Cellular encoding using typed development operators in which basic types are determined for the basic components of a structure being developed. Each development operator for developing the structure is associated with one or more of the basic types. Organisms are generated using tree arrangements of the development operators by matching the basic types associated with connections among the development operators in the trees. The matching among typed development operators reduces the likelihood of creating unfit organisms. Cellular encoding with typed development operators may also be used to evolve the structure.