Michael Soule, a pioneer in the field of conservation biology, is a cofounder and current board member of The Wildlands Project, a group dedicated to maintaining and enhancing biological diversity in North America. HCN editor Paul Larmer interviewed Soule recently to explore North America's ecological history and what it can teach us about conservation in the modern world.

Paul Larmer: Michael, why should we care about ecological history?

Michael Soule: The deep paleontological history of the planet opens our eyes to many interesting and relevant things, such as the fact that almost all of North America's fauna came from Asia. Only three families of mammals originated here: the dogs, the camels and the horses. So when people say today, "We've got to get rid of these horses and donkeys on the Western range - they're not native," well, by god, they are native, though they are different species than those that once lived here.

We find even more relevance when we focus on a much shorter period of history - the last 12 or 13,000 years, when there were three or four horse species around, three or four species of camels. This was the time of the mass extinction. Though all these species disappeared, their food, the plants, didn't. So what we have are decapitated ecosystems with the large herbivores mostly gone - including elephants * as well as the large carnivores, such as the dire wolf and saber-toothed tiger. These species really shaped the landscape.

If you go to Africa, which still retains most of its Pleistocene animals, and you look around, it looks terrible. The riparian-area vegetation is all beat down, the river banks are all trampled with the hooves of large animals. If that happened here, people would say, "Oh my god, overgrazing, compaction, siltation!" We have this almost Japanese view of what our backcountry areas should look like - very neat and tidy. It probably wasn't that way in the Pleistocene.

LARMER: Do you believe humans wiped out the Pleistocene mammals?

SOULE: I believe humans did it, but there are always interactions. Every scientist is looking for a single smoking gun, but in most cases ecological change has several interacting causes. Climate doesn't act alone, overkilling doesn't act alone.

One lesson from the extinction of the megafauna is that anytime anyone comes to a new place with a new technology, they wipe everything out. And it takes 200 or 300 years to figure out how to live in that ecosystem without destroying it.

LARMER: Then we should now, 500 years after Columbus, be at a place of equilibrium with nature, right?

SOULE: The trouble now is that we are such an inventive species that there's no time to adjust to our new technologies. We probably could have learned how to live with just a flintlock, but then came the rifle and the repeater, and the automatic weapons and the assault rifles. On top of that there are ATVs, snowmobiles, and radios, cell phones, rifle scopes. We have so many tools and the tools come so fast that we never have time to develop an equilibrium between culture and nature.

When the Inuit tribe says, "we have a right to continue hunting whales," I say, "maybe you do, but maybe you don't if you hunt with modern weapons, because you could wipe out every species of whale and marine mammal that you come in contact with. If you want to hunt, fine, but do it in the traditional way. You're not any different than any other human: With a new technology you will abuse it until it's too late."

LARMER: What should be our conservation priorities in an age of such rapid technological change?

SOULE: We should take our cues from history, which informs us that our categories of ecosystems are time-bound. They don't persist. There were very different associations of plants and animals 5,000 years ago than there are today, though many of the species were the same. The lesson is that if we want to protect nature while the world is rapidly changing, all we can do is save all of the pieces - all of the species - and let them sort themselves out. That's not easy, though, because it's hard for species to get from one place to another in a human-fragmented world.

LARMER: And yet, in one sense, what we have going on now is too much connectivity. Humans are mixing species from around the globe at an unprecedented rate.

SOULE: I know. It's as if we built these land bridges connecting all the continents with giant conveyor belts just taking things back and forth and mixing the flora and fauna. Ecological change is happening very rapidly now and many of the species are very aggressive. Especially the herbaceous species and grasses. They are completely changing the nature of the habitat.

We're in the phase where things like cheat grass have no natural enemies, so they can take off and take over an ecosystem. We've left their enemies behind and they are suddenly free. How long will it take for native species to figure out how to take advantage of this huge new food source or for the ancient enemies to come over and discover it? That's probably in the centuries. There's a disconnect between the rate of cultural change and the pace of evolution.

LARMER: Is the environmental movement off-base by focusing so much attention on protecting wilderness, which some critics describe as a human construct?

SOULE: One sitting in the ivory tower can argue that wilderness is a human construct, but all of that pales into insignificance when you realize that large, undisturbed lands are the only places where native species will survive. Once you've built roads and access into an area, you start getting edge effects and fragmentation, and it's all downhill from there.

If the keystone species, like the large carnivores, disappear, the ecosystem can change dramatically, as we've seen in Rocky Mountain National Park. The absence of wolves has meant that there has been no new recruitment of aspens and willows for nearly a century; the elk have browsed them down. The absence of riparian vegetation has eliminated the beavers; and the absence of beavers has meant fewer ponds, streams down-cutting into their channels and a dropping water table. The whole system can shift into a state that is very hard to recover.

LARMER: Some people would argue, though, that humans have replaced wolves and other species as the real keystone species.

SOULE: We're certainly a dominant species, but that's not the same as a keystone species. A keystone species is one that, when you remove it, the diversity collapses; we're a species that when you add us, the diversity collapses. We can change everything, dictate everything and destroy everything.

LARMER: We can also try to restore things. How do we restore the West, especially our heavily impacted middle-elevation lands?

SOULE: We've got to be pragmatic. We're not going to be able to get rid of many of the exotics, but we should maintain intact ecosystems by limiting road building; restoring connectivity and linkages in the landscapes between roadless areas; and preventing extinction. Those are the tools that will allow a lot of things to survive for a century or two, at which time the world will have changed so much that we will have no idea what will be needed or what will be the conservation philosophies then. But at least we will have passed on the raw material, a sort of temporal Noah's Ark.