Computation and Life

David Peak
Utah State University


Analogies of computational elements‹such as information storage and retrieval, I/O hardware, problem solving, and so on‹have been identified in various biological systems. These analogies have led to the speculation that computation and life are inextricably interrelated. One wonders if this supposed relationship is rigorously justifiable or if it is merely an attractive metaphor. To examine this question, Keith Mott (USU Biology), our students, and I have been conducting a series of experiments, analyses, and simulations dealing with the coordinated opening and closing of stomata‹microscopic pores on the surfaces of plants. Through their stomata, plants solve a sophisticated, formal problem, namely, how to maximize CO2 uptake from the atmosphere while experiencing no more than a fixed amount of evaporative water loss. In this talk, I will show movies of plants struggling to solve this problem under difficult environmental conditions. I will then compare these movies with others generated by simulations of emergent, distributed computation‹a nonstandard form of computation in which networks of large numbers of information processing units that are only locally connected to each other carry out global tasks. I will demonstrate that the stomatal dynamics we observe in the laboratory is indistinguishable from the dynamics of emergent, distributed computation. This result, I will argue, provides quantitative support for the hypothesis that plants compute.