"Our theory is thus about processes in the human mind. Those processes evolve in tandem with culture. They require culture for their support while they enable culture through their capacities. In particular, we believe that the genetic elements of culture are to be found in the external world, in the properties of artifacts and behaviors, not inside human heads. Hays first articulated this idea in his book on the evolution of technology and I have developed it in my papers Culture as an Evolutionary Arena"