HSU Professor of Geology William Miller III recently published two chapters in “Evolutionary Theory: A Hierarchical Perspective.” For those with an interest in evolutionary theory, this volume offers a comprehensive and thorough introduction to the hierarchy theory of evolution and in doing so, potentially provides a broader view of how life has changed over millions of years.
The chapters are:
Miller, W., III. 2016a. The species problem: concepts, conflicts, and patterns preserved in the fossil record. In: Allmon, W. D. and Yacobucci, M. M. (Editors), Species and Speciation in the Fossil Record. University of Chicago Press, p. 28-58.
Miller, W., III. 2016b. Unification of macroevolutionary theory: biologic hierarchies, consonance, and the possibility of connecting the dots. In: Eldredge, N., Pievanni, T., Serrelli, E. and Temkin, I. (Editors), Evolutionary Theory: A Hierarchical Perspective. University of Chicago Press, p. 243-259.
Over the course of the two separate chapters, Miller describes his theory of macroevolutionary consonance and challenges facing paleobiologists when it comes to interpreting the fossil record.
•••
When it comes to digging through the fossil record and attempting to make sense of the trajectory of evolution, paleontologists and evolutionists have typically viewed their findings through a metaphorical “zoom lens on a camera,” with the focal point fixed on incremental changes occurring within a single species—call this the reductionist version of evolutionary theory. As a contrast, a group of scientists have been developing a hierarchical version of the theory of evolution that attempts to look at evolution through a camera’s “wide angle lens,” thus capturing a broader and more complete picture that overlays evolution within the context of large, regional ecosystems.
Hierarchical theory applied to biology seeks to provide an all-encompassing understanding of evolution that helps recognize the basic patterns that propel living systems. This view of evolution offers a unifying perspective on the natural world and puts forward an operational framework for scientists seeking to understand the way complex biological systems work and evolve.
According to Miller’s theory of Macroevolutionary Consonance, evolution and ecology are intricately related and cooperate to drive the formation of distinct species.
Miller explains that macroevolutionary patterns are the result of the interaction of evolutionary processes and development of large-scale ecological systems. “In other words, it simply isn’t the case that ecology is a by-product or backdrop to evolution; both evolutionary and ecologic processes ‘cooperate’ at regional scales to produce much of the adaptive speciation during the last 500 million years,” he says.
A Change in Theory
Hierarchy theory was first applied by eminent paleontologist and evolutionist Niles Eldredge. According to the Hierarchy Group, which is a group of scientists dedicated to expanding the theory, it provides “a unifying approach to represent the complex multi-level structure of the organic world, and an explanatory framework for a wide range of natural phenomena.”
In other words, the traditional reductionist approach focuses on minute changes occurring over decades or centuries to explain large-scale patterns in the fossil record. By contrast, the hierarchical expansion of theory considers the possibility that the “focal level” of evolution could be broader in scope by looking to populations within species or groups of genealogically related species for answers.
This perspective has gained momentum since the 1970s owing to new observations and interpretations of patterns in the fossil record. One of the main findings is that for many animals with a good fossil record, most evolutionary change seems to happen when new species first appear, species-lineages appear to be remarkably stable for hundreds of thousands to millions of years, and all species ultimately die out by extinction, whether or not they give rise to descendants.
This pervasive pattern—species introduction followed by a long stable period culminating in extinction—was not anticipated by the reductionist view.
Miller describes other patterns that have encouraged a hierarchical view of evolution: including the rather sudden origin of the major groups of animals about 540 million years ago (known as the Cambrian Explosion, during which most animal phyla appeared), the possibility of selection at the species level, global mass extinctions and recoveries, and causal connections, not just correlations, between macroevolutionary processes and development of large, regional ecologic systems. Miller’s theory of Macroevolutionay Consonance attempts to address the interplay between evolution and ecology.
Miller’s experience with the hierarchical theory of evolution reaches back to the mid-1980s, right after arriving at HSU with a new Ph.D. in paleontology from Tulane, when he came across Eldredge’s Unfinished Synthesis: Biological Hierarchies and Modern Evolutionary Thought and Stanley N. Salthe’s Evolving Hierarchical Systems, which both support a hierarchical theory as applied to evolutionary and ecologic systems. “I’ve been hooked on these ideas ever since.” Miller also serves on the editorial board of Evolution: Education & Outreach, an open-access quarterly magazine devoted to expanding the knowledge and teaching of evolutionary theory to a wide audience.
Anyone who has a deep interest in science and is open to new ways of thinking should dive into these books. “I think upper-level undergraduates, graduate students, and researcher-teachers looking for fresh, innovative ideas about how life works on this planet would benefit from reading the new books.” The volumes are both a source of new ideas and a way to monitor progress in the application of hierarchical thinking in the expansion of evolutionary theory in general.
To learn more about the book, visit http://press.uchicago.edu/ucp/books/book/chicago/E/bo25468890.html.