More From Less by Andrew McAfee

Author:Andrew McAfee
Language: eng
Format: epub
Publisher: Simon & Schuster UK
Published: 2019-09-30T16:00:00+00:00

The State of Nature

Let’s first consider our impact on our planet and start with one of humanity’s greatest harms: causing other species to go extinct.

In addition to the passenger pigeon, we humans have entirely wiped out hundreds of other animal species. Our appetite for destruction has led some observers to warn that we’re facing a sixth “mass extinction” event, comparable to five previous episodes over the past 450 million years when at least half of all species on Earth vanished.

In an essay for the online magazine Aeon, however, Stewart Brand explained how implausible this is: “If all [currently threatened species] went extinct in the next few centuries, and the rate of extinction that killed them kept right on for hundreds or thousands of years more, then we might be at the beginning of a human-caused Sixth Mass Extinction.” However, Brand points out that documented extinctions are relatively rare (with about 530 recorded within the past five hundred years) and appear to have slowed down in recent decades; for example, no marine creatures have been recorded as extinct in the past fifty years.

The good news is that we humans are pushing back against our own tendencies toward annihilation in four main ways. First (and closest to science fiction), research is taking place on how to bring back extinct animals by making use of the DNA that remains in their corpses. Brand is a prominent exponent of this “de-extinction” movement and is working with the geneticist George Church and others to adapt an elephant into a species more akin to a woolly mammoth.II Second, we’re fighting to preserve some of the most threatened species living on islands (where a disproportionate number of extinctions take place) by removing imported predators. To date, at least eight hundred islands have been protected in this way.

Third, we humans have created a great many new species around the world. We do this both deliberately by crossbreeding, as with the cattle-bison hybrid “beefalo,” and inadvertently. Many animals have tagged along with us on our journeys around the world and have both speciated (evolved into new species) and hybridized (interbred with local creatures). Some people believe that, over the Industrial Era, our activities have led to a net gain in biological variety in many parts of the world. As the ecologist Chris Thomas puts it, “It appears to be empirically true that, over the last couple of hundred years, those parts of the world that we know about as regions have increased numbers of species.”

Brand argues, though, that the biggest threat to animal species isn’t absolute extinction, but instead huge declines in population size due to overhunting and habitat loss. Here, recent news is mixed. Overhunting continues, especially of marine life. As Jesse Ausubel points out, “Fish biomass in intensively exploited fisheries appears to be about one-tenth the level of the fish in those seas a few decades… ago.”

Ocean overfishing is a classic example of the “tragedy of the commons,” an unhappy phenomenon named in a 1968 Science article by the ecologist Garrett Hardin.

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