A dataset covering 1,176 mammal and bird species shows the heterogametic sex (XY in mammals, ZW in birds) tends to die younger. In mammals, females outlive males in ~75% of species; in birds, males outlive females in ~68%—consistent with X/X or Z/Z redundancy protecting against harmful mutations.
— This shifts male–female longevity debates from lifestyle alone to a biological baseline, with implications for medical research priorities and how we interpret sex differences in health.
Devin Reese
2026.09.08
60% relevant
Both ideas concern the causal role of sex chromosomes and sex systems in biological outcomes; this article provides a counterpoint by showing environment-driven phenotype/genotype decoupling (XX phenotypic males) can change assumptions about sex‑linked demographic effects — e.g., predictions that rely on stable genotype→phenotype mappings (such as sex‑chromosome driven life‑history patterns) may need revision when sex reversal is common.
EditorDavid
2025.10.04
100% relevant
Washington Post report on Colchero and Staerk’s analysis of 528 mammal and 648 bird species kept in zoos showing sex‑biased longevity patterns aligned with chromosome systems.
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