Baldwin effect
Encyclopedia
The Baldwin effect, also known as Baldwinian evolution or ontogenic evolution, is a theory
of a possible evolutionary processes that was originally put forward in 1896 in a paper, "A New Factor in Evolution," by American
psychologist
James Mark Baldwin
. The paper proposed a mechanism for specific selection for general learning ability. 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 behavior of a species or group can shape the evolution of that species. The "Baldwin effect" is better understood in evo-devo (evolutionary developmental biology
) literature as a scenario in which a character or trait change occurring in an organism
as a result of its interaction with its environment becomes gradually assimilated into its developmental genetic or epigenetic repertoire (Simpson, 1953; Newman, 2002). In the words of Daniel Dennett
,
.
Baldwin gives the following case involving cooperation: "Animals may be kept alive let us say in a given environment by social cooperation only; these transmit this social type of variation to posterity; thus social adaptation sets the direction of physical phylogeny and physical heredity is determined in part by this factor" (Baldwin, 1896, p. 553).
The appearance of lactose tolerance
in human populations with a long tradition of raising domesticated animals for milk production has been suggested as another example. This argument holds that a feedback loop operates whereby a dairy culture increases the selective advantage from this genetic trait, while the average population genotype increases the collective rewards of a dairy culture.
in 1953 (p. 3). Simpson "admitted that the idea was theoretically consistent, that is, not inconsistent with the Modern Evolutionary Synthesis" (p. 4), but he doubted that the phenomenon occurred very often, or if so, could be proven to occur.
There have been a number of arguments against the effect. For example, it has been argued that the change from learning to instinct might not constitute an improvement, because only very stable environments where change is extremely slow would favour innate traits as opposed to the plasticity of learning (especially social learning
, which doesn't have such high costs as individual learning by trial-and-error). The very mechanism of the transition has also been questioned, as genetic variations which "tend to decouple [...] behaviour from environmental signals" might be "distant from those genotypes that mediate plastic, learned response".
Still, "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'" (p. 4). These Baldwin boosters
According to Dennett
, recent work has rendered the Baldwin effect "no longer a controversial wrinkle in orthodox Darwinism" (p. 69).
Theory
The English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
of a possible evolutionary processes that was originally put forward in 1896 in a paper, "A New Factor in Evolution," by American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
psychologist
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
James Mark Baldwin
James Mark Baldwin
James Mark Baldwin was an American philosopher and psychologist who was educated at Princeton under the supervision of Scottish philosopher James McCosh and who was one of the founders of the Department of Psychology at the university...
. The paper proposed a mechanism for specific selection for general learning ability. 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 behavior of a species or group can shape the evolution of that species. The "Baldwin effect" is better understood in evo-devo (evolutionary developmental biology
Evolutionary developmental biology
Evolutionary developmental biology is a field of biology that compares the developmental processes of different organisms to determine the ancestral relationship between them, and to discover how developmental processes evolved...
) literature as a scenario in which a character or trait change occurring in an organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
as a result of its interaction with its environment becomes gradually assimilated into its developmental genetic or epigenetic repertoire (Simpson, 1953; Newman, 2002). In the words of Daniel Dennett
Daniel Dennett
Daniel Clement Dennett is an American philosopher, writer and cognitive scientist whose research centers on the philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the Co-director of...
,
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. (p. 69, quoting Dennett, 1991)
Examples
Suppose a species is threatened by a new predator and there is a behavior that makes it more difficult for the predator to kill individuals of the species. Individuals who learn the behavior more quickly will obviously be at an advantage. As time goes on, the ability to learn the behavior will improve (by genetic selection), and at some point it will seem to be an instinctInstinct
Instinct or innate behavior is the inherent inclination of a living organism toward a particular behavior.The simplest example of an instinctive behavior is a fixed action pattern, in which a very short to medium length sequence of actions, without variation, are carried out in response to a...
.
Baldwin gives the following case involving cooperation: "Animals may be kept alive let us say in a given environment by social cooperation only; these transmit this social type of variation to posterity; thus social adaptation sets the direction of physical phylogeny and physical heredity is determined in part by this factor" (Baldwin, 1896, p. 553).
The appearance of lactose tolerance
Lactose intolerance
Lactose intolerance, also called lactase deficiency or hypolactasia, is the inability to digest and metabolize lactose, a sugar found in milk...
in human populations with a long tradition of raising domesticated animals for milk production has been suggested as another example. This argument holds that a feedback loop operates whereby a dairy culture increases the selective advantage from this genetic trait, while the average population genotype increases the collective rewards of a dairy culture.
Contrary effect
The opposite of the Baldwin effect is 'shielding'. Modern medicine for example could artificially control a pathogen preventing any genetic immunity against the pathogen from being selected for. Here learned behaviour that improves fitness prevents genetic adaptation.Status
The Baldwin effect theory has been controversial, with scholars being split between "Baldwin boosters" and "Baldwin skeptics". The theory was first called the "Baldwin effect" by George Gaylord SimpsonGeorge Gaylord Simpson
George Gaylord Simpson was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern evolutionary synthesis, contributing Tempo and mode in evolution , The meaning of evolution and The major features of...
in 1953 (p. 3). Simpson "admitted that the idea was theoretically consistent, that is, not inconsistent with the Modern Evolutionary Synthesis" (p. 4), but he doubted that the phenomenon occurred very often, or if so, could be proven to occur.
There have been a number of arguments against the effect. For example, it has been argued that the change from learning to instinct might not constitute an improvement, because only very stable environments where change is extremely slow would favour innate traits as opposed to the plasticity of learning (especially social learning
Observational learning
Observational learning is a type of learning that occurs as a function of observing, retaining and replicating novel behavior executed by others...
, which doesn't have such high costs as individual learning by trial-and-error). The very mechanism of the transition has also been questioned, as genetic variations which "tend to decouple [...] behaviour from environmental signals" might be "distant from those genotypes that mediate plastic, learned response".
Still, "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'" (p. 4). These Baldwin boosters
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 DennettDaniel DennettDaniel Clement Dennett is an American philosopher, writer and cognitive scientist whose research centers on the philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the Co-director of...
, himself a Baldwin booster, calls an "evolutionary crane," an instrument to do some heavy lifting fast.
(p. 4)
According to Dennett
Daniel Dennett
Daniel Clement Dennett is an American philosopher, writer and cognitive scientist whose research centers on the philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the Co-director of...
, recent work has rendered the Baldwin effect "no longer a controversial wrinkle in orthodox Darwinism" (p. 69).
See also
- EvolvabilityEvolvabilityEvolvability is defined as the capacity of a system for adaptive evolution. Evolvability is the ability of a population of organisms to not merely generate genetic diversity, but to generate adaptive genetic diversity, and thereby evolve through natural selection.In order for a biological organism...
- Genetic assimilationGenetic assimilationNote: Genetic assimilation is sometimes used to describe "eventual extinction of a natural species as massive pollen flow occurs from another related species and the older crop becomes more like the new crop." This usage is unrelated to the usage below....
- James Mark BaldwinJames Mark BaldwinJames Mark Baldwin was an American philosopher and psychologist who was educated at Princeton under the supervision of Scottish philosopher James McCosh and who was one of the founders of the Department of Psychology at the university...
- LamarckismLamarckismLamarckism is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring . It is named after the French biologist Jean-Baptiste Lamarck , who incorporated the action of soft inheritance into his evolutionary theories...
- PangenesisPangenesisPangenesis was Charles Darwin's hypothetical mechanism for heredity. He presented this 'provisional hypothesis' in his 1868 work The Variation of Animals and Plants under Domestication and felt that it brought 'together a multitude of facts which are at present left disconnected by any efficient...
- Phenotypic plasticityPhenotypic plasticityPhenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. Such plasticity in some cases expresses as several highly morphologically distinct results; in other cases, a continuous norm of reaction describes the functional interrelationship...
- Weismann barrierWeismann barrierThe Weismann barrier is the principle that hereditary information moves only from genes to body cells, and never in reverse. In more precise terminology hereditary information moves only from germline cells to somatic cells .This does not refer to the central dogma of molecular biology which...