By fortunate circumstance of timing, bizarre behavior patterns of a primitive fish believed long extinct have been exposed to public scrutiny. This comes even as the latest fallen American presidential candidate demonstrates anew the bizarre nature of U.S. political campaigns.

Scientific expedition photographs taken deep in the Indian Ocean and just published in the British scientific journal Nature show coelacanths "performing occasional headstands, swimming belly up and sometimes swimming backward, among other unusual behavior," according to an account in The New York Times. The same report, published on the day that Sen. Joseph R. Biden Jr. (D-Del.) withdrew from the presidential contest, says:

"The strange movements of these coelacanths, survivors of a biologically ancient line, surprised and delighted the scientists who ventured into their habitat in a research submarine. Scientists believe that analysis of the pictures may shed light on the aquatic ancestry of all land vertebrates, including humans."

Their behavior, therefore, offers fresh clues to evolution and human behavior -- and just in time, too. As recent political behavior demonstrates, such clues that help create understanding of political actions are desperately needed.

Democratic presidential aspirants, for example, are behaving like characters in an Agatha Christie mystery. They're doing a good job of doing themselves in, and it is a messy, self-destructive business. The way the campaigns are going, more little Indians than Gary Hart and Joe Biden seem certain to fall.

The reasons for the self-destructive behavior differ. In general, the Hart and Biden cases involve individual questions of personal character and judgment, with Hart's problems of far greater severity than Biden's. But every politician, and every citizen, can identify with observations Biden made after he, like Hart, was forced from the race.

"I'm angry with myself for having been put in the position . . . of having to make this choice," he said. "And I am no less frustrated at the environment of presidential politics that makes it so difficult to let the American people measure the whole Joe Biden and not just misstatements that I have made."

Obviously, the present political environment is difficult. The question is whether it's worse than usual.

The answer is probably not. American political campaigns evolved out of a background of personal assaults, misrepresentation, exaggerated or false claims, dirty tricks and sleazy behavior.

Some of the earlier kinds of political practices make today's exchanges seem benign. "He is a man of splendid abilities but utterly corrupt," the pale, dyspeptic 19th-century politician, John Randolph of Roanoke, remarked of a rival. "He shines and stinks like rotten mackerel by moonlight." A more contemporary example -- and a personal favorite -- of the art of outrageous political insult was labor leader John L. Lewis' characterization of Franklin D. Roosevelt's vice president, John Nance Garner, as a "labor-baiting, poker-playing, whiskey-drinking, evil old man."

So the 1988 presidential election cycle, with its dismaying, destructive, cynicism-producing aspects, hardly sets standards.

Still, with 14 months until the presidential election, evidence strongly suggests that something beyond problems with certain candidates is wrong.

Too many substantial people are choosing not to enter the race. Too many examples exist of promising candidacies gone awry. Too many expressions of public disgust are heard about self-destructive politicians and a self-righteous, supercritical press. Too many people feel let down and turned off.

Some reasons for this political state of affairs are evident. The campaign period is far too long and infinitely too costly. There are far too many presidential primaries and senseless straw-vote samplings, too much media sound and fury.

The failures of Hart and Biden point to problems with the candidates and their staffs. Biden, for one, was ill-served by advisers and speechwriters who either failed to alert him to the dangers of plagiarism or contributed directly to the pattern by supplying him wholesale with verbatim, lifted passages.

At its heart, though, the problem involves the process and the practitioners. Both are flawed. Like the coelacanths, the presidential campaign performs erratically. Sometimes it moves backward. Sometimes it goes belly up. It is in danger of extinction and deserves to be. Another evolutionary phase is in order.