"Live and let live" is a more accurate statement of the law of the jungle than the commonly-accepted "dog-eat-dog" philosophy, William L. Brown Jr., and Edward O. Wilson, research zoologists of the Museum of Comparative Zoology, said in a recent research paper.

This new principle of animal relations will require zoologists to change their methods of distinguishing one species from another, Brown and Wilson said.

The zoologists do not deny that competition for food exists among species, but say that animal life is constantly evolving to avoid it. If two closely-related species fight over the same food and one group has a slight tendency to prefer what the other doesn't, this tendency is reinforced through evolution, Brown said.

In illustration of their principle, Brown and Wilson, both specialists in entomology, described one kind of jungle ant which breakfasts at nine on other insects. By noon, it is asleep while a cousin species hunts for similar insects. No fights, occur, they stated.

Such specializations are common, Brown and Wilson said, when two closely-related species live in the same area and compete for the same types of food. When related species are geographically isolated, however, the similarities tend to remain, the zoologists said.

Brown and Wilson used the term "character displacement" to describe this principle of differentiation and similarity based on proximity. They compared it to the Harvard and Cornell teams, which both wear red uniforms, except when they play each other. Then one wears red, the other white.

The character displacement principle means that zoologists can no longer use as a "species yardstick" the range of differences between two species in the same area, for great differences may evolve between closely-related species living near one another. Neither can this range be applied to determine if two closely-related but isolated groups are distinct species, the scientists stated.