"Why an extended evolutionary synthesis is necessary" - review
The article "Why an extended evolutionary synthesis is necessary" by Gerd B. Müller argues that the modern synthesis (MS) of evolutionary biology is no longer sufficient to account for the full range of evolutionary phenomena. Müller identifies three main limitations of the MS:
It is gene-centric, focusing on the role of genes in evolution.
It is adaptationist, assuming that all evolutionary change is adaptive.
It is selectionist, assuming that natural selection is the only important evolutionary force.
Müller argues that these limitations can be overcome by an extended evolutionary synthesis (EES) that incorporates new insights from fields such as developmental biology, behavioral ecology, and cultural evolution. The EES emphasizes the following concepts:
Constructive development: The process by which organisms build their own bodies and minds through interactions with their environment.
Reciprocal causation: The idea that genes, environment, and behavior all influence each other in a dynamic, interactive process.
Multiple inheritance: The idea that genes are not the only source of heritable variation. Other factors, such as epigenetics, can also be inherited.
Niche construction: The idea that organisms can modify their environment in ways that affect their own evolution and the evolution of other species.
Cultural evolution: The idea that cultural traits, such as language and technology, can evolve in a similar way to biological traits.
The EES is still under development, but it has already generated a number of new research questions and hypotheses. For example, the EES can help us to understand how developmental plasticity, niche construction, and cultural evolution can all contribute to evolution. It can also help us to understand how evolutionary change can be rapid and directional, even in the absence of strong natural selection.
The EES is a significant departure from the MS. The EES largely bypasses the MS as it incorporates new insights from a range of other fields. The EES is likely to be the dominant paradigm in evolutionary biology for many years to come.
Here are some additional points that Müller makes in the article:
The MS is incomplete. It does not account for all of the known facts about evolution.
The EES may replace the MS. It is an extension past the MS that incorporates new insights from other fields.
The EES is still under development, but it is already generating new research questions and hypotheses.
The EES is likely to be the dominant paradigm in evolutionary biology for many years to come.
Article snippets:
Why an extended evolutionary synthesis is necessary
Since the last major theoretical integration in evolutionary biology—the modern synthesis (MS) of the 1940s—the biosciences have made significant advances
The rise of molecular biology and evolutionary developmental biology, the recognition of ecological development, niche construction and multiple inheritance systems, the ‘-omics’ revolution and the science of systems biology, among other developments, have provided a wealth of new knowledge about the factors responsible for evolutionary change.
Some of these results are in agreement with the standard theory and others reveal different properties of the evolutionary process
The resulting theoretical framework differs from the latter in its core logic and predictive capacities.
Whereas the MS theory and its various amendments concentrate on genetic and adaptive variation in populations, the extended framework emphasizes the role of constructive processes, ecological interactions and systems dynamics in the evolution of organismal complexity as well as its social and cultural conditions
Among other consequences, the extended framework overcomes many of the limitations of traditional gene-centric explanation and entails a revised understanding of the role of natural selection in the evolutionary process.
A century ago, it was noted in the domain of physics that ‘concepts that have proven useful in ordering things easily achieve such an authority over us that we forget their earthly origins and accept them as unalterable givens. Thus, they come to be stamped as “necessities of thought”, “a priori givens”, etc. The path of scientific advance is often made impassable for a long time through such errors.
Evolutionary biology finds itself in a similar situation today. A well-established paradigm that has its roots in a major theoretical integration that took place approximately eight decades ago, traditionally labelled the modern synthesis (MS) or Synthetic Theory, still dominates evolutionary thought today
In the meantime, the biological sciences have progressed extensively
new evolutionarily relevant factors have been described, including non-genetic inheritance, developmental bias, niche construction, genomic evolution and others
Clearly, our understanding of evolution has significantly expanded, and it would be surprising if these empirical and conceptual advances had no theoretical consequences, so that in the midst of a substantial growth of knowledge, the central theory uniting the different fields of biology remained unaltered
In fact, our theoretical understanding of biological evolution has not remained unaltered
But in the past decade, without much notice by general audiences, a more wide-ranging debate has arisen from different areas of biology as well as from history and philosophy of science, about whether and in which ways evolutionary theory is affected, challenged or changed by the advances in biology and other fields
As usual in such cases, more conservative perspectives and more progressive ones are in conflict with each other, with differences ranging from minor to intense.
A rising number of publications argue for a major revision or even a replacement of the standard theory of evolution [2–14], indicating that this cannot be dismissed as a minority view but rather is a widespread feeling among scientists and philosophers alike.
evolutionary theory cannot be expected to remain static but is subject to change in the light of new empirical evidence.
a growing number of challenges to the classical model of evolution have emerged over the past few years,
Sometimes these challenges are met with dogmatic hostility, decrying any criticism of the traditional theoretical edifice as fatuous
more often the defenders of the traditional conception argue that ‘all is well’ with current evolutionary theory,
it will be useful to characterize some of the differences that exist between the MS theory and proposed alternatives.
whether explicitly or implicitly, still offer a theoretical framework that is largely based on the MS of the 1930s and 1940s.
Even though claims have been made that classical evolutionary biology has continuously incorporated aspects from new conceptual domains [33,36], the majority of tenets and explanations that appear in characterizations of the current theory are still derived from the MS
As can be noted from the listed principles, current evolutionary theory is predominantly oriented towards a genetic explanation of variation, and, except for some minor semantic modifications, this has not changed over the past seven or eight decades.
Whatever lip service is paid to taking into account other factors than those traditionally accepted, we find that the theory, as presented in extant writings, concentrates on a limited set of evolutionary explananda
But it has become habitual in evolutionary biology to take population genetics as the privileged type of explanation of all evolutionary phenomena, thereby negating the fact that, on the one hand, not all of its predictions can be confirmed under all circumstances, and, on the other hand, a wealth of evolutionary phenomena remains excluded.
Criticisms of the shortcomings of the MS framework have a long history
the MS has inherited from the Darwinian account of evolution. Darwin saw slight, incremental and accumulating variation as the essential prerequisite without which ‘my theory would absolutely break down.’
Today, all of these cherished opinions have to be revised, not least in the light of genomics, which evokes a distinctly non-gradualist picture
it is necessary to realize that all models of gradual variation are based on empirical measurements of precisely this kind of change and to the exclusion of other forms of variation
If cases of gradual variation are chosen and quantified, and theoretical models are derived from them, it should not be unexpected that it is gradual variation that will be explained.
in the late 1970s, Gould & Lewontin [41] described the adherence to pervasive adaptationism as an ‘old habit,’ but despite extensive learned discussions of the subject that habit has not receded.
Natural selection, the cornerstone of the MS theory so intimately linked to both gradualism and adaptationism, has itself been the subject of a fair share of critical debate.
it is not so much the principle itself that is contested, but the uniqueness of the causal agency that has been ascribed to it.
Are all features of biological organisms necessarily the result of natural selection, and is it the only factor in the evolutionary process that provides directionality to organismal change?
Numerous authors have challenged the pervasiveness of natural selection as a unique ‘force’ of evolution, whereas others have questioned whether the individual is the sole and appropriate ‘target’ of selection or whether other levels of selection at supra- and infra-individual levels also need to be included in selectionist scenarios
it is apparent that nearly all of the relevant predictions that derive from the MS theory are based on genetic principles and gene determinist convictions.
the long-held belief that genes are the unique determinants of biological form in development and evolution has been challenged by an extensive number of commentators
the genetic program idea underlying MS theory has remained unaltered.
The limitations of the MS theory are not only highlighted by the criticisms directed against several of its traditional tenets but also by the failure to address some of the most important phenomena of organismal evolution
the MS theory lacks a theory of organization that can account for the characteristic features of phenotypic evolution, such as novelty, modularity, homology, homoplasy or the origin of lineage-defining body plans
evo-devo, niche construction, systems biology and other areas harbour the capacity to address at least certain aspects of these topics where the classical theory fails.
this brief overview indicates that the problem agenda associated with the MS theory is extensive.
the current evolutionary paradigm is still dominated by the very same basic assumptions that marked the origin of the synthesis approach
Despite the fact that substantial challenges to these positions have arisen in the past decades from a host of different areas of biology, they have rarely resulted in alternative proposals
The predictions that follow from the MS framework continue to be based on these prerequisites and ignore all predictions derived from alternative models.
the claim of continuous incorporation of new conceptual components by the MS theory is misleading.
Comments
Post a Comment