A herd of elephants walk on the plains of Masai Mara game reserve November 14, 2008.

WASHINGTON, Dec. 11 (Xinhua) -- Female elephants living in protected populations in Africa and Asia live longer than those in captivity in European zoos, an international team of researchers reported Thursday in the journal Science.

The findings could mark the end of a long-standing debate about the physical and mental well-being of zoo elephants and may also bring about improvements in how these animals are kept, the researchers said.

Using data on more than 4,500 elephants, researchers from Britain, Kenya and Canada found that zoos can cause shortened adult life spans in both African and Asian elephants.

In the most endangered species of elephant, the Asian, calf death rates also were elevated. For this species, the researchers found that being born in a zoo (rather than being imported from the wild), being moved between zoos, and the possible loss of their mothers put the animals at particular risk.

The authors looked at data on female Asian and African elephants from Amboseli National Park in Kenya and compared that to data on elephants in European zoos to reach their conclusions.

The authors recommend screening all zoo elephants for signs of stress and obesity in order to identify those that might be in trouble. The researchers also called for an end to the importation of elephants from their native countries and the minimizing of inter-zoo transfers.