Table 2 summarizes the material we have reviewed in this article. We surveyed data from rodents genetically predisposed to drink or not drink, and those predisposed to experience more or less severe withdrawal after dependence on alcohol had been established. In addition to the complexity of the human LR target, the inherent problems of not being able to truly know what motivates animals to drink alcohol or why they elect to drink more or less alcohol makes choosing or developing a LR phenotype in animals that closely parallels the human situation difficult. However, it might not be necessary to understand this in order to successfully identify parallel mechanisms that may underlie LR across species. For instance, even if the phenotypes and motives for drinking in humans and rodents are either opaque or appear different to the experimenter, it may be that some physiological mechanisms that underlie LR (variously described) seen in some rodent genotypes and in humans are very similar and that the same sets of genes underlie those physiological mechanisms. If this is true then identifying a smaller set
