“When a lobster that has just lost a battle is exposed to serotonin, it will stretch itself out, advance even on former victors, and fight longer and harder.9 The drugs prescribed to depressed human beings, which are selective serotonin reuptake inhibitors, have much the same chemical and behavioural effect. In one of the more staggering demonstrations of the evolutionary continuity of life on Earth, Prozac even cheers up lobsters.”