200-Year-Old Whale May Hold Clues to Long Life

Bowhead whales, which can live over 200 years with almost no evidence of age-related disease, could help humans to live longer, healthier lives, suggests a new study that presents the complete bowhead whale genome.

The genome, published in the latest issue of Cell Reports, represents the first time that any big whale's complete set of genes has been sequenced. The minke whale's genome was previously sequenced, but the minke is a much smaller, shorter-lived whale.

Researchers are studying the information on bowheads to determine how these whales, which can grow to about 60 feet long and weigh 60 tons, live so long. One male might even be around 250 years old. The species is now believed to be the longest-lived mammal.

"We discovered changes in bowhead genes related to cell cycle, DNA repair, cancer and aging that suggest alterations that may be biologically-relevant," senior author João Pedro de Magalhães of the University of Liverpool told Discovery News.

"So my own view," he added, "is that this points toward improved DNA repair and cell cycle regulation mechanisms to prevent DNA damage accumulation during the life course, which in turn promote longevity and resistance to age-related diseases."

De Magalhães suspects that other large whales, such as the blue and fin whales, are also very long lived. He explained that these whales have few natural predators. This allows them to evolve a life of slow growth and delayed reproduction. Cellular, molecular and genetic mechanisms then help to suppress age-related diseases and degeneration.

Remarkably, there's only one known case of a bowhead whale dying due to natural causes. Humans kill them and they can suffer from predation by orcas, but even orcas rarely mess with such enormous whales.

Humans are clearly not the shortest-lived mammals. Dogs and cats, for example, have much shorter average lifespans. But our average longevity is just a drop in the bucket compared to that of bowhead whales.

Humans, for example, reach physical sexual maturity at around 12 or 13 years old, and sometimes even younger. Bowhead whales do not reach sexual maturity until about the age of 20, and may then enjoy intercourse for literally hundreds of years.

Even bowhead whales have their problems, though.

"Bowheads can carry parasites and harmful microbes, and without the benefits of medicine, this might result in discomfort and pain," de Magalhães explained.

"So even though bowheads can live longer than humans and appear to be protected from age-related diseases, I wouldn't assume they have a better quality of life."

Nevertheless, scientists are always looking for ways to extend human longevity. In the future, the researchers hope to identify specific genes in the whales that allow for this to happen. They have already identified gene ERCC1 as playing an important role in DNA repair.

De Magalhães and his team think it could be possible to manipulate the same, or similar, genes in humans to prevent aging and certain diseases.

Steven Austad, chair of the Biology of Aging and the Evolution of Life Histories Department at the University of Alabama at Birmingham, told Discovery News that it's reasonable to conclude that changes in certain of the bowhead whale's genes associated with DNA repair may play a role in its exceptional longevity and ability to ward off cancer.

"This paper is an exciting and necessary start in trying to understand the exceptional longevity and cancer resistance of this very unusual species," Austad said.

Introduction

Originally designed to live on land, marine mammals are a diverse, charismatic group of animals that include more than 120 species. The animals share key characteristics of land mammals. They have hair, breathe air, give birth to live young, which feed off mother's milk when young. They have warm bodies and usually thick blubber to keep their body temperatures high. The bottlenose dolphin is probably the most widely recognized marine mammal, easily spotted just offshore from beaches around the world. Small groups of 20 or less can live in close proximity to shorelines, but groups living more offshore can reach several hundred. Bottlenose dolphin calves stay with their mothers for up to six years, learning how to hunt and become good dolphin citizens. Full-grown dolphins reach eight to 12 feet in length and can weigh up to 1,430 pounds. The bottlenose dolphin is protected in U.S. waters.

Humpback Whale

What makes them "marine" depends on the animal. They either live mostly in the sea or, like polar bears, depend on the ocean for food. The largest in the group are whales -- including humpback whales. These massive animals reach up to 50 feet in length and weigh up to 79,000 pounds. To maintain their weight, the animals feed on tons of krill and fish. They neared extinction due to whaling, but have recovered somewhat since a 1966 moratorium on whaling was introduced.

Polar Bear

While polar bears live mostly on land or ice, they are excellent swimmers and have been known to swim up to 45 miles a day. The massive animals, weighing up to 1,500 pounds, hunt mostly seals. In recent years, biologists have observed that the bears are swimming now more than ever as melting stretches the distances between Arctic ice flows. Because they depend on sea ice to hunt seals, the polar bear is considered threatened as global warming melts and thins ice in this region.

Sea Otter

This member of the weasel family is also the smallest marine mammal, with females weighing about 60 pounds and males weighing up to 90 pounds. They may be small, but they're also clever. They're the only marine mammals known to use tools. They use stones to break open clams and store food they gather in the folds of their armpits! Another feature that sets them apart is their lack of blubber. These marine mammals depend mostly on their fur to stay warm. That feature makes them particularly vulnerable to oil spills, which can compromise their fur's insulating effect.

Sea Walrus

Immediately recognizable by its long tusks and whiskers, the sea walrus is a hefty, flippered member of the Odobenidae family and is, in fact, the last living member of this group. Since both the males and females have big tusks and not much for teeth, the animals feed by sucking up shellfish from the ocean floor. So, just what are those tusks for? The longer they are (they grow to be up to four feet long in males), the higher an animal is ranked in the group. Males attack each other with their tusks to establish dominance. The ivory appendages are also handy for poking holes in the winter ice and for helping the animals pull themselves out of the water.

Manatee

Manatees, also known as sea cows, are gentle herbivores that live in marshy areas in tropical and subtropical waters. The average adult manatee can weigh up 1,200 pounds and is around 10 feet long. Because of their slow metabolism, these animals can only survive in warm waters. Due to the unusually long, cold winter this year in part of the southeastern United States, populations of manatees throughout Florida were devastated. During the day, manatees usually like to stay close to the surface. At night, manatees will often sleep about three to 10 feet below sea level. This is why these gentle animals are so often accidentally injured, maimed or killed by passing boats.

Harbor Seal

Found up and down the North American coastlines, these marine mammals spend half of their lives swimming. Although they can reach up to six feet in length and weigh around 180 pounds, when on land and in plain sight harbor seals may not be easy to spot. Their spotted brown or tan fur allows harbor seals to blend in with sand and rocks. Unlike their very vocal relatives -- sea lions and elephant seals -- harbor seals are quiet creatures that make little noise. They like to hang out on beaches, sand bars and rocks during low tide to bask in the sun and sleep, but they never go far from the water. At the slightest sign of danger, they will quickly slip back under the waves. These expert swimmers have been known to plunge to depths of more than 1,600 feet and stay underwater up to 28 minutes.