The undersea monarch Namor is one of Marvel Comics' oldest characters, in both fictional terms and as regards his publication history. The hero's new series Namor the Sub-Mariner by Christopher Cantwell and Pasqual Ferry introduces the potential secret to his perceived immortality, putting a fantastical spin on real marine biological principles.
Debuting in 1939, "The Avenging Son" Namor McKenzie is estimated to be over a century old at the least. He would soon become an ally of Captain America and the original Human Torch against the Axis powers, relying on his longevity to balance being King of Atlantis with being an ally to the heroes of Earth. The new Marvel series takes place decades into a future where a war with the Kree has all but covered the planet in permanent high tide. Most humans have fled to the stars, but Namor stays behind to protect those who couldn't. A visit from the old Torch fires him up, initiating a brief chase that reveals something fascinating about Namor's biology.
Namor's iconic, Mercurial ankle-wings still work even in the future—but poorly. He says spending so much time in the sea makes him forget how to navigate the skies. He quickly loses pace with the Torch and decides to plunge into the sea below, where he's immediately greeted by a sense of revival. "Here I feel no age. I am reborn upon every re-entry." Is this mere poetic waxing about his love for the wide blue wonder, or is there something more literal at play here?
How The Sea Keeps Namor Alive
The largest animals to ever stalk the Earth have all been swimmers. A full-grown blue whale can reach an estimated maximum of 220 tons, several times the size of the biggest dinosaurs on record. But what enables its incredible size? There are a few reasons, and all of them are directly connected to living in the sea. Glacial sheet formation 3 million years ago affected seasonal climates and caused regular upwelling of nutrient-rich water from the depths of the ocean. This combined with their typical diet (several tons of krill) creates a recipe for gigantism; not to mention it's easier to gain weight when you don't have to support all of it on your own. The buoyancy of water takes the pressure off of joints and bone, allowing for more growth.
Similarly, it seems that Namor's ocean-dwelling contributes, along with his mutant-Atlantean genetics, to keeping him physically youthful. This means underwater, the Sub-Mariner is strong as ever—but once he breaches, the effects of his biological age catch up to him. The implication is just that, suggesting these effects of time are compounded every time Namor breaches the surface, but abated when he submerges. But the line between science and fantasy is not easily drawn when it comes to Namor, meaning fans will continue to debate the source of his vitality for years to come.