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A drawing of one of the teeth discovered by Charles le Moyne. The first published mention of the bones is on a map entitled Carte de la Louisiane Cours du Mississipi et Pais Voisins (Map of Louisiana, the Course of the Mississippi, and Neighbouring Countries). It is dated 1744 and was prepared by ‘N. Bellin‘ (Jacques-Nicolas Bellin 1703-1772).
A drawing of one of the teeth discovered by Charles le Moyne. The first published mention of the bones is on a map entitled Carte de la Louisiane Cours du Mississipi et Pais Voisins (Map of Louisiana, the Course of the Mississippi, and Neighbouring Countries). It is dated 1744 and was prepared by ‘N. Bellin‘ (Jacques-Nicolas Bellin 1703-1772).

The Sixth Extinction: The world has endured five mass extinctions. Can we survive a next one of our own making? Add to ...

  • Title The Sixth Extinction: An Unnatural History
  • Author Elizabeth Kolbert
  • Genre science
  • Publisher Henry Holt and Co.
  • Pages 336
  • Price $32

“No other creature has ever managed this, and it will, unfortunately, be our most enduring legacy,” Kolbert writes.

The notion that we are wreaking havoc on the planet is hardly a surprise. The impact of Kolbert’s approach is in showing how widespread and unintended are the consequences of our sudden and startling rise as the global grim reaper.

It’s not just about paving paradise, to paraphrase as Joni Mitchell. While we are indeed encroaching on wilderness at every turn, all the parking lots in world can’t account for the epic changes that are under way. Simply by going about our daily business, we’re rewiring the ecological circuitry of the planet, and triggering blackouts aplenty.

Kolbert demonstrates this effect at her first stop, a conservation centre in Panama that serves as a “frog hotel” for endangered amphibians. But like the Hotel California, the centre is a place where the guests can never leave. Beyond its walls, the tropical streams that formerly teemed with colourful species like the Panamanian Golden Frog have been emptied of its amphibian inhabitants, a wholesale disappearance that swept over the area a decade ago.

The culprit has turned out to be a kind of fungus that infects frogs’ skin and deprives them of electrolytes. As Kolbert explains, “this causes them to suffer what is, in effect, a heart attack.” By the time it was noticed, the fungal wave was already a global phenomenon. Largely because of it, amphibians – an ancient and hardy group that sailed through with barely a wrinkle when the dinosaurs perished – are now the most endangered class of animals on Earth.

Significantly, unlike the hapless dodo or the passenger pigeon, the frogs that are vanishing before our eyes are not the direct target of human action. Yet, their demise is just as surely the product of human invention, thanks to modern air travel, which connects pathogens to potential hosts in ways that have not been possible since all the continents were together in one land mass. One theory posits that the disease was transported around the globe by shipments of African clawed frogs, which can carry the fungus but are unaffected by it, and which were widely used for pregnancy tests throughout the 1950s and 1960s.

Using airplanes to recreate a “New Pangaea” is an immediate effect of our far-reaching presence. But longer term and more profound transformations are also in motion. The entire suite of changes has so altered the planet that some scientists argue we are living in a new geological era – dubbed the Anthropocene – in which it is impossible to separate what’s happening on Earth from what we’re doing to it.

Kolbert’s most poignant chapters deal with a subject she knows well, the effects of climate change. Here, we have a sneak preview of the ecological pressures that are most likely to drive the sixth extinction for centuries to come.

While visiting researchers at Australia’s Great Barrier Reef, Kolbert capture a sense of the fragility of an entire ecosystem that is poised to be undone by ocean acidification. This is extinction supersized. In an effort to capture what it means, Kolbert quotes from one researcher who suggested in a recent Nature paper that by 2050, based on current trends, visitors to the Great Barrier Reef will arrive to find only “rapidly eroding rubble banks.”

Such assessments could make for a gloomy read but but Kolbert manages to avoid being depressing or preachy by keeping her focus on the science, which is engrossing, and the scientists she meets along the way. Together, they form a remarkable cast of characters, all grappling with an unprecedented moment in the story of life.

It’s also a story that is propelled by a cliffhanger ending. While humans have become the largest force at work on the planet, we remain fundamentally dependent on its systems for our own survival. Just because we can start a mass extinction doesn’t mean we can outlast it.

As Leakey and Lewin wrote: “Our inability to imagine a world without Homo sapiens has a profound impact on our view of ourselves; it becomes seductively easy to imagine that our evolution was inevitable. And inevitability gives meaning to life, because there is a deep security in believing that the way things are is the way they were meant to be.”

Such hubris leads to a kind of blindness. Until Cuvier, it prevented scientists from recognizing the truth in a pile of exotic bones. Unless we shake it off altogether, it will prevent us from recognizing the truth of our own situation: that we are walking a tightrope without a safety net. Kolbert is telling us its time to look down. The view is scary but it’s also amazing.

Ivan Semeniuk reports on science for The Globe and Mail.

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