Polar bear training (IMAGE) Species360 Caption Researchers found a significant improvement in longevity and lifespan equality for four marine mammal species from the 1990s onwards, which is believed to be a result of advancements in zoological practices, such as implementing advanced veterinary, environmental, nutritional and enrichment measures, as well as the voluntary cooperation of animals in routine examinations through positive reinforcement training Credit Assiniboine Park Conservancy Usage Restrictions Please credit photographer License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.