The Ghosts of Evolution

by Connie Barlow

"In October 1977, Dan Janzen, an ecologist then in his late thirties, wrote to the famous paleontologist Paul Martin, saying "I've got a screwy idea." What had led to Janzen's "screwy idea" was a mundane observation about the Costa Rican forest that, as he thought about it more and more, made less and less sense: There was a lot of uneaten fruit lying around on the forest floor. Fruit evolved to be eaten - it's a strategy plants employ to get animals to scatter their seeds - so such massive piles of rotting fruit made no evolutionary sense. Janzen wanted Martin to tell him what animals might have eaten the fruit in past eras. The paper the two co-wrote, published in Science in 1982, became an enduring classic in the ecological literature.". "Janzen and Martin had put their finger on an unnoticed contradiction in ecological thought. First, ecologists know that all living species evolve intricate, mutually dependent relationships with other species. Second, ecologists had also assumed th