Director of the Human Origins Program, Dept. of Anthropology, National Museum of Natural History, Smithsonian Institution in Washington

Over 4.6 billion years, the most important evolutionary inventions have been those that code, store, and use information in new ways. DNA; nervous systems; organic devices enabling cultural transmission of information. In large perspective, the most important invention over the past 2 thousand years will likely be something related to computers, electronic information coded and handled outside of living bodies. Its importance, however, has not yet been fully realized. I'm going with something whose impact so far is more apparent. The paleontologist in me wants to say something like the discovery of time — from inventions that have led to an intense sense of personal time to others that have found out the age of the universe or the human species. These inventions are perception-altering. But there's another invention with greater impact. My vote is for flying machines.

Before 2 thousand years ago, sea craft allowed the overcoming of water; the wheel, the conquest of earth. And now flying machines, the conquest of air — an invention that taps into the center of our mythologies.

Many inventions change our lives but stay in the predictable range of human nature. Firearms, for example, have had their impact mainly by extending existing tendencies to bluff, subjugate, or kill in immediate, face-to-face situations. Air craft have altered our perceptions in ways that were evolutionarily unpredictable. They changed the delivery of weapons, vastly destructive weapons, to a inter-continental scale — a wholly new scale, unprecedented in evolutionary history. A flu virus that mutates in Kennedy Airport is spread around the world within a day or two. And so the history of disease has been altered by moving the month- or year-long dispersal of disease to a time scale of hours.

We now meet other people en masse anywhere in the world in less than a day's travel. Thus things foreign and strange have become familiar. Ancient phobias and bias toward hatred and exclusion have been altered widely. The CNN culture (instantaneous worldwide information) is an extension of this; in my view, the actual intermingling of people from one place to another has been the more important, precedent-shattering development. Despite international information media, civil strife remains the worst where cultural and physical insularity reigns.

Finally, flying machines have meant a global altering of how societies approach food and other resources, tying humanity together in a worldwide economy (resource exchange) driven by our interdependence. Two million years ago, the movement of resources (like food and stone tools) had become a development with extraordinary implications for human evolution. But even 2 thousand years ago, no one could have foreseen just how far this process of resource exchange has gone today — largely due to flying machines.