Sharon Levy

Beginning with the stately mastodon of North America, in chapters that move from continent to continent Sharon Levy documents what we know about prehistoric and ancient megafauna: how they lived, how they influenced their environments with respect to other fauna and flora, and ultimately how they died. She describes the ways in which the loss of top predators in many biomes today is having an enormous and unanticipated tumble-down effect, resulting in devastating losses of biodiversity. She also discusses current endeavors and ideas intended to restore habitats altered by humans and their domesticated animals, such as (re-)introducing elephants or camels into the American West, ideas simultaneously fascinating and fantastic.

That it took me over four months to finish this book should not be taken as evidence of it being bland, boring or unreadable; it was rather my mistake in selecting it as bedside reading and often being very, very sleepy.… (más)

13,000 years ago there was a die-off of large animals in North America - lions, camels, horses, sloths. No one knows for sure why but there are at least four theories, including human-caused, since the extinctions coincided with the first arrival of people on the continent. Similar extinctions of megafauna happened elsewhere: Australia, New Zealand, Madagascar, also coinciding with the arrival of people. It is now becoming clear the loss of large animals, in particular top predators, has changed ecosystems making them less diverse. In places like the Arctic large herds of mammoths and other creatures once turned it into a lush grassland, but with their absence it is today a boggy mossy marsh with consequences for global warming. Some believe that by restoring the big creatures of the Pleistocene, including top predators or their modern equivalents, is one path to restoring balance to the environment.

Sharon Levy's fascinating book examines theories about what caused the extinctions of the late Pleistocene, ideas about re-wilding, and current projects around the world to re-wild megafauna. Much of this material was already known to me in outline and is not new, but Levy presents detailed case examples from past and present as well as more nuanced understanding of the theories. For example early humans probably didn't "blitzkrieg" animals into immediate extinction, rather because the big animals are so long-lived and re-create slowly, and because of already heavy predatory pressure, it only took a small number of additional human predators to tip the balance towards declining populations and eventual extinction. It happened quickly in geologic time but slowly for those who experienced it (except in New Zealand which saw the extinction of the Moa in about 20 years).

One of the key points of the book is that top predators are vital to a healthy ecosystem. This is a controversial area, there are ongoing battles over wolves in the American West and in Europe, typically with political conservatives against the wolf and in favor or farmers. As well Levy suggests, by way of ancient examples, that humans play an important role, nature should not be "left alone" in isolated parks, but actively managed with controlled burns and other methods. By looking to the past we have much to learn about the present and future in how to best care for the land, planet and ultimately the people who live on it.

--Review by Stephen Balbach, via CoolReading (c) 2011 cc-by-nd… (más)