The extended evolutionary synthesis and the role of soft inheritance in evolution

Last month, Tom Dickins and Qazi Rahman published a provocative review article with the above title in Proc R Soc B (hat tip Emma Cohen):

I made a rather longwinded comment about the article on Emma’s Facebook page, which I thought it might be better to post here…

From a quick skim of the paper I find it a bit polemical. The argument is persuasive as far as it goes. I like the idea of “developmental calibration” (neat term). But the abstract and introduction seem much more ambitious than what they actually show in the paper. I just don’t see how demonstrating that epigenetic effects and learning biases can be adaptive in terms of an individual’s inclusive fitness invalidates the whole idea of “soft inheritance”.

Two observations:

(i) The article is really about epigenetics rather than soft inheritance more generally. They highlight niche construction in the abstract and introduction, but only use the term once after that, in their discussion of Bolhuis et al. in Section 4. Unless I missed it, nowhere do they directly address the key insight of niche constructionism, which is that genes can causally influence the environment as well as vice versa. The implication of this insight is that natural selection is a dynamic system: the idea that information flows only downstream, from environment to genotype to phenotype, is a useful fiction that (like Newtonian physics) may approximate 99% of reality, but breaks down under extreme circumstances – i.e. when animals evolve complex enough behaviour to change their environment radically. In these circumstances, does it make sense any more to speak of “maximising fitness”, since fitness is always relative to a given environment? Is the ability to change one’s environment part of one’s fitness? I would think it makes more sense to see things in terms of a fitness landscape with attractors dotted around it. I have no idea how to flesh that out theoretically, but I get the sense that the modern synthesis does break down a bit there.

(An aside about fitness: To be honest, the phrase “maximising fitness” gets my hackles up at the best of times. I tend to think of evolution as a deeply historical, stochastic process, and this phrase just seems like an abstraction too far to me. I don’t think I’m the only one… How does one know what the maximum fitness is in a given environment and for given developmental constraints? And as Emma pointed out, the maximum will vary wildly as the environment varies anyway. So maybe the phrase makes as much sense with niche construction as it ever does. I guess my intuition is just that allowing genes to feed back into the environment makes the system truly dynamic. And there is an important difference between viewing behaviour as an extended phenotype – as I suppose Dickins & Rahman do – and viewing it as niche construction, which is that niche construction affects all members of a community, whereas conceptually, an extended phenotype is likely to be seen as affecting only the bearers of a particular genotype. Maybe that distinction needs to be highlighted more, I don’t know: I’ve never seen it made before, but then I feel a bit out of my depth here … Sometimes I wish I had a biology degree!)

(ii) Section 5 mainly talks about rats. Despite the fact that they criticise Bolhuis et al.’s argument about human brain evolution, nowhere do they acknowledge the point that a human mind is qualitatively different from a rat mind. As Dawkins noted back in the 70s (and probably others before him) humans are different because we have symbolic cultural systems (e.g. language) that are replicated by exact imitation. This is a parallel evolutionary system, a form of “soft inheritance” that must interact with “hard inheritance” in conceptually very problematic ways. Yes, niche construction might be a footnote if we looked only at the rest of the animal kingdom, but one of the most exciting things about the idea – for me at least! – is that it provides a really nice way to think about how human culture may on the one hand be rooted in non-human social learning – since other animals practise ‘primitive’ forms of niche construction – while on the other hand taking things to a whole new level in terms of our ability to impact our environment. Dickins & Rahman’s focus on epigenetics, in this article, leaves that appeal completely intact, in my mind.

Really interested  in getting a proper discussion going about this, particularly from people who have the biological training that I lack!

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4 Responses to The extended evolutionary synthesis and the role of soft inheritance in evolution

  1. C McC says:

    Hey I may as well share what I sent to you earlier so people can butcher it 😉

    “Hey Gordon, saw your post on that paper. Just downloaded it. I’ve been loosely following the literature on the EES since the big Altenberg conference in 2008. You probably heard of it – was organised by Massimo Pigliucci, cited in the Dickens et al paper. I read a few chapters of the edited book that came out of it (Pigliucci & Muller)and I am sympathetic to the EES idea. There was a trashy science ‘journalism’ book came out of it that was an overblown take on EES that kind of ruined any proper discussion that would have been had about it.

    I’d absolutely agree that niche-construction is a part of an organisms ‘fitness’, and I’d also agree that ‘maximising fitness’ is a limited concept given that environments change, and can be changed by organisms’ agency. Steven Rose is quite good on this, as is Richard Lewontin (see Triple Helix: gene, organism, environment).

    A lot of scientists are dismissive of philosophers but I think the discussion of ‘fitness’ and related ideas requires conceptual clarity that simply amassing empirical data cannot give. Lewontin/Levin’s concept of ‘dialectical biology’ (unashamedly related to their marxist politics, which I am of course sympathetic to) I think does make sense. The relationship isn’t one-way – it is dynamic, genes can probabilistically influence an organisms behaviour in particular directions, and in turn that organism can change it’s environment to suit itself, effectively influencing the selective pressures on itself.

    I think this relates to Dawkins’ ‘extended phenotype’ – though he is of course reluctant to see this as an sort of extension of the modern synthesis and is happy to subsume it within standard modern synthesis Darwinian theory.

    For me, the notion of fitness is a tad ephemeral one, forever fluid, dynamic and changing. I actually try to slip in the notion into lessons that evolution (and its many processes, ie not just natural selection) might usefully, to my mind at least, be thought of as a ‘sufficientizing’ process, instead of perhaps an ‘optimising/maximising’ one. In this sense, i’d see that because of the ever-changing nature of the organism-environment interaction, it’s better to be a generalist that is reflexive in adaptive terms, as opposed to ‘optimally’ fit in one direction. Take the example of predator prey relationships – you don’t need to be the ‘fittest’ in your pack to escape a predator, but simply ‘fit enough’ so as not to be last! I think I personally am in need of some conceptual clarity! 😉 [I understand that played over large populations, over long periods, this will move toward optimisation, but because it’s fluidity, is forever playing catch-up]

    That’s probably way over-simplistic and full of flaws, but I’m just thinking out loud here, and admittedly teach the standard story which as you say, is useful 99% of the time. The school textbooks haven’t caught up with any of these fancy discussions yet anyway!

    It’s refreshing to hear you talk about stochastic contingent processes. Although I must confess, my impression is that it’s not usually the language of those working close to evolutionary psychology!! 😉

    I don’t know if you’ve read Fodor/Palmarini’s ‘what darwin got wrong’ and the associated barrage of abuse it got from both biologists and philosophers, mostly warranted to my mind, but I think it also has partial relevance to the discussion. If anything the numerous reviews it got taught me more than the book itself.
    Fodor also debated Massimo Pigliucci and, separately, Elliott Sober on the Infidel Guy and Bloggingheads podcasts/vidcast respectively, worth a look. A fair bit on epigenetics and EES.

    You have to remember I’m not NOT an academic – just a lowly old secondary school biology teacher 😉


  2. Gordon says:

    Thanks Conor, those are some useful references. And don’t try to deceive people by saying that you’re not an academic: I know that you could easily have been one, you just chose a different (and in many ways more difficult) path!

    It’s reassuring for me to read someone who has read widely in evolutionary theory (much more widely than me, anyway) and who thinks much the same way I do about the key concepts. I agree with everything you write above. But I have encountered an awful lot of people who think in very “billiard ball” terms about things like fitness and adaptations – particularly in evolutionary psychology, indeed. I guess the sort of psychologist who gets drawn to evolutionary thinking tends to have that kind of mind. Not me though!

    Mind you, I finally got round to reading the Dickins & Rahman paper properly today, and funnily enough they also talk about evolution as a stochastic process, on the one hand; and yet on the other hand, they see natural selection as a fitness-maximising process, and everything (even epigenetics) as an adaptation. Go figure!

    Your idea of natural selection as a sufficientising, rather than maximising/optimising, process is very apt, actually. Surely a good slogan for evolution would be “You don’t have to be the best; you just have to be better than the competition.” This is after all why local species so often get wiped out when new competitors get introduced from other locations. If they were ‘perfectly’ adapted to their local environment, this wouldn’t happen, because they’d be able to exploit it in ways that the invaders wouldn’t.

  3. C McC says:

    Lemme digest some of this and get back to you, but quickly…

    Your observation that the paper subsumes epigenetics within the standard darwinian paradigm is consistent with how, say, Dawkins’ views both epigenetics and gene-environment interactions. In an interview on an epigenetics article in New Scientist in 2008 ( Dawkins was open about seeing this as falling under the explanatory power of standard adaptationist accounts. You might also like Larry Moran (biochemist) and his blog
    Moran is very much a ‘pluralist’.

    Dawkins interview of Steven Rose is a worth a quick watch
    Though not about epigenetics, is certainly relevant as Rose has spent most of his career trying to move biology out of the standard adaptationist accounts into a more pluralistic approach.

  4. Ken Jopp says:

    As the extended synthesis progresses, a pattern that seems to progress with it is that of exogenous factors exerting a lesser influence on evolution and endogenous factors exerting a greater role. Extrapolating from this trend points toward evolution being a developmental process, a conclusion asserted at .

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