Where have all the animals gone?


The bigger the animal, the greater the chance for extinction: This is a tapir. (Mauro Galetti, file photo, location unknown)

Here’s a phrase to remember: the Anthropocene defaunation. That’s a fancy way of saying that the animals are disappearing.

Humans already did their worst in the Pleistocene, wiping out many of the largest terrestrial animals on Earth (mammoths, mastodons, ground sloths, giant camels, glyptodonts, saber-toothed cats, gomphopheres, stag moose, giant short-faced bears, the North American horse, giant kangaroos, marsupial rhinos, giant armadillos, dire wolves, etc.). In more recent centuries the spread of invasive species, carried by humans in their cargo and in the treads of their boots, has led to all manner of biological chaos and loss of biodiversity. Some animals are going extinct, and many more are dwindling in number. Tropical forests are getting cleaned out. Marine ecosystems are overfished.

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Scientists are studying the effects of defaunation in tropical forests. (Mauro Galetti)

The new issue of Science, published Thursday online, features a series of articles on disappearing animals, and the overall message is an alarming one. We still haven’t halted the decline in wildlife around the globe. “We live amid a global wave of anthropogenically driven biodiversity loss,” declares a review of the issue by Stanford University’s Rodolfo Dirzo and colleagues.

The report states that 322 land-based species have now gone extinct in the last 500 years. Among closely monitored species, two-thirds showed a mean decline in population of 45 percent.

We all know about habitat destruction: Cut down a rain forest and that’s bad for the tigers who live there, and all the birds and the beetles and the frogs and so on. And we all know about anthropogenic global warming, which poses a challenge to species that can’t adapt quickly or shift locations. But the new issue of Science reminds us that one way that people are driving down the numbers of wild animals is by directly killing them. We shoot them. We hook them and net them. We eat them.

[Update: "In contrast to deforestation, defaunation tends to go unnoticed, but our research indicates that, ironically, given its consequences for humankind it can soon become a painfully visible anthropogenic global chance," Dirzo told me by email.]

So much of the discussion about eating meat here in the U.S. and in the developed world pivots on ethical and health issues (what about the suffering of that pig that gets slaughtered in a factory farm to make bacon that you probably shouldn’t be eating anyway?), and downstream environmental effects (the carbon footprint of a steak is enormous). But there are a billion people in the world who are very poor and aren’t eating protein from a factory farm — they’re hunting for it in the forests or fishing it out of coastal waters and rivers.

Even if we solved climate change tomorrow, and even if we never clear-cut another acre of forest, we’d face this problem of defaunation. People need to eat. Given a choice between staying alive and preserving an endangered species, people will invariably choose dinner. There are 7 billion of us and that number will soon reach 9 or 10 billion. An opinion piece in Science by Joshua Tewksbury and Haldre Rogers points out that 2.6 billion people get their protein primarily from ocean animals.

A particularly eye-opening article comes from Justin Brashares, an ecologist at Berkeley, and his colleagues. They report that the harvesting of wild animals from the land and sea is a $400 billion business on which 15 percent of the people of this planet depend for their livelihood. They say the decline in wildlife destabilizes societies, and fuels terrorism and exploitative labor practices, including slavery (for example, in Thailand men are “sold” to fishing vessels and spend years at sea without compensation).


Aldabra giant tortoises introduced to Round Island, Mauritius, as ecological replacements for the extinct Mauritian giant tortoises (Nik Cole).

“We have a process going on, the consumption of nature – eating our way through ecosystems – that we’re feeling the consequences of right now, and they’re immense,” Brashares told me in an interview Thursday.

What can we do? For starters, we can realize that our current way of approaching the disappearing wildlife problem — primarily through law enforcement — isn’t working, he said. There are biological, ecological trends that underlie the social and economic drivers of poaching, he said.

“We’re trying to yoke together the biological and the sociological, and in the process try to emphasize the fact that our policy response needs to integrate those things,” he said. “It needs to go deeper than trying to arrest middle men in the ivory trade.”

A final point to make: Here in the affluent West, we’re largely insulated from this unfolding disaster. But this is happening right now. This doesn’t come from computer models.

Figuring out how to create a sustainable and just human society that doesn’t obliterate the rest of the natural world is the paramount challenge of the next century. Let’s not wind up with a planet of weeds, as David Quammen once put it — a planet of white-tailed deer, cockroaches, rats and humans.

(For more along these lines, see this A-blog post, and this A-blog post, and this one, and this story from 2012 on Spaceship  Earth and this National Geographic piece I did on extinct Australian megafauna.)

Joel Achenbach writes on science and politics for the Post's national desk and on the "Achenblog."
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Joel Achenbach · July 22