From Nautil.us Earth:
We are ignoring the gains that balance the losses.....MUCH MORE
After decades of researching the impact that humans are having on animal and plant species around the world, Chris Thomas has a simple message: Cheer up. Yes, we’ve wiped out woolly mammoths and ground sloths, and are finishing off black rhinos and Siberian tigers, but the doom is not all gloom. Myriad species, thanks in large part to humans who inadvertently transport them around the world, have blossomed in new regions, mated with like species and formed new hybrids that have themselves gone forth and prospered. We’re talking mammals, birds, trees, insects, microbes—all your flora and fauna. “Virtually all countries and islands in the world have experienced substantial increases in the numbers of species that can be found in and on them,” writes Thomas in his new book, Inheritors of the Earth: How Nature Is Thriving in an Age of Extinction.
Thomas is a professor of conservation biology at the University of York in England. He is not easily pigeonholed. He has been a go-to scientist for the media and lawmakers on how climate change is scorching the life out of animals and plants. At the same time he can turn around and write, “Wild geese, swans, storks, herons and cranes are returning as well, and the great whales, the largest animals ever to have lived on Earth, are once more plying their way across our seaways in numbers after centuries of unsustainable butchery.” Glass half empty, meet Chris Thomas.
Inheritors of the Earth collects years of Thomas’ field research, illuminating plant and animal species—notably one of his specialties, butterflies—flourishing all over the Earth. Thomas also puts big ideas on display. Humans are just another animal on the planet, he wants us to know. Our actions are not outside the engine of evolution, even though we have the most horsepower. Environmentalists need to stop fencing off nature from humans, he argues, understand the mechanics of evolution better, including our role in it, and quit being such nattering nabobs of negativity. Once they do all those things, real conservation has a chance. The Sixth Great Extinction, he tells us, is premature.
There may be a bit too much of Dr. Pangloss in Inheritors of the Earth, and despite its ample footnotes, I would have liked to have learned more about how Thomas quantifies some of his general assertions about increases in species. I did ask Thomas to cite the research he has drawn from to support his views, and he responded with the names of five scientists who have influenced him. You can read his answer in a footnote at the end of the interview.1 (I didn’t include it because it seemed kind of wonky.) In any event, Thomas was a pleasure to talk to. What is it about a wry Englishman that so enchants an American interviewer? Thomas and I had a jolly conversation, even if it got contentious at times, as I reminded him of the environmental wreckage that hung like a dark cloud over his thesis.
You write, “It is entirely possible that the long-term consequence of the evolution of Homo sapiens will be to increase the number of species on the Earth’s land surface.” That sure goes against the grain of what we have been hearing for generations.
Yes, it does.
What first caused you to you come to that conclusion?
I knew there was a new hybrid plant living in my hometown of York, England, and nowhere else in the world, and I had also heard about a new kind of fly evolving on introduced apple trees in North America. I started to reflect on the fact that so many of our crop plants started out as hybrids between different species. So I privately asked myself: How many new species might come into existence because of humans? All I needed was a pencil and the back of an envelope for my first calculation. I was gobsmacked, and eventually pleased with my preliminary answer. I reckoned that we might, very roughly, double the number of species on Earth over the next million years. Brought up on stories of extinction and environmental doom, it took me several years to believe my own answer.
Give us a convincing example of how humans boost the number of species.
The Italian sparrow is a really good example of a rapid evolution of a new species. It began when the house sparrow colonized out of Asia, following the development of agriculture. In the Mediterranean Basin, it met the Spanish sparrow. At some point, probably about 6,000 years ago, the house sparrow and the Spanish sparrow hybridized, and their offspring became sufficiently genetically distinct. Although they can interbreed with both of their parents, they basically don’t. So a new species came into existence by hybridization. I really like this example because the Italian sparrow has probably already survived for several thousand years. It’s not one of these species that come into existence and suddenly disappear.
Yes, there are monsters. Biodiversity is not a one-way street to a beautiful, happy world.Most of the new hybrids exist because we humans have either deliberately or accidentally brought the parents—which used to live in different parts of the world—into contact with one another. This is an extraordinary feature of the modern world. There has been no time in the history of life when species have been mixed up within and between continents at the rate that’s going on at the moment. The consequence of this human-caused transport is that hybrids must be coming into existence faster than ever before.
Is there a mammal that fits your scenario? Mammals have not fared well with humans.
You are quite right. The heavyweight, large body-sized mammals are where we have most systematically exterminated other species over the last 60,000 years. There’s no doubt about that whatsoever....
