John Henry Holland, a computer scientist whose seminal work on genetic algorithms, or computer codes that mimic sexually reproducing organisms, proved crucial in the study of complex adaptive systems, a field he helped create, died on Aug. 9 at his home in Ann Arbor, Mich. He was 86.

The cause was cancer, his daughter Gretchen Sleamon said.

While a graduate student at the University of Michigan in 1953, Dr. Holland, wandering through the school’s mathematics library, chanced upon “The Genetical Theory of Natural Selection,” a 1929 book by the English statistician and evolutionary biologist R. A. Fisher. In one arresting example, Mr. Fisher described the seemingly random fluttering of a colony of butterflies as a dynamic information network that could be mapped mathematically.

“The fact that you could take calculus and differential equations and all the other things I had learned in my math classes to start a revolution in genetics — that was a real eye opener,” Dr. Holland told M. Mitchell Waldrop, the author of “Complexity: The Emerging Science at the Edge of Order and Chaos” (1993). “Once I saw that, I knew I could never let it go.”

He began thinking about using computers to analyze complex adaptive systems: continually evolving aggregates that emerge through the spontaneous interaction of myriad agents and develop multiple organizational levels. Examples include the human brain, ant colonies, economies and tropical rain forests.

“I look at big, buzzing complex systems and ask what mechanisms and properties seem central,” he told The New York Times in 1995.

One of his most innovative ideas was to develop computer codes, which he called genetic algorithms, that mimicked evolutionary processes by mating and mutating possible solutions; they in turn generated new solutions leading to an optimal result — a computer version of the survival of the fittest.

Read the full article "John Henry Holland, Who Computerized Evolution, Dies at 86" at The New York Times.