"Life is subordinated to the laws of thermodynamics and destined to decay. Suffering is unavoidable because of accidents, defeats, illnesses and aging. Happiness is avoidable; it can be terminated at any point in time. There are genetic defects which cause immense suffering (e.g. Sickle-cell disease). No corresponding phenomenon is known which causes immense happiness. There are more cases of chronic pain than cases of long-lasting pleasure. Due to evolutionary pressure, creatures are capable of experiencing more intense pain than pleasure. The pleasure of orgasm is less than the pain of deadly injury, since death is a much larger loss of reproductive success than a single sex act is a gain [Shulman]. ... It is easy to make someone unhappy but much less easy to make that person happy again. It is easier to produce suffering than to produce happiness."