John Holland was born in Fort Wayne, Indiana, on 2 February 1929 and brought up in Ohio.
He studied for a BSc in physics at the Massachusetts Institute of Technology (1950) and then an MA in mathematics at the University of Michigan (1954), where he went on to be awarded the first PhD in computer science (1959) for his work on “cycles in logical nets”.
The chance discovery of a book by the English statistician and biologist R. A. Fisher, The Genetical Theory of Natural Selection, shaped his thinking for the rest of his life. Already an expert computer programmer, Professor Holland was employed by IBM as part of the team developing the company’s first calculator using networks of artificial neurons. It was this that led to the theory of “genetic algorithms”. If Darwinian evolution relies on a process of species adapting to the environment over many generations, programmers could also start with different populations of nodes, test which ones were most successful and use those to build the next “generation”.
Professor Holland’s central ideas were published in his much-cited book, Adaptation in Natural and Artificial Systems (1975), which formed the basis for the whole field of evolutionary computation.
His other important texts included Hidden Order: How Adaptation Builds Complexity (1995), Emergence: From Chaos to Order (1998), Signals and Boundaries: Building Blocks for Complex Adaptive Systems (2012) and Complexity: A Very Short Introduction (2014).
After a short period at IBM, he returned to the University of Michigan for the rest of his career, becoming both professor of computer science and engineering and professor of psychology as well as the founder of the Center for the Study of Complex Systems.
Professor Holland also helped found, and retained close links with, the Santa Fe Institute (SFI), a thinktank devoted to the study of complex systems, where he established the programme in adaptive computation and delivered the first series of Stanisław Ulam Memorial Lectures.
What made his research distinctive, says SFI president David Krakauer, is that “he took ideas from evolutionary biology in order to transform search and optimisation in computer science, and then he took what he discovered in computer science and allowed us to rethink evolutionary dynamics. This kind of rigorous translation between two communities of thought is a characteristic of very deep minds.”
A fellow of the World Economic Forum, Professor Holland died of cancer on 9 August and is survived by three daughters and four grandchildren.