IN THE northernmost reaches of the globe, beneath thick sea ice, a bowhead whale can live for over two hundred years.

These whales spend their winters in the depths of the ocean, coming up to breathe at a few cracks in the ice that covers the sea at these latitudes.

Their lifespans were first noted by the Alaskan Inupiat people, whose relationship with the bowhead whale is centuries old. Oral histories noted that the same whale would be seen over multiple generations —the whales “lived two human lifetimes.”

Discoveries such as a stone harpoon point from the 1880s embedded in a whale that was killed in 1992, as well as investigations of bowhead whale eye lenses and isotope analysis, have supported these observations. It is now believed that the maximum lifespan of bowhead whales could be over two hundred years.

Bowhead whales are endangered, having been hunted almost to extinction by whalers from the 1600s onward. Although the Inupiat have hunted whales as part of their longstanding cultural tradition, their method of hunting is a spiritual process, with the whale considered as a gift to the entire community that must be respected; if disrespect is shown to the prey, repercussions will ensue. Only as much as is needed is taken.

The mechanised, ruthless slaughter of commercial whaling expeditions is a sharp contrast to this process. In the early 1990s, there were only a few tens of bowhead whales left. Now, bans on commercial whaling have meant that the population has climbed.

A study from 2015 speculated that the whalers’ slaughter eliminated bowhead whales that migrated to warmer winter seas, leaving only those populations that tended to reside deep beneath the ice during the winter. The commercial whaling boats found this impassable sea ice difficult to breach, and thus the whales that spent their winters in the far north were protected.

The Inupiat are an exception to the commercial whaling ban, and their hunts provide a key source of tissue samples to biologists wishing to study the bowhead whales.

Recently, a study published in Nature used such samples to investigate why bowhead whales seem impervious to cancer and other age-related diseases. The huge body mass of the bowhead whale (over 80,000kg) should predispose it to accumulating a large amount of DNA mutations throughout its life (something we wrote about in our last column).

The fact that these whales live to over double the average lifetime of a human without high levels of cancer is puzzling.

The process of transformation from a normal cell into a cancerous cell is believed to involve multiple distinct genetic “hits,” or mutations. At first, researchers hypothesised that the bowhead whales’ longevity may come from their cells being more resistant to cancerous mutations.

However, their study revealed that the opposite is true: fewer mutations were required before the whale cells “underwent malignant transformation” (became cancerous), as compared to human cells. Instead, the bowhead whale experiences reduced mutation rates in its cells, because they are better at repairing damaged DNA.

The researchers found that a protein called CIRPB, which is implicated in DNA damage-responses, was markedly abundant in bowhead whale tissue, but largely undetectable in other mammals (aside from humpback whales and dolphins).

This protein is “cold-inducible;” it activates in cold conditions, meaning that the icy climate of the whales could be the key to their long lives. The enhanced DNA repair leads to the improved maintenance of genome integrity, and thus to their resistance to age-related diseases such as cancer.

It is still not understood exactly how CIRBP promotes DNA repair, which is an avenue for future study.

Prior to this study, it had been suggested that improving DNA repair for cancer prevention would be difficult or even impossible.

The bowhead whale is one example of an animal that has evolved this ability. But could this be implemented to reduce the risk of cancer in humans?

The researchers conducted experiments on lab-grown human cells, introducing bowhead whale CIRBP proteins and observing their effect on damaged DNA.

They found that this did improve genome stability and thus, in theory, could enable the development of a treatment. However, it might have other side-effects or trade-offs: there may be reasons why high levels of this protein have not evolved in humans.

Bowhead whales are currently growing in number, a rare positive story compared to declines in many other species. But climate change is having a devastating effect on their natural habitat.

Given enough time, the bowhead whale might be able to evolve to cope with changing sea temperatures, with the diminishing of sea ice and the change in overall ecosystems.

But the pace of change is dangerously fast, particularly when compared to its lifetime. A whale born around the Industrial Revolution could still be alive today, and evolution proceeds one generation at a time, meaning that populations of slow-growing, long-living individuals are the most vulnerable to rapid changes.

Despite the impregnable role the Arctic still plays in our imaginations, its ice is melting. Earlier this year at the North Pole the temperature rose above zero Celsius, and the Arctic Ocean is predicted to lose its summer sea-ice cover at some point in the next two decades.

The bowhead whale has evolved its long lifetime over millions of years, but the speed of change predicted in the coming years will mean a great deal of nature’s diversity is likely to be lost.