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Eternal Ephemera

Anthony K Campbell

Adaptation and the Origin of Species from the Nineteenth Century through Punctuated Equilibria and Beyond, by Niles Eldredge, Columbia University Press, 416 pp, €35, ISBN 978-0231153164

This is a lovely book, focused on the evolution of ideas about evolution, how they developed, and why. It is written by a distinguished palaeontologist, who has contributed much to our understanding of evolution, being most famous for his ideas on punctuated equilibria (Eldredge, 1985), developed with Stephen J Gould. It is particularly interesting to read Eldredge’s analysis, which is a mix of the history of evolutionary thought, with how even individual humans have changed their ideas with time, and why. Central to the book is an autobiographical voyage through the development of the author’s own ideas, which all students would benefit from reading. Too often, this philosophy is missing in university and school teaching, which can rely far too much on what are presumed to be facts. Yet, as the title of this book implies, many “facts” turn out later to be ephemeral.

Ephemera are things that exist for only a short time. We must therefore assume that the theme the author wants to develop is that, not only do living things change all the time, but also ideas come and they go, either evolving or becoming extinct. An important theme throughout the book is the development of ideas about species. So Eldridge acknowledges that Linnaeus was really the founder of species identificatio, as we know it. But he also points out that, by the sixth and final edition of The Origin of Species, Darwin had essentially given up on how to explain the origin of a new species. Importantly, Darwin always made much of “Natura non facit saltum(s)” ‑ Nature makes no leaps. Yet a major part of Eldredge’s contribution has been based on apparent discontinuities in the fossil record, including mass extinctions. It is clear Darwin was wrong when he thought of evolution being continuous, like a wave moving across the ocean. From molecular evidence, we now know of many examples where just one base change in a gene, or just a few mutations, can cause it to cross a Rubicon, and change dramatically the property of its daughter protein. For example, a few amino acid mutations can cause a luminous beetle to emit yellow instead of green light, or a jelly fish to produce light at all (Campbell, 2012), and a single amino acid change in the sodium channel can give the puffer fish resistance to one of the most potent toxins known, tetrodotoxin, produced by a culture of bacteria within the fish (Campbell, 2015). Discontinuities, or Rubicons as I like to call them (Campbell, 1994), have not been considered enough.

Eldredge’s book is in two parts, with just six chapters, notes, a bibliography and an index. The first part deals with the history of evolutionary thought in the nineteenth century, and the second with the development of the author’s ideas and hypotheses. In the first part – Birth of Modern Evolutionary Theory ‑ I was pleased to see an acknowledgement of the importance of Robert Grant of Edinburgh, one of the first mentors of Charles Darwin. As well as Lamarck, in fact, Grant was also very keen of the ideas of Erasmus Darwin. The second part – Rebellion and Reinvention: the taxic perspective, 1935 – focuses rightly on Dobzhansky’s important early ideas, that evolution has depended much more on discontinuities than continuities. Eldredge then takes the reader on a voyage towards punctuated equilibria. But the author concludes that this is ephemeral, and now, in the light of current knowledge, needs to redrafted. However, the importance of the taxic approach, and individual groups of species, remains central to understanding how new species appeared.

There are major sections on Darwin and his Beagle voyage and beyond, and how Darwin’s brain evolved to transmutation and Natural Selection. In the middle of the book, there is a substantial section on the origins, development, and eventual fate of Eldredge and Gould’s punctuated equilibrium concept. Ephemeral as it may be now, it remains a very important contribution to evolutionary thought, and woke up the scientific world, and beyond, to discontinuities in evolution, quite distinct from the biblical flood! Darwin started On the Origin of Species with pigeons and other domesticated species, as clear examples that a selective force could cause dramatic changes in the shape, colour and behaviour of organisms. Yet in spite of thousands of years of breading, leading to amazing varieties of chickens, cows, goats, sheep, cereals, and other plants, the species involved still remain the same species. A chicken is still a chicken, wheat is still wheat, and a pigeon is still a pigeon. The Rubicon crossed from one species into another still remains a challenge, especially to molecular scientists.

I was sorry to see that the historical discussion missed Georges-Louis Leclerc, Comte de Buffon. Furthermore, the importance of Erasmus Darwin and Alfred Russel Wallace are weakly discussed. However, it was nice to see Patrick Matthew’s famous work pre-empting both Darwin and Wallace on the power of Natural Selection. Interestingly, Eldredge points out that Matthew was particularly interested in mass extinctions. The origins of the process of evolution can be found in Buffon’s amazing thirty-six-volume Histoire Naturelle, générale et particulière, avec la description du Cabinet du Roi (1749-1804), a natural history of the world. Lamarck was Buffon’s pupil, and Buffon’s work also had a major influence on George Cuvier, who also features prominently in Eldredge’s current book. Some twenty years ago I met Stephen J Gould in Wales, and told him about Erasmus Darwin. You will find a clear description of evolution as we understand it today, and the beginnings of the concept of Natural Selection, in his Zoonomia (Darwin, 1794/1796), and his wonderful poem The Temple of Nature (Darwin, 1803), published the year after Erasmus’s death. His grandson, Charles, may have eventually said it was too speculative. Nevertheless, there is no doubt that his grandfather sowed the seeds of Natural Selection in Charles’s mind. Furthermore, the Wallace line in the Malay Archipelago is a legacy of Wallace, related to the geographical distribution of particular species, so important in allowing a separated population to evolve into different species. Understandably, the evidence for Eldredge’s ideas is firmly based on structures observed through palaeontology. There is little about the modern struggle to use DNA, genomic and protein analysis to solve the species problem, and their origins. There is still much to learn about evolution, particularly at the molecular level ‑ the origin of enzymes and ionic gradients across the outer membranes of all cells, a universal feature in animals, plants, fungi and microbes of all types (Campbell, 2015).

The last chapter is a summary of about Speciation and Adaptation, ending with a quote from Darwin’s mentor, when a medical student at Edinburgh, Robert Grant, describing “eternal ephemera”: “Numberless species and even genera and tribes of animals, the links which once connected the existing races, have long since begun and finished their career.” One can only hope that these final words are not alluding to Eldredge himself, as this book clearly shows that his agile and creative mind still has much to give us on the puzzles that still exist about evolution.

References

Campbell, AK 1994. Rubicon: the fifth dimension of biology, London, Duckworth.
Campbell, AK 2012. “Darwin shines light on the evolution of bioluminescence”. Luminescence, 27, 447-449
Campbell, AK, 2015. Intracellular calcium, Chichester, Wiley.
Darwin, E 1794/1796. Zoonomia; or, the Laws of Organic Life, Part I, Part I–III, London, J Johnson.
Darwin, E 1803. The Temple of Nature; or, the Origin of Society, London, J Johnson.
Eldredge, N 1985. Time frames: The rethinking of Darwinian Evolution and the Theory of Punctuated Equilibria, New York, Oxford University Press.

1/7/2015

Anthony K Campbell is honorary professor, School of Pharmacy and Pharmaceutical Sciences, Cardiff University and scientific director of the Darwin Centre, Pembrokeshire.

 

 

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