What is Devolution (biology)?
Devolution, de-evolution, or backward evolution is a concept in biology that suggests species can revert to supposedly more primitive forms over time. This idea is often associated with the notion of teleology, or the idea that evolution is purposeful and progressive. However, evolutionary biology makes no such assumptions, and natural selection shapes adaptations with no foreknowledge or foresight regarding the outcome.
History and Key Figures
The concept of devolution was widely believed in the 19th century, particularly among zoologists and palaeontologists. Zoologists such as Ray Lankester and Anton Dohrn, and palaeontologists Alpheus Hyatt and Carl H. Eigenmann, advocated for the idea of devolution during this time. However, the idea was later disputed by the discovery of Dollo's law of irreversibility, first stated in 1893 by the palaeontologist Louis Dollo.
Dollo's Law of Irreversibility
Dollo's law, which denies the possibility of devolution, states that evolution is unlikely to follow the same path twice. This means that even if a species were to revert to a supposedly more primitive form, it is unlikely that it would do so in exactly the same way as it evolved in the first place. British evolutionary biologist Richard Dawkins explains Dollo's law as being simply a statement about the improbability of evolution's following precisely the same path twice.
Examples and Implications
The concept of devolution appears in Kurt Vonnegut's 1985 novel Galápagos, which portrays a society that has evolved backwards to have small brains. While this is a fictional example, it illustrates the idea that devolution could potentially occur in a hypothetical scenario. However, in reality, devolution is not a recognized process in evolutionary biology, and the concept is not supported by scientific evidence.
Relationship to Evolutionary Biology
Evolutionary biology makes no assumptions about the direction or outcome of evolution. Natural selection shapes adaptations with no foreknowledge or foresight regarding the outcome, and species can evolve in complex and unpredictable ways. Devolution, as a concept, is not compatible with a proper understanding of evolution due to natural selection.
FAQ
What is the main argument against devolution in evolutionary biology? The main argument against devolution in evolutionary biology is Dollo's law of irreversibility, which states that evolution is unlikely to follow the same path twice.
Is devolution a recognized process in evolutionary biology? No, devolution is not a recognized process in evolutionary biology, and the concept is not supported by scientific evidence.
Who first stated Dollo's law of irreversibility? Dollo's law of irreversibility was first stated by the palaeontologist Louis Dollo in 1893.
How does devolution relate to teleology in evolutionary biology? Devolution is often associated with the notion of teleology, or the idea that evolution is purposeful and progressive.
What is the relationship between devolution and natural selection? Evolutionary biology makes no assumptions about the direction or outcome of evolution, and natural selection shapes adaptations with no foreknowledge or foresight regarding the outcome.