Scaling life as an interspecies hallmark of aging.

Across species, the "pace of life"-encompassing development, reproduction, and senescence-varies widely, yet the molecular mechanisms that regulate these interspecies trajectories of aging remain elusive. Even among vertebrates, a 1000-fold difference in life span is observed between species, ranging from several months in the turquoise killifish to half a millennium in the Greenland shark. As a relatively "young" area of investigation, aging research lacks the unifying conceptual frameworks that anchor more established disciplines, such as neuroscience. Therefore, current theories, which in some cases provide contradicting predictions, rely heavily on experimental data to mature. These contradictions not only define key outstanding questions but also illuminate fertile ground for transformative research.