Behavioural and endocrinological changes during the process of domestication in guinea pigs

In this study wild (Cavia aperea) and domestic guinea pigs (Cavia aperea f. porcellus) were compared with respect to spontaneous behaviour and endocri nological parameters to elucidate the process of domestication in this spec ies. In 120h of observation time the behaviour of 5 groups of wild and 7 gr oups of domestic guinea pigs, each consisting of one adult male and two adu lt females, was analysed quantitatively. To assess the reactivity of the pi tuitary-adrenocortical(PAC) and the sympathetic-adrenomedullary(SAM) system s, serum cortisol-, epinephrine- and norepinephrine-titres were determined. The following significant behavioural differences were found: the domestic ated guinea pigs were distinctly less attentive to their physical environme nt; they were less aggressive and displayed more sociopositive behaviours t han their wild ancestors. Male domestic guinea pigs displayed more male cou rtship behaviour towards the females than wild cavies. The organism's endoc rine reactions of adjustment to the environment also differed between wild and domestic forms: the reactivity of the SAM and the PAC system was marked ly reduced in the domesticated animals. Thus, in guinea pigs the process of domestication has led to typical behavioural traits which have also been f ound in comparisons between wild and domestic forms of other species. The d ecreased reactivity of the organism's stress axes can be regarded as a phys iological mechanism which helps domesticated animals to adjust to man-made housing conditions.