In an interview with The Boston Globe before his 100th birthday last year, Mayr said he always had "tremendous curiosity" and balked at suggestions he stop working.

"People say to me, Why don't you retire?' I say, 'My God, why should I retire? I enjoy what I'm doing,'" he told the Globe.

Through his travels in New Guinea and the Solomon Islands, Mayr showed what Darwin had never quite established: that new species arise from isolated populations.

Mayr's death came amid renewed debate in the United States over the teaching of evolution. One Pennsylvania school district recently became the first in the country to begin teaching "intelligent design" -- an alternative to evolution that contends nature was created by an all-powerful being.

Born in 1904 in Kempten, Germany, Mayr earned a medical degree from the University of Greifswald in 1925. Descended from generations of doctors, he broke off his medical career and turned his attention to zoology, earning a doctorate from the University of Berlin just 16 months later.

"I was curious about far places," he told the Harvard Alumni Bulletin in 1961, "and decided that as an M.D., I should have but small chance of traveling."

He got the chance to do just that in 1927, when he met Lord Rothschild at a zoological convention in Budapest, Hungary. Rothschild had been looking for someone to travel to New Guinea to collect birds of paradise.