Key Points

Tom Ray was a field biologist for 15 years in the rain forest before he began studying artifical life. In this session, he said that the only form of evolution with which humans are familiar is based on carbon chemistry. He said that life on earth is a product of evolution, but digital evolution does not necessarily have to follow the same path.

He then went on to describe his work on Tierra, a project that attempts to create evolution using a digital model. Tierra consists of bits of machine code that act as creatures who live within a subnet of the internet.

One of the concepts Tierra introduced was the flipping of bits to represent mutation, and the use of a program mechanism which he called "the reaper," which would cull non-viable and old organisms.

He found that organisms that could not reproduce on their own were borrowing their code from organisms that could. This was significant because it was the emergence of a primitive ecology from a digital ecosystem.

His current work uses cell differentiation in an attempt to poise his digital organisms at the beginning of a situation analogous to the Cambrian explosion, introducing the possibility of evolving creatures of a greater complexity than their ancestors.

Larry Yaeger approaches artificial intelligence the same way nature does. He uses a fairly simple development process looking for ecological behaviors that are not programmed into a computer.

He said that Life is a condition we attribute to systems exhibiting a high degree of behavioral complexity. He created Polyworld to explore the kind of system necessary to evolve intelligence. Polyworld was Yaeger's primordial soup experiment, wherein creatures exhibited complex emergent behaviours.

By definition, life has to exhibit a high degree of complexity, and since intelligent systems generate such complexity, there is an implied connection between complexity and life.

Yaeger recommended the following as essential reading:

• Valentino and Braitenberg's non-fiction work Vehicles
• Theodore Sturgeon's short story Microcosmic God