Why are there whales that can live for more than 200 years?

In 2007, a team of hunters and scientists from the Inupiad, an Arctic people, captured a whale in the Bering Sea, near the coastal town of Utqiaġvik. During the processing of the animal, they made an exceptional discovery: they found metal fragments of a 19th-century explosive harpoon embedded in the subcutaneous tissue. Since these harpoons had not been used for over 120 years, it allowed them to estimate that this whale could be between 115 and 130 years old, or even older. This finding reinforced the now well-established hypothesis that bowhead whales are the longest-living mammals on the planet, with individuals that can exceed 200 years.

Why do these marine animals have such long lifespans, far longer than those of any other mammal? Recent research led by biologist Daniel Sol, from the Institute of Evolutionary Biology at Pompeu Fabra University in Barcelona and the Spanish National Research Council (CSIC), has found the answer. According to a study published in Nature Communications, the adoption of a marine lifestyle, with all the morphological and physiological adaptations it entails, spurred evolution toward slow-paced life strategies and exceptional longevity, such as prolonged development and late maturation, yet leaving few offspring. The classical theory of evolutionary life cycles has been marked by a biological dichotomy: live fast, die young, and have many offspring, or alternatively, live slowly, die old, and have fewer. This dichotomy explains why many small organisms have short lifespans and reproduce quickly and frequently. But when analyzing species such as large whales and certain seabirds, the pattern is radically different: they take years to reach maturity, reproduce late, have few offspring, and live for many decades. One of the most extreme cases is that of bowhead whales (Balaena mysticetus), which can live for over 200 years.

A vital 'slow life' strategy

The study conducted by Sol and colleagues highlights that a low mortality rate alone is insufficient to explain these strategies. Physiological and morphological adaptations are necessary to enable adults to survive effectively in a harsh environment and justify investing many years in the growth and maturation process. The authors analyzed nearly 4,400 mammal species and 10,000 bird species, both terrestrial and marine, quantifying seven life traits: maximum longevity, age at first offspring, gestation and rearing duration, breeding season, rearing period, progeny size, and total fecundity. When they plotted this data, the result was very clear and revealing. The marine species analyzed are mostly located at the extreme end of the slow life strategies graph, compared to terrestrial and freshwater species. That is, they exhibit prolonged development, low fecundity, and long lifespans.

Why have they evolved this life strategy? The work carried out by these researchers shows that adaptation to the marine environment, especially in the open pelagic ocean where prey is dispersed, unpredictable, and often scarce, has forced them to adopt adaptations that promote energy efficiency, the ability to store reserves, and the skills to locate and capture distant or difficult prey. These adaptations, however, come at a biological cost: they require more time to mature, since the organisms must grow more, learn more, and invest more resources. They also decrease adult mortality and, therefore, allow them to reproduce for a longer period throughout their lives, albeit with fewer offspring so they can protect them while they grow and learn slowly.

Evolution rewards a slow pace

But the story doesn't end there. The authors of the study have identified other important morphological aspects of this life strategy, such as larger body size, a hydrodynamic shape, and also high encephalization—that is, larger brains relative to body size. These characteristics favor adult survival and allow them to successfully navigate the uncertainties of the ocean, justifying the need to invest many years before reproduction. This approach offers two key insights. First, that the evolution of longevity is not just a matter of having fewer predators or a larger body, but rather an ecological style, or way of life, that rewards a slow pace. Second, that the adaptations that enable this strategy come at a cost, such as growing more slowly, investing more in development, having fewer offspring, and waiting longer to reproduce. This perspective also provides an important conservationist nuance. These slow-life organisms, such as large cetaceans, have extremely vulnerable populations. Reproducing late, having few offspring, and developing slowly means that any impact that increases adult mortality, such as collisions with ships, entanglement in fishing nets, noise pollution, or climate change, has far more severe effects than in fast-lived species.