As it happens, 1998 will mark the 30th year of natural regulation in Yellowstone National Park.

No one denies that there are philosophical problems with the idea of natural regulation.

So, left alone under the rubric of natural regulation, most have gone into steep decline.

Yet the Park Service clings to natural regulation, despite its scientific shortcomings, for political reasons.

What is different is Yellowstone's experimentation with the unproven "theory of natural regulation."

A catastrophic failure of the planet's natural regulation could well prompt a broader desire for radical change.

The debate has crystallized around a policy known here as natural regulation.

Some light might be shed on the natural regulation of elk once the newly introduced wolves have been at work for some time.

But by clinging to "natural regulation" as the best form of bison control, Yellowstone officials ignore history.

During long voyages, fresh vegetables were indispensable, and also the plants served to provide a natural regulation of the ship's atmosphere.