When people ask me what I studied for my PhD, I tend to mumble something about “computer science” or “engineering”, but although it contained elements of both, neither is strictly accurate. In truth, my field is Cybernetics, the little-known and rarely trendy study of circular and self-regulating systems. Taking its name from the Greek word for the man who steers a ship, it encompasses control systems, robots and, yes, mechanical limbs, but also less obvious things like endocrinology and the population dynamics of rabbits. What unifies these very different systems is their circular, self-referential nature: they control their own futures.

Self-regulating systems are defined by their negative feedback: they resist attempts to push them out of equilibrium (positive feedback, despite the name, is usually bad). The homeostasis that keeps your body from freezing, overheating and drying out relies on this. Systems of this kind will resist any attempt to destroy them, even if it means warping beyond all recognition. This runs counter to how we usually think about built objects, which are very often engineered to be hard, but brittle. From reinforced concrete and steel plating to firewalls and encryption, the things we make are resilient only until broken, so prioritise not breaking at all. This is not a strategy you will see often in nature, because no living thing can afford it. No exoskeleton can be thick enough to deflect every possible tooth, claw and stinger that nature has to offer, so each organism must be able to recover from injury.