The World Without Us
In his book The World Without Us, Alan Weisman begins with the question of what would happen to the planet if humans suddenly ceased to exist. Weisman, a journalist, expanded this book from his essay "Earth Without People," which was selected for Best American Science Writing 2006. Weisman begins with this question of what would happen to our cities, monuments, farms, and other vestiges of civilization were we to disappear, examining the possibility of a world without us really helps the reader to understand how the world works with us in it. The book takes an objective look at the role Homo sapiens has played in the global ecosystem from around the time we migrated out of Africa to the present day, and then moves to describe what would happen to various parts of our society should we disappear and nature be allowed to take its course without us. Weisman devotes each chapter to what would happen to different aspects of our lives, from the Panama Canal to the WIPP storage system for nuclear waste to the Pyramids at Giza. In the process, he examines how these things are currently effecting the rest of the world.
I had expected this book to take a very environmentalist tack, and contain grim warnings about the vast amounts of time it would take for carbon levels in the atmosphere to drop and the irreparable damage we have done and are doing to the world. I also expected some kind of nightmarish explanation for the sudden disappearance of humanity, like nuclear holocaust or disease. There was a certain amount of this, and there were some startling figures. For example, in describing the impact of plastic on the environment in general and oceans in particular, Weisman notes a discovery in 1998 that there was "more plastic by weight than plankton on the ocean's surface" (123). Information like this, however, does not come with stern advice to stop using plastic bags, and the emphasis is not on the fact that "every bit of plastic manufactured in the world for the last 50 years or so still remains" (126). Rather, he notes that plastic will disappear once microbes have evolved which can digest it, and that they have already evolved to digest oil, so it is not an impossible concept.
There certainly was shock value in the the discussion of things like plastics and uranium, but the most interesting part of the book by far was the chapter called "The Lost Menagerie." It explores the disappearance of megafauna and the arrival of Homo sapiens in North America. It was interesting because normally when I consider my environmental impact, I think of my carbon footprint, or something else that has to do with my use of technology; I had not considered how humans pre-civilization would interact with the ecosystem they inhabit. I had assumed that they would take an unassuming position on the food chain, not disrupting things more than any other species. Weisman, however, begins the chapter by challenging that assumption, asking "Had we never appeared, would those now-missing mammals still be here?"
This question of megafauna is a good illustration of science as storytelling. Weisman relays the story of paleoecologist Paul Martin, who noticed in 1956 that an explosion of extinctions occurred 13,000 years ago at the end of the Pleistocene epoch, so that by the beginning of the next epoch, 40 species of large terrestrial mammals had disappeared, while smaller terrestrial and marine mammals had been left "unscathed" (56).
Looking for an explanation, Martin noticed that these massive extinctions occurred simultaneously with the arrival of Homo sapiens to the area, which archaeologists then theorized to have been approximately 13,000 years ago, and today have pinpointed to 13,325 years ago using carbon dating in Clovis sites. In Martin's words, "It's pretty simple. When people got out of Africa and Asia and reached other parts of the world, all hell broke loose" (58).
Martin's theory, known as the Blitzkrieg theory, is that humans moved into the area, discovered massive animals that were easy to kill, and then did not stop hunting them until they were extinct. To support his theory, Martin points to fourteen sites where "Clovis points were found with mammoth or mastodon skeletons, some stuck between their ribs" (59). Skeptics, however, question if Clovis people were actually the first people in North America. Different sites throughout the Americas have dated human activity back as far as 30,000 years, though there have been questions about the validity of radiocarbon dating. This is a prime example of the idea of science as storytelling, and a story in which we cannot even be sure of our observations. Theories about the extinction of megafauna are very tentative, and contingent upon observations and data which may change at any time.
There are two leading theories in opposition to the Martin's "overkill" theory. The first, "over-chill," places the blame on dramatic climate change and has the most supporters. The second, "over-ill," still blames humans to a certain extent. This theory suggests that humans introduced pathogens that animals in the Americas did not have the antibodies to resist, analogous to the first Americans who died after contact with Europeans. However, Weisman only devotes a paragraph to each of these theories, while Martin is the main focus of the entire chapter.
Martin points to giant ground sloths as the clincher for his theory, as they disappeared from the Americas when humans arrived, but continued to thrive in the West Indies; had there been a climatic shift, it would have effected the West Indies as well. His explanation for the need for humans to kill so many megafauna is simple: "Big animals were the easiest to track. Killing them gave humans the most food, and the most prestige" (63). His theory is certainly convincing. The story makes sense from the observations Weisman relays to us, though I would like to know more details about the alternate theories. It seems that Weisman is attempting to convince us of Martin's theory for the purpose of his argument, and I would not be surprised if he were leaving out some details. Martin's framing of his theory is somewhat problematic. At the release of his book, he says the extinction of megafauna amounts to a genocide, and that they "were all exterminated, simply because it could be done" (66). Martin implies and Weisman states that we have always possessed "acquisitive instincts that also can't tell us when to stop, until something we never intended to harm is fatally deprived of something it needs," a trait which is easily seen in the destructive tendencies of our habits that support our way of life.
However, species have been going extinct throughout history, and we have never called it genocide until humans were responsible. I would need to be convinced that this was something more malicious than simply change, and I do not think it is fair for Martin to liken the extinction of megafauna to the Holocaust or the genocide in Darfur, which were very differently motivated. It is, though, still a useful lesson for humans today. If it is true that humans were responsible for the extinction of megafauna in North America with just atlatls and Clovis points, we can extend that to the effect we may be having environmentally today. This does not mean that we should see environmental destruction as genocide, or as anything more sinister than out-competing, but it does mean we should examine whether or not we want to cause that kind of destruction. I think we should want to preserve other species, and we should examine our behavior accordingly to identify how we may be harming other parts of the ecosystem today.