1 Dec 2007, 7:47pm
Wildlife History
by admin

Twilight of the Mammoths

Martin, Paul S., Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America. 2005. Univ. of California Press.

Review by Mike Dubrasich

Twilight of the Mammoths is a first-person account of one of the greatest scientific discoveries of modern times, and that statement deserves some explanation.

In the main, Twilight of the Mammoths is about the Overkill Hypothesis. The end of the Ice Age saw the extinction of mammoths, mastodons, giant ground sloths, saber-toothed tigers, camels, horses, and all told, over 40 species and 30 genera of large mammals in the Western Hemisphere. These extinctions took place more or less contemporaneously with the arrival of the first humans, the Clovis People, approximately 13,000 calendar years ago. Dr. Martin hypothesizes that the two phenomena were linked, that paleo hunters decimated large mammal populations in North and South America within a few centuries (and perhaps in as little as 70 years after people first arrived).

But Twilight of the Mammoths is so much more than that.

The Overkill Hypothesis is a crude substitute for a much larger concept. Paul Martin should more properly be known as the Father of the Anthropogenic Predation Theory, which holds that human beings have been impacting wildlife populations for millennia, on all continents (except Antarctica), much as the Anthropogenic Fire Theory contends that humans have also been impacting terrestrial vegetation everywhere for a long time, too.

At their cores, the Anthropogenic Theories are an extension of Darwin’s Theory of Natural Selection. The principal selective agent in nature has been human beings for as long as we have existed on this planet. People have been driving natural selection, and hence evolution, wherever we have lived (13,000 years in the Western Hemisphere, 25,000+ years in Europe, 40,000+ years in Australia, 50,000+ years in Asia, and 100,000+ years in Africa).

A convincing case is made by Baz Edmeades in Megafauna—First Victims of the Human-Caused Extinction [here] that sapiens and pre-sapiens hominids in general have been the Keystone Predators and Masters of Fire in Africa for more than a million years. (Edmeades’ e-book is based ideas first presented by Dr. Martin, who wrote the Foreword to it.)

Darwinism changed the natural sciences. The Anthropogenic Extension of Darwinism is equally paradigm-shattering. Dr. Martin’s work is huge in terms of the Advancement of Science and the understanding of our world. As an early proponent of Anthropogenic Predation (his first writings on the subject were in the 1950’s), Paul Martin is a giant among scientists. Like Darwin, Martin’s work was also very controversial early on, but has been widely accepted for more than a decade by most archaeologists, geographers, natural historians and paleontologists. (Unfortunately, many modern wildlife and forest ecologists are still in the dark.)

To add icing to the cake, Twilight of the Mammoths is a first-person, popular account of a key scientific discovery, and that puts it in special company with John Imbrie’s Ice Ages: Solving the Mystery and James Watson’s The Double Helix. Dr. Martin is a polished writer with wit and incredible wisdom. Twilight of the Mammoths is a scientist’s memoir, in part, and very kind and good humored in that regard. It is also an exemplary presentation of deductive reasoning, a scientific detective story.

The first chapter in Twilight of the Mammoths is a review of Late Quaternary large mammal extinctions and the advent and critical scientific role of radiocarbon dating. There are tables and lists, and a huge amount of information, but it is very readable as well as fascinating.

The second chapter is a review of the Overkill Hypothesis. It is a masterful exposition:

To me the core piece of evidence for human involvement is that when viewed globally, near-time extinctions took place episodically, in a pattern not correlating with climatic change or any known factor other than the spread of our species. Extinctions followed prehistoric human colonization in a “deadly syncopation” to use the words of mammalogist Ross MacPhee. … Simply stated, as humans moved into different parts of the planet, many long-established huntable animals died out.

The best part of Twilight of the Mammoths is the rest of the book, though. In it Dr. Martin tells the story of a scientific detective gathering clues, making logical deductions, and piecing the truth together bit by bit. The detective is himself, and the story is his to tell, and it is remarkable. If you want to know how deductive science is done, Twilight of the Mammoths is the book to read.

It is a personal story, too, the life and times of a great scientist. Twilight of the Mammoths is very compelling in that regard, too.

Although Twilight of the Mammoths is mostly about animals, Dr. Martin included some interesting bits about forests:

Ponderosa is widespread today, ranging from the Sierra Madre Occidental of northern Mexico through the Southwest and the lower elevations of the Rocky Mountains into western Canada. In the last late or full glacial, it might well be expected to have occupied lower elevations in many parts of the West. Instead, the [packrat] middens suggest that it was absent from much of its modern range. Fossils of ponderosa pines more than 10,000 years old have yet to turn up in the midden record in the Grand Canyon (Cole 1990) or in glacial-age middens outside of Arizona. …

… The postglacial spread of ponderosa is so extraordinary that it challenges us to consider forcing functions beyond climate change. That is, did something happen to favor ponderosa after the last ice age, something in addition to the climactic warming that led most forest and woodland species to ascend in elevation? A major change in fire history, including season and intensity of firing, is one possibility. Ponderosas are fire-adapted. And with the arrival of people in the New World around the end of the last ice age, a change in wildfire frequency could be expected. Julio Betancourt (personal communication, December 2001) suggests that ponderosa pine benefited by fires set by Native Americans, artificial ignitions of relatively light intensity, set well in advance of the normal summer lightning strikes and ignitions. By removing excess fuel in advance of the season when firestorms are likely to develop, cool fires could have favored the ponderosas.

In the last two chapters in Twilight of the Mammoths, Dr. Martin advocates restoring some of the Pleistocene megafauna to North America. He would like to see mammoths, or their near equivalents in elephants, roaming again the parklands in the U.S. and Canada.

Twilight of the Mammoths is a keystone book in the annals of science history, and is destined to be a classic.

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