Opinions diverge on how milk exploitation in prehistoric times should be reflected in mortality profiles of dairy species. The debate has focused on whether the slaughter of the offspring would have enhanced or reduced milk availability for human consumption. This article aims at explaining why, due to differences in the physiology of lactation, the answer may be different for cattle and caprines. The fraction of cisternal milk, available by simple pressure on the udder, compared to alveolar milk, which has to be actively expelled by induction of the ejection reflex, is considerably higher in caprines than in cattle. Induction of milk let down is primordial in cattle to insure both the quantity and quality of milk production, and to maintain lactation, whereas consequences on milk production of inhibition of milk let down are less important in caprines. Moreover, stimulation of caprine females requires considerably less effort than stimulation of a cow, in which the presence of the calf is still necessary in modern poorly improved breeds to initiate milk ejection. This suggests that removal of the young would have seriously compromised the milking of cattle, whereas it would not have precluded it in caprines.