Sims received a B.S. from MIT in 1984, and a M.S. from the MIT Media Lab in 1987. He worked for Thinking Machines as an artist-in-residence, for Whitney-Demos Production as a researcher, and co-founded Optomystic. Sims was the CEO of GenArts, a Cambridge, Massachusetts company that develops special effects plugins used in film and advertising. In June 2008 he moved to a role on the board of directors and Katherine Hayes became CEO of GenArts.
At Optomystic, Sims developed software for the Connection Machine 2 (CM-2) that animated the water from drawings of a deluge by Leonardo da Vinci, used in Mark Whitney's film Excerpts from Leonardo's Deluge.
Sims' animations Particle Dreams and Panspermia used the CM-2 to animate and render various complex phenomena via particle systems. Panspermia was also used as the video for Pantera's cover of Black Sabbath's Planet Caravan.
Sims wrote landmark papers on virtual creatures and artificial evolution for computer art. His virtual creatures used an artificial neural network to process input from virtual sensors and act on virtual muscles between cuboid 'limbs'. The creatures were evolved to display multiple modes of water and land based movements such as swimming like a sea snake or fish, jumping and tumbling (walking was not achieved). The creatures were also co-evolved in different species to compete for possession of a virtual cube, displaying the red queen effect. The cover of Artificial Life: An Overview by Chris Langton notably used an image of the creatures generated by Sims. In 1997, Sims created the interactive installation Galápagos for the NTT InterCommunication Center in Tokyo; in this installation, viewers help evolve 3D animated creatures by selecting which ones will be allowed to live and produce new, mutated offspring.
His paper "Artificial Evolution for Computer Graphics" described the application of genetic algorithms to generate abstract 2D images from complex mathematical formulae, evolved under the guidance of a human. He used this method to create the video Primordial Dance, as well as parts of Liquid Selves. Genetic Images was an interactive installation also based on this method; it was exhibited at the Centre Georges Pompidou in Paris, 1993, as well as Ars Electronica and the Los Angeles Interactive Media Festival.
In 1998, Sims was awarded a MacArthur Fellowship. He has won two Golden Nicas at the Ars Electronica Festival, in 1991 and in 1992. He has also received honors from Imagina, the National Computer Graphics Association, the Berlin Video Festival, NICOGRAPH, Images du Futur, and other festivals.
- Evolved Virtual Creatures, 1994 (archive.org copy)
- Liquid Selves, 1992 (archive.org copy)
- Primordial Dance, 1991 (archive.org copy)
- Panspermia, 1990 (archive.org copy) (Incorporated into Beyond the Mind's Eye, 1992) )
- Particle Dreams, 1988 (archive.org copy)
- Excerpts from Leonardo's Deluge, 1989 - software developer
- Karl Sims (August 1990). "Particle Animation and Rendering Using Data Parallel Computation". SIGGRAPH '90 Proceedings: 405–413.
- Karl Sims (1992). "Choreographed Image Flow". Journal of Visualization and Computer Animation 3: 31–43. doi:10.1002/vis.4340030106.
- Karl Sims (July 1991). "Artificial Evolution for Computer Graphics". SIGGRAPH '91 Proceedings: 319–328.
- Karl Sims (July 1994). "Evolving Virtual Creatures". SIGGRAPH '94 Proceedings: 15–22.
- Karl Sims (1994). "Evolving 3D Morphology and Behavior by Competition". In Brooks & Maes. Artificial Life IV Proceedings (MIT Press): 28–39.