Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life
Eva Jablonka and Marion J. Lamb
MIT Press, 2005
Ten years ago, Jablonka and Lamb published Epigenetic Inheritance and Evolution, a book with the provocative subtitle, The Lamarckian Dimension. In this new work, they update and pursue their project to expand evolutionary biology beyond what they see as its gene-centred approach.
The authors dispute Dawkins’ claim that the gene is the only biological hereditary unit, discussing other inheritance systems where his distinction between replicator and vehicle does not seem to hold. Research on bacteria seems to show that some mutation is non-random, i.e. is to some extent directed by environmental or developmental factors. Hence evolution by natural selection may itself produce mutation-generation systems that confer selective advantage.
Such talk seems to flout the central dogma of modern biology, that inheritance of acquired characteristics is impossible, as it would require that what happens to a body’s proteins be somehow "back-translated" into information stored in DNA. This, as Dawkins put it, would be like the accidental burning of a cake somehow affecting its recipe. However, the authors argue that genetic changes simulating acquired changes would concern regulatory, not coding, sequences in DNA.
Sifting through the many technical issues involved in such phenomena as chromatin marking, prions and RNA interference is no light task, but Jablonka and Lamb make things easier by including great illustrations by Anna Zeligowski, and by ending each chapter with a dialogue with an imaginary critic. Only in the first half of the book, concerning genetic and epigenetic inheritance, does the reader face the details of biological research. The sections on behavioural and symbolic inheritance are relatively non-technical.
The significance of imitation in animals is noted thus: "a new habit can result in animals constructing for themselves an alternative niche in which they and their offspring are selected. Animals are... not just passive subjects of selection because their own activities affect the adaptive value of their genetic and behavioural variations" (p.176).
Discussing symbolic inheritance, the authors criticize meme enthusiasts for ignoring the importance of the construction and interpretation of symbols, and how cultural milieux develop. The above quotation is essentially generalized, via symbols, to cover human evolution.
The upshot seems to be that Darwinism is thriving but Lamarck is no longer taboo. This is still an acquired taste.
This review is reproduced by kind permission of The Skeptic.
© Paul Taylor 2005