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OPINIONS

Ecological Opportunity in the Modern “Homogocene”

Steller’s sea cow. The dodo. Passenger pigeons.

These are names many of us have heard. They’re part of a sad list, now dozens of species long, of animals that human activity has driven extinct in recent history. Many other members of this list — the quagga; the Tasmanian tiger; the golden toad — are less well known, either because they lacked the charisma to become the stuff of legend, or because they have already faded from our collective memories.

Hundreds of other plants and animals perch precariously on other lists. They are “endangered,” “red-listed,” “threatened”: all in all, they’re likely to go extinct soon enough, leaving behind only photos, videos and perhaps a test tube of DNA in the back of a conservation biologist’s freezer.

Extinction events themselves are hardly a rarity: almost all species that have lived on Earth have gone extinct. As the world changes and new species evolve, some of these species invariably fall behind in the race of natural selection. Evidence from the fossil record suggests that, on average, 1-5 species go extinct each year. But sometimes, extinction rates spike, with many hundreds, or even thousands, of species dying out at once. Today, these extinctions are happening at an unprecedented rate.

We call synchronized events “mass extinctions.” From what we can learn of the fossil record, there have been at least five mass extinctions in Earth’s history. The most recent occurred 65 million years ago and wiped out the dinosaurs. Each of these events occurred long before our species evolved. We have no idea what these mass extinctions were like, what caused them and what their effects were on the living ecosystems at the time.

But now, we’re about to find out. We are in the midst of the sixth mass extinction — and this time, we know the cause: human activity.

The human population is booming. In the time it takes you to read this column (say, fifteen minutes) 3,500 babies will have been born. Today, the global population stands at 7.2 billion, and growing.

As our population grows, so too does our impact on the planet. We each need space to live and work, farmland to grow our food and maybe even some room to play. The amount of technology that we use affects the scale of these impacts: Picture the difference between a city and a village, or between an industrial-strength farming operation and a small, carbon-neutral vineyard.

Today, our impact on the planet has become so profound that it will be recorded in the geological record. Scientists call this time period the “Anthropocene,” the time in which human activity has become a driving force in nature, affecting everything from the carbon cycle to the climate.

Not only are we dramatically changing the planet, we are also homogenizing it — which is why, in the last few years, a new term has come into vogue: “Homogocene.” From the way we construct our homes, to our preference for a few key food crops, to our ability to transport goods (and inadvertent hangers-on) around the world in a matter of hours, we are turning the planet into a giant human playground.

On the one hand, this is necessary. For example, we cannot hope to feed 7 billion people without high-intensity agriculture. But on the other hand, our doing so has severe consequences for other life on the planet. Many, many species that cannot survive in human-dominated landscapes will be increasingly squeezed into tiny scraps of “preserved” land. Most are unlikely to survive this transition — and it’s the start of these extinctions that have catapulted us into the sixth mass extinction.

But this story is not entirely a tragedy. Yes, some charismatic and cuddly mammals may go, literally, “the way of the dodo.” But plenty of species will thrive in the ecological opportunities created by the Homogocene.

For example, we’d be hard-pressed to find a better success story than the corn plant, once a humble grass that now covers 30 percent of American farmland. And many of our most despised “pest” species are only known as such because they’re thriving in man-made environments. House mice, cockroaches, even dandelions and deer: these species have found ways to make a living in and around human habitation.

Meanwhile, evolution carries on, providing living organisms with the chance to adapt to human-dominated systems. From bacteria that can consume oil to fungi that can degrade plastic, we will continue to observe new life forms and patterns shaped by our influence.

Historically, mass extinctions often precede explosions of diversification, as the surviving organisms spread out to fill in the gaps. (For example, the dino die-off likely made room for our mammalian ancestors to spread, diversify and eventually give rise to us.) What will follow the sixth mass extinction remains to be seen.

 

Contact Holly Moeller at hollyvm@stanford.edu.

About Holly Moeller

Holly is a Ph.D. student in Ecology and Evolution, with interests that range from marine microbes to trees and mushrooms to the future of human life on this swiftly tilting planet. She's been writing "Seeing Green" since 2007, and still hasn't run out of environmental issues to cover, so to stay sane she goes for long runs, communes with redwood trees and does yoga (badly).
  • anonymous

    “[T]iny scraps of “preserved” land”? Hardly. Only 3% of the US is developed. By contrast, there are 747 million acres of forest land in the US. The Forest Service alone manages 8% (193 million acres) of the country! (http://en.wikipedia.org/wiki/Public_land)

    Cities and towns are but a small part of the world, but that is all most people see in a typical day, so they assume that’s what the whole planet looks like.

    Of course I won’t argue that we have altered many ecosystems, and vastly diminished the numbers of a variety of animals — particularly those that require larger areas, such as apex predators. But please be careful to check your assumptions before publishing anti-population-growth propaganda.

  • Holly Moeller

    There is a big difference between “undeveloped” and “preserved.” I agree that physical structures (i.e., cities, towns) are strikingly “developed,” but would also argue that “modified” (i.e., for agriculture, forestry, etc.) also has significant impacts on the form and function of ecosystems. Current estimates suggest about 12% of the Earth’s territorial land area is placed in protected areas — not all of which are completely closed from human influence.

    http://www.unep-wcmc.org/medialibrary/2012/04/18/2cbc1a44/The%20IUCN%20UNEP%20World%20Database%20on%20Protected%20Areas%20-%20Siobhan%20Kenney.pdf

    “Protected areas” can mean many things — from our own National Wilderness Areas that are intended to remain free of any additional human development, to National Forests which are managed for human use, including both recreation and forestry. In any case, even those reserves that are intended to remain “pristine” (i.e., no human influence) will of course be affected by human-driven global change.

    But my larger message here is that humans are transforming the planet. A few species will only survive if we managed and protect relatively un-modified tracts of land for them. But plenty of species will thrive in human-dominated landscapes, and others may yet evolve there.

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