Mentioned a few posts ago that pretty much everything posted by the EES (Extended Evolutionary Synthesis) project seemed to be valuable to my own research agenda. I also noted at that point that I wasn’t really sure who they were, simply a large collection of like-minded thinkers posting under the one on-line banner. I realised pretty quickly the reason I am plugged into EES is because some of the individuals I follow (including eg @MassimoPigliucci and @DanielDennett) were amongst them.
Today Massimo’s post on his own Footnotes to Plato blog was specifically about the distinction between epi-genetics and Lamarckian inheritance in the EES sphere. Biologically, clearly, only materials present in the gametes (sperm or egg) can be inherited at conception (or in the cells that divide-off in asexual reproduction). However it gets replicated into all (relevant) cells of the new adult and offspring of the new adult, if it does, it’s inherited. If it can be systemically modified by environmental exposure of the individual, that can be over and above random mutation in the DNA-based gene. The bit that’s Darwinian either way is the mechanism by which divergent populations eventually turn-out (with hindsight) to be distinct species.
Genes / genetic have suffered the same evolution in meaning as atoms / atomic – conceptually the smallest units, or simply the first such units so named? Really the smallest particles of heritable reproduction are genetic, whether in the stuff we now call “genes” or elsewhere in the reproducing cell structures of the new individual.
What is clear is that what is inherited “genetically” is particulate / digital at the cellular level – even if modifications can be acquired by environmental exposure – they are not acquired qualitatively by degrees between whole individuals. In that sense there is no Lamarckian (biological) inheritance of acquired “traits” per se – where a cell is the smallest unit of identity and cells don’t have traits as properties.
The reason I’m more relaxed about hanging on to Lamarckism is because I’m interested (like Dennett) in the whole human evolutionary design space (0,0,0 to 1,1,1 Darwinian) which includes mental / cultural evolution as well as cellular / biological. In that space memes (and patterns / memeplexes) are even less objective than genes (in the generic non-DNA sense) and as I say even genes are not that well defined objectively. Epi-genetic, like “sub-atomic” is a somewhat artificial category, simply a consequence of what has previously been defined as genetic / atomic.
Need to re-read Pigliucci more closely – using the genotype / phenotype language around species and populations of individuals – and see if this digital distinction is apparent.
[Hold – epigenetics beyond cell contents – post-fertilisation development environment?]
[Hold – systemic bio-DNA-gene modification beyond random mutation?]
Guess I’m reacting to the hard statement – implying no such thing as Lamarckism. Quite happy with questioning how much use is left in the word, and where. (I already inhabit a physical world where the fundamentals are digital information, so no suggestion that the Lamarckian / non-Darwinian end of the scale is about traits acquired by an individual being “somehow, to some extent” inherited by future offspring as a whole.)
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Post Note: After rambling around the issues in my doubts above, I read again focussing on the genotype phenotype distinctions, and the whole question was made clear in this Twitter exchange.
Still have trouble not seeing environmentally modifiable heritable features as Lamarckian. (Whatever bio layers, Lamarck was never about how.)
” Ian Glendinning (@psybertron) September 19, 2017
I get that’s what you’re doing – just thinking / writing some thoughts – maybe just a language problem with “not Lamarckian” meaning … ?
” Ian Glendinning (@psybertron) September 19, 2017
but hm “phenotype is not inherited” for epigenetics? It’s the same for genetics: only genotypes are inherited. Phenotype is always indirect.
” Mary P”niscus (@marypaniscus) September 19, 2017
“Only genotypes are inherited.
Phenotype is always indirect.”
Mary’s point says it clearly, Darwinian or Lamarckian, inheritance is genetic (DNA-genetic or generic / epi-genetic). Phenotypic properties – however developed / acquired – are never inherited directly between individuals.
Mary goes on to make a further important point, although it doesn’t yet seem signigicant to my own agenda:
Yes. I was skeptical of the essay, since one does see heritable phenotypes. But that it usually seems maladaptive is actually a huge point.
” Mary P”niscus (@marypaniscus) September 19, 2017
The point is neither Lamarck, nor Darwin, was really saying anything about the mechanism of inheritance. Darwin’s key point was that the population divergence and speciation was “natural selection”. Neither even imagined the underlying digital significance; inheritance at the information level.
Massimo’s headline claim is true – “Epigenetics is not Lamarckism” – but the rant against Lamarck per se (almost nobody writing today has actually read Lamarck) seems unwarranted?
What is (relatively) new and important in the work behind Massimo’s essay is not what it says about Lamarck, but what it says about the enormous possibilities for acquired mutations in reproductive development lifecycles, beyond simply DNA (mis)replication. Epigenetics. Genetic biology is more than “genes” in the same sense that atomic physics is more than “atoms”. Biology or physics, what matters is information.
[Aside – Even Crick knew we were talking about information.
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