Phoenix Giant (1995)
Reinventing Darwin: The Great Debate at the High Table of Evolutionary Debate by Niles Eldredge, centers around a new twist on Charles Robert Darwin’s theory of evolution, called "punctuated equilibria." This book explains the debate between Ultra-Darwinians and Naturalists over the true nature of evolution.
Niles Eldredge is a paleontologist who works as a curator at the American Museum of Natural History in the Department of Invertebrates. He, along with Stephen Jay Gould, proposed a new theory of evolution, punctuated equilibria. He has written numerous scientific books and papers including The Miner’s Canary: Unraveling the Mysteries of Extinction, Life Pulse: Episodes from the Story of the Fossil Record, and Fossils: The Evolution and Extinction of Species.
Eldredge begins by setting the "High Table" with descriptions of the two main interpretations of Darwin’s evolution theory. One school of thought is Ultra-Darwinian, made up mostly by geneticists. They believe that evolution is constantly happening as a result of the mutations of genes, passed on to offspring, eventually changing an entire population. The Ultra-Darwinian approach maintains that all organisms act for the sole purpose of reproduction, that organisms are in a constant battle to replicate their genes and pass them on to the next generation. Naturalists, who are mainly evolution-minded biologists, ecologists, systematists, and paleontologists, belong to the other school, believing that evolution happens in spurts, caused by major changes in a species habitat.
Eldredge talks about Darwin’s original theory: that life has an incredibly long history, and that all species have descended from a common ancestor. He explains that adaptation is the root of diversity, and commonly the cause of evolution. But Eldredge suggests that species tend to change locale rather than anatomical features, whenever possible. They only adapt to environmental change when there is no longer suitable habitat. So when habitat is stable, natural selection tends to perfect, rather than modify, adaptation. Stasis is the phenomenon of species being fundamentally stable entities. So even in the face of environmental change, as long as there is appropriate habitat, naturalists notice that stasis prevails. Ultra-Darwinians, however, question stasis, without offering solutions, asking why organisms have "not done nearly as much evolving as we should reasonably expect," [George Williams, Natural Selection: Domains, Levels and Challenges (1992)].
The theory of punctuated equilibria has excited much interest, sparked much debate, been widely cited, and profoundly misunderstood, since its publication in 1972. In Layman’s terms, punctuated equilibria is the notion of stasis in relation to speciation, the evolutionary process of creating new species when populations are isolated. Instead of the original idea of evolution as a continuous process, punctuated equilibria posits that speciation provides the context for evolution, being the only process with the ability to break stasis. This is where the core of the debate begins.
So far, there has been the disagreement between
Ultra-Darwinians and Naturalists about the nature of evolution. At this point,
the details begin to be contested: mass extinction, evolutionary trends, species
selection and sorting, and speciation, become the focus of the debate.
Eldredge completes the book with Paradoxes in Ultra-Darwinism. The first inconsistency
is called the paradox of altruism. It asks why, if adaptations are done for
the good of the organism, rather than for the good of the species, are some
individuals acting in the interest of others, even at their own expense? The
second paradox is that of sexual reproduction. In this case, naturalists ask
why sexual reproduction would exist, since sex presents variation when somatic
cells simply divide into two identical sets of chromosomes.
In class we covered many aspects of evolution, as they relate to Nile Eldredge’s
book, Reinventing Darwin. We discussed Darwin’s theory of evolution,
very similarly to how Eldredge explains it. We also talked about habitat,
and the niches that different species fill. We considered how species adapt
to changing environments, or to more efficiently fill their niche. Speciation
was one way that evolution was personified.
I understood evolution as a process of mutations that occurred in genes, giving some members of a species advantages over others. These advantages increased those members’ ability to survive, and therefore reproduce, passing on their favorable genes onto their offspring. (I would consider this to be a neutral stance as far as Ultra-Darwinians and Naturalists are concerned.)
Species must compete for niches; the stronger species winning, and the loser doing one of three things: evolving, migrating, or becoming extinct. Species must also adapt to environmental changes. Habitats change: species become extinct; climate changes; or catastrophic events, like a meteor impact, completely change the environment.
Speciation is what happens when two or more populations of a species become separated into differing environments, and therefore evolve differently, into independent species.
Niles Eldredge effectively explains his theory of punctuated equilibria in Reinventing Darwin. The pages of this book contain massive amounts of information, aimed at the scientific community or the educated reader. The topic being both about a new scientific theory and the debate it has sparked, gives the book a two-dimensional feeling that a textbook could never accomplish.
Eldredge efficiently argues an impressive case for
the naturalists and his punctuated equilibria theory. After reading this book,
I tend to believe the paleontologists’ view of evolution. Evolution no
longer seems to be a constant process of competition of organisms to transmit
their genes from generation to generation, but rather a stasis broken by evolution
initiated by environmental forces.
I would recommend this book to those who are interested in evolution, and
are willing to look at a different point of view. Both sides of the debate
being represented give the opportunity for questions to be answered, as well
as a strong grounding for the naturalists’ point-of-view to be portrayed.
Reviewed By Jessica Carmen
For Environmental Science 204, Bellevue Community College, 2002