Project Tierra: https://en.wikipedia.org/wiki/Tierra_(computer_simulation) - by Thomas S. Ray 

Tierra is a computer simulation developed by ecologist Thomas S. Ray in the early 1990s in which computer programs compete for time (central processing unit (CPU) time) and space (access to main memory). In this context, the computer programs in Tierra are considered to be evolvable and can mutate, self-replicate and recombine. Tierra's virtual machine is written in C.[1] It operates on a custom instruction set designed to facilitate code changes and reordering, including features such as jump to template[2].

Aesthetically Evolved Virtual Pets: http://life.ou.edu/pubs/alife7a/

Aesthetic, emotional, and empathetic selection are applied to a derivative of Karl Sims' Evolved Virtual Creatures. The resulting Creatures can be beautiful or strange, and provoke strong reactions in human observers. It may be possible to evolve virtual pets to which humans can form strong emotional bonds.