiosyncratic “penchant” for fins, wings and intelligence as opposed to some other potential solutions to the challenges of moving through water and air, and of social life. And finally you argue that knowing this fact tells us nothing about intelligence in other planets.

  16. 16 16 Steve Landsburg

    Biopolitical: You might (or might not) have been reading this post without first reading my “Are We Alone” post from the previous day, which dealt with this issue more specifically. The multiple (intertwined) arguments are that

    a) Evolution shows no “penchant” for developing animals, let alone animal-like intelligence.

    b) Terrestrial animals seem to show a penchant for bigger brains, but this tells us very little, because all terrestrial animals are relatively slight variations of a single common ancestor.

    c) Even among terrestrial animals with a penchant for bigger brains, there is no apparent penchant for human-like intelligence.

  17. 17 17 Biopolitical

    Lineweaver writes:

    “In the absence of humans, other species do not converge on human-like intelligence as a generic solution, or even a specific solution to life’s challenges.”

    Replace humans with dolphins or crows or parrots or elephants, and the sentence is equally true (or wrong). For example:

    “In the absence of dolphins, other species do not converge on dolphin-like intelligence as a generic solution, or even a specific solution to life’s challenges.”

    Replace intelligence with wings:

    “In the absence of bats, other species do not converge on bat-like wings as a generic solution, or even a specific solution to life’s challenges.”

    Humans are more intelligent than dolphins. Bats are more wingy than flying squirrels. Intelligence has increased in several lineages as a response to the challenges of social life (itself being a response to resource clumpiness or whatever). Winginess has increased in several lineages as a response to the challenges of flying life.

    Do these facts tell us anything about intelligence and winginess in other planets? Yes or not? If not, does life on Earth tell us anything at all about life in other planets?

  18. 18 18 Ryan M

    While sitting on one planet in one solar system in one galaxy we haven’t seen any signs of inter-planetary colonization. We can therefore assume that, in a theoretically infinite universe, there have been no successful attempts at inter-planetary colonization.

    Point #2 sounds rock solid to me.

  19. 19 19 Robert Wiblin

    Maybe the SIA principle used by Katja also shows the many worlds interpretation of quantum physics is probably correct: http://robertwiblin.wordpress.com/2010/03/26/news-flash-multiverse-theory-proven-right/

  20. 20 20 Al V.

    The universe is a very big place. It is quite plausible (perhaps likely) that there is intelligent life out there, but so far away that we can’t detect it. It could be millions or even billions of light years away. For that matter, what percentage of our own galaxy can we see? If there is intelligent life on the other side of our galaxy, directly across the galactic center, our “line of sight” is blocked by the center. How much of the universe can we reasonably think we’re scanning? one billionth of one percent?

  21. 21 21 Zach

    I think you’re looking at the wrong part of Katja Grace’s (paraphrased) argument: “The fact that we’re around suggests that intelligent life is likely to be common.” This isn’t really key.

    “If they haven’t succeeded, why should we?” This, I think, is the real root of an answer to “Will we reach the stars or not?”

    It doesn’t matter whether there is only 1 species in the universe capable of doing math or one around every star if there isn’t a method to transfer between stars in a reasonable amount of time. The real question is if it’s possible to travel the breadth of the universe in less than the time it will be in existence?

    Colonizing the universe is a somewhat meaningless question, it’s neither a necessary nor sufficient condition for the existence of other intelligent life. And the universe is so vast, there are so many stars, that occupying even a significant fraction of the inevitable planets seems implausible. Even given instantaneous transportation and infinite physical resources, how long would it take us to to generate a large enough population to put representatives on planets around 10^22 stars, or even a sparse sample like 10^10?

    I think a far more interesting question would be “Will we ever explore our galaxy,” or “Will our species outlive our sun?” But these are much harder to answer, I think, than “Will we be able to populate infinity.”

  22. 22 22 Leo Shine

    Maybe the reason why intelligence didn’t evolve on the other continents wasn’t just because of need for intelligence in those areas but more because the evolution of intelligence is rare enough that the chance that two intelligent species evolving separately on these different continents within a timeframe which meant that one did not colonize the other continent taking the niche for intelligence in that area. This explanation does not conflict with the convergentist view of intelligence.

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