Bret Weinstein goes awry when claiming that neo-Darwinian theory is missing an important part

After Bret Weinstein and Heather Heying resigned from The Evergreen State College under trying circumstances, Bret started a Patreon site and a YouTube channel in which he discusses evolutionary biology. As I mentioned in a post yesterday, Weinstein has been claiming in some of his onstage conversations that modern evolutionary theory has made no progress since the publication of Richard Dawkins’s book The Selfish Gene in 1976. And I discussed why I didn’t think that was a fair criticism, suggesting that Weinstein might be unaware of the progress that’s been made in the three areas he singled out as stagnant: speciation, sexual selection, and the correlation of diversity with latitude.

In this 9-minute video, Bret argues not only that evolutionary biology is stagnant, but its central paradigm—evolution via natural selection—is lacking a very important part.

As he argues, “The most important unanswered question, at least in evolutionary biology, has to do with where the power of evolution comes from.” He claims that the standard story that random mutations (mostly bad but occasionally good), winnowed by selection, doesn’t come “anywhere close to explaining how a shrewlike animal becomes a batlike animal by having membranes and bones extended in its hands, that become wings”.  He says that “There’s a flaw in the story that surrounds the question, ‘How do mutations alter the morphology of one creature so that it can take on a different ecological role?'”

Listen to Bret’s answer.

Bret’s answer to the question that he sees as heretofore unanswered is the evolution of “explorer modes,” which he defines as “mechanisms in which an evolved clade [related group of organisms] explores design space, so they can discover opportunities that it would not find by accident.”

What does this mean? He argues that an “explorer mode” gives natural selection a way to create new types of organisms in a way “that would not be discovered by accident”. I presume he means here that there are many organisms in which a combination geographic isolation “by accident”—e.g., via haphazard colonization of a new area such as an island, or separation of populations by geographic barriers or continental drift—followed by random mutation and selection, is a combination simply inadequate to explain evolution.

But why not? Bret argues that mutation and selection are “not powerful enough to account for the vast array of niches that have been discovered by species over the history of life.” But he gives no calculations to show this; he’s merely hazarding a guess, a guess without any empirical support. In other words, he’s making up a problem that hasn’t been shown to be a problem.

So what Weinstein is positing is not that animals invade new niches by accident and then evolved new species and morphologies, but that there are evolved “explorer modes” built into organisms by natural selection that help them find new niches.

He gives two examples of this. The first is Pacific salmon, which home to their natal streams, returning to fresh water from the sea every couple of years to breed. Very rarely, a salmon might invade a new stream, and, if that stream was devoid of other salmon, it would find a bonanza: lots of food and empty space. The descendants of that first explorer would thrive, and eventually, perhaps, become sufficiently genetically different that they’d constitute a new species.

The invasion of a new stream by a few stray individuals surely must have happened in evolution, but Weinstein insists that this is not an accident—a case of wayward salmon losing their way—but that they have evolved to explore. And that evolution was prompted by a form of selection that, while risky, has big payoffs: finding a new stream. He sees this form of selection as general, and essential to account for Earth’s diversity.

But there are big problems with this scenario. First, it applies only to changes in behavior: migration or wandering behavior. It does not and cannot explain the difference in morphology between a bat and its ancestor, or any differences between species in morphology, physiology, and so on. Those still require random mutation and selection. Even if his mechanism operates—and I don’t think it does in the way he posits—it only explains how an animal finds a new habitat in which garden-variety mutation and selection then proceed to work, and to create new morphology. The morphological differences evolve by same-old same-old.

But are “explorer modules” even plausible? Perhaps occasionally, but surely the cost of leaving your habitat and finding another one must frequently exceed the chance of finding a new, open niche in which you can thrive. At present, for instance, Pacific streams are pretty much tapped out for salmon residents, so invading a new stream would have no payoff. In other words, even if “explorer modules” were advantageous, they are self-defeating. Selection would favor not exploring.

Weinstein, then, hasn’t shown that the payoff from an explorer mode would generally exceed the costs. Yes, an individual could hit the jackpot, but what about all those individuals that don’t? If the average cost of exploring exceeds the benefit of a rare payoff, then exploring won’t evolve.

Further, and importantly, if these modules were favored by selection, you would see many more animals exhibiting them than do. If all salmon had evolved explorer modes, then you’d see many, many salmon leaving their streams and trying to find new ones. You don’t see that: migration is rare. This supports the idea that, in salmon, colonization of new streams is an accident: a bug rather than a feature. Weinstein has failed to explain the infrequency of exploring.

It’s clear that Bret thinks that “explorer mode” is something that is selected for. As he says, “It stands to reason, then, that selection would discover a mechanism that searched design space, rather than finding opportunities in design space haphazardly.” That’s clearly a claim that exploring is somehow built into an organism’s genes. Further, he says, it creates new morphologies faster than the conventional scenario. But we don’t know that the conventional scenario—wandering followed by the conventional mutation + selection—is too slow to create life’s diversity.

Now there are animals in which “exploration” is ubiquitous and a general phenomenon. One is the ballooning of spiders, in which spiderlings, when hatched, throw out a thread of silk to waft them away on the wind. Another is, of course, the dispersal of dandelion seeds via their fluff. Still another is the migration of young male lions away from their pride.

But these phenomena aren’t what Bret means by “explorer mode”, as they are ubiquitous in the species, and have evolved because finding a new habitat is essential if you are to avoid competition and thus leave your genes.  And even in these cases, the difference between species in morphology—why a tiger is striped but leopards are spotted—evolves by conventional natural selection.  Yes, a different habitat may be involved in creating that selection, but there are many ways that animals can find themselves in different geographic areas by accident. I don’t think that finches colonized the Galápagos island because they were showing their evolved tendency to explore. Most finches heading out over the Pacific, or blown over the ocean, would perish.

The other example Bret uses is human consciousness. We evolved consciousness, he says, so we can explore new ways of life. But this is not at all analogous to a salmon evolving “wandering behavior” because that kind of behavior helps you invade an empty niche. True, consciousness helped us invade a “cognitive niche”, and that may have had ramifications for the evolution of other parts of our body, like our brains or our hands, but you don’t need to invoke a new type of evolution to see how consciousness (or big brains) might have evolved. They could have evolved simply because they give individuals a reproductive advantage. There was no real “exploring” here analogous to Weinstein’s scenario of salmon taking risks because they could have big payoffs, as there was no risk involved in acquiring a mutation that made you more conscious. So I’ll ignore that scenario.

In general, I think Bret advances a thesis here that a.) isn’t needed, because there isn’t really a question that needs answering (nobody is worrying, “Hey, evolution was faster than mutation and selection could create”), b.) has its own problems, as payoffs have to be greater on average than the costs of exploring, c.) fails to explain why exploring is so infrequent, and d.) completely fails to account for the morphological differences between species that, he says, prompted this theory.

I think Weinstein’s explanation, then, is misleading: certainly so if it’s a general one intended to fill an important lacuna in evolutionary theory. Weinstein hasn’t shown that such a lacuna exists. And if there’s no need for such a theory because neo-Darwinism hasn’t been shown to be insufficient to explain diversity, then invoking “explorer modes” is an exercise without a motivation.

 

 

78 Comments

  1. Neil H Shubin
    Posted September 20, 2019 at 11:12 am | Permalink

    Based on his comments, I’m not sure he is familiar with the literature. The bat example is particularly unfortunate for Weinstein because it has seen quite a bit of developmental genetic work in recent years. Here is an older paper:

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1458926/

    • Posted September 20, 2019 at 1:18 pm | Permalink

      I was thinking that this one is mainly a story of variations in embryonic development that slightly effect the webbing that already develops between the fingers. All mammals form this webbing. Here, some ancestors to bats had embryos that simply kept some of the webbing. These would be small arboreal mammals that leap between tree branches, and having any degree of webbing would give them more of a ‘gliding flight’ in their leap. This would then be a great example of non-random survival of random variants (you know, good ‘ol natural selection), rather then an intentional ‘exploring’ process.

  2. Mike Mayer
    Posted September 20, 2019 at 11:22 am | Permalink

    Is he saying that organisms “want to” evolve, so they have an explorer module?

    That’s like the assumption that evolution “wants to” create more complex life forms from simpler life forms.

    Neither seem to be necessary to explain the fossil record as far as I know (I’m not an evolutionary biologist).

    • Posted September 20, 2019 at 11:28 am | Permalink

      He comes close to that kind of teleology but is pretty vague about it.

    • Jonathan Wallace
      Posted September 20, 2019 at 11:31 am | Permalink

      Yes, I though the language used was suggesting that evolution has some kind of ‘intention’ without it being at all clear where that might come from.

    • rickflick
      Posted September 20, 2019 at 5:40 pm | Permalink

      I think the term “explore” is rather loaded with intentionality. It doesn’t help him make a clear hypothesis.

    • Posted September 23, 2019 at 12:08 pm | Permalink

      People do talk about the evolution of evolvability. I suppose in some far reaching sense, then, one could have that represented somehow in an organism, but … (This is unlikely to say the least and certain is not needed as a hypothesis.)

  3. Randall Schenck
    Posted September 20, 2019 at 11:24 am | Permalink

    Thanks much for explaining this for the less informed. Possibly Weinstein is too attached to speculation and not enough to science.

  4. Jonathan Wallace
    Posted September 20, 2019 at 11:29 am | Permalink

    I certainly don’t know the developmental genetic literature referred to by Neil Shubin but it seems to me that in the case of the bat the mutation that initially lead to some aerodynamic capability (e.g. limited gliding ability, say) was a necessary precursor to it exploring the design space of an aerial life style.

    • Posted September 20, 2019 at 11:31 am | Permalink

      Same with feathers in birds, which started out in dinosaurs as a feature not used for flying. No “explorer mode” there, either.

    • EdwardM
      Posted September 20, 2019 at 11:35 am | Permalink

      It was harder still for the bats because flying animal niches were mostly filled by the time they evolved. So they had to explore the nocturnal design space of an aerial life style as well.

      • gravelinspector-Aidan
        Posted September 21, 2019 at 6:34 am | Permalink

        I wonder … which came first, the light independent sonar find-and-eat sense or the nocturnal flight?

        • darrelle
          Posted September 21, 2019 at 7:33 am | Permalink

          Probably a very large overlap, more or less at the same time.

          • gravelinspector-Aidan
            Posted September 21, 2019 at 7:55 am | Permalink

            I threw that question in straight from the second deck (up my sleeve). Now I’m thinking about it.
            And spotted zebras.
            And eight-toed horses. You could say I’ve been Incitatus-ed into thinking about eight toed horses. But I also need to get my messages.

  5. Charles Jones
    Posted September 20, 2019 at 11:31 am | Permalink

    One appeal of creationism is the feeling that nature is amazing that it couldn’t have just happened by natural processes. Ergo god.

    Is Weinstein’s premise that bats couldn’t have evolved fast enough really based on essentially the same thing: A feeling not backed up by any science?

    Science often starts with a feeling, but surely he knows that any gut feeling should be followed up with some actual data to see if the intuition is right.

    • Posted September 20, 2019 at 6:34 pm | Permalink

      My thoughts exactly. It appears he just has a hunch or feeling that something is missing, but has failed to make a convincing case about why current theories are insufficient. I’m not buying it.

  6. A C Harper
    Posted September 20, 2019 at 11:32 am | Permalink

    Some people are committed to ideas of free will, consciousness transcending the material world and teleological evolutionary processes (such as explorer modes). They are often unaware that their particular use of language includes teleology as a ‘hidden assumption’.

    It can be a comfortable world to live in – but there is no magic.

    • EdwardM
      Posted September 20, 2019 at 12:04 pm | Permalink

      Yes. After listening I think Dr. Weinstein might actually be thinking this way. I could be wrong but as noted elsewhere here, he was a bit vague.

    • darrelle
      Posted September 20, 2019 at 12:21 pm | Permalink

      Yes, I think Dr. Weinstein may have shown his hand. I don’t know if he does actually lean this way but he talks very much like a knowledgeable person, though perhaps not an expert, with a strong prior commitment to religion or mysticism of some variety. Or perhaps he is just overly sloppy with language that implies agency.

      But when you put together what he is saying along with how he is saying it, it is pretty suggestive of a belief in something other than what can be easily supported by modern science.

  7. Posted September 20, 2019 at 11:35 am | Permalink

    It is interesting that the belief evolution needs some sort of “drive” beyond mutation and selection is so pervasive that even professional biologists sometimes fall for it. I attribute this to the fact that the results of Darwinian evolution in terms of the stunning diversity of flora and fauna are simply so astonishing.

    Regarding Weinstein’s hypothesis, I do wonder about the natural curiosity one observes in many animals and whether it might play a role in them finding novel geographic niches. On the other hand, famously, curiosity killed the cat.

    • Posted September 20, 2019 at 11:39 am | Permalink

      Yes, but you can get curiosity evolving simply by individual selection: you might find more food if you’re investigating a lot of stuff. You don’t need an explorer mode to explain that.

      • darrelle
        Posted September 20, 2019 at 12:24 pm | Permalink

        I hadn’t made that connection reading through your article, but reading your comment here made the light bulb go off. His idea does entail group selection doesn’t it?

        • just josh
          Posted September 20, 2019 at 2:24 pm | Permalink

          Weinstein’s “explorer modes” aren’t really about behavior of an animal, like exploring new streams, but are meant to somehow apply to genetics. In that case one could imagine “meta” evolution in which some lineage evolved traits that increase the rate of mutations in descendants. I.e., if mutations happen more often then there is more grist for the selection mill and perhaps the more quickly evolving lineage will out compete another with moderate mutation rates. But, (so it seems to me), as with group selection this is a sort of higher order effect and you would need some specific circumstances for the math to work out: higher mutation rates probably have a cost in terms of deleterious effects and the very long term benefit would have to outweigh the more immediate effects of maintaining or adapting directly to the current niche.

          However, I think Bret wants more than this, since this scenario would still be quite compatible with modern Darwinism. I think he’s hinting at some sort of teleology but it’s very vague and I’m not sure he has any clear idea other than feeling that normal mutation plus selection is somehow not enough.

        • Posted September 20, 2019 at 2:25 pm | Permalink

          I think so. If I understand Weinstein correctly, he is asserting that organisms evolved the ability to explore the fitness landscape. In other words, organisms evolved the ability to take advantage of the ability to evolve. An interesting idea, but I can’t see how such meta-evolution could come about by individual selection.

          • darrelle
            Posted September 20, 2019 at 2:51 pm | Permalink

            What I hadn’t thought through at first but seems obvious now is that his explorer modes idea is almost certainly not unrelated to his ideas about group selection.

            Taking his salmon example, a trait that inspires a salmon to wander off and find a random stream might conceivably benefit the species in the long run because every once in a while one of these loners will be successful in establishing a new population. But it seems like it would be extremely unlikely to benefit the individual. Most such loners surely die without issue. Neither individual or Kin selection work to get you any selection pressure in this scenario. You’d need group selection, or something else that somehow produces a selection pressure for the trait even when the genes for the trait make it more likely that individuals carrying them won’t pass them on.

            • Posted September 20, 2019 at 3:05 pm | Permalink

              Yes, but I have never been completely convinced that species (genome) selection doesn’t happen. See Mike Anderson’s interesting example at 21 below, which sounds to me like species selection.

              • darrelle
                Posted September 20, 2019 at 3:37 pm | Permalink

                I agree with Mike’s comment at 21. He’s explained how conventional, long tested basic mechanisms of evolution could explain Weinstein’s salmon example without the need for any higher level mechanisms, including group selection.

                I think it’s probably too early to rule out group selection altogether but it does not seem to have a very strong case when kin selection models are so successful and group selection models are not. From what I understand in nearly all, or perhaps in all of the relatively rare instances in which a group selection model was successful a simpler kin selection model of the same scenario was also successful, while the reverse is not the case. There has never been a group selection model devised for any scenario that couldn’t also be modeled by a kin selection model.

  8. HBB
    Posted September 20, 2019 at 12:16 pm | Permalink

    I would add that we have plenty of good examples of an “anti-explorer mode” in the narrow sense of “the ability to explore for new habitat.” The well-documented and numerous cases of reduction/loss of dispersal ability in island species seems like a counter example. New Zealand has a couple excellent examples of flightless birds that are mentioned often here, for instance.

  9. Desnes Diev
    Posted September 20, 2019 at 12:24 pm | Permalink

    “But are “explorer mod[es]” even plausible? Perhaps occasionally, but surely the cost of leaving your habitat and finding another one must frequently exceed the chance of finding a new, open niche in which you can thrive”

    Without a detailed description of these “modes” and of the underlying substrate (neural networks, cellular metabolism, genes?), they are just vague ideas. And if they are not testable, how could they be plausible (or useful)?

  10. Liz
    Posted September 20, 2019 at 12:24 pm | Permalink

    “’So it stands to reason then that selection would discover a mechanism that searched design space rather than finding opportunities in design space haphazardly.’” 5:38 to 5:48 in.

    “’And if we think about what we are, clearly this is the case. We have a creative capacity that can search for opportunities that are nearby, hypothesize about how they might be exploited, and then test those hypotheses and refine some answer. We got that cognitive capacity through evolutionary dynamics. In other words, we were favored to become conscious because consciousness has an advantage and that advantage is that it allows us to discover opportunities that would otherwise be missed.’” 5:49 – 6:21 in.

    “’Why do we assume that we are the only creatures or that consciousness is the only mechanism that can do this?’” 6:22 – 6:26 in.

    It almost seems like he was thinking about consciousness and what it does first, then maybe thought of it as a mechanism that he is calling an explorer mode, and then generalized a human’s experience with consciousness to all other species. But in other species it doesn’t have to be consciousness. It is an explorer mode? I don’t think he gave any other suggestions about how an explorer mode might work in other organisms besides the salmon and that was confusing. Can anyone test what he’s saying in a salmon? How is the salmon’s explorer mode different from a human’s explorer mode? How is an orca’s consciousness different from a human’s in the context of the explorer mode?

  11. elissa
    Posted September 20, 2019 at 12:32 pm | Permalink

    His explanation sort of reads like a mutation on the Baldwin effect

  12. Mark Reaume
    Posted September 20, 2019 at 12:32 pm | Permalink

    Is there any literature about the ‘speed of evolution’? I’d imagine that it would be a similar problem set to the modelling of star formation, or the evolution of a galaxy.

    (I’m way out of my depth here fwiw).

    • gravelinspector-Aidan
      Posted September 21, 2019 at 6:53 am | Permalink

      “Speed of evolution” needs a lot of refining as an idea.
      There is a lot of work on “molecular clocks”, but most such work looks at variation in genes which are thought to be not subject to close selection. For example, and enzyme has a number of binding sites (in chemical sense) for the substrate(s), which are held in a physical relation to each other by a molecular “scaffolding” of alpha helices and beta sheets. Mutations in the binding site parts of a gene are likely to be pretty strongly selected – for or against – but mutations in the scaffolding are likely to be subject to much weaker selection. The weakly-selected regions are where you’d look for trying to apply molecular clock.
      “Molecular clockery” has an underlying assumption that the process of transcription, duplication etc have a certain error rate which is suppressed by elimination of “bad” mutations in important regions but ticks along steadily in less-important regions.
      Molecular clockery is certainly an interesting idea, but it needs calibration against the fossil record – itself an acknowledgedly very imperfect record – and remains prone to “contamination” by lower-but-not-zero levels of selection in the actual regions considered.
      I listen to results from molecular clockery, while holding a salt cellar.

  13. Posted September 20, 2019 at 12:36 pm | Permalink

    Explorer modes are just physical, deterministic mechanisms. There is a lot to unpack here, but here’s a simple example.

    Gravity enforces an asymmetry in all living organisms and their respective ecologies. Gravity is an ‘explorer mode’.

    The prescription of physical laws is precisely what makes up any shortcomings of random mutations, i.e., explorer modes are the physical constraints. Thermodynamic, mechanical, metabolic, even quantum mechanical process of single photon detection are unavoidable constraints. I think Weinstein is just calling them explorer modes.

    • Posted September 20, 2019 at 12:38 pm | Permalink

      I disagree. Weinstein makes it clear that “explorer modes” are evolved mechanisms, coded in the DNA, that compel organisms to find new niches. They are not the working of physical laws.
      And I’m not exactly clear what you’re talking about when you say “the prescription of physical laws are what makes up any shortcomings of random mutations.”

    • gravelinspector-Aidan
      Posted September 21, 2019 at 6:59 am | Permalink

      Gravity enforces an asymmetry in all living organisms and their respective ecologies.

      Gravity has little influence on planktonic organisms – those that live their lives in the water column, not on the seabed or the air-water interface. If you get rid of the factor of light and food transport (which vary in the same direction as gravity, generally) then you start to see organisms which really don’t care about gravity. Cave organisms prompted me to think in that direction, but it probably applies as well to infaunal detritivores (mud-eaters).

      • Posted September 23, 2019 at 12:13 pm | Permalink

        Surface tension and viscosity also matter to some organisms, I think.

        (I read somewhere that to a bee, flying through the air would be like us swimming in molasses – I do not know if that is correct.)

        • gravelinspector-Aidan
          Posted September 23, 2019 at 3:19 pm | Permalink

          Oh really, yes. As your mass goes down and your surface area goes up, then surface tension and viscosity become far more important. The oft-repeated tale of a cat surviving a drop from a 5th or 6th floor window is in part due to the relative effects of air viscosity and edge turbulence.

  14. Scott Draper
    Posted September 20, 2019 at 12:39 pm | Permalink

    Bret Weinstein got his 15 minutes of fame, then started to turn that in to a role as a public intellectual. I haven’t found that he had anything interesting to say once the Evergreen story got old.

  15. Steve Gerrard
    Posted September 20, 2019 at 12:40 pm | Permalink

    All mutations are initially low risk. If they don’t work out, they don’t replicate, and the loss to the population is tiny. If they do work out and replicate, they are beneficial to the population.

    Who cares if a few salmon swim up the wrong river and fail to reproduce? Not the population of salmon as a whole. If instead they do successfully reproduce, good for them, and the species is that much more successful.

    Natural selection favors a low rate of mutation, rather than a zero rate producing no change at all, or a high rate producing chaos. You can call that exploring if you must.

  16. Posted September 20, 2019 at 1:04 pm | Permalink

    Whoa. That is strange thinking. I don’t have nearly the evolution-cred of our host, and even I see this as a worryingly eccentric idea that is full of holes and lacking in evidence. Further, the naysayers of evolution will delight in his provocations, as they can then point out that the theory is in crisis.

    So he will certainly receive more push-back from other biologists, and then perhaps double-down on his musings. It’s too bad because I want to like him and see him as one of the good guys.

  17. Daniel Engblom
    Posted September 20, 2019 at 1:07 pm | Permalink

    Sounds like Bret Weinstein has been hanging around creationists a bit too much, when his rhetoric is almost indistinguishable from the argument from incredulity, though he just claims that natural selection is insufficient without much justification at all.

    “What can be asserted without evidence can be dismissed without evidence.” – Hitchens

    • EdwardM
      Posted September 20, 2019 at 1:22 pm | Permalink

      I’m not sure that’s quite fair. He isn’t saying Natural Selection is insufficient, he’s saying there is another “mode” that has not been acknowledged by which evolution works. I agree (without benefit of expertise, mind you) that his proposed “mode” is unnecessary to understand how evolution works and it doesn’t really explain what he purports it does. Apart from the suspected teleology (as noted above), I don’t think he is making the kinds of claims on Natural Selection you suggest.

  18. Jonathan Gallant
    Posted September 20, 2019 at 1:27 pm | Permalink

    Weinstein’s idea of a genetically determined “explorer mode” reminds me of two older memes—both of which involve “exploration” mechanisms, but of a haphazard variety.

    Many years ago, Martin Heisenberg (yes, son of THAT Heisenberg) reported on flying behavior experiments with pinned Drosophila. The flies responded to various visual cues, but he also observed that they periodically changed “flight” direction for no apparent reason. He could find no extrinsic stimulus to explain these changes, IIRC—It was as if they were simply programmed to “explore”.

    The second case is mutator alleles of DNA repair genes in bacteria. There is a considerable literature (some by Miro Radman in Paris) about the idea that mutator alleles confer a selective advantage under conditions of environmental stress, such as antibiotic challenge. I don’t know how this idea has fared in recent years.

  19. wonderer
    Posted September 20, 2019 at 1:42 pm | Permalink

    I just wanted to say, that to the best of my knowledge, all female salmon lay unfertilized eggs in freshwater streams, that are then fertilized by a male at the site.

    I don’t think an isolated female, swimming up an otherwise salmon free stream, could colonize the new stream.

    Someone please correct me, if I am wrong.

    • Posted September 20, 2019 at 1:47 pm | Permalink

      Yes, of course you’re right. I will correct the text.

    • gravelinspector-Aidan
      Posted September 21, 2019 at 7:10 am | Permalink

      Hmmm. Gender can be flexible in a fair number of fish. Someone will provide the fish’s name, but there was recent discussion (here? Probably.) of a species of fish where if the dominant male of a society (reef) is removed, then after mere days the biggest bossiest female “grows a pair” (and a skull protrusion, IIRC) and becomes the fertile male of the society.
      Other forms of parthenogenesis appear sporadically throughout the vertebrate clade.
      How closely have the fishy people searched salmon eggs for sporadic development, for example? If the sporadic development rate is 1 per thousand eggs, and the accidental isolated female lays 2000 eggs, then the likelihood of getting a potentially breeding pair out of an accidental colonisation is a lot higher than zero.

  20. DANIEL C LEWIS
    Posted September 20, 2019 at 1:58 pm | Permalink

    Quite agree! Well done!

  21. Mike Anderson
    Posted September 20, 2019 at 2:12 pm | Permalink

    I’ve tinkered with evolutionary software systems and one thing that becomes very obvious is the way pressure – specifically intense pressure like predation – can kick evolution into high gear. Populations evolve much faster when something like predation is introduced.

    Brett Weinstein’s “explorer modes” is a creative story, but evolutionary pressure is a more evidence-based explanation for things like the exploratory salmon.

    Consider a clade of salmon with perfect unerring homing instincts – they always return to where they were hatched to spawn. Now imaging a group of bears discover their spawning migration route and feast on these unerring salmon and wipe them out. (Alternatively a small localized ecological disruption could also wipe them out.)

    Now consider a clade of salmon with more erroneous homing instincts – most of them return home to spawn but some get lost. The lost ones are less evolutionarily successful in general but in the case of disruption (bear influx or chemical spill) they become the surviving lineage.

    My point is we don’t need Bret Weinstein’s “explorer mode” to explain exploration – the basic mechanisms of evolution explain exploration. It’s easy to see, using only “basic evolution”, why an imperfect homing mechanism in salmon makes the lineage more resilient and why unerring salmon lineages were filtered out.

    Bret is correct when he says “high risk high reward activities are often viable” but to me it’s not much of a mystery why that is. He seems to posit some complex emergent force is needed, when all that is needed is environmental pressure (bears and chemical spills).

    • rickflick
      Posted September 20, 2019 at 6:00 pm | Permalink

      A certain level of variability withing a species is probably optimal. Too narrow a gene pool leads to extinction. I suppose too much variation would be pruned by the environment.

  22. Jody Hey
    Posted September 20, 2019 at 2:34 pm | Permalink

    There is an explorer mode, and for most organisms it happens every meiosis in the production of gametes. It is called recombination. That is when existing gene sequences are broken up and rejoined with related sequences. Recombination, as a process of creating new kinds of genomes, can be explained in terms of selection at several levels, including the population, the organism, or the gene (see e.g. Otto & Barton 1997).

    • HBB
      Posted September 20, 2019 at 2:45 pm | Permalink

      Yes! And throw in random union of gametes from 2 reasonably heterozygous parents for a quantitative trait that gets genetic input from a handful of loci and you’ve got all kinds of potential variability in that trait in the next generation.

      • EdwardM
        Posted September 20, 2019 at 2:56 pm | Permalink

        If it’s already got a name -recombination- why call it an “explorer mode”?

        • Posted September 20, 2019 at 5:54 pm | Permalink

          Recombination is, with mutation, well ensconced in the modern synthesis and population genetics, as you know well. Why rename it “explorer mode”? This isn’t what Bret is talking about at all: he’s saying that there’s a huge lacuna in evolutionary biology that isn’t settled by the existing paradigm. But recombination is well within the existing paradigm, and of course could have evolved for other reasons than to allow species to “explore new niches.”

  23. aljones909
    Posted September 20, 2019 at 4:30 pm | Permalink

    Explorer mode? Sounds a bit fishy.

    I’m surprised he hasn’t latched on to this one. Here in the UK we are Europe’s number 1 bird feeders (guilty). Blackcaps spend the summer in Germany and migrate to Africa in the winter. Humans have made this very hazardous. Southern Europeans like to capture these migratoty birds in the most inhumane manner. They eat them.
    There are now blackcaps which migrate west to England. They don’t escape the winter, but a winter in England is much less harsh than a German winter. Their main food source is garden feeders.
    I think the Darwinian explanation would be that some birds inevitably have faulty programming. They fly west instead of south. The “fault” becomes an advantage.

  24. Posted September 20, 2019 at 5:04 pm | Permalink

    Why does no one mention the role of epigenetics as a mechanism driving morphological evolution?

    Epigenetics provide much more explanatory power than random mutation.

    Random mutations may happen, but not frequently enough to explain the rate of changes necessary for successful adaptation.

    Epigenetics explain how environment and organism exist symbiotically, where environmental demands not only select for genes, but influence which genes are expressed, which carve out a path forward for future genetic selection.

    Perhaps it’s not at all random. Perhaps the environment nurtured the selection of certain genes, which continue their expression.

    I imagine this happens on a thermodynamic and biochemical level not yet properly accounted for.

    Randomness is not an adequate explanation for genetic selection. There are specific environmental demands which “call forth” genetic adaptations which are selected.

    • Posted September 20, 2019 at 5:51 pm | Permalink

      I’m sorry to say this, but you appear to have no idea what you’re talking about. First, you claim without any evidence that “random mutations don’t occur frequently enough to explain the rate of changes necessary for successful adaptation.” Do you know Lenski’s work that refutes that? Then you go on to claim that mutations are nonrandom, but channeled into an adaptive direction. There is NO evidence for that. You seem to be unaware of the considerable literature bearing on this issue. Instead, you have made a comment that is essentially gibberish: contentless and data-less speculation. Why not just say that God did it: there’s as much evidence for that as for your epigenetic hypothesis.

  25. rickflick
    Posted September 20, 2019 at 5:35 pm | Permalink

    Weinstein seems to be baffled by geologic and evolutionary time scales. That’s the first thing a new student of evolution learns. You get that on the first day in the first lecture. Weinstein teaches it, I’m sure.

    Natural selection is a perfectly good “explorer mode”. If Weinstein wants to propose a newfangled one, he needs to show us a mechanism analogous to natural selection, but he has none. He asks us to look for it. Without that specific evolutionary mechanism, his suggestion is redundant.

    • gravelinspector-Aidan
      Posted September 21, 2019 at 7:20 am | Permalink

      geologic and evolutionary time scales.[…] You get that on the first day in the first lecture.

      You get told it in the fist lecture. Lecturers get to say it once a year in the first lecture. That’s a lot different to “getting it”.
      Of a sample of around a hundred geology students who shared my first year and then got whittled down to a graduating class of about 25, everybody knew the words (including the generally closeted Creationist), but only about a dozen actually did “get it”. I saw people getting it in first, second, third and fourth years. And less than a third of the class went on to work in geology at all.
      I suspect that an awful lot of people in the life sciences don’t actually appreciate the size of the gaping abyss of geological time behind their lifeforms.

      • rickflick
        Posted September 21, 2019 at 10:29 am | Permalink

        I remember the lesson well. The lecturer brought in the large ball of twine and asked for a volunteer to pull out the end. It was a model of geologic time since the earth cooled. I volunteered, and as I walked back up the isle of the lecture hall the twine had labels attached at important milestones – the first life, the first multicellular life, etc. When it reached the Pleistocene, I was out in the hallway. Humans were around for the last inch or so of twine.

        • gravelinspector-Aidan
          Posted September 22, 2019 at 11:48 am | Permalink

          Hmmm, that’s an interesting, and graphic, way of presenting the idea. Visceral.

          • Posted September 23, 2019 at 12:15 pm | Permalink

            I dare say more copies of Sagan’s “cosmic calendar” should be made – at the scale he used, too.

            • gravelinspector-Aidan
              Posted September 23, 2019 at 3:50 pm | Permalink

              I actually had to check what exactly “Sagan’s cosmic calendar” referred to – I’ve seen enough snippets of his work, but never felt a need to sit down and watch it “from cover to cover”, as it were. I noticed a multi-DVD Sagan set in a shop not long ago, but wasn’t sufficiently motivated to free a wallet moth for it.
              But yeah, the general concept needs advertising because it’s one of the great debunkings of human exceptionalism. Copernicus (with understudying from Galileo and Kepler) debunked humans from thinking they were the centre of the universe. Darwin debunked humans from having a special creation within biology. “Deep time” (who to ascribe that to? Kelvin, for getting it wrong? Holmes for getting it right? Penzias and Wilson for discovering the CMB that gives us one measure of deepest time? You could put Crick & Watson in there for tieing humankind even more firmly into the rest of life.
              If the 1996 “Martian Microbes” paper had paid out it’s promise, which it didn’t, then that might have been another debunking of humankind’s claims to being special.

  26. Posted September 20, 2019 at 6:47 pm | Permalink

    I have been trying to think of how to test the hypothesis of an explore mode. It occurs to me that animals with their motility could better utilize such a mode than could plants. So is there any measurable differences in the rates of evolution or the ability to colonize new niches between plants and animals? I think not.

  27. Posted September 20, 2019 at 6:48 pm | Permalink

    It all seems so strange to me, and I can’t understand what Brett is trying to say. I wish he would write up a paper about it so he can flesh the idea out more thoroughly than in an 8 minute video.

    I study animal personality, and we often measure things like exploration and boldness. And, not surprisingly, both individuals and groups differ in these traits! I don’t see why the existence of some anomalously explorative salmon need a more grand explanation than this. There is variation in each species with respect to any personality or physical trait. At the tail ends of this distribution there will be extreme individuals. Why do we need to posit something more deeply hidden and mysterious than that?

    It also sounds like Bret is suggesting these “explorer modes” are a group-level adaptation as well. Hard to see that being selected for in salmon, or most species for that matter.

    I’ll wait for him to respond to criticisms, but so far I am very skeptical of his claims, and think it may even be damaging because of the fuel he’s giving to the Intelligent Design crowd. Bret has a large platform, and I worry his statements of evolution being in a “crisis” are doing harm to the field and misleading the public.

    I guess we’ll see.

    • Posted September 20, 2019 at 6:57 pm | Permalink

      Yes, unless he develops a precise and testable model of the explorer mode, he is only a few steps away from honorable membership at the Discovery Institute.

  28. FB
    Posted September 20, 2019 at 11:37 pm | Permalink

    It seems to me that changes in the environment are a more plausible explanation for a faster evolution than “explorer modes”.

  29. gravelinspector-Aidan
    Posted September 21, 2019 at 7:50 am | Permalink

    I think that Weinstein is not accounting for the cost of maintaining error-free information transmission between generations. The error rate of copying DNA is low, but non-zero. It’s in the order of an error per million base pairs copied. But there are quite extensive, and biochemically and energetically expensive, error-checking and duplication systems which can catch those errors in some cases, but not in others. Systems like the structure and operation of ribosomes are heavily duplicated, so to get an effective mutation you need to change dozens of copies in the same way, in the same generation … and you result in a net error rate for those genes down in the parts per billion range. But single-copy genes can have considerably higher error rates.
    Copy fidelity is expensive.
    Looking at his salmon example – making a sensor system (smell, memory, GPS, whatever) with the fidelity to return 100.000% salmon back it’s stream of origin is going to produce a salmon weighed down by a backpack of navigation equipment and vulnerable to environmental change. Making a simpler sensor system which returns 99.990% of the salmon to the correct stream will put several salmon per year into adjacent streams – the individual salmon all being appreciably less backpack-laden (or laying more eggs) on all of their journeys. In many years, some of those salmon will breed, leading to a far more resilient species.
    There’s an assumption in there that all adjacent streams host distinct salmon species with no salmon ligers and tigons (or for that matter, mbwa na matanguzo) ; that actually pretty unlikely in the real world.

  30. Posted September 21, 2019 at 11:44 am | Permalink

    One friend mentioned to me that if Weinstein thinks his idea is so revolutionary, and so important a caulk to plug up the gaps in evolutionary theory, then why doesn’t he publish it in a scientific paper? I think that’s a good suggestion, for vetting by people who know the literature is essential to evaluate this idea properly.

    • jonstatedclearly
      Posted October 14, 2019 at 8:16 pm | Permalink

      He claimed on twitter that atheists are now trying to “Peer review him into obscurity”. I’m pretty sure he was talking about you.

      That said, maybe by “explorer mode”, he means an if/then clause has evolved: If there’s lots of food and low stress, stay with the mom and siblings, if not, run away and never return!

      This sort of if/then evacuation clause is common in social animals. One study may have found it in bacteria. https://www.nature.com/articles/s41467-018-04409-z

      It seems to me that kin selection could account for costly evacuation behaviors “explorer modes”, rather than Bret’s idea that biology somehow yearns to evolve.

  31. Roo
    Posted September 21, 2019 at 1:58 pm | Permalink

    I wonder if what Weinstein is getting at would better be described as the adaptive benefit of intelligence and / or cognitive flexibility, rather than consciousness. For example – I have been reading about the ‘nesting instinct’ during pregnancy recently as I keep wondering if this is a real biological thing or an old wive’s tale. From what I have read biologists do see it as a real thing. What I think is interesting is how easily this instinct translates to 2019, even though none of the manifestations of this urge (organizer bins, cleaning products, baby gadgets, etc.) really existed in direct form in the Paleolithic era. Somehow human brains have enough flexibility with categories to take a general instinct and apply it to a modern-day equivalent, even at the subconscious level. And presumably this was all selected for due to survival value. I wonder if this is the kind of thing that Weinstein means – that ‘explorer mode’ is more a general way of being or problem solving activated under certain circumstances vs. a more rote behavior such as wandering (he seems to imply this as I believe he says here or somewhere else that maybe we don’t give animals enough credit in the consciousness department – again, to my mind consciousness is a separate debate and it might be clearer to say ‘the intelligence department’.)

  32. John Sadowsky
    Posted September 21, 2019 at 9:31 pm | Permalink

    Random mutation + selection IS the explorer mode of evolution. Weinstein is arguing that something more powerful is needed. The onus is on him to prove it. For example, is there some way to reformulate the Lenski experiment to show the necessity of an “enhanced explorer mode”?

    I am a probabilist, and I view evolution as one huge Markov chain – a random engine + selection. The random walk is recurrent in one or two dimensions, but add a tiny (arbitrarily small) drift (= selection) and it becomes transient. The aggregate behavior of the process changes. That is the simplest mathematical proof of the POWER of selection.

    And, as pointed out by others, if “explorer mode” is itself evolved, what is the selection pressure and how does it persist?

  33. Posted September 22, 2019 at 2:28 am | Permalink

    Would it be possible for a “bug”, as in the salmon reference, to eventually become a ” feature” if the groups consistently find themselves in environments/circumstances wherein the bug was, on average, more advantageous?

  34. Peter Dodson
    Posted September 22, 2019 at 7:05 am | Permalink

    Weinstein moves, without sufficient explanation from ‘design space’ (presumably ‘possible, viable alterations of the genome’) to actual space (new niches – in his example, unpopulated streams). ‘Explorer mode’ seems to mean a feature of the genome which ultimately induces or promotes novel or risky behaviour.
    Why is this teleological feature needed?
    Mutation isn’t just random, it’s compulsory. Due, maybe, to the unquenchable gregariousness of carbon, hydrogen and oxygen atoms which occasionally do the unexpected.
    The process is massively parallel: trillions of simultaneous, fallible chemical processes all over the planet.
    In the case of bats, applying the relevant timescale to the generation period doesn’t suggest that some new mechanism is needed. Bats reach sexual maturity in 1-2 years. Their ancestors appeared in the early Eocene – 50-57 MYA. Tens of millions of generations, ratcheting advantages, produces modern animals, vastly different from the early versions but virtually indistinguishable, generation to generation.
    As others have pointed out in various ways.

  35. Richard Wallace
    Posted September 22, 2019 at 12:12 pm | Permalink

    Excellent analysis. My one quibble is that the optimal evolutionary strategy is not to maximize the average but to maximize the minimum number of descendants.

  36. Nick
    Posted September 23, 2019 at 6:51 am | Permalink

    This idea has Jordan Peterson written all over it. Bret and Jordan are friends, and both part of the ‘Intellectual Dark Web’.

    Jordan Peterson has a difficult to read 600 page book called ‘Maps of Meaning’ in which he talks about evolution and ‘exploration’.

    It seems obvious to me that Bret and Jordan have been discussing this idea.

    Jordan also seems to believe that culture is teleological.

  37. Torbjörn Larsson
    Posted September 23, 2019 at 1:55 pm | Permalink

    It’s been evident since the first self-description of Weinstein’s work that he is in “searcher mode” looking for fame instead of doing the hard work of science – his questions are not really interesting (and if not supported by quantification as it seems here also useless).


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