Dr. Niles Eldredge has been a paleontologist on the curatorial staff of the American Museum of Natural History since 1969. His specialty is the evolution of trilobites-a group of extinct arthropods that lived between 535 and 245 million years ago.

Eldredge's main professional passion is evolution. Throughout his career, he has used repeated patterns in the history of life to refine ideas on how the evolutionary process actually works. The theory of "punctuated equilibria," developed with Stephen Jay Gould in 1972, was an early milestone. Eldredge went on to develop a hierarchical vision of evolutionary and ecological systems, and in his book The Pattern of Evolution (1999) he has developed a comprehensive theory (the "sloshing bucket") that specifies in detail how environmental change governs the evolutionary process. (more ...)