Honoring a Pillar of Evolutionary Biology
Unifying biology, one concept at a time
When the American Society of Naturalists bestows the Sewall Wright Award, it honors a scientist who has spent a lifetime weaving together the disparate threads of biological science into a coherent tapestry. The 2006 award recognized one of the most influential evolutionary geneticists of our time—Brian Charlesworth. This award is more than a prize; it is a testament to a career dedicated to illuminating the fundamental forces that shape the living world.
Established in 1991, the Sewall Wright Award is presented annually by the American Society of Naturalists to a "senior-level, active investigator" who has made profound contributions to the "conceptual unification of the biological sciences" 1 . It honors the legacy of its namesake, Sewall Wright, one of the three founding fathers of population genetics.
The award carries a plaque and an honorarium of $1,000, and the recipient need not be a member of the society or an American citizen 1 . It is designed to celebrate scientists who, like Wright himself, bridge specialized fields to create a more integrated understanding of biology.
To appreciate the significance of the award, one must understand the monumental contributions of the man it honors. Sewall Wright (1889–1988) was an American geneticist who, alongside R.A. Fisher and J.B.S. Haldane, laid the mathematical foundations of modern evolutionary theory 2 6 .
Wright's signature theory explains how populations can evolve from one genetic "peak" to another through genetic drift, selection, and migration 8 .
Sewall Wright is born in Melrose, Massachusetts.
Earns his PhD from Harvard University.
Publishes his seminal paper on evolution in Mendelian populations.
Receives the National Medal of Science 7 .
Passes away at the age of 98, leaving a profound legacy in evolutionary biology.
In 2006, the American Society of Naturalists selected Brian Charlesworth as the recipient of the Sewall Wright Award 1 3 . Charlesworth is a towering figure in evolutionary biology, whose work has been instrumental in formalizing and testing many of the theories first proposed by Wright, Fisher, and Haldane.
Research on the evolutionary genetics of aging and life-history evolution.
Studies on the maintenance of genetic variation in natural populations.
Charlesworth's body of work exemplifies the award's goal of conceptual unification, seamlessly combining theoretical models with empirical data to answer some of the most persistent questions in evolution.
The research honored by the Sewall Wright Award often revolves around a core set of concepts and methods. The following table outlines some of the essential "tools" used in this field.
| Concept/Reagent | Function in Evolutionary Genetics |
|---|---|
| Population Subdivision | Studying a species as a collection of semi-isolated groups to understand the effects of drift, selection, and migration 8 . |
| F-Statistics (FST) | A measure developed by Wright to quantify genetic differentiation between subpopulations 2 . |
| Path Analysis | A statistical method for evaluating causal hypotheses and the relative influence of different variables 2 5 . |
| Model Organisms | Used for controlled breeding experiments and to test evolutionary theories like the shifting balance 2 8 . |
| Mathematical Modeling | Using equations to describe and predict the dynamics of evolutionary processes like selection and drift over time 8 . |
At the heart of much of this work is Wright's adaptive landscape 4 . Imagine a map where:
So, how does a population cross from a lower peak to a higher one? Wright's answer was his Shifting Balance Theory, a process that relies on the interaction of multiple evolutionary forces 4 8 .
While the full shifting balance process is difficult to observe in nature, scientists have designed experiments to test its key phases. One such experiment was conducted by Wade and Goodnight (1991) using the flour beetle, Tribolium castaneum 8 .
The experiment was designed to mimic Phase 3 of the shifting balance, where successful populations (on higher peaks) spread their advantageous genes to others. The results showed that the experimental groups with non-random migration based on productivity saw a much greater increase in average fitness across the entire metapopulation compared to the control groups 8 .
The work honored by the Sewall Wright Award, from Wright's original theories to Charlesworth's refined models, continues to shape how biologists view evolution. It underscores that evolution is not a simple, linear march toward perfection, but a complex dance on a rugged landscape, driven by both deterministic forces like natural selection and the random, creative chaos of genetic drift.
The legacy of Sewall Wright and the work of Brian Charlesworth remind us that true understanding in biology comes from looking at the big picture, where mathematics, genetics, and ecology converge to explain the magnificent diversity of life.