Headmen, shamans, and mothers: natural and sexual selection for computational services (grasshoppermouse.github.io) ABSTRACT Computer engineers face a dilemma. They must build systems with sufficient resources to solve the most complex problems the systems are expected to solve, but the systems will only need to solve such problems intermittently, resulting in inefficient use of expensive computational resources. This dilemma is commonly resolved with timesharing, networking, multitasking, and other technologies that enable computational resources to be shared with multiple users. The human brain, which evolved to acquire, store, and process information to make beneficial decisions, is likewise energetically expensive to build and maintain yet plausibly has idle capacity much of the time. We propose that humans evolved to use advantages in information or computational resources to provide computational services to others via a language-based “network” in exchange for payments of va