Baldwin effect
In
"A New Factor in Evolution"
The effect, then unnamed, was put forward in 1896 in a paper "A New Factor in Evolution" by the American psychologist James Mark Baldwin, with a second paper in 1897.[1][2] The paper proposed a mechanism for specific selection for general learning ability. As the historian of science Robert Richards explains:[3]
If animals entered a new environment—or their old environment rapidly changed—those that could flexibly respond by learning new behaviours or by ontogenetically adapting would be naturally preserved. This saved remnant would, over several generations, have the opportunity to exhibit spontaneously congenital variations similar to their acquired traits and have these variations naturally selected. It would look as though the acquired traits had sunk into the hereditary substance in a Lamarckian fashion, but the process would really be neo-Darwinian.[3]
Selected offspring would tend to have an increased capacity for learning new skills rather than being confined to genetically coded, relatively fixed abilities. In effect, it places emphasis on the fact that the sustained behaviour of a species or group can shape the evolution of that species. The "Baldwin effect" is better understood in
Thanks to the Baldwin effect, species can be said to pretest the efficacy of particular different designs by phenotypic (individual) exploration of the space of nearby possibilities. If a particularly winning setting is thereby discovered, this discovery will create a new selection pressure: organisms that are closer in the adaptive landscape to that discovery will have a clear advantage over those more distant.[6]
An update to the Baldwin effect was developed by
Subsequent research shows that Baldwin was not the first to identify the process; Douglas Spalding mentioned it in 1873.[8]
Controversy and acceptance
Initially Baldwin's ideas were not incompatible with the prevailing, but uncertain, ideas about the mechanism of transmission of hereditary information and at least two other biologists put forward very similar ideas in 1896.[9][10] In 1901, Maurice Maeterlinck referred to behavioural adaptations to prevailing climates in different species of bees as "what had merely been an idea, therefore, and opposed to instinct, has thus by slow degrees become an instinctive habit".[11] The Baldwin effect theory subsequently became more controversial, with scholars divided between "Baldwin boosters" and "Baldwin skeptics".[12] The theory was first called the "Baldwin effect" by George Gaylord Simpson in 1953.[12] Simpson "admitted that the idea was theoretically consistent, that is, not inconsistent with the modern synthesis",[12] but he doubted that the phenomenon occurred very often, or if so, could be proven to occur. In his discussion of the reception of the Baldwin-effect theory Simpson points out that the theory appears to provide a reconciliation between a neo-Darwinian and a neo-Lamarckian approach and that "Mendelism and later genetic theory so conclusively ruled out the extreme neo-Lamarckian position that reconciliation came to seem unnecessary".[4] In 1942, the evolutionary biologist Julian Huxley promoted the Baldwin effect as part of the modern synthesis, saying the concept had been unduly neglected by evolutionists.[4][13][14]
In the 1960s, the evolutionary biologist Ernst Mayr contended that the Baldwin effect theory was untenable because
- the argument is stated in terms of the individual genotype, whereas what is really exposed to the selection pressure is a phenotypically and genetically variable population;
- it is not sufficiently emphasized that the degree of modification of the phenotype is in itself genetically controlled;
- it is assumed that phenotypic rigidity is selectively superior to phenotypic flexibility.[15]
In 1987 Geoffrey Hinton and Steven Nowlan demonstrated by computer simulation that learning can accelerate evolution, and they associated this with the Baldwin effect.[16][17][18]
Paul Griffiths[19] suggests two reasons for the continuing interest in the Baldwin effect. The first is the role mind is understood to play in the effect. The second is the connection between development and evolution in the effect. Baldwin's account of how neurophysiological and conscious mental factors may contribute to the effect[20][21][1] brings into focus the question of the possible survival value of consciousness.[22]
Still, David Depew observed in 2003, "it is striking that a rather diverse lot of contemporary evolutionary theorists, most of whom regard themselves as supporters of the Modern Synthesis, have of late become 'Baldwin boosters'".[12] These
are typically
evolutionary psychologists who are searching for scenarios in which a population can get itself by behavioral trial and error onto a "hard to find" part of the fitness landscape in which human brain, language, and mind can rapidly coevolve. They are searching for what Daniel Dennett, himself a Baldwin booster, calls an "evolutionary crane," an instrument to do some heavy lifting fast.[12]
According to Dennett, also in 2003, recent work has rendered the Baldwin effect "no longer a controversial wrinkle in orthodox Darwinism".[6] Potential genetic mechanisms underlying the Baldwin effect have been proposed for the evolution of natural (genetically determinant) antibodies.[24] In 2009, empirical evidence for the Baldwin effect was provided from the colonisation of North America by the house finch.[23]
The Baldwin effect has been incorporated into the extended evolutionary synthesis.[25][26][27]
Comparison with genetic assimilation
The Baldwin effect has been confused with, and sometimes conflated with, a different evolutionary theory also based on phenotypic plasticity, C. H. Waddington's genetic assimilation. The Baldwin effect includes genetic accommodation, of which one type is genetic assimilation.[28] Science historian Laurent Loison has written that "the Baldwin effect and genetic assimilation, even if they are quite close, should not be conflated".[29]
See also
- Evolvability – Capacity of a system for adaptive evolution
- Maternal effect – Influence of mother's environment and genotype on offspring's phenotype
- Meme – Thought or idea that can be shared, in analogy to a gene
- Pangenesis – Darwin's proposed mechanism for heredity
- Weismann barrier – Distinction between germ cell lineages producing gametes and somatic cells
Notes
- ^ a b Baldwin 1896a.
- ^ Baldwin 1897.
- ^ ISBN 978-0-226-71199-7.
- ^ a b c Simpson 1953.
- ^ Newman 2002.
- ^ ISBN 978-0-262-23229-6.
- .
- Stigler's law.
- PMID 17735249.
- PMID 17734840.
- ^ Materlinck, Maurice (1901). The Life of the Bee. Dodd, Mead and Co. pp. Chapter VII section 102.
- ^ ISBN 978-0-262-23229-6.
- S2CID 9214778.
- ISBN 978-0-429-97145-7.
- ISBN 978-0-674-03750-2.
- ^ Hinton, Geoffrey E.; Nowlan, Steven J. (1987). "How learning can guide evolution". Complex Systems. 1: 495–502.
- S2CID 5476916.
- ISBN 9780262232296.
- ISBN 9780262232296.
- PMID 17780356.
- PMID 17835006.
- ISBN 978-90-272-5157-2.
- ^ PMID 19324617.
- S2CID 20023879.
- ^ Pigliucci, Massimo. Phenotypic Plasticity. In Massimo Pigliucci, and Gerd B. Müller (eds), Evolution: The Extended Synthesis (Cambridge, MA, 2010; online edn, MIT Press Scholarship Online, 22 Aug. 2013).
- PMID 29763656.
- doi:10.1086/714999.
- S2CID 9292273.
- PMC 8059632.
References
- Bateson, Patrick (2004). "The Active Role of Behaviour in Evolution". Biology and Philosophy. 19 (2): 283–298. S2CID 85267141.
- S2CID 7059820.
- PMID 17781159.
- Hall, Brian K. (2001). "Organic Selection: Proximate Environmental Effects on the Evolution of Morphology and Behaviour". Biology and Philosophy. 16 (2): 215–237. S2CID 80821399.
- Newman, Stuart A. (2002). "Putting Genes in their place" (PDF). Journal of Biosciences. 27 (2): 97–104. S2CID 1162454. Archived from the original(PDF) on 2008-12-17.
- PMID 17734840.
- JSTOR 2405746.
- Sznajder, B.; Sabelis, M. W.; Egas, M. (September 2012). "How Adaptive Learning Affects Evolution: Reviewing Theory on the Baldwin Effect". Evolutionary Biology. 39 (3): 301–310. PMID 22923852.