Alchemy: The Dark Art and Curious Science of Creating Magic in Brands, Business, and Life

by Rory Sutherland

Pete Trimmer, a biologist at the University of Bristol, observed that the ability of Siberian hamsters to fight infections varied according to the lighting above their cages – longer hours of light (mimicking summer days) triggered a stronger immune response. Trimmer’s explanation was that the immune system is costly to run, and so as long as an infection is not lethal, it will wait for a signal that fighting it will not endanger the animal in other ways. It seems that the Siberian hamster subconsciously fights infection more energetically in summer because that is when food supplies are sufficiently plentiful to sustain an immune response. Trimmer’s model demonstrated that in challenging environments, animals fared better by weathering infections and conserving resources. Humphrey argues that people subconsciously respond to a sham treatment because it assures us that it will weaken the infection without overburdening the body’s resources. In populations where food is plentiful we can, in theory, mount a full immune response at any time, but Humphrey believes that the subconscious switch has not yet adapted to this – thus it takes a placebo to convince the mind that it is the right time for an immune response.