Extinction: Bad Genes or Bad Luck?

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Summary: highly readable and informative book on extinction
Review: David M. Raup does an extraordinary job in this fine work on the mysteries of extinction. Addressing not only the infamous K-T extinction event that wiped out the dinosaurs, pterosaurs, prehistoric marine reptiles, ammonites, and many less well known organims of the Mesozoic, he addresses other significant extinction events in earth's history, ranging from the Cambrian period all the way up to extinctions in recent centuries, such as the heath hen in the eastern United States. Raup is able to draw many interesting theories and conclusions by analyzing extinction as an event and process seperate from and beyond the details of the individual organisms. Too many works, at least popular works, dwell overmuch on the extinction of the dinosaurs and related archosaur fauna (and to a lesser extent the mammalian and avian megafauna at the end of the Pleistocene)and fail to draw overall conclusions about what extinction is, how it comes about, and what roles it plays in the history of life on earth. Though the details of particular organims that become extinct are important, Raup seeks to draw broader and more widely applicable conclusions, and in this he succeeds brilliantly.

Raup analyzes and addresses a variety of potential causes of extinction from biological (such as predation, epidemic disease, etc.) to physical (sea level rises and falls, volcanism, etc.) to fairly exotic (cosmic radiation, asteroid impact, etc.), as well of course interactions between various causes. He also discusses the importance of small population sizes playing a role in and of themselves in a species extinction, how small populations (using the heath hen as an example) are uniquely vulnerable to such factors as demographic stochasticity, extrinsic forces, social dysfunction, and so forth, all described in informative but very readable format. The debate over the role of small population size is particularly interesting in discussions of potential modern day extinctions, a probelm faced by modern day conservationists and environmentalists.

Weaving in discussions of probability, statistics, geology, astronomy, climate, and the overall history of life on earth, Raup does an excellent job on the subject of extinction. Any amateur paleontologist or indeed biologist, as well as those involved in conservation efforts, would be well served by this book.

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Summary: Neither: Bad Title
Review: David Raup collaborated with Jack Sepkowski in suggesting Earth's been bashed by comets periodically, almost predictably. The research suggested that we take a harder look at extinction than has been done previously. He thinks we avoid looking at extinction as too frightening. Since it logically applies as much to ourselves as to all those species lost in the remote stretches of time, it's a valid argument. But it happens, and we should educate ourselves on extinction's record.

Raup tries to further our education with a fine description of the fossil record. His depiction of the Ediacaran and Cambrian eras is a joy to read. Few have provided such a vivid account in so little space. His account of the Cambrian gives laudatory credit to Gould's Wonderful Life. That Gould's analysis has been devastated by later research doesn't detract from what Raup's given us. His presentations are intelligible and vividly depicted.

He presents some numerical models, citing genus and species counts of various extinction scenarios. His graphical presentation of the "kill curve" is designed to show high percentage population losses are rare events. He defends his catastrophist thesis with accounts of near- extinctions from which species recovered. Except for attributable human intervention, he argues, "the chances of a field biologist catching a species at the instant of global extinction are small". Quite true, but his assertion fails to reflect that "speciation" is a term devoid of clear definition. We can't determine whether a current species could successfully reproduce with individuals from an earlier time.

In his look at catastrophic extinction, Raup takes some sidelong swipes at gradualism in the evolutionary process. While he's correct in asserting we need to understand extinction better than we do, his assault on gradualism is misplaced. By limiting his view, he's ignored the role of adaptation in species creation and extinction. He states that there's no known reason why a species couldn't live forever. This is fallacious since the world is constantly changing and species must adapt or go extinct. There's no such thing as a "bad gene", there are only genes which survive change, or don't. When enough don't the species disappears. Perhaps he should have entered into another collaboration, this time with a biologist.

What Raup has contributed to extinction debates is the need to look more closely at the correlation between significant geologic [or cosmic] events and species loss. A reasonable undertaking and Raup presents a wealth of reasoned evidence for many extinctions. He presents a list of "exotic" causes of extinctions, finding few of them statistically convincing. His conclusion is that those earth-bashing comets and meteorites need further investigation. Craters, the only physical evidence of cosmic impact, are elusive subjects for study. They weather, are erased by continental subduction and may lie undersea. The recent discovery of the Chicxulub crater in the Caribbean wasn't sought by paleontologists. But Raup must have rejoiced at the find. It's apparently from the bolide that coincides with the extinction of the dinosaurs. It certainly supports his contention that the Big Five extinctions are the results of cosmic impacts.

Raup did himself a disservice in choosing Stephen J. Gould to write the Introduction to this book. Gould's "punctuated equilibrium" concept has simply proven little more than a feeble attempt at Darwin bashing. His assertion that Charles Lyell's "credo makes little sense" is outrageous. It's a self-serving comment attempting to indirectly shore up his failed thesis. Geologic processes don't operate in fits and starts. Even Raup, further in the text, recounts that in our lifetimes we're unlikely to witness continents moving, suffer catastrophic earthquakes or be struck by meteors. Gould's statement so early on nearly caused the book to be put aside unread. Pity. It's worth a read.

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Summary: Assignment
Review: I don't think I would recommend this book to the average person. If someone was curious about extinction and different theories then they might like this book. I was hoping it would be more about extinction and dinosaurs. Anyway the author did a good job explaining his thoughts on extinction. It was interesting seeing how the author kind of explained how extinction could be as simple as bad luck, a species just being in the wrong place at the wrong time. A lot of the points are expressed well and some of the information was interesting but it still wasn't my type of book.

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Summary: Forgot to mention this in my previous review
Review: I forgot to mention this in my previous review.

In addition to Raup's idea that meteors account for periodic die-offs, his idea is interesting for another reason.

Back in the early 19th century, when geology and paleontology were becoming sciences, it used to be thought that sudden, catastrophic changes in the earth's geology were the main mechanisms by which the earth's surface was changed over time and transformed.

For example, there were the Vulcanists (no, they are not from Star Trek) who believed that diastrophic processes (i.e., vulcanism and other heat-generated processes) were responsible for transforming the earth's surface and atmosphere in geologic times.

Then there were the Neptunists, who held that great floods had transformed the earth's surface (such as in the case of the Noachian Deluge, in the Bible).

Then in the mid-1800's came Charles Lyell (who was also Darwin's geology professor), who documented gradual changes, such as those occurring as a result of erosion. Lyell's ideas become known as Uniformitarianism, which contrasted with the earlier theories of Catastrophism, of which Vulcanism and Neptunism are examples.

So Raup's idea is essentially a return to an earlier form of geological explanation, in that it lands him back in the Catastrophism camp.

Rating:
Summary: A good question...
Review: Raup does a great job outlining many of the leading ideas regarding extinction theory. Ideas in the book are presented with examples that are easy to follow, and Raup points out possibilities without overburdening the reader with a heavy-handed dose of bias, leaving readers to make up their own minds about things. I particularly appreciated the range of ideas covered by the author regarding current thought about extinction. The book seemed a bit light for a scientific audience, but it is pitched well for the lay naturalist reader. I'm glad I read it.

Rating:
Summary: Extinction
Review: This is a delightfully well written book on the phenomenon of extinction, from the background rates of species death to the massive die-offs of the KT and other major extinction events. The author approaches the subject from a statistical/probabilities standpoint, looking at extinction as a continuum which is characterised, as he notes, by "long periods of boredom interrupted occasionally by panic." He introduces the concept of Gambler's Ruin, which makes his thesis understandable even to the statistically challenged like myself. The sense of humor with which he injects his work makes a complex subject entirely enjoyable.

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Summary: >99% of all Species that have ever existed no longer do!
Review: This thought provoking book covers details not discussed in many books about past life and past extinctions. Looking at the big picture of extinction, he provides insight to the nature of evolution, our past and possible futures. Using a skillful combination of specific data on individual mass die-offs and statistical examination of the entire history of life on this planet, he brings many difficult (or unpleasant) theories of extinction into focus. He analyzes many theories, from older standard views to the downright wacky, but eventually makes a strong case for celestial impacts as cause of many mass extinctions.