In the early 22nd century, humans worldwide completed a large-scale secondary differentiation, and human secondary sexual characteristics were divided into Alpha, Beta, and Omega. Differentiated Betas didn't differ much from their pre-differentiation selves, but Alphas and Omegas could attract and bond with each other through their pheromones. By the end of the 22nd century, humans faced a fertility crisis. The Federal Republic launched pheromone matching pods, where highly compatible Alphas and Omegas would be forced to pair up.