There appears to be no end to how far we animals will go to get more and more dopamine. One study of gambling suggested that it is not money at all which motivates addicts. Instead, their brains release dopamine in the case of “near-misses” as if they were actual wins. The molecule has likewise been associated with just about all forms of addiction and “out of control” behavior. Amphetamines, for example, raise the dopamine levels to ten times higher than anything seen naturally in the brain. The dopamine itself even appears to be addictive. When an animal is given the opportunity to either eat or receive a dose of dopamine, it will choose the dopamine right up until the point it dies.
— The Joy of Craft (Claes Zane), Loc. 844–50