Recursion resides at the core of all intelligence. Recursion requires the ability to reference an algorithm or procedure, and keep the reference distinct from the contents. And this capacity to refer is a centerpiece of the way that organisms form models of the world around them and even of themselves. Recursion is a profoundly computational idea and lies at the heart of Godel’s incompleteness theorem and the philosophical consequences that flow from that work. Turing’s own work on computable numbers requires recursion at its center. It’s an open question about how recursion is implemented biologically, but one could speculate that it has been discovered by evolution many times.