Stuff happens – and stuff happens in the garden. But, these things can’t be talked about with neighbors who notice my mail box tilts drunkenly or who remark that the new people across the street should mow their lawn more frequently, especially now that it’s getting warmer. Walking alone in my garden with coffee cup in hand, the night dew still slickening the leaves, I pause at a new plant at another struggling to survive. I notice fungus on my rose bushes and fret about the future of mankind.
It’s the weekend. I can think about whatever I want. Right?
OK. So I’m told that, not tomorrow or the next day, but in the future, say 65 million years from now, we may not be here. I peer at the roses, the fungus exhaling millions of spores as I stand mute in my ignorance and bathrobe, and wonder if this is the beginning of the end, wonder if this is proof that we’re all doomed. The world is ending, not in a cataclysm, but in the stealthy creep of must and mildew, pathogens will rule the world.
Silly? I’m not alone in this concern, as dramatic as it sounds. Writer Elizabeth Kolbert has written The Sixth Extinction: An Unnatural History, an epic, riveting story of our species that reads like a scientific thriller–only scarier because it talks about now and and what may happen in the future.
What I got from the article she published in The New Yorker is that pathogens, specifically, fungi are attacking various life forms and killing them – frogs, bats and California oak trees.
Of the numerous species that have ever existed on earth, scientists say more than 99 percent have disappeared. But, extinction, which is seen as bad and preventable, causes a lot of argument and finger pointing, not to mention investment of tax dollars to prevent it.
I worry these attempts are futile, even silly. Are we homo sapiens merely putting our fingers in the evolutionary dike and pretending we can make a difference in the history of the universe? Is global warming the single cause of our demise? Are we all doomed? I study my roses for the answer.
Throughout the 18th century, the prevailing view was that species were fixed they exist and always will if human will just stop annihilating them. Charles Darwin believed extinction happened slowly, but he was wrong. In Kolbert’s article, she noted that researchers have found that during the past half billion years, there have been at least 20 mass extinctions. Five of these—the so-called Big Five—were so devastating that they’re usually put in their own category. Keep in mind, I’m talking Earth time, which spans about 4.5 billion years.
Kilbert notes the fifth extinction, the end-Cretaceous event, occurred a mere 65 million years ago. The event exterminated not just the dinosaurs, but 75 percent of all species on earth. Once a mass extinction occurs, it takes millions of years for life to recover, and when it does it’s generally with a new cast of characters.
In this way, mass extinctions have played a big role in evolution’s course. It’s hard to say when the current extinction event—sometimes called the sixth extinction— began, but we’re in it. Scientists speculate that its opening phase started about fifty thousand years ago, when the first humans migrated across Australia and America.
If current trends continue, by the end of this century as many as half of earth’s species will be gone. For example, researchers first noticed something odd was happening to amphibians. The main culprit in the wavelike series of amphibian population crashes it turns out is a chytrid fungus, known as Bd. At this point, Bd appears to be unstoppable and its killing effect is spreading.
In 2007, biologist Al Hicks, of the New York State Department of Environmental Conservation, and the National Wildlife Health Center, started looking at mysterious bat deaths in the U.S. Many of the dead bats were discovered with a white substance on their nose, which was cultured and found to be an unidentified fungus. In California, millions of native oak trees have died from the fungus-like Phytophthora ramorum, a photo of how destructive it can be is show here.
Just in the last century, carbon dioxide levels in the atmosphere have changed by as much as they normally do in a hundred-thousand-year glacial cycle. In the end, the most deadly aspect of human activity may simply be the pace of change itself, moving too fast for life as we know it to catch up.
One of the maddening puzzles of mass extinction is why, at certain junctures, the resourcefulness of life seems to falter. If we’re getting ahead of ourselves, pathogens jump into the breach. Today Fungi account for about 30 percent of emerging plant diseases. These microscopic maladies are the bane of gardeners and farmers who watch in dismay as plants wilt and succumb to these microscopic killers. Fungal diseases radically alter natural ecosystems, as well as food and our environment.
A recent report in Science Daily noted that fungus, including chestnut blight fungus, which eliminated nearly 100 percent of native chestnut trees throughout eastern American forests during the last century, and at the same time Phytophthora cinnamomi fungus is threatening native forests throughout Australia.
And, in human time, fungal pathogens have been around for a long time, sometimes changing the course of history. For example, potato blight was responsible for the epidemic leading to the Irish potato famine in the 1840s and the largest immigration event in U.S. history. More recently, stem rust disease of wheat, first identified in Uganda in 1998, is threatening crops in North Africa, the Middle East and Asia.
If more fungus is creeping across our landscapes, if it is occurring more frequently, what’s going on? Is it climate change or sun spots? Is it signs the Sixth Extinction is accelerating and the end of life as we know it is near? What’s going on? Should we worry?
“It’s the next annihilation of vast numbers of species and it is happening now, and we, the human race, are its cause,” explains Dr. Richard Leakey, the world’s most famous paleoanthropologist and co-author of the 1995 book The Sixth Extinction: Patterns of Life and the Future of Humankind. He says every year between 17,000 and 100,000 species vanish from our planet.
“For the sake of argument, let’s assume the number is 50,000 a year,” Leakey says. “Whatever way you look at it, we’re destroying the Earth at a rate comparable with the impact of a giant asteroid slamming into the planet, or even a shower of vast heavenly bodies.”
The statistics he has assembled are staggering. Fifty per cent of the Earth’s species will have vanished inside the next 100 years; mankind is using almost half the energy available to sustain life on the planet, and this figure will only grow as our population leaps from 5.7 billion to 10 billion inside the next half-century.
A dramatic and overwhelming mass extinction threatens the entire complex fabric of life on Earth, Leakey said, including the species responsible for it: Homo sapiens, that all life as we know it is destined to vanish.
Oh, boy. That’s a lot to worry about as I contemplate my garden. Do you think my neighbors want to hear one peep about the end of the world out of me? Like I said, I worry and wonder, study the underside of leaves in my garden and don’t care one way or another about how often my neighbors mow their lawns.
But, all this talk about the nature of pathogens is raising startling new questions in my peanut brain. I wonder about the role of fundamental scientific research and how the study of evolution plays into our understanding of emerging disease. I get another cup of coffee.
Then there’s this: Associated Press reported last year that coffee farmers and harvesters in Central and South America have been hit by Roya, or “coffee rust,” a fast-spreading fungus that infects the leaves of coffee plants. Roya has caused an estimated $1 billion in damage, and threatened the livelihoods of more than half a million farm families from Mexico to Peru.
This is a bad situation and an example of what worries me. In particular, I’m concerned about how specific new species occur when a subset of a fungal population shifts to a new host. Another example? Fungus is now attacking frogs and bats. All of this is just too much to contemplate. When a neighbor passing by my garden asks how I’m doing, I say “fine” and hope they don’t notice the mildew on my roses.