Half-Earth: Our Planet’s Fight for Life

Nonfiction | Book | Adult | Published in 2016

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Summary

Chapter Summaries & Analyses

Prologue-Part 1, Chapter 1

Part 1, Chapters 2-5

Part 1, Chapters 6-9

Part 2, Chapters 10-12

Part 2, Chapters 13-16

Part 3, Chapters 17-21

Key Figures

Themes

Symbols & Motifs

Important Quotes

Essay Topics

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Discussion Questions

Themes

Earth is a “Little-Known Planet”

One of Wilson’s central arguments in Half-Earth is that we know very little about the planet’s biodiversity. The public and scientists are most familiar with vertebrates—mammals, birds, amphibians, fishes, and reptiles. Wilson suggests that this familiarity is due to these organisms’ size (i.e., most are fairly large) and their importance to human life (21). In contrast, very little is known about the rest of life. Estimates suggest that scientists have only identified about 20% of “Earth’s biodiversity at the species level” (23). To Wilson, this fact is deeply troubling given the rate of extinction, which is around 1,000 times higher today than during the pre-human era. We do not have a complete understanding of the species we are losing. Human activities are “breaking many threads,” and how they impact ecosystems is “still impossible to predict” (106).

By providing a naturalistic portrait throughout the book, Wilson pays tribute to creatures both big and small as well as the various environments in which they live. Among the species Wilson cites is one he finds to be “‘the most bizarre,’ at least as a human would judge it” (128): the Osedax worm (128). These worms feed on lipids found in whale carcasses that sink to the ocean floor. Their method of feeding is especially interesting. The female worms, which are about the length of a human finger, penetrate “the bones with bodily extensions that contain symbiotic bacteria” (128). These bacteria share the energy source with their worm host after they metabolize the lipids.

Wilson’s examples of biodiversity are meant to inspire a reaction in readers. We are meant to stop and think about how interesting or bizarre an organism is. The reader is also encouraged to confront what happens when we destroy a habitat. For example, in every single “best place” listed in Chapter 15, Wilson mentions that most species found there are not found anywhere else in the world. Many of these places are not well studied, which means there is likely even more uniqueness and richness than we fully appreciate. The purpose of this approach is to inspire readers to see the value of nature and the true tragedy of the species we are extinguishing, especially when we do not realize what we are losing.

The Interconnectedness of the Webs of Life

Wilson emphasizes that each ecosystem “is a web of specialized organisms braided and woven together” (88). Individuals of the same species interbreed with one another, but they also interact with other species within the ecosystem. Wilson provides numerous examples of these interactions, including several dealing with the “evolution of predator and prey” (86). One example is that of the collembolan and ants in Great Smoky Mountains National Park. The collembolan has one of the greatest locomotory forces in the natural world. These small hexapods can launch themselves as far as the length of a football field via a lever beneath their bodies. This response occurs when predators, such as ants, get too close. However, ants have developed techniques to “defeat the high jumps” (86), including placing huntresses all over a field so that the collembolan are continuously jumping near them.

As a result of organisms’ interconnectedness within an ecosystem, extinguishing one species has ramifications for others. For example, the clear-cutting of old-growth forests in the southeastern United States caused the extinction of the ivory-billed woodpecker (99). The introduction of invasive or alien species into an ecosystem also upsets its order. Hawaii, known as the “extinction capital of the world” (39), is one such example. A combination of Polynesian, European, and Asian colonists, bringing with them both non-native species and their own destructive activities (e.g., habitat destruction and overhunting), killed off almost all of the archipelago’s native bird species, such as the flightless ibis, native eagle, and drepanidid honeycreepers (39).

To Wilson, allowing one species to die means that we “erase the web of relationships it maintained in life” (106). He believes “our actions are ignorant and permanently destructive” (106). While new conservationists suggest that these extinct species can be cloned and brought back to life, Wilson strongly disagrees. His opinion is tied to his belief that organisms are interconnected. Species extinctions do not happen in isolation. There are effects throughout the ecosystem, and bringing them back will likely not reverse these impacts.

Humans are Biological Organisms

For Wilson, “the most dangerous worldview” (71) is that held by new conservationists and anthropocentrists. These individuals believe that “humanity has already changed the living world beyond repair” (71); thus, humans must “adapt to a life on a damaged planet” (71). Extremists believe that nature is meant to serve humans and that the survival of a species depends on its usefulness to us. As Stewart Brand, a futurist, wrote, “We are as gods” (47). From the very beginning of Half-Earth, it is obvious that Wilson vehemently disagrees with the notion that humans are superior to the biosphere. A central tenet for him is that we are biological organisms, like all other living species.

Our more complex and larger brain is due to evolution by natural selection. Like other surviving organisms, we have managed to be champions. In a changing environment, humans have been able to adapt to these changes and successfully reproduce for the last several million years. Unfortunately, according to Wilson, we are still driven by our basest instincts. To him, “we are still too greedy, shortsighted, and divided into warring tribes to make wise, long-term decisions” (49). One consequence is that we are changing the climate and environment in a way that is bad for us presently and that will make the lives of future human generations significantly more challenging (49).

Wilson also argues that our human nature will cause us to cease viewing ourselves as rulers of the living world and to begin viewing ourselves as stewards instead. Humans are fundamentally “thinking organisms trying to understand how the world works” (205). We have an innate interest in the natural world. We also have an instinct to put the group above our own individual interests, which Wilson terms “true altruism.” In combination, these human tendencies will enable a moral shift in reasoning for our species. We will come to value nature and realize that we must give a greater commitment to protecting its biodiversity, which is tied to our own survival.