Overview

• Analyzing records from more than 1,176 species in global zoos, the study reports that females outlive males in about 72% of mammals.
• In birds, the pattern reverses, with males living longer in roughly 68% of species examined.
• The authors propose that differences in sex chromosomes help explain the flip between mammals (XX/XY) and birds (ZW/ZZ).
• Sexual selection and male competition for mates correlate with shorter male lifespans, especially in polygamous mammals with intense rivalry.
• Parental care and mating system matter, with greater caregiving linked to longer life and monogamous species showing smaller sex gaps.