Does evolution have a purpose?


That was easy. Guess I’ll just have another cup of tea, sit back, and put my feet up…

Oh, wait. Robert Wright wants to argue otherwise, badly. Guess I’ll gnaw on him for a bit, as long as I’m lacking in biscuits to go with my tea.

Here’s what got him going: he did an interview with William Hamilton, in which Wright asked him if there could be some kind of transcendental purpose to our existence.

He answered: “Yes, yes. There’s one theory of the universe that I rather like — I accept it in an almost joking spirit — and that is that Planet Earth in our solar system is a kind of zoo for extraterrestrial beings who dwell out there somewhere. And this is the best, the most interesting experiment they could set up: to set up the evolution on Planet Earth going in such a way that it would produce these really interesting characters — humans who go around doing things — and they watch their experiment, interfering hardly at all so that almost everything we do comes out according to the laws of nature. But every now and then they see something which doesn’t look quite right — this zoo is going to kill itself off if they let you do this or that.” So, he continued, these extraterrestrials “insert a finger and just change some little thing. And maybe those are the miracles which the religious people like to so emphasize.” He reiterated: “I put it forward in an almost joking spirit. But I think it’s a kind of hypothesis that’s very, very hard to dismiss.”

This gets Wright very excited. It shouldn’t.

This argument no more favors an overall purpose to evolution than the increasing milk yields of dairy cows under domestication, or that the changes in average beak size of finch populations track climate changes. Some aspects of evolution are non-random and responsive to external forces; apply a pressure, and the population will conform. This is not surprising.

Hamilton was making some fanciful speculation that if aliens existed, and if they meddled with life on Earth, then they could be a selective force that imposes a direction on life’s history. That’s it. He is correct. But notice the ifs — he’s also saying he has no evidence for such a phenomenon, and is speaking purely hypothetically.

So yes, if aliens, fairies, gods, or mole people at the center of the earth existed, and if they interacted with humans, they would represent an environmental influence which might affect human history. OK? OK. We’re done. This is compatible with evolutionary theory, it just lacks any reasonable evidence, and is simply yet another possible contingent detail.

This is stupid. Back to my tea.

Wait, oh no, he keeps babbling. Now he claims this refutes a bunch of myths scientists hold.

Myth number one: To say that there’s in some sense a “higher purpose” means there are “spooky forces” at work.

When I ask scientifically minded people if they think life on earth may have some larger purpose, they typically say no. If I ask them to explain their view, it often turns out that they think that answering yes would mean departing from a scientific worldview — embracing the possibility of supernatural beings or, at the very least, of immaterial factors that lie beyond scientific measurement. But Hamilton’s thought experiment shows that this isn’t necessarily so.

Define “spooky forces”. Like Hamilton, I’d say that you can get directional selection if you have an agency or force imposed on a population. So? It’s not the scientists claiming that there are “spooky forces”, it’s merely Wright trying to create a straw man as an alternative to his vague, unevidenced “higher purpose”.

Myth number two: To say that evolution has a purpose is to say that it is driven by something other than natural selection.

The correction of this misconception is in some ways just a corollary of the correction of the first misconception, but it’s worth spelling out: Evolution can have a purpose even if it is a wholly mechanical, material process — that is, even if its sole engine is natural selection. After all, clocks have purposes — to keep time, a purpose imparted by clockmakers — and they’re wholly mechanical. Of course, to suggest that evolution involves the unfolding of some purpose is to suggest that evolution has in some sense been heading somewhere — namely, toward the realization of its purpose.

It’s really hard to drink my tea when my jaw is hanging open like this.

Wright got an interview with William Hamilton 25 years ago; he has to be able to talk with other evolutionary scientists now and then. Does he realize how dumbfounded most would be at this ridiculous claim that evolution’s sole engine is natural selection?

Maybe he talks to scientists, but he doesn’t listen.

Also, so far all he has proposed as an engine of higher purpose is selection — artificial selection is still selection. It’s rather ironic that he is so unaware of the content of his own “theory” that he’s suggesting that if others were aware of other forces than selection, they’d accept his idea about selection.

Myth number three: Evolution couldn’t have a purpose, because it doesn’t have a direction.

The idea that evolution is fundamentally directionless is widespread, in part because one great popularizer of evolution, Stephen Jay Gould, worked hard to leave that impression. As I and others have argued, Gould was at best misleading on this point. And, anyway, even Gould admitted that, yes, on balance evolution tends to create beings of greater and greater complexity. A number of evolutionary biologists would go further and say that evolution was likely, given long enough, to create animals as intelligent as us.

Speaking of misleading…Gould argued that increasing complexity would emerge out of evolutionary history because evolutionary trajectories, even if purely random, would tend to drift away from minimal functional complexity. He used the analogy of a drunkard’s walk. Imagine a drunkard stumbling along a sidewalk; to the left is the impenetrable wall of the tavern, while to the right is the gutter and the open street. He’s going to bump off the wall and go no further in that direction, but he can freely stagger rightwards, so his overall movement will tend towards the gutter.

He’s right. He’s also not arguing for a force, “spooky” or otherwise, pushing populations in a specific direction towards greater complexity. I rather dislike seeing Wright misrepresent Gould’s views to twist them into supporting Wright’s half-assed argument.

Wright triumphantly concludes:

With these three myths dispelled, you’re left with this philosophically liberating upshot: You can entertain the possibility that evolution has a purpose, a kind of goal (a “telos,” as philosophers say), without departing from a strictly Darwinian view of evolution — without abandoning belief in natural selection as evolution’s only engine, and without surrendering your credentials as a modern, scientifically minded kind of person.

Modern, scientifically-minded people all abandoned the belief that natural selection was evolution’s only engine back in the 1930s, guy. Do you also put on a zoot suit and claim that you’re wearing clothing from the future?

He also hasn’t dispelled any myths, but only exposed his own weird, confused assumptions about evolution.

Now, my tea is getting cold…GODDAMNIT, HE JUST KEEPS ON PRATTLING.

Myth number four: If evolution has a purpose, the purpose must have been imbued by an intelligent being.

Shit. His justification now is that nonsense from Nick Bostrom and Elon Musk that the universe is a simulation, which he somehow thinks is compatible with the idea that the universe wasn’t created by intelligent beings? What the fuck? I’m out. This is too scatter-brained and vacuous to cope with further.

And this got published in the New York Times? Jesus. Don’t they at least have word limits on their opinion pieces?


  1. ajbjasus says

    Hamilton’s fanciful “what if” conjecture” brings to mind Slartibartfast and Franky and Benjy.

    Good old Douglas Adams

  2. says

    If the purpose is that humanity is a joke played upon the universe, then sure, maybe it has a purpose.

    “Look at them destroying each other and their only possible home, and they think they’re the pinnacle of evolution and/or creation! HAAHAHAHAHAAHAHA!!!”

  3. slithey tove (twas brillig (stevem)) says

    [slight spur track] does he not understand how “cluster’ occur in large stochastic distributions? like pour a large quantity of variously colored marbles onto the floor. Let them settle, now observe the distribution of the colors. Notice the clump of a single color in that part of the room? It it then reasonable to assume that there was some mysterious agency forcing thos marbles of that color to clump in such a region?
    is the simile getting across? of all the possible results of evolutions natural selection process, is it really so unexpected that one possible result is a very adaptable, educable brain? Occam’s Razor says an agent to direct such a result is one factor more than reasonable, so no need to even consider it as plausible.

  4. handsomemrtoad says

    RE: “There’s one theory of the universe that I rather like — I accept it in an almost joking spirit — and that is that Planet Earth in our solar system is a kind of zoo for extraterrestrial beings who dwell out there somewhere. And this is the best, the most interesting experiment they could set up: to set up the evolution on Planet Earth going in such a way that it would produce these really interesting characters — humans who go around doing things — and they watch their experiment, interfering hardly at all so that almost everything we do comes out according to the laws of nature.”

    This theory is nicely explored in The Dosadi Experiment by Frank Herbert (who also wrote Dune).

  5. a_ray_in_dilbert_space says

    You could view evolution as having a “purpose”–namely as a mechanism whereby the next generation has as high or a higher proportion of individuals suited to the environment in which they live as the current generation–or at least a “sufficiently high” proportion that there will be a generation beyond that. If there were an “intelligence” directing evolution:
    1) It could muck things up, making the species less likely to survive in its environment
    2) It could have no effect
    3) It could speed things along

    There are many more ways to do 1) than 2) and 3). And humans need no help when it comes to speeding toward extinction.

  6. monad says

    To say there’s some “higher purpose” doesn’t mean there is anything “spooky” happening! It could actually be caused by unknown and hidden extraterrestrials keeping humanity as some kind of experiment and then manipulating us for their own secret purposes. What could possibly be less spooky than that?

    Also, I guess this higher purpose would be to entertain? Made-up aliens could prefer anything from proteobacteria to pines. But if they have tastes at all like people, I guess that means the purpose of evolution has best been served by cats that do hilarious things. I hope humans can come to terms with our supporting role.

  7. screechymonkey says

    Bob Wright is a frustrating guy. His Bloggingheads site has managed to stick around for long time, and I still listen to the occasional discussion even though I generally prefer written discussions to video or audio. (Though he’s had some missteps there, too, such as the time Bloggingheads had a “Science Saturday” discussion that gave an uncritical platform to a creationist.)

    I also think he’s a decent writer and I enjoyed some of his books, though I wonder if I’d feel the same way now that I know a little more about the shaky foundations of evolutionary psychology on which he leans so heavily.

    But he certainly has a bee in his bonnet about this higher purpose thing: he clearly wants to believe in some form of deity without stepping into all the baggage of existing religions — in fact, I seem to recall a discussion where he admitted as much.

    At times it seems like he’s bucking for a Templeton Prize, with statements like this one from the linked article:

    When an argument for higher purpose is put this way — that is, when it doesn’t involve the phrase “higher purpose” and, further, is cast more as a technological scenario than a metaphysical one — it is considered intellectually respectable. I don’t mean there aren’t plenty of people who dismiss it. I’m talking about how people dismiss it. The Bostrom paper drew flack, but a lot of it was from people who thought the chances that we’re living in a simulation are way less than 50 percent, not from people who thought the idea was wholly crazy.

    If you walked up to the same people who gave Bostrom a respectful hearing and told them there is a transcendent God, many would dismiss the idea out of hand.

    Wright thinks he’s found some “irony” here, by which I think he really means “hypocrisy.” But I think there’s a sound, principled reason why many scientists would react differently to the two claims. When you start using the word “God,” you are either intentionally smuggling in a whole ton of unstated assumptions, beliefs, and cultural baggage, or giving others the opportunity to do so. Consider all the discussion about Einstein’s “God does not play dice” comment; if he had simply said “the universe does not play dice,” it probably wouldn’t even be remembered as a quotation.

    It’s as if Wright were to note the “irony” that when I tell zoologists that I think there may be species on earth that we have yet to document, they consider it a respectable hypothesis. But when I tell them that I think Bigfoot may exist, they dismiss it out of hand. Well, yeah — new species are identified from time to time, whereas “Bigfoot” is understood as being a more specific claim. “There is some purpose to the universe” is a more modest claim than “there is a superintelligent being that created the universe and has plans and rules for humanity and hears prayers and forgives sins and controls everything, including the fate of your conscious existence after physical death….” which, whether you intend it or not, is what a good portion of your audience is likely to think when they hear you say “there is a transcendant God.”

  8. Crip Dyke, Right Reverend Feminist FuckToy of Death & Her Handmaiden says

    PZ, from the original post:

    Guess I’ll just have another cup of tea,

    Really? You pick tea over coffee? I knew there was a reason I loved you….

  9. Crip Dyke, Right Reverend Feminist FuckToy of Death & Her Handmaiden says

    With these three myths dispelled, …
    You can entertain the possibility that evolution has a purpose … without abandoning belief in natural selection as evolution’s only engine,

    Myth number four: If evolution has a purpose, the purpose must have been imbued by an intelligent being

    Wait, WTFreud? Wright’s logic doesn’t even hold if you accept errors in the premises (i.e. the argument isn’t even valid, much less sound).

    So, up through the myth #3 portion of Wright’s argument, we get:
    1. Natural selection is evolution’s “only engine”.
    2. …so without natural selection, there is no evolution.
    3. Even with natural selection, if anything else affects the distribution of traits in a population, there is no evolution.

    This can only remotely hold true if we accept a specific definition of “evolution” for the purposes of the argument. Defined such that only natural selection drives evolution, and maintaining that evolution is change in a population over time, we must conclude
    4. We can have population change, of course, but it can’t be called evolution if anything other than natural selection is even partly responsible for the change, because evolution, as we mean the word for the purposes of this argument, can’t be present when anything other than natural selection changes a population’s trait pool. Natural selection isn’t just an engine of evolution, it’s the only engine of evolution, i.e. the only cause of the presence of any given distribution of traits.

    Okay, got it.

    then, in the myth#4 portion of Wright’s argument we find out that evolution’s ***purpose*** must have been instilled by an intelligent designer.

    An intelligent designer, mind, is not natural selection.

    So, let’s think about this: in what we would it be possible for an intelligent designer to impose a purpose on evolution ***without at all affecting the distribution of traits in any living (or formerly living) population – not even a single, small population***?


    Yeah. That’s what I thought.

  10. unclefrogy says

    To think about the idea of a purpose is to make a judgment, a ranking of things, of outcomes as better or more desirable and to do that from a point of view and in this case is centered on humans and human intelligence as the most important. I do not see any other way it could be made and still be about some “higher purpose”.
    Like above comparison of the distribution of colored marbles on the floor you have to disregard all the rest of the marbles because you are attracted by the patterns within the distribution as being some how significant.
    if I look at the whole earth at once it is just as easy to see that the purpose is to create and distribute variations on bacteria and viruses.
    That is a little silly but all things that exist exist now and are adapting to be better able to survive now and reproduce and it seems pretty clear that there are a vary great number of way or strategies to do that who’s to say which is better?
    We have the ability to recognize this and are beginning to see all the patterns in it but I do not see how that could be seen as a purpose of any kind. As far as the whole earth is concerned and our place in it as it is now it is just as easy to see us as a dangerous parasite to the biosphere then as the highest achievement of it.
    uncle frogy

  11. John Morales says

    ajbjasus @1, before Douglas Adams was Stanislaw Lem’s The Star Diaries (1957), where Gorrd and Lod drunkenly emptied a slop bucket onto prebiotic Earth.

  12. anbheal says

    Can someone explain to me the distinction between the goobledygook term “higher purpose” and the somewhat less gobbledookish term “spooky forces”?

  13. anchor says

    @#14 – from, say, the viewpoint of a cockroach, an example of a “higher purpose” is when it has sex, while a “spooky force” is when somebody accidently steps on it

  14. khms says

    Clearly, that higher purpose was to create trilobites.

    That happened a while ago.

    Ever since, that’s just the remains of the experiment, hanging around until the experimenter goes to clean up and sterilize their tools.

    Or perhaps, we’re already in the autoclave, it’s just waiting a few more billion years for the cheaper energy (when our sun goes red giant).

  15. johnhodges says

    For the sake of argument, let us suppose that there is a grand, cosmic intelligence, a GOD, and this God created the Universe with a plan in mind. He carefully tuned the physical constants of this Universe so that it would develop stars with systems of planets, and planets hospitable for life; he then guided the evolution of life to produce intelligent, social creatures capable of awareness and choice. He watches the drama of their lives, sometimes intervening to move the story along a better path, favoring some individuals, peoples, and nations above others so as to carry out the drama and the story he wishes to see.

    All of this is happening in a star cluster in the Andromeda Galaxy. That is where the central drama of the Universe is being played out, that is where God’s attention is focused. Life on Earth is an accidental byproduct of the Universe being the kind of Universe where God’s Plan can be enacted. He needed stars with planets hospitable for life, and made a Universe finely tuned to create them; he got enough for his purpose, and a few more scattered about in the hinterlands. We arose accidentally; God hasn’t even noticed that we are here, and would not care about us if He did.

    SO: There IS a meaning and a purpose for the Universe, but it’s not about US.

    Would that satisfy the folks who want to believe in a God? I think not. It just HAS to be all about US.