A study of emotional behaviour in four coat colour genotypes of the golden hamster (Mesocricetus auratus).

The study investigated aspects of emotional behaviour in two piebald and two non-piebald genotypes of hamster, to confirm anecdotal reports that piebald hamsters were more fearful than other types. Behavioural differences were hypothesized to relate to psychological functions and to be associated with the recessive piebald gene, thereby representing a major gene effect which could merit further investigation by a behavioural geneticist. Limitations on uses of the terms 'fear' and 'emotionality' were acknowledged, and evidence that they were unlikely to refer to unitary states was discussed. Genetic, maternal and sibling effects were controlled for, so that a single cross could produce the four genotypes in any litter. The hamsters were bred by a geneticist, Roy Robinson. On arrival at four weeks of age they were housed solitarily or in small groups for about three weeks when they were all isolated; experiments began at eight weeks of age. Behavioural and nonbehavioural tests, designed to measure emotionality, were based on previous work and a priori reasoning. They included reaction to handling, the open field, novel situation, activity, aggressive encounter, passive avoidance learning, and measures of body weight, food intake, adrenal gland weight, gastric ulceration and mortality. The results from the experiments were subjected to analyses of variance tests; significant genotype, sex and housing differences were discussed. It was concluded that hamsters carrying the piebald gene could be described as more emotional than golden or brown hamsters. although there was no consistent pattern shown by either sex or differentially housed hamster in terms of emotionality. The piebald hamster may thus provide a starting point for investigations into a gene-behaviour pathway. The data were compared with other rodent studies on emotionality and how findings contributed information as to whether fear was a unitary condition assessed. One type of organization responsible for emotionality could be studied in the piebald hamster and this may contribute more generally to literature on physiological and behavioural expressions of fear.