2. The life of most animals in captivity is an unusual one. Most animals are forced to make considerable adjustments to captive life. Furthermore, many of these creatures are captured as infants, which precludes satisfactory parental and hierarchical relationships during periods crucial for normal psychological development. This environmental upheaval is likely to have an important effect on behaviour, morbidity and mortality. For example, hypertension, gastric ulcers, eclampsia and remarkable cerebral arteriosclerosis are not unusual in captive primates.