Wednesday, December 06, 2006
BBS: Evolution in Four Dimensions (Jablonka and Lamb)
A preprint paper for Behavioral and Brain Sciences* (BBS) with the same title as Jablonka and Lamb's recent book**:
Precis of Evolution in Four Dimensions (pdf file)
by Eva Jablonka* & Marion J. Lamb
*Cohn Institute for the History and Philosophy of Science and Ideas
In his theory of evolution, Darwin recognized that the conditions of life play a role in the generation of hereditary variations, as well as in their selection. However, as evolutionary theory was developed further,heredity became identified with genetics and variation was seen in terms of combinations of randomly generated gene mutations. We argue that this view is now changing, because it is clear that a notion of hereditary variation that is based solely on randomly varying genes that are unaffected by developmental conditions is an inadequate basis for evolutionary theories. Such a view not only fails to provide satisfying explanations of many evolutionary phenomena, it also makes assumptions that are not consistent with the data that are emerging from disciplines ranging from molecular biology to cultural studies. These data show that the genome is far more responsive to the environment than previously thought, and that not all transmissible variation is underlain by genetic differences. In Evolution in FourDimensions we identify four types of inheritance (genetic, epigenetic, behavioural, and symbol-based), each of which can provide variations on which natural selection will act. Some of these variations arise in response to developmental conditions, so there are Lamarckian aspects to evolution. We argue that a better insight into evolutionary processes will result from recognizing that transmitted variations that are not based on DNA differences have played a role. This is particularly true for understanding the evolution of human behaviour, where all four dimensions ofheredity have been important. [Lamarck]
*BBS publishes important and controversial interdisciplinary articles in psychology, neuroscience, behavioral biology, cognitive science, artificial intelligence, linguistics and philosophy. Articles are rigorously refereed and, if accepted, are circulated to a large number of potential commentators around the world in the various specialties on which the article impinges. Their 1000-word commentaries are then co-published with the target article as well as the author's response to each. The commentaries consist of analyses, elaborations, complementary and supplementary data and theory, criticisms and cross-specialty syntheses.
**A recent post on a review of Jablonka and Lamb's book:
Evolution in Four Dimensions: Genetic, Epigentic, Behavioral and Symbolic Variation in the History of Life
From The Skeptic: Ten years ago, Eva Jablonka (homepage) and Marion J. Lamb (retired) 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 Richard 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.
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