The Sixth Extinction: Chapter 11 Summary & Analysis

Kolbert travels to the Cincinnati Zoo to meet Suci, an enormous rhinoceros. Dr. Terri Roth, the conservation director for the zoo, tells Kolbert that Suci, a Sumatran rhinoceros (Dicorohinus sumatrensis), is one of only five rhino species left on the planet. Sumatran rhinos are small and endangered. Thus, Roth has been trying to artificially inseminate Suci with no success.

Sumatran rhinos used to live in the Himalayas, as well as on Sumatra and Borneo. They were once common, but they’re now headed for extinction. Recognizing their inevitable extinction, a conservation group decided to send a small number of Sumatran rhinos to American zoos in hopes of perpetuating the species in captivity. However, five of these rhinos died almost immediately, thanks to a disease spread by flies. Then, several rhinos captured in Borneo died from tetanus and other injuries. To compound the problem, zookeepers then realized that rhinos couldn’t eat dry hay—they needed fresh leaves to survive. By this time, there were only three Sumatran rhinos in the U.S. Roth’s job is to inseminate a Sumatran rhino and perhaps prevent the species from dying out forever.

Roth had tried to inseminate a rhino named Emi, who was living in a zoo in Los Angeles. After many false starts, Emi birthed Suci and a male named Harapan. These are “pretty much” the only Sumatran rhinos born anywhere in the last thirty years. Much the same is true for other rhino species—humans have wiped out rhinos and scientists are now trying to preserve their numbers in captivity. Other large mammals, such as elephants, jaguars, pandas, and cheetahs, now exist mostly or entirely in zoos and preserves, where scientists are trying to get them to bear offspring.

Kolbert observes Suci eating food and is later permitted to pet Suci. “Face to face” with Suci, Kolbert is struck by the animal’s awesome, “majestic” size. Many of the largest mammals in the world are peaceful herbivores; their size keeps them safe from dangerous predators like tigers and jaguars. At the end of the last Ice Age, the planet was full of enormous animals—cave bears, giant elk, mastodons, etc. As early as the mid-19th century, biologists had posed an important question—why is it that so many extinct species are exceptionally large, by modern-day standards? And, similarly, why did so many of these enormous creatures go extinct?

To answer the question, Kolbert travels to a famous fossil site, Big Bone Lick. Here, 19th century fossil-hunters discovered some of the world’s most famous fossils. Some 19th century thinkers, such as Charles Lyell, argued that the creatures whose remains were discovered at Big Bone Lick went extinct because of a “great modification in climate.” Charles Darwin agreed, writing that the end of an Ice Age must have killed off creatures like the mastodon. Other scientists, however, argued that these large creatures died out because human beings hunted them. The implications of such a theory are startling—the modern era of mass extinction, then, might actually have begun “in the middle of the last ice age,” suggesting that human beings have always been capable of—or even prone to—bringing about extinction.

There are a few good reasons to believe that humans were responsible for the mass-extinction of large mammals. First, it’s likely that the extinction of large mammals took place in “pulses,” not as one continuous event. This suggests that extinction “syncs up” with human colonization of the globe. Second, large mammals had survived numerous droughts and other environment catastrophes before the arrival of human beings. Third, the fossilized remains of large mammals’ excrement show no signs of death from malnutrition. In all, the insufficiency of purely environmental explanations for large mammals’ mass-extinction make it very likely that humans, not environmental factors, were responsible for the mass-extinction.

There are also some researchers who argue that human beings did not wipe out the large mammals of the late Ice Age because humans couldn’t have been that dangerous so many millennia ago. However, the scientist John Alroy has tested the hypothesis that small nomadic bands of humans could have wiped out large mammals, and he found that “humans could have done in” the large mammals with “only modest effort.” Alroy’s findings suggest that the Anthropocene really began many thousands of years ago, long before the Industrial Revolution.

Before the dawn of man, it was an excellent “survival strategy” to be a large, peaceful mammal. However, environmental changes—above all, the new presence of human beings—made being a large mammal a “loser’s game.” Large mammals were slow to reproduce and were easy prey to human hunters. Today, most of the large mammals of the ancient world have died out, and smaller mammals like the rhinoceros are on the verge of extinction. It seems that there was never a time when “man lived in harmony with nature”—humans have always hunted other creatures.