Imagine the following. Aliens land on Earth in a field near Clinton Lake. Upon emerging from the spaceship, the aliens' first words are not the proverbial, "take us to your leader." Instead, they wave a wand-like device at the horizon and say: "Your planet is teeming with life. Our sensors tell us that there are millions of life forms here many more than on our planet. Can you describe the millions of animals and plants and microbes that live on your world? Can you tell us where and how they live, what they need to survive and how you interact with them?" We look at one another, scratch our collective heads and respond, "Sorry, we can't do that just yet, we're still working on it."
The aliens promptly get back into their spaceship and depart, recording in their galaxy database that intelligent life in this solar system is still quite primitive. That night on CNN, pundits and president-elect Bush bemoan our inability to answer the aliens. They are embarrassed that after 300 years of the biological exploration of the planet we still do not have a census of life on Earth. They agree that we would ask the same questions if we landed on a distant planet and found it swarming with life.
When Bush and his science advisers plan the nation's scientific frontier for the next four years, perhaps they should consider the four embarrassing questions aliens would ask about life on Earth.
First, the diversity of life what are the plants, animals and microbes that inhabit the Earth? After 300 years, we have identified about 2 million species, but surveys and field expeditions indicate that somewhere between 15 million and 50 million species still live undiscovered in oceans, soils and tropical forests. Essentially, we don't know what we don't know.
Why is a census of Earth's life so important? Basically, be-cause life is here. It pervades the planet. It provides us with essential food, fuel, fiber, pharmaceuticals and "free" environmental services that clean our air, water and soil. And, life on Earth may be alone, not occurring anywhere else in the galaxy or universe. If so, we should know the extent of this uniqueness.
The second fundamental question encompasses the tree of life what is the genealogy of all the plants, animals and microbes on the planet? We know from fossils that the tree of life goes back 3.8 billion years, ever since simple bacteria first appeared on Earth. The leaves of the tree are the millions of species on Earth, both living and extinct; we need to decipher the connecting twigs, branches, trunk and roots.
Why is decoding the genealogy of life so important? For advancing knowledge in virtually every endeavor that uses biology. For example, in agriculture to understand species of crops, pests and the soil organisms that make the land fertile; in medicine to untangle the causes, origins and spread of viruses, parasites and disease; in drug discovery to harvest pharmaceutical products from wild plants, animals and microbes.
Knowing the tree of life also will enable us to know the history of life on Earth, how and why communities of plants and animals came, went and changed through time, and how life today might respond to ongoing changes in climate and the environment.
Plus, anyone who has ever dabbled in their family's genealogy knows the visceral satisfaction of uncovering one's roots. The genealogical tree of all 15 to 50 million species on Earth would reveal our ultimate roots, our common genetic heritage with all other plants, animals and microbes, and our shared, equal membership in Homo sapiens across race, tribe, color and culture.
The third big puzzle is the web of life ecosystems: what makes oceans, grasslands, forests, wetlands, deserts and tundra tick? How do these ecosystems form from myriads of species of plants, animals and microbes, each with its own evolutionary path and environmental role? How many species does an ecosystem, such as the tallgrass prairie, need to remain healthy to keep pumping out oxygen, absorbing carbon dioxide, storing nutrients and recycling water? And how many species can become extinct in an ecosystem, say a rainforest or kelp forest, before it crashes to wasteland? It's akin to asking how many rivets we can safely pop out of an airplane's fuselage while flying at 30,000 feet. Ecosystems are Earth's natural capital. Understanding them is critical if we are to manage and invest this capital for current and future generations.
Fourth is the grand synthesis: how do life's diversity, genealogy and ecosystems interact and affect one other? One unifying thread is the genetic machinery of plants, animals and microbes and how it shapes their physical design, behavior, environmental role and evolutionary end. Another is the chaotic interplay between Earth's physical forces and living systems. The answers will integrate DNA, species, habitats and environmental change across space and time.
This scientific agenda will take large doses of the three "I's" ingenuity, initiative and investment as did the Manhattan Project in WWII, putting a man on the moon in the 1960s and decoding the human genome in the 1990s. Centuries ago, explorers charted the geography of the planet and learned how to navigate the globe. Today's grand challenge is to chart the life of the planet and learn how to navigate the global systems on which all of life depends.
Leonard Krishtalka is director of the Natural History Museum & Biodiversity Research Center at Kansas University.