1.   But, researchers say, in some basic ways fruit and fruit eaters remain in constant conflict.

2.   Fox bats are ordinarily fruit eaters, but some biological tinkering suddenly has them eating anything.

3.   Others trick fruit eaters into gorging themselves by loading up with nonsugar sweeteners, chemicals that entice but have no nutritional value.

4.   Thus all bats seen today, from large, big-eyed fruit eaters to small, echolocating insect hunters, descend from a common ancestor.