This is the kind of thing that really excites me: fundamental connections among biology, design, and human behavior. A group of Japanese scientists has shown that "the slime mold Physarum polycephalum forms networks with comparable efficiency, fault tolerance, and cost to those of real-world infrastructure networks--in this case, the Tokyo rail system."Comparing an organism's behavior to a designed human system, then learning from that organism's 'reinterpretation' of the system in order to develop better models of design...amazing.
Link to summary article and full report ("Rules for Biologically Inspired Adaptive Network Design").