Historically, there are two main methods for applying evolutionary processes to architectural design in terms of utilised computation procedures. The first approach uses digital computation to represent computational models of evolutionary processes from micro to macro scales for form-finding experiments. The second approach proposes to go beyond the simulation of evolutionary processes by integrating physical evolutionary processes directly into architectural design. The novelty is in embedding physical evolution processes into architectural design through physical computation, which takes place through a direct interaction of living organisms or materials with their environment. One of the organisms that has started to be observed and utilised in architectural design processes is Physarum polycephalum, a single-celled and multi-headed slime mould.

Although many design theories and models have been proposed for using Physarum polycephalum in architectural design, more research is still needed to evaluate the role and critical limits of digital and physical computation as a bridge between evolutionary processes and architectural design. Bio-digital design arguments have been barely challenged by focusing on the capacities and limitations of the organism’s physical computation and its simulation through digital computation. This article foregrounds and evaluates various bio-digital design theories by focusing on the limits, potentials, and differences between physical and digital computation to critically review the relationship between evolution, computation, and the built environment.

The idea of introducing the cognitive capacity of Physarum polycephalum into architectural design is challenged by referring to the characteristics of both digital and physical computation procedures. Moreover, the challenges arising from scale and context differences between Physarum polycephalum and design project sites are discussed. The original contribution is the first comparative review of Physarum polycephalum’s applications in architectural design processes through a critical methodology founded upon the theory of digital and physical computation.