The atmosphere at the research station is probably similar to that at Los Alamos, New Mexico, in the 1940s, when a group of the world's top physicists were cloistered together trying to design the atom bomb. They justified the creation of a nuclear weapon by assuming it would provide the ultimate deterrent that could be used to reinforce peace in a democratic world. Similarly, the longer-term future of human civilization on earth is dependent on the earth's forests, which act as its lungs, livers and kidneys. That is why scientists on B.C.I. are struggling to unravel the mysteries of the forests before they disappear.

At first the forest in Panama just looks like a wall of green. Then you start to notice differences between plant species, and the sheer diversity seems suddenly overwhelming. Variations between plants are often subtle and only apparent for the short period of time that a species bears flowers or fruit. Slowly you begin to identify specific types and family groups such as the palms, heliconias and fig trees. Yet each of these families contains many species, every one a subtle variation on an evolutionary theme that has found a slightly different way of competing for limited light and nutrients, or escaping from predators and diseases.

The fig trees provide a spectacular example of the complex interaction of species that enables forests to function. Of more than 1,000 species of figs in the world, at least 20 are found in Panama. Most tree species on B.C.I. bear fruit only seasonally, producing an abundance of it at the beginning of the rainy season in May and June. This is all consumed by a variety of birds, monkeys and bats, and by the end of the rainy season, in October through December, there is a major shortage of food in the forest. Saving the day are the fig trees, which may bear fruit at any time.

Why do fig trees follow a different fruiting strategy from that of other trees? It turns out that figs are pollinated by tiny insects called fig wasps. The female wasp enters the fig flowers when they appear, lays her eggs and then dies. In the process she brings in fig pollen, which fertilizes the flower and spurs development of the fig fruit. Meanwhile the wasp's eggs develop within the flower into larvae, which feed on some of the fruit before metamorphosing into adults and mating within the fruit. The males then die, while the females, by now covered in pollen, leave the fig in search of a new flower in which to lay their eggs, thus keeping the pollination going. Research by Allen Herre and colleagues at B.C.I. has shown that adult female fig wasps live for only two days and that each species of the fig wasp is specific to a species of fig. Thus there always has to be a fig in flower while one is in fruit to ensure that the cycle continues. Since a fig-tree population must bear fruit all year because of the wasp's short life-span, the figs keep fruit-eating mammals alive during the dry season when other food sources are scarce. The fig trees are in turn dependent on these fruit-eaters as dispersers of their seed. Of course, the fruit-eaters also disperse the seeds of other plant species that produce fruit during the rainy season. This creates a long-term dependence of the other plants on the presence of figs.

All this suggests that a minimum number of fig trees is essential for a healthy tropical forest. Furthermore, studies from a variety of other habitats indicate that the disappearance of just one or two keystone species can lead to extinctions throughout the local community. In some cases it may take decades before trouble starts to show up.

Ultimately the forest has the vast potential of time to recover from almost anything we do to it. Like a large green heart, it has often expanded and contracted on a time scale of tens of thousands of years, while simultaneously fostering the diversity of species that inhabit the planet, including our own species. Unfortunately our human ability to understand our relationship to the forest and other habitats has to be mustered on a much faster time scale. Luckily scientists trying to demonstrate the dependence of humans on natural communities are making huge strides. History will show that their long-term contribution to the quality of life far exceeded those of other scientific endeavors such as the bombmaking at Los Alamos. It will also be far easier to justify their work to our grandchildren.