Why does the placebo effect work?

The placebo effect is a long-recognised phenomenon that has played an important part in the history of medicine — from the healing powers of Stonehenge to administering placebo drugs to modern day patients. But it’s not until recently that science has begun to truly understand how the placebo effect really works.

Professor Nicholas Humphrey asks why placebos work and reveals their central paradox: If we can effectively cure ourselves by taking placebo medicine, why don’t we just heal ourselves straight away?

Exploring this paradox from the perspective of evolution, Professor Humphry looks at the associated costs and benefits of pain or illness. How can placebo medications readdress this balance and is a “dose of contrived optimism” just what the doctor ordered?