Humans have played a role in large animal extinctions since time immemorial. The giant ground sloth of Texas. Siberian mammoths. A bear-size wombat in Australia. We harry our competitors for meat—and our predators—out of existence. Or at least to the margins of the planet.
Now a study in the journal Science shows the impact of this wholesale elimination of large predators and other animals at the top of local food chains. [James Estes et al., "Trophic Downgrading of Planet Earth"]
Such absence can be seen throughout ecosystems: biomes haunted by the ghosts of missing species. Lakes grow cloudy with algae once bass are gone. Rainforests thin with the absence of jaguars. Coral reefs lose their abundance when unpatrolled by sharks.
None of these changes were obvious to ecologists, until the top animals were removed. And the fix may require aggressive conservation efforts, such as reintroducing predators like the wolves added back to Yellowstone and throughout the West. In fact, that's the kind of massive range—and scale of effort—such animals require to thrive. And it may just be the price of coexistence.
[The above text is a transcript of this podcast.]