Recent research highlights that females generally live longer than males and maintain a younger metabolic age in the brain throughout adulthood. These differences persist even under harsh conditions such as famine and pandemics, with studies noting that female brains show slower age-related decline in cognitive function and energy consumption. The underlying causes of these disparities remain a mystery, prompting scientists worldwide to investigate the silent role of the X chromosome in brain health. Insights from this research could pave the way for new therapies targeting age-related diseases and potentially increase human longevity.