Niles Eldredge has been a paleontologist on the curatorial staff of the American Museum of Natural History since 1969. A specialist in mid-Paleozoic phacopid trilobites, Dr. Eldredge, along with Stephen Jay Gould of Harvard, formulated a theory challenging Darwin's premise that evolution occurs gradually. Their theory, known as Punctuated Equilibria, asserts that evolution occurs in dramatic spurts interspersed with long periods of stasis. Dr. Eldredge has also analyzed the relationship between global extinctions of the geologic past and the present-day biodiversity crisis, as well as the general relationship between extinction and evolution. Today, he continues to seek integration of repeated patterns in the history of life with evolutionary theory through scientific research. Dr. Eldredge has embarked on a major program to compare patterns and processes of biological and material cultural evolution, using his extensive database on the manufactured diversity of cornets. Most recently, Eldredge has curated the exhibition Darwin, and has written a companion book entitled Darwin. Discovering the Tree of Life (2005).