The Greenland shark: The vertebrate that reaches a century and a half before puberty

In the freezing and inhospitable depths of the Arctic Ocean lives a creature that defies the biological concept of time: the Greenland shark (Somniosus microcephalus). This slow-swimming shark holds the record as the longest-living vertebrate on the planet, with an estimated lifespan of at least 272 years, comfortably capable of exceeding four centuries of existence.

The most puzzling aspect of its physiology is the extreme slowness with which its life unfolds. Its body grows barely 1 centimeter per year and its heart beats only once every 12 seconds to conserve vital energy in freezing waters. Due to this slow-motion metabolic rate, females do not reach sexual maturity until nearly 150 years; they must live a century and a half before being able to reproduce.

To calculate the age of these animals lacking visible bone plates, scientists from the Greenland Institute of Natural Resources used a revolutionary technique:

• The eye lens: The core proteins of the eye are synthesized in the mother's womb before birth and are never renewed or degraded.
• Radiocarbon dating: By analyzing the isotopic traces in these proteins, they dated specimens that were already swimming in the Arctic depths in the early 17th century.

This shield against aging lies in a prodigious cellular machinery capable of repairing genetic mutations and resisting oxidative damage for entire centuries.