Beyond the Modern Synthesis: A Framework for a More Inclusive Biological Synthesis


The Modern Synthesis (MS), the dominant paradigm in evolutionary biology for much of the 20th century, unified Darwinian evolution with Mendelian genetics. However, recent discoveries and theoretical advancements have exposed limitations in the MS framework. This paper argues for a new approach – the Inclusive Biological Synthesis (IBS)(EES) – that moves beyond the MS while incorporating insights from diverse biological subfields.

The Case for Moving Beyond the Modern Synthesis

The MS focused on natural selection acting on genetic variation within populations. While successful in Microevolution, it struggled to fully account for:

  • The Role of Development: Evo-devo (evolutionary developmental biology) demonstrates how developmental processes influence phenotypic variation and evolution. The MS largely ignored the intricate dance between genes and development.

  • Non-Genetic Inheritance: Epigenetic modifications, for instance, can be heritable and influence phenotypes across generations, challenging the MS's strict gene-centric view.



  • Symbiosis and Cooperation: The MS primarily emphasized competition; however, cooperation and symbiosis play crucial roles in evolution, as highlighted by fields like microbial ecology.

  • Multilevel Selection: The MS primarily focused on selection acting on genes within populations. However, selection can occur at multiple levels, from individual organisms to entire ecosystems.

These limitations have spurred calls for a more encompassing framework. Terms like "postmodern synthesis," "integrative synthesis," and "extended evolutionary synthesis" reflect this desire.

The Inclusive Biological Synthesis: A New Framework

The IBS proposes a broader perspective on life, focusing on its fundamental nature as a contingent dynamic process – a continuous "survival enterprise." This framework emphasizes the constant challenge of acquiring resources and reproducing in a particular environment, with biological survival and reproduction representing the core existential problem driving all biological phenomena.

Key principles of the IBS include:

  • Life as a Survival Enterprise: All living entities are constantly adapting to environmental pressures. Epigenetics allows rapid adaptation too fast for random mutations and natural selection. Epigenetics acts 100,000 times as fast as mutations. There's the challenge of acquiring resources and reproducing defines all biological processes.

  • Contingency and Historical Context: Evolutionary pathways are contingent on initial conditions and historical events. Different starting points can lead to diverse outcomes, even under similar selection pressures.

  • Multiple Levels of Organization: Selection can occur at various levels – genes, organisms, populations, species, and even ecosystems. Each level can influence evolutionary outcomes.

  • Integration of Diverse Biological Phenomena: The IBS aims to integrate insights from various subfields like evo-devo, microbial ecology, and epigenetics to create a more comprehensive picture of life's processes.

  • Focus on Process, Not Just Pattern: Understanding the ongoing dynamics of how biological systems acquire resources, reproduce, and adapt takes precedence over simply documenting observed patterns.

Advantages of the Inclusive Biological Synthesis

The IBS offers several advantages over the MS:

  • Greater Explanatory Power: The IBS can more readily account for phenomena not fully explained by the MS, such as the evolution of complex morphologies, the importance of cooperation, and the role of epigenetics in inheritance.

  • Enhanced Integration: The IBS fosters a more unified understanding of biology by bridging the gap between evolutionary theory and various subfields.

  • Focus on Dynamics: By emphasizing processes rather than static patterns, the IBS encourages a more dynamic view of living systems.

Explanatory Power of the IBS: A Deeper Dive

The IBS sheds light on phenomena challenging the MS. Take the evolution of complex morphologies. Under the MS, such intricate structures were primarily explained by gradual accumulation of beneficial mutations. However, the IBS, by incorporating evo-devo concepts, can account for the role of gene regulatory networks in orchestrating developmental pathways. Subtle changes in these networks can lead to significant morphological changes, providing a more nuanced understanding of how complex traits evolve.

Another example is the prevalence of cooperation and symbiosis in nature. The MS primarily emphasized competition; however, the IBS recognizes that cooperation can enhance survival and reproduction. Microbial communities, for instance, often exhibit intricate cooperative interactions that enhance their collective ability to acquire resources. The IBS allows for a more comprehensive view of the diverse strategies organisms employ to navigate their environments.

Criticisms and Refinements of the IBS

The broad nature of the IBS might invite criticism. As the framework develops and incorporates more specific models from various disciplines, its predictive power will increase. Additionally, the vastness of the IBS could pose challenges in formalization. Here, fostering collaboration between evolutionary biologists and researchers from other fields is crucial. By drawing on diverse theoretical tools, the IBS framework can be refined and formalized without sacrificing its inclusivity.



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