Because there may be bowhead whales alive today that were born before Moby-Dick was published in 1851 — and they could teach us a thing or two about living longer and healthier.

Whales ruled the world’s oceans undisturbed for millions of years, with few predators save some shark species. Among the heftiest of the behemoths? The bowhead whale, tipping the scale at around 100 tons and boasting the thickest blubber of any whale — perfect for the frigid waters off the Arctic Circle.

Less than perfect for avoiding American whalers, who whittled their population from about 50,000 in the 1850s down to only around 1,000 by 1915.

But conservation efforts have boosted the bowhead’s numbers, allowing scientists to unearth some fascinating insights, namely that these creatures aren’t just huge. They can also get really freaking old. How old? About 5 percent of the population is over a century old, and scientists calculated that one bowhead was born well before Herman Melville published Moby-Dick in 1851. Mind-blowing age aside, these mega Methuselahs of the sea might also yield clues on how to extend our own life spans.

Commercial whalers wiped out all but 1,000 or so bowheads by 1915.

“They are truly aged animals, perhaps the most aged animals on Earth,” said Jeffrey Bada, a marine chemist at the Scripps Institution of Oceanography in La Jolla, California.

Second only in size to blue whales, bowheads can grow to 60 feet and earn their name from their massive bow-shaped skulls, used to headbutt thick ice whenever they need to break through for a breather. A dense, roughly 17-inch layer of blubber keeps them toasty and buoys them to the surface after death. That, combined with their lumbering, docile nature, made them ideal targets for commercial whalers, who coveted the oil in their blubber for lamps, soaps and margarine.

Beginning around the mid-19th century, excited whalers swarmed to the Sea of Okhotsk and the Bering Strait, depleting the bowhead population in one region and then migrating to the other as they waited for their numbers to replenish. They killed as many as 2,682 bowheads in the Bering Strait in 1852. The discovery of kerosene and vegetable oil put whaling on the decline, but not before commercial whalers wiped out all but 1,000 or so by 1915.

The International Whaling Commission (IWC) banned commercial whaling of bowheads in 1946 but allowed indigenous groups that have traditionally hunted the whales to kill a certain number each year for food and oil. Based on his records of the number of bowheads that have migrated past Point Barrow in Alaska in the past 30-plus years, Craig George, senior wildlife biologist with the North Slope Borough Department of Wildlife Management, estimates there are now about 15,000.

Five male bowheads were at least 100 years old — and one was closer to 200.

Examining whale carcasses from an annual Inupiat Eskimo hunt as part of an IWC survey program in the 1990s, George noticed several stone harpoons lodged in their flesh. Such harpoons, which fell out of use around 1860, suggested that the whales were more than a century old. Incredulous, he sent tissue samples to Bada, who used an age-determining technique that takes advantage of the orientation of amino acids in the lenses of the eye.

When animals generate new tissue through active metabolism, they produce amino acids with a left-handed orientation. But when active metabolism stops, a special biological process makes many of the left-handed amino acids right-handed. Bada calculated the rate of this process to estimate that five male bowheads were at least 100 years old — and one was closer to 200. That means they might have been alive when John Adams was president.

Molecular biologists seeking to delay aging could take a few tips from the bowhead whale. After identifying several genes and gene activity patterns that allow the naked mole rat and Brandt’s bat to live longer than related species, Vadim Gladyshev, a professor at Harvard Medical School, plans to compare the genomes and gene activities of about 50 mammals with unexpectedly long or short life spans, including the bowhead whale.

Gladyshev hopes that understanding the genes linked to long life spans across different mammals will enable scientists to activate their human gene equivalents so that we could potentially extend our own life spans and stall the onset of age-related diseases. Meanwhile, João Pedro de Magalhães, a senior lecturer at the University of Liverpool, has launched a project to sequence the bowhead’s genome with similar goals.

And to think that these founts of knowledge were nearly lost to us forever.