We’ve all seen people bump into telephone poles and nearly get hit by cars when walking around looking at their cellphones. (Hell, I’ve done it myself, at least with the telephone poles; I never look at a phone while crossing the street.) When I almost bumped into one of these metal poles in Paris, I realized that if they were a little shorter, and had a more injurious top than a simple ball, they could be used to select against heedless cellphone users.
The scenario: someone is walking along and looking at their cellphone, and bumps into a shorter version of one of these poles, say with a metal spike on top. Voilà! Their gamete-producing organs are injured, hurting their fertility. If there’s any genetic variation for using cellphones while oblivious to the external environment, that variation will be reduced by colliding with these “anti-gamete” poles. Within a generation, more people will be using their cellphones responsibly.
Of course this will work only for males, but that’s still selection on half the population, and presumably the genes for obliviousness are expressed in both sexes. Eventually only the nongenetic (socially conditioned) variation will remain.
My hand shows the height that the spikes needs to be; but of course it can be a foot or more in length, dealing with most of the height variation in human males.