When people think of conservation, they think of setting aside some land for animals that they have seen in that area before.

Yellowstone National Park, for example, was created to preserve some of the West’s geological wonders and wildlife.

However, when viewing bison, elk and grizzly bears, few people realize that North America — indeed most of the world — was once home to as much big game as can be found in modern-day India and Africa.

When humans arrived in the Americas some 14,000 years ago, they encountered not only the cougars and mule deer we would recognize, but also mammoths, camels, lions and many other animals not found here today.

There are several possible reasons for their disappearance, but evidence is mounting that overkill — or over-hunting large herbivores and out-competing large carnivores — was a major factor in the extinction of North America’s megafauna around 10,000 years ago.

Humanity may have caused the loss of these animals, but it is within our means to bring them back as well.

This dream is already turning into a reality. Groups like the Intertribal Bison Cooperative, the Great Plains Restoration Council and others are already working to set aside part of the Great Plains as a buffalo commons, or nature preserve, where native and rural people can interact in a sustainable way with the land and its animals.

Bringing back bison, moose, elk, deer, pronghorn and peccaries is a wonderful idea, but why stop there? Why not bring back horses and donkeys as well? These animals are not “nonindigenous pests,” but rather reintroduced natives that have been sorely missed.

Members of the camel family once lived in North America, too, so camels and llamas could help keep plants in the Great Plains and Southwest in check, if only given the chance. Elephants in Texas and the humid Southeast could do much to help disperse the seeds of trees that once relied on mammoths.

These herbivores need not compete with cattle, sheep or goats, either; we could set aside land for both wild and domestic animals, and allow for a sustainable take from these populations, too.

Historically, we have had a much harder time getting along with carnivores, because we do not want them to harm us, our pets or our livestock. Given enough space and an abundant prey base, though, even carnivores could be part of this rewilding plan.

It is time we recognize that while we have the power to destroy life, we also have the power to encourage it. The whole world is currently experiencing yet another extinction spasm, but there are many actions we can take to help reverse that trend.

One such action is to reintroduce the animals that once roamed North America in spectacular numbers, as they still do in some remote reaches of the planet today.

In so doing, we will not only be sharing our world with our fellow creatures, but enriching it for ourselves and our children.

Gaddy Bergmann is a graduate research assistant in the Department of Ecology and Evolutionary Biology at the University of Colorado.