For many species, including bees, wasps and termites, the members of a colony may not be closely related but still cooperate. This seems to run counter to the spirit of the selfish gene. The theory's proponents solve this puzzle by arguing that the cost of recognising alien genes in other colony members is too high and would lead to losses in efficiency. Order for free offers a more direct and simple solution. There is one other important property of colonial rhythms that the model revealed.
Rhythmic activity emerges suddenly above a critical density.
One example is the sudden appearance of magnetic properties in iron as it is cools below a critical temperature. Above this temperature the kinetic energy of the atoms, each of which behaves as a magnetic dipole, is too high for them to become aligned, so they move independently of one another. Below the critical temperature, the kinetic energy falls low enough to let the dipoles line up, north pole to south pole along the metal, so that a collective magnetic field emerges. The ants are doing something similar, but now it is density, and hence the amount of stimulation between them, that is the critical parameter. We see from the model that at the critical density, what was a collection of individuals doing their own local thing begins to change as global order emerges via activation waves that propagate through the entire colony.