How Do You Age a Shark That Lives for Centuries?

How can scientists estimate the age of an animal that may outlive generations of people? The Greenland shark's eye lens offered an unexpected clue. Follow early-formed proteins to radiocarbon measurements, a model, and an age range that matters as much as the headline number. A later retina study opens a separate question about life in dim water. 392 ±120 years is the model estimate for the largest sampled animal, not a known birthday or the verified age of any shark in the encounter footage. CHAPTERS 00:00 How do you find centuries inside an eye? 00:52 The problem of measuring age 02:07 A sample from early life 03:18 Carbon and the historical marker 04:36 An estimate with uncertainty 05:52 What the model can establish 07:05 Lens and retina are different 08:14 What the evidence can tell us RESEARCH Nielsen et al. (2016), Science: https://doi.org/10.1126/science.aaf1703 Fogg et al. (2026): https://doi.org/10.1038/s41467-025-67... COSEWIC (2025) Greenland Shark assessment: https://www.canada.ca/en/environment-... PRODUCTION NOTES Narration is a synthetic voice (Kokoro, bm_george). Diagrams and music treatment were created for this film. No AI-generated footage or imagery is used, and no protected 2016 Science figures appear. Field and laboratory context pictures are labeled and do not depict the 2016 experiment. Embedded source-video audio is excluded. PICTURE CREDITS NOAA Ocean Exploration (2013 Northeast U.S. Canyons Expedition; 2017 American Samoa Expedition), NOAA Office of Ocean Exploration and Research, NOAA Fisheries (including 2008 Arctic mapping b-roll and the 2023 Shark Finning Report to Congress). US government works, credit retained. https://oceanexplorer.noaa.gov/multim... USGS public-domain imagery, incl. Pacific Coastal and Marine Science Center; photos by Amy West and other USGS staff. General laboratory context, not the 2016 experiment. US DOE/NNSA Nevada Site Office: historical atmospheric test photograph. Jonathan Couch (1877) plates, University of Washington Freshwater and Marine Image Bank (public domain). Figures under CC BY 4.0, resized with surrounding labels, panels not redrawn: Devine, Wheeland and Fisher (2018), Sci Rep 8:974, https://doi.org/10.1038/s41598-017-19... Nielsen et al. (2025), Ecol Evol, https://doi.org/10.1002/ece3.71564; Claes et al. (2014), PLOS ONE, https://doi.org/10.1371/journal.pone.... Edwards et al. (2019), Front Mar Sci, https://doi.org/10.3389/fmars.2019.00087. https://creativecommons.org/licenses/... Thumbnail: "Greenland shark profile" by Hemming1952, Wikimedia Commons, CC BY-SA 4.0, unaltered. https://commons.wikimedia.org/wiki/Fi... MUSIC AND SOUND "Ambiment" by Kevin MacLeod (incompetech.com), CC BY 4.0: https://creativecommons.org/licenses/... "An Ocean in Outer Space" by HoliznaCC0 (CC0). Freesound CC0: "Cinematic Impact" (177242), "Stick - Whoosh 7 (Soft)" by Sadiquecat (802465), "Click / Finger Snap" by OwlStorm (151214). The Hadal Archive explores the ocean through scientific evidence and careful observation. #GreenlandShark #DeepSea #MarineBiology #OceanDocumentary #4K