The Organism in Evolutionary Explanation: From Early Twentieth Century to the Extended Evolutionary Synthesis- review


Article, The Organism in Evolutionary Explanation: From Early Twentieth Century to the Extended Evolutionary Synthesis (3/2023)

Introduction

The organism has played a central role in evolutionary biology since its inception. However, the way in which organisms are conceptualized and explained has changed significantly over time. In the early twentieth century, there was a strong emphasis on the organism as a passive product of its genes and environment. This view was challenged by the organicist movement, which emphasized the active role of organisms in their own development and evolution. The Modern Synthesis (aka NeoDarwinism), which emerged in the middle of the twentieth century, largely ignored the organicist perspective and instead focused on gene-based explanations of evolution. However, in recent years, there has been a renewed interest in the organism, and this has led to the development of the Extended Evolutionary Synthesis (EES). The EES seeks to integrate the insights of the organicist movement into evolutionary biology by emphasizing the role of development, behavior, and niche construction in evolution.

The Early Twentieth Century: The Organism as a Passive Product of Genes and Environment

The early twentieth century was a time of great ferment in evolutionary biology. The rediscovery of Mendel's laws of inheritance and the development of population genetics led to a new understanding of how genes are transmitted from generation to generation. This, in turn, led to the view that organisms are essentially passive products of their genes and environment. This view was further reinforced by the rise of behaviorism, which emphasized the role of environmental stimuli in shaping behavior.

The Organicist Movement: A Reaffirmation of the Active Organism

The organicist movement, which emerged in the 1920s and 1930s, challenged the prevailing view of the organism as a passive product of genes and environment. Organicists argued that organisms are active agents that play a role in their own development and evolution. They emphasized the importance of internal factors, such as an organism's developmental history and its capacity for self-regulation, in shaping its phenotype.

The Modern Synthesis: Genes Take Center Stage

The Modern Synthesis, which emerged in the 1940s, largely ignored the organicist perspective and instead focused on gene-based explanations of evolution. The Modern Synthesis was a highly followed research program, and it is still followed by evolutionary biology today. However, some critics have argued that the Modern Synthesis is too gene-centric and that it does not adequately account for the role of organisms in evolution.

The Extended Evolutionary Synthesis: A Return to Organism-Centered Explanations

The Extended Evolutionary Synthesis (EES) is a recent development in evolutionary biology that seeks to integrate the insights of the organicist movement into evolutionary theory. The EES emphasizes the role of development, behavior, and niche construction in evolution. It also emphasizes the importance of understanding the organism as a whole system, rather than simply as a collection of genes.

Conclusion

The role of the organism in evolutionary explanation has changed significantly over time. The early twentieth century was dominated by the view of the organism as a passive product of genes and environment. This view was challenged by the organicist movement, which emphasized the active role of organisms in their own development and evolution. The Modern Synthesis largely ignored the organicist perspective and instead focused on gene-based explanations of evolution. However, in recent years, there has been a renewed interest in the organism, and this has led to the development of the Extended Evolutionary Synthesis. The EES seeks to integrate the insights of the organicist movement into evolutionary theory by emphasizing the role of development, behavior, and niche construction in evolution.

The Extended Evolutionary Synthesis (EES) is a proposed expansion of evolutionary theory that emphasizes the role of organisms in shaping their own evolution. In contrast to neo-Darwinism, which focuses primarily on genes and populations, the EES argues that organisms are active participants in their own evolutionary trajectories. This perspective has significant implications for our understanding of evolutionary processes, and it challenges the fundamental assumptions of neo-Darwinism.

One key challenge to neo-Darwinism is the EES's emphasis on development. Neo-Darwinism tends to treat development as a relatively passive process, with genes providing the blueprint for an organism's form and function. However, the EES argues that development is an active and complex process that can influence evolutionary outcomes. For example, an organism's development may constrain the range of possible evolutionary changes, or it may create new opportunities for evolutionary innovation.

The EES also challenges neo-Darwinism's view of the organism-environment relationship. Neo-Darwinism tends to view organisms as passive recipients of environmental influences. However, the EES argues that organisms are actively engaged with their environments, and that these interactions can have a profound impact on evolutionary change. For example, an organism's behavior may influence its exposure to environmental stressors, or its ability to exploit new resources.

Finally, the EES challenges neo-Darwinism's view of agency. Neo-Darwinism tends to view evolution as a purely mechanistic process, with no role for agency or choice. However, the EES argues that organisms can exhibit a degree of agency, and that this agency can play a role in shaping evolutionary outcomes. For example, an organism may choose to mate with a particular partner, or it may learn new behaviors that help it to survive and reproduce.

The EES is a still-developing field, and there is much that we still do not know about the role of organisms in shaping their own evolution. However, the EES offers a promising new perspective on evolutionary theory, and it has the potential to revolutionize our understanding of how life has evolved on Earth.

Here are some specific examples of how the EES challenges neo-Darwinism:

  • The EES emphasizes the role of phenotypic plasticity. Neo-Darwinism tends to focus on genetic changes as the primary driver of evolutionary change. However, the EES argues that phenotypic plasticity, the ability of an organism to change its appearance or behavior in response to environmental cues, can also play an important role in evolution. For example, an organism that is able to develop a thicker coat in colder weather may be more likely to survive and reproduce, even if it does not have any genetic changes that make it more cold-tolerant.

  • The EES emphasizes the role of epigenetic inheritance. Neo-Darwinism tends to focus on genetic inheritance as the only mechanism for passing on traits from one generation to the next. However, the EES argues that epigenetic inheritance, the transmission of traits through non-genetic means, can also play an important role in evolution. For example, an organism that is exposed to a stressor during development may pass on the effects of that stressor to its offspring, even if there are no genetic changes involved.

  • The EES emphasizes the role of niche construction. Neo-Darwinism tends to view organisms as passive recipients of their environments. However, the EES argues that organisms can actively modify their environments, and that these modifications can have a feedback effect on evolution. For example, a beaver that builds a dam may create a new habitat that is more suitable for certain species, while making it less suitable for others.

The EES is a complex and multifaceted theory, and it is still being developed by biologists. However, it is clear that the EES has the potential to revolutionize our understanding of evolution. By emphasizing the role of organisms in shaping their own evolution, the EES offers a more nuanced and holistic view of evolutionary processes.


References

The extended evolutionary synthesis: its structure, assumptions and ... https://royalsocietypublishing.org/doi/10.1098/rspb.2015.1019

Evolutionary biology today and the call for an extended synthesis - https://royalsocietypublishing.org/doi/10.1098/rsfs.2016.0145

Why an extended evolutionary synthesis is necessary - PMC - NCBI https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566817/

https://link.springer.com/article/10.1007/s12064-018-0269-2




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