Ernst Mayr, the Harvard biologist who took the sweeping evolutionary claims of Charles Darwin and showed how the complex process actually works, died Thursday. He was 100.
Mr. Mayr died in Bedford, Mass., after a short illness.
He created the first working definition of what a species is and showed how genetics and population movements combined to create new species, an intellectual process known as evolutionary synthesis.
He was also a pioneer in studying the history and philosophy of biology.
“He’s the Darwin of the 20th Century, the defender of the faith,” said science historian Vassiliki Betty Smocovitis of the University of Florida, Gainesville.
In biology, said F. Clark Howell of the University of California, Berkeley, “everybody stands in some way in his shadow.”
Mr. Mayr’s ideas trace back to Darwin’s 1859 publication, “On the Origin of Species,” which established the concept of natural selection, better known as survival of the fittest.
In contrast to the biblical theory that all species on the planet were created in their current form by an almighty power, Darwin reasoned that all creatures were continually developing minor changes that made them more or less fit to survive in their ecological niches.
Although Darwin’s conclusion was widely accepted, the question of how those small changes occurred was hotly debated. Most researchers thought the process of accumulated changes in individual genes required far too long to occur to account for the great variety of species now present.
Mr. Mayr, a Bavaria native, concluded that the driving force for natural selection was the geographic isolation of small populations.
