By comparing the carbon-14 signatures in the outer layers of the lenses against those in the core, the scientists could differentiate between sharks born before the nuclear age ("pre-bomb") and those born afterward. The results were nothing short of revolutionary. The smallest specimens displayed the elevated carbon-14 levels of post-1960s calves, while the larger specimens carried carbon signatures that stretched back centuries into the pre-industrial era.
The Evolutionary Paradox: Why Live So Long?
The staggering longevity of the Greenland shark is not an isolated evolutionary accident; it is the ultimate masterclass in metabolic adaptation. Marine experts often describe the pace of life for Somniosus microcephalus as "wildly slow."
1. Frigid Temperatures and Torpid Metabolism
The deep waters of the Arctic and North Atlantic hover perilously close to freezing, frequently dropping below $2^\circ\text{C}$ ($35^\circ\text{F}$). To survive in an environment with such scarce nutritional resources, the Greenland shark evolved an exceptionally sluggish metabolism. Its body conserves every ounce of energy, resulting in a growth rate of less than 1 centimeter (about 0.4 inches) per year ($\text{VIMS, 2016}$).