Overview

• The team compiled records for 1,176 bird and mammal species in zoos and added wild data for 110 species, publishing the findings in Science Advances.
• In 72% of mammals, females lived about 12–13% longer than males, aligning with expectations from sex-chromosome biology.
• In 68% of birds, males lived roughly 5% longer than females, with monogamous systems associated with smaller sex gaps.
• Strong male competition and pronounced size differences correlated with shorter male life expectancy, while the caregiving sex tended to live longer, especially in primates.
• Sex differences narrowed in zoos yet rarely disappeared, and notable exceptions such as many raptors indicate chromosomes are only part of the explanation.