The proposal's authors, led by Cornell University grad student Josh Donlan, include paleontologist Paul Martin, the father of the overkill hypothesis. Their commentary appears in the August 18 issue of Nature.

Overkill theorizes that hunting by humans led to the extinction of large mammals like mammoths and mastodons as the last Ice Age drew to a close. Many overkill proponents also believe "reintroducing" similar species like African and Asian elephants will restore the North American ecology to what it was prior to mankind's interference.

Just a few weeks ago, University of Florida ornithologist David Steadman stated that the extinction of ground sloths 4,400 years ago on Cuba and Hispaniola was caused by humans when they reached the islands -- even though he offered no evidence of human activity in context with sloth remains. Steadman also suggested filling the ecological niche left empty by extinct 1,200-lb. ground sloths by introducing 10-lb. tree sloths to the islands.

But nevermind that. Donlan and the rest want to transplant African and Asian elephants, lions, and cheetahs to private western ranches where the populations can be overseen and managed. Not only will this generate ecotourism, but in the words of a Reuters report, the plan "could spark fresh interest in conservation, contribute to biodiversity and begin to put right some of the wrongs caused by human activities." Wrongs such as overkill.

To give one example, the authors believe the pronghorn antelope owes its speed to being chased by an extinct American form of cheetah. Introducing African cheetahs to the American wilderness will "restore what must have been strong interactions with pronghorn."

Overkillers feel that North American megafauna were "nave" to the hunting techniques of the first Americans and were easy targets. They argue that megafauna in Africa, which co-evolved alongside humans, was conditioned to avoid two-leggers and therefore survived.

So the reintroductionists' doublethink is this: American megafauna went extinct because their behavior was different from that of African megafauna, but introduced African megafauna will fulfill the same ecological role as American megafauna because their behavior is identical.

To be fair, such "reintroduction" has already taken place accidentally with wild horses and burros in the west and other isolated areas, like the ponies of Maryland and Virginia's Assateague Island. All of these equines are the apparent descendants of escaped riding and pack animals. While these populations necessitate roundups and other management steps, it's safe to say they're welcome to most. The Assateague ponies are probably the island's main tourism draw.

Donlan is a strong supporter of eradicating invasive species on islands, though I suspect he's more inclined to kill rats and tree snakes than ponies. Yet his advocacy of introducing some species into an environment while terminating others suggests he is more concerned with preserving an idealized stasis than he is in determining the long-term consequences of such actions.

By all means, let's have private parks where the elephants roam and the cheetahs and the antelope play, where tourists can enjoy an African safari without hepatitis and polio boosters. Throw in a timber-frame lodge and dinners of hot chili under the stars and my boys and I will be the first to buy tickets. And if the parks promote and conserve these species, so much the better.

But let's not kid ourselves -- Donlan and company are not reintroducing anything. They would be introducing foreign species into an environment that has proven it can sustain itself just fine without them. Considering the controversy surrounding the reintroduction of gray wolves into Yellowstone, I'd say the authors have their work cut out for them adding lions and cheetahs to the mix.

Why not? What do I care? Just like Donlan, I live in the east.