Whales are regarded as the kings of longevity among mammals. Some whales live over 100 years, and there is a case of a bowhead whale living up to 211 years. However, such longevity records could only be obtained through the analysis of rare tissue samples using complex technologies.
An international research team from the University of Alaska Fairbanks, the University of Pretoria in South Africa, and Griffith University in Australia reported on the 20th (local time) that the life expectancy of some whales was found to exceed nearly double the estimates made in previous studies, utilizing statistical techniques used by life insurance companies. The research findings were published that day in the international journal "Science Advances."
The researchers conducted the study focusing on the North Atlantic right whale (Eubalaena glacialis) and the southern right whale (Eubalaena australis). Existing methods of aging whales relied on counting earwax layers accumulated in the ear canal or analyzing chemical changes in eye proteins; however, these methods were difficult for sample collection and challenging to apply to certain species. Notably, the two species studied faced significant population declines due to the whaling industry, making tissue sample collection even more difficult.
The research team utilized a catalog of photographs accumulated since the 1970s. They identified individual whales from the pictures and documented their disappearance. This information was then entered into statistical models used by life insurance companies to predict human mortality rates and set insurance premiums. By combining decades of photographic records with statistical techniques, they were able to estimate the lifespan of whales.
The analysis revealed that the average lifespan of the southern right whale is about 73 years. Among them, 10% are estimated to live over 132 years. This result far exceeds the previous life expectancy estimates of 70 to 80 years. Gregory Breed, a professor at the University of Alaska Fairbanks, explained, "Southern right whales live much longer than we thought."
In contrast, the average lifespan of the North Atlantic right whale is 22 years, with only 10% potentially living beyond 47 years. The researchers analyzed that "the reason North Atlantic right whales live shorter lives is due to frequent ship strikes and entanglement in fishing gear."
As a result, the southern right whale exhibits more active living than the bowhead whale but shows unexpected longevity. The bowhead whale is believed to enjoy longevity due to its ecological characteristics of slow metabolism, slow growth, and movement. Hans Te wiss en, a professor at Northeast Ohio Medical University, noted, "The secret to their longevity remains a mystery."
Professor Breed stated, "This research suggests that not only southern right whales but other whale species may also live much longer than currently known lifespans," adding, "We still do not truly know the real lifespan of whales."
Reference materials
Science Advances (2024), DOI: https://doi.org/10.1126/sciadv.adq3086