Evolution and the Conquest of the Galaxy

Peeled Orange

What’s that picture doing up there? Be patient, you’ll see. There being no news to report, we shall use this time to consider the eventual human exploration and occupation of the Milky Way galaxy. In What Are We Learning from SETI? we optimistically estimated that this might occur in as little as one million years. We’ll copy a bit from that earlier post to give you the general idea:

Assume we could travel at, say, around one-third of lightspeed, so that a large shipload of settlers could travel to a nearby star in about a dozen years. … Then assume that stars with habitable planets are, on average, not more than about 5 light years away from each other, so we can gradually expand our domain without encountering any impossible distance barriers. And then assume that each new settlement — if educated and well-equipped — could develop itself sufficiently so that in, say, about three generations (less than a century) it would be able to launch some of its own people to settle the next habitable system.

[…]

If those assumptions are reasonable — and we’ll all be dead before anyone really knows — then the domain of human-occupied space can expand every century at a rate of roughly 5 light years in every direction. That’s a sphere which grows 10 light years in diameter every 100 years. In a thousand years the sphere of human-occupied space will be 100 light years across. …

Multiply our expansion time by 1,000, and conservatively assume no technological improvements over all that time. You get a sphere of human space that’s 100,000 light years across in only a million years. Think about that. The Milky Way galaxy is roughly 100,000 light years across.

Others have made such estimates — often in the range of ten million years — but if we don’t encounter any roadblocks, then however long it takes us it’s going to happen. That’s fine, but what does it mean in terms of evolution?

Here’s where we need that picture of a peeled orange. Imagine that the Earth is at the stem, from which our brave settlers move out in various directions to occupy the habitable planets of nearby stars. Each segment of the orange represents the path taken by different settlers, heading for different stars. In due course, each path will be extended as the original settlers send their descendants ever farther from Earth, and the pattern will continue as their descendants move farther still to expand the domain of human-occupied space.

But each segment will be a separate breeding population, with the occupants of each world rarely traveling to the worlds of adjacent stars, and never going much father than that. After a few extensions of the path in any one direction, the farthest world’s people will never visit the Earth, nor will they visit worlds in other lines of expansion. The distances will be too great. Any mutations that occur will be isolated to a limited population, and will be passed on to other worlds only as each unique path is extended further into the galaxy.

Using the peeled orange as a visual aid, we can refer to each path of expansion as Segment A, Segment B, Segment C, etc. In time, say ten thousand years, because of the founder effect, the people of the most recently-settled part of each segment will have mutated into a unique sub-species — which we’ll call Sapiens 2. In another ten thousand years, their descendants who reach the farthest worlds in that segment will have become Sapiens 3, and so on.

What mutations will there be? That’s impossible to predict, but assuming they’re beneficial, we can imagine that by the time each segment has become Sapiens 3, they’ll have better mental abilities than we do (photographic memories, for example), immunity to our diseases, and perhaps much greater longevity. That’s good stuff, and it’s ridiculous for us to recommend that they take precautions against mutating “too far” away from their parent stock. After all, where would we be if our distant ancestors had followed such advice?

Mutations can also cause incidental changes that are harmless, but that go along for the ride. We see this in dogs selected for hunting, burrowing, etc. Various breeds have floppy ears, curled tails, different muzzles, coloring, etc. It’s therefore predictable that Sapiens 3 in Segment A won’t look like their distant ancestors who pioneered that segment. And they’ll be quite different from Sapiens 3 in Segment B, etc. Each segment will be mutating in its own unique way.

But so what? Even if, by the time each segment gets to Sapiens 3 or Sapiens 4, they’re separate species that could no linger interbreed, what difference does it make? It’s not as if a lonely boy on some world beyond the constellation Taurus is ever going to meet a girl at the opposite end of the human sphere, who lives on a world beyond Scorpio. So who cares if by that time they’re different species?

Human speciation may not matter for most of our expansion throughout the galaxy, but remember — the orange is round and so is the Earth. The original humans who migrated out of Africa, whose descendants followed different routes to Europe and to Asia, didn’t need to worry very much either. But eventually their distant descendants met — in the Western Hemisphere and on various islands of the Pacific. It often wasn’t pleasant, even though they were all still the same species.

What will happen when the descendants of each segment eventually get to the far side of the galaxy (analogous to the other “pole” of the orange)? Sapiens 5 from Segment A will be exploring new worlds, and they’ll encounter Sapiens 5 from Segment B who are doing the same thing. Try to imagine the movie, “Bigfoot meets the Abominable Snowman,” where each has advanced technology. Sooner or later, the same will happen with the descendants of all the other segments.

It won’t be as simple as when Hernán Cortés encountered Montezuma. That was a walk in the park — the Spanish and the Aztecs were the same species. By the time we get to the Far Side, it’s going to be a lot more interesting.

See also: Humanity’s Next Adventure — Trek Three.

Copyright © 2014. The Sensuous Curmudgeon. All rights reserved.

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30 responses to “Evolution and the Conquest of the Galaxy

  1. There are so many excellent hard science fiction books that explore this idea. House of Suns (Alistair Reynolds) is excellent and retains the speed of light limit for millions of years. Also by Reynolds is the Revelation Space series which discusses how colonies interact with a light speed limit.

    One of my favorites is Larry Niven’s “The Legacy of Heorot” which discusses colonization efforts at STL speeds.

  2. I ain’t no skin o’ oranges!

  3. OgreMkV says: “There are so many excellent hard science fiction books that explore this idea.”

    Yup. It’s an old theme in SF.

  4. I guessed wrong. I thought the punch line would be that the only thing the orange had to do with the article was “Orange you glad you read it?”

  5. People need too many resources for long-term space flight. We got it right with Voyager 1 and 2.

    We’ll send robots.

    Although, personally, I’d like to start with the “B Ark.”

  6. We could rename our galaxy “The Citrus Way”
    I think this over estimates willing settlers and underestimates how fast we can go. If we can make 1/3 light speed we could probably do 90% light speed.

  7. @Troy: Milky Way + Orange = Orange Julius.

    And Megalonyx, we are kin to orangs!

  8. Well, that certainly puts a damper on the Aliens movies and Star Trek episodes/movies!

  9. @rsg:I need to get out more–I’ve never heard of Orange Julius. Apparently also a chain of restaurants only around Minneapolis.
    The orange makes perfect sense, at least in Star Trek. An orange has sections, the galaxy has sectors. Galaxy quadrants are easy enough to divide an orange into quadrants as well. Botanically oranges are a Herperidium, which is derived from the golden apples of the Greek gods. The galaxy is made up of many stars which are a bit like golden apples (ok that’s a stretch, I’m brainstorming here!)

  10. Ceteris Paribus

    I had to follow the link to “founder effect” to get up to speed on the subject. The Wikipedia page says: “The founder effect occurs when a small number of migrants that are not genetically representative of the population from which they came establish in a new area.”

    This is cause for great celebration and optimism for the future. The news a few days ago mentions that a small number, 534, of US citizens have migrated to Washington DC to take up seats in Congress. Of that number no less than 268 [50.2%] have an average net worth of at least $1 million.

    First time ever that millionaires make up the majority of Congress. And certainly not genetically representative of the US popluation. If the founder effect works as advertised, in just a few generations we might expect to see on this continent a new nation populated entirely by millionaire citizens.

  11. Ceteris Paribus prognosticates, “If the founder effect works as advertised, in just a few generations we might expect to see on this continent a new nation populated entirely by millionaire citizens.”

    Yes — and it will be due to inflation. Might also be the reason for all the millionaires in congress.

  12. To be just a tad more scientific, the space travel scenario should include the effects of relativistic time dilation, where time for the moving traveler runs more slowly than for someone left back home. Over a long time period, this could warp the path of evolution astronomically (pun intended).

    We can apply the theory of evolution to space traveling humans as well, the presumption being that environmental pressures guide the direction of evolution no matter where we go, on Earth or beyond.

    Even if people all started from a single common origin fanning out across the stars, when their descendants got together for a drink millions of years later, it would probably resemble a Star Wars movie bar scene.

    Most likely, the different evolutionary pressures would have caused them to evolve in different directions as well and there would no longer be much resemblance to the common progenitor species from which they all derived and no longer any genetic compatibility either. They would probably become like space aliens relative to each other after such a long divergence.

    I made a simple program to perform some computations. All the following computations are real and based on general relativity theory. It takes into account actual acceleration and deceleration during the trip.

    It works something like this:

    Imagine traveling to the Andromeda galaxy at about 2,500,000 light years distance from Earth. We accelerate a 1G until we reach the halfway point and then reverse thrust and decelerate at the same rate until we reach our destination. Then we turn around and come back in similar manner.

    If we could actually travel in such a way that the people on the ship experienced the effect of gravity similar to that on Earth (1G), due to the ship accelerating, then they could reach Andromeda in about 28.6 years, according to a clock on the spacecraft.

    Returning to Earth the same way would take another 28.6 years of travel time. In other words, simply traveling to and from the Andromeda galaxy would take about 57.2 years of round-trip travel time according to the space traveler’s clock, but from an Earth-based perspective, the round-trip would have taken some 5 million years.

    Imagine a 10-year-old boy leaving on such a trip today and returning 5 million years in the future. When he returned he would be about 67-years-old, while the entire world and people he knew before would be long since passed away and all but forgotten. Imagine how much human evolution would have advanced during his 5 million year absence (57 years from his reckoning) and how different from other people he would look. Consider how we look when compared to people of only 150,000 years ago, much less, 5 million years.

    Of course, we don’t yet have the kind of technology to build such a spacecraft, but we do have the knowledge to compute very closely what the time-experience would be like.

    🙂

    To the moon, Alice!

  13. what is interesting is that the subject of human-directed evolution, or deliberate human shaping of the genome, is not being considered. Frankly, my guess is that as time goes on, deliberate modification of the genome will become the dominant factor in the genetic future of our descendants.

  14. Jay says: “To be just a tad more scientific, the space travel scenario should include the effects of relativistic time dilation, where time for the moving traveler runs more slowly than for someone left back home.”

    Time dilation is always on my mind. But traveling at only one-third of lightspeed, the effect is trivial. It doesn’t become noticeable until you’re traveling at least 50% of lightspeed, and even then you’ll be aging around 92% as much as your twin brother back home — whom you’ll never see again anyway. It’s not until you get up to 85% of lightspeed that time dilation means you’re aging only 50% as much as folks back on Earth, and your mass has doubled, etc.

  15. SC: “…and your mass has doubled…”

    Aye, and there’s the rub. The increasing mass as you approach light speed makes it increasingly difficult to maintain a rate of acceleration. Taken to the extreme, you would need an infinite amount of energy to attain the speed of light.

    Off-topic, but are any other readers here old enough to catch the reference at the end of Jay’s comment — “To the moon, Alice!” ?

    Ralph Cramden (Jackie Gleason) to his wife Alice in “The Honeymooners” skits as he swings his arm wildly in an upper-cut motion. TV would never use that kind of threat of spousal abuse in a comedy skit today.

  16. Ahh, a trip down politically-incorrect Memory Lane!

    My (aged) recollection has it as, “One of these days, Alice! Pow! Zoom! To the moon!”

  17. It may be severely doubted whether biological humans will ever be transported across interstellar space. By the time we have ships that can go to the stars in reasonable time, it seems we will also have fully realized artificial intelligence. (The EU-sponsored Human Brain project expects to have mapped out the neurons of the human brain around 2023, replicating their workings in a computer.)

    If you believe there is some kind of magical, transcendent, God-given “soul” that cannot be replicated by machine intelligence, truly conscious computers may be impossible. But I suspect most people reading this blog don’t subscribe to such ideas.

    So it will be robots that go to the stars, I guess. Realy no point in bringing along fragile, impermanent biological bodies which need many times their own weight in life support systems.

  18. What about the idea of transmitting by radio the instructions to form our robots? I realize that there is a major barrier to having the instructions carried out at interstellar distances, but let’s just assume that somebody figures out how to do that. Or who knows, maybe some extraterrestrial intelligence has set things up for our convenience? (Maybe if we asked really politely, the aliens would help us out?)

  19. Although not directly germane to the OP topic, the logical inference from this expansionist line of reasoning is – if this scenario is reasonable, why have we not had other star-colonizing civilizations cluttering up our planet over the last billion years or so. This is the Fermi Paradox.

  20. @air: We (meaning intelligent life) may actually be very rare, if not unique. Not because the Grand Ol’ Designer made earth the privileged planet, but just by random chance circumstance.

    It took at least 4 billion years, or close to it, for technologically-capable intelligence to evolve on earth once life got started. That’s a very long time for conditions to remain as stable as they have been on our planet. Many factors came together to make it so:

    1) The right-sized star, capable of lasting 5+ billion years.
    2) A large-enough moon to stabilize our rotational axis.
    3) A not-too-crowded place in the galaxy so that the orbits of the sun’s planets (including ours) have not been perturbed by passing stars.
    4) A galaxy that hasn’t been in a recent collision with another galaxy.
    5) Not being too close to a supernova.
    6) Being the right distance from our star.
    7) Perhaps most importantly, living on a planet where conditions are not perfect. Think about it. Dolphins probably rival us in intelligence, but they have no technology. Why? they have no hands to manipulate their surroundings. Why don’t they have hands? They don’t need them. They can get everything they need to survive without having to use hands. They catch their food in their mouths, they have built-in sonar to find their food, the oceans are a stable environment — everything is perfect.
    8) Our skies are clear enough to see that there are other worlds out there to go to. Might not be the case everywhere out there. Would we have developed aerospace technology if our skies were perpetually cloudy?

    It’s also been said that we may be the first civilization in our galaxy to get as far as we have. Someone’s got to be first. Or maybe there are others out there, but they just haven’t reached us yet. They could be as close as 4 light years away (or closer if in a self-contained craft) and we’d never know it if they didn’t send out radio signals.

  21. retiredsciguy:8) Our skies are clear enough to see that there are other worlds out there to go to. Might not be the case everywhere out there. Would we have developed aerospace technology if our skies were perpetually cloudy?
    Without astronomy, what science would we have developed?

  22. @retiredsciguy – your argument is a qualitative version of the Drake equation, which has been batted about for years. Since the most recent estimate from the Kepler project is that there are some 8.8 billion Earthlike planets in the Milky Way, I’m skeptical that we are unique.

    Iain M. Banks has written science fiction set on a world in extragalactic space – Against a Dark Background; a really good read.

  23. @air: Sorry if I gave the impression that any of what I wrote above is my original thinking (except maybe the part about clear skies being necessary for the development of aerospace technology. I just don’t remember reading that anywhere.).

    At any rate, almost all the ideas in my head have gotten there via reading what others have written. A few have come by personal observation, but very few of my personal observations have not already been observed and written about by someone else. Like everyone else, I then mix ‘n match ideas to synthesize something new. It’s not really an original thought; just something stated in a new way.

    The points I laid out were an attempt to answer your original question — ” if this scenario [existence of expansionist civilizations] is reasonable, why have we not had other star-colonizing civilizations cluttering up our planet over the last billion years or so.”

    I, too, doubt that we are unique, for the same reason you state. Multiply 8.8 billion in our galaxy times the number of galaxies within our visible portion of the universe (perhaps 400 billion galaxies? Who knows? What we do know is that there are A LOT of galaxies!), and we come up with about 3.5 x 10^21 earth-like planets.

    Certainly, with that many possibilities one would think there are at least a few other places that have enjoyed stable conditions for as long a time as earth has. Still, although I doubt that we are unique, I don't think intelligent life is at all common.

  24. TomS asks, “Without astronomy, what science would we have developed?”

    Boy, that’s a good question! Very thought-provoking. Biology, probably. We probably would not have attempted sailing the oceans since navigation would be difficult. I have to do other things right now (like eating), so I’ll leave it to others.

  25. retiredsciguy says: “Still, although I doubt that we are unique, I don’t think intelligent life is at all common.”

    It could be common, but I think the big problem is developing a technological society. That requires so many factors to be present. We’ve had an intelligent species on Earth (ourselves) for a long time. But it’s only in the last 200 years or so that we’ve begun to be seriously technological. The galaxy could be swarming with intelligence that never gets beyond the level of ancient Egypt or the Roman empire. Intelligent? Yes. Detectable by SETI? Not at all.

  26. SC observes, “But it’s only in the last 200 years or so that we’ve begun to be seriously technological. The galaxy could be swarming with intelligence that never gets beyond the level of ancient Egypt or the Roman empire. Intelligent? Yes. Detectable by SETI? Not at all.”

    And the $64 question is, “What was the trigger?” What would appear to be a huge leap with few intermediate steps was the development of radio at the beginning of the 20th Century. Of course, that’s the step necessary for SETI detection.

  27. retiredsciguy says:

    And the $64 question is, “What was the trigger?” What would appear to be a huge leap with few intermediate steps was the development of radio at the beginning of the 20th Century.

    A whole lot of things. You need the discovery and development of electricity. That requires inventors with the leisure and means to do that kind of thing. You need a patent system to encourage inventors. That requires a society with a keen understanding of and protection for private property. It requires an economic system that encourages development and manufacturing. It requires a fairly sophisticated monetary and banking system. A hundred different factors need to be in place before a society starts broadcasting radio signals.

  28. And when you want to compress the maximum amount of information into a carrier, you end up with a signal that is indistinguishable from noise. How can we expect to recognize a signal when we see it? Especially given that we’re talking about a completely different species, more distantly related to us than are dandelions. It’s hard enough to figure out paleolithic art.

  29. @retiredsciguy
    I didn’t mean to accuse you of plagiarism :). I just wanted to give some additional sources for thinking about the concepts you advanced. I will say that if our technological and expansionist form of life is a unique product of Earth, then you are right.

    However, I think we both agree that given the incredible number of potential homes for ‘Earthlike’ life (and an unknown number of additional sites for whatever else can evolve), we are not unique. My original point was that as soon as that lack of uniqueness is acknowledged, the question immediately becomes ‘then why aren’t they here?’ given a billion years or so to arrive.

    If they are not here than either a) we are the first b) an expansionist model as proposed doesn’t work for some insurmountable reason which prevents others from reaching us or c) something else (Zoo/Matrix models, maybe there’s someplace more interesting to go, whatever).