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”.
(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!