What is the longevity record for a cetacean?

If you had to bet on the oldest mammal ever identified, you might think of an elephant, or of a human being. The reality is quite different: the outright longevity record holder among mammals lives in the icy waters of the Arctic. It is the bowhead whale (Balaena mysticetus), also called the Greenland right whale. And the records it holds are beyond imagining: individuals of more than 200 years have been identified with certainty.

The bowhead whale: 200 years and more

The bowhead whale is a large Arctic mysticete, which can reach 18 metres and 100 tonnes. It does not migrate: it stays all year round in the icy waters of the Arctic Circle, forcing a path through the sea ice with its massive head and its enormous layer of blubber (up to 50 centimetres thick). It is in these waters at -1.8 °C that it attains one of the most extraordinary life spans in the animal kingdom.

The best documented record was established by means of a dating technique based on aspartic acid racemisation in the proteins of the lens of the eye. The method measures the “molecular ageing” of an amino acid whose spatial configuration changes very slowly over the decades. A study published in 1999 applied it to several bowhead whales: one female was dated at 211 years. Several others exceeded 100 years, and three fell in the 130-170 year range.

Unexpected physical evidence

More extraordinary still, bowhead whales taken in recent years by Inuit peoples under their subsistence hunting quota have yielded chance archaeological finds. In several animals, researchers recovered harpoon points of stone or ivory, along with fragments of metal bomb lances characteristic of 19^th-century commercial whaling, lodged in the blubber or the muscle.

This gear has been identified precisely: some points date from the 1879-1885 period. That means the animals carrying them in 2007 had been harpooned, and had escaped their hunters, more than 130 years earlier, and had gone on living, ageing and probably breeding throughout that time. This direct physical evidence, independent of the molecular techniques, supports the idea of a genuinely extraordinary life span.

A projection to 268 years

More recent genetic analyses have pushed the boundary further still. By examining DNA methylation marks: epigenetic modifications that accumulate with age and provide a very precise “molecular clock”, researchers have estimated that the theoretical maximum life span of the species could reach 268 years. This projection, statistical though it is, shows the exceptional biological potential encoded in the genes of this animal.

A study published in 2023 even identified features of the bowhead whale’s DNA repair system that could explain this longevity. Its cells repair genetic damage more efficiently than those of other mammals. That capacity reduces the accumulation of cancer-causing mutations linked to ageing and partly explains why bowhead whales, despite their considerable body mass (and hence the enormous number of potentially cancerous cells), develop extremely few cancers.

The other long-lived cetaceans

Beyond the bowhead whale, several other cetaceans show remarkable life spans. The female killer whale can exceed 80 years, sometimes 100 years. In the emblematic case of Granny (J2), matriarch of the Southern Resident killer whales (north-east Pacific), her age was put at 105 years when she died in 2016, although later analyses revised that figure downwards, probably to between 65 and 90 years.

The sperm whale can reach 70 years, sometimes more. Humpback whales, fin whales and blue whales live on average 70-90 years. Common bottlenose dolphins, surprisingly long-lived for their size, can exceed 50 years. At the other end of the range, harbour porpoises rarely live beyond 15-20 years, a short life span that reflects their modest size and their high metabolic rate.

Why such longevity?

Biologists of ageing study these long-lived species keenly in order to understand the mechanisms of senescence. Several converging hypotheses are emerging. A slow metabolism, tied to large size and cold water, reduces cellular wear. Exceptional DNA repair limits the accumulation of damage. The stable, matriarchal social structures of certain species (killer whale, sperm whale) give an advantage to the transmission of knowledge across several generations, creating a selective pressure in favour of longevity, what biologists call the grandmother effect.

The bowhead whale, with its longevity far outside the norm, remains the most valuable animal for biomedical research on human ageing. Understanding how it manages to live two centuries in its gigantic body without developing either cancer or dementia could, in time, open therapeutic prospects for our own species. One among many indirect benefits of cetacean conservation.

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