A Greenland Shark Was Born Before Newton Wrote the Principia

Julius Nielsen, a marine biologist at the University of Copenhagen, sectioned the eye lenses of 28 female Greenland sharks that had been pulled out of the cold Arctic and North Atlantic as bycatch. The crystalline proteins at the very center of a vertebrate eye lens form before birth and never get replaced. They are, in effect, a chemical archive of the moment the animal was conceived.

Nielsen's lab radiocarbon-dated those nuclei. The smaller sharks — under about 220 cm — carried the unmistakable spike of bomb-pulse carbon, the radiocarbon dumped into the atmosphere by aboveground nuclear tests in the late 1950s and early 60s. That gave the team a calibration point: if a shark's lens shows the bomb pulse, it was conceived after 1955.

The larger sharks didn't show the spike. Their lenses were old enough to predate atmospheric testing entirely. Working from a fitted growth curve, the team estimated the longest of the 28 — a 502-cm female — at 392 ± 120 years. Even at the lower bound of that error bar, she was alive when the Mayflower landed.

The paper, published in Science in August 2016, made Somniosus microcephalus the longest-lived vertebrate on record, beating the bowhead whale by a century. The same analysis put age at sexual maturity around 156 years, which has hard implications for fisheries: a Greenland shark caught as bycatch in the 1990s might have been a teenager from the time of George Washington who had not yet had its first pup.