Much mainstream biology of ageing focuses on within-species polymorphisms, e.g. APOE in humans; or evolutionarily conserved, nutrient-sensing, metabolic fine-tuning pathways such as insulin-like signaling and target of rapamycin, that are involved in modest longevity interventions such as the caloric restriction diet in short-lived model organisms (Steele, 2020). Comparative biology and genomics of species differences in ageing and longevity is a smaller field, though it is gaining steam (Austad, 2022; Bahry, 2022). This note highlights two genes of interest from two comparative genomic studies: FAM126B, coding for a protein related to hyccin, from a study of mammals (Li & de Magalhães, 2013); and OBSCN, coding via alternate RNA splicing for giant and small obscurins, from a study of rockfish (Kolora et al., 2021). Existing knowledge and disease associations are summarized, and implications for the evolution of longevity across species discussed. Version 2 (Dec 2023): Some of the FAM126B in-text citations were missing from the references section; I've added them. Nothing else is changed for this version. References Austad, SN. (2022). Methuselah's Zoo: What Nature Can Teach Us About Living Longer, Healthier Lives. MIT Press. Bahry, D. (2022). Book review: Methuselah's Zoo by Steven N. Austad. BioEssays [early view]: 2200144. https://doi.org/10.1002/bies.202200144 Kolora, SRR. et al. (2021). Origins and evolution of extreme life span in Pacific Ocean rockfishes. Science 374: 842–847. https://doi.org/10.1126/science.abg5332 Li, Y. & de Magalhães, JP. (2013). Accelerated protein evolution analysis reveals genes and pathways associated with the evolution of mammalian longevity. Age (Dordr.) 35: 301–314. https://doi.org/10.1007/s11357-011-9361-y Steele, A. (2020). Ageless: The New Science of Getting Older Without Getting Old. Bloomsbury.