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Why Don’t Big Dogs Live as Long as Small Dogs?

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Large animals tend to live longer (sometimes much more so) than smaller ones*. A cat is going to live longer than a rat, you’re going to live longer than a cat and a Galapagos tortoise is going to live longer than you. The world’s smallest mammal, the bumblebee bat, is thought to live 5 to 10 years, while the largest, the blue whale, lives for 80 to 90. Scientists think that this happens because of the way differently-sized animals use energy. Big animals’ cells are slower and more efficient, so their parts wear out slower and last longer.

Forget about all the other animals and focus on just one species, though, and you see this trend reverse. Within a species, larger size seems to carry a longevity cost. Scientists have seen this is in mice, horses, and even humans**. The phenomenon is well known to dog lovers: Dogs from bigger breeds don’t live as long as smaller ones. The small breeds have an average life expectancy of 12 to 14 years; for larger breeds, it's 8 to 10; and for the so-called “giant breeds,” lifespan is 5 to 8 years. 

This strange flip in the relationship between size and lifespan isn’t completely understood, and many, if not all, of the factors at play are probably species-specific. This is certainly the case for dogs, and scientists think that the reasons big breeds die young have to do with the way humans have bred them and the way they grow. 

Larger dogs grow very big very fast. Take a one-year-old Great Dane, for example. It’s huge. From birth to their first birthday, they increase 100-fold in weight. In that same time frame, wolves increase 60-fold, poodles 20-fold and humans only threefold. Research in the last decade has suggested that larger individual animals die younger because this sort of accelerated growth comes with increased free-radical activity. 

A new study published last month focused only on dogs and likewise concludes that big dogs die young because they age quickly. The European researchers looked at veterinary data for 74 breeds and more than 50,000 individual dogs, including when and how they died, and found that “large dogs age at an accelerated pace, suggesting that their adult life unwinds in fast motion.”

Faster aging isn’t the only explanation, though. Larger dogs are more prone to health issues like developmental disorders, musculoskeletal and gastrointestinal diseases, and tumors—all of which are also linked to their accelerated growth and appear to be the nasty side effects of selective breeding for large size over a short (relative to the millennia other animals have had to evolve by natural selection) period of time.

* There are some notable exceptions, of course, like the relatively small African grey parrot, which can live 50 to 60 years. 

** Tom Samaras has been studying links between human height and other characteristics for decades. After looking at height and age of death for people in a number of historical samples, he found that shorter stature is strongly linked to longer life. Among 3200 deceased pro baseball players, for example, he worked out that every cm of height a player had over the average shortened his life by .35 years.

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Animals
Fisherman Catches Rare Blue Lobster, Donates It to Science
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FRED TANNEAU/AFP/Getty Images

Live lobsters caught off the New England coast are typically brown, olive-green, or gray—which is why one New Hampshire fisherman was stunned when he snagged a blue one in mid-July.

As The Independent reports, Greg Ward, from Rye, New Hampshire, discovered the unusual lobster while examining his catch near the New Hampshire-Maine border. Ward initially thought the pale crustacean was an albino lobster, which some experts estimate to be a one-in-100-million discovery. However, a closer inspection revealed that the lobster's hard shell was blue and cream.

"This one was not all the way white and not all the way blue," Ward told The Portsmouth Herald. "I've never seen anything like it."

While not as rare as an albino lobster, blue lobsters are still a famously elusive catch: It's said that the odds of their occurrence are an estimated one in two million, although nobody knows the exact numbers.

Instead of eating the blue lobster, Ward decided to donate it to the Seacoast Science Center in Rye. There, it will be studied and displayed in a lobster tank with other unusually colored critters, including a second blue lobster, a bright orange lobster, and a calico-spotted lobster.

[h/t The Telegraph]

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Animals
Australian Scientists Discover First New Species of Sunfish in 125 Years
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Courtesy Murdoch University

Scientists have pinpointed a whole new species of the largest bony fish in the world, the massive sunfish, as we learned from Smithsonian magazine. It's the first new species of sunfish proposed in more than 125 years.

As the researchers report in the Zoological Journal of the Linnean Society, the genetic differences between the newly named hoodwinker sunfish (Mola tecta) and its other sunfish brethren was confirmed by data on 27 different samples of the species collected over the course of three years. Since sunfish are so massive—the biggest can weigh as much as 5000 pounds—they pose a challenge to preserve and store, even for museums with large research collections. Lead author Marianne Nyegaard of Murdoch University in Australia traveled thousands of miles to find and collected genetic data on sunfish stranded on beaches. At one point, she was asked if she would be bringing her own crane to collect one.

Nyegaard also went back through scientific literature dating back to the 1500s, sorting through descriptions of sea monsters and mermen to see if any of the documentation sounded like observations of the hoodwinker. "We retraced the steps of early naturalists and taxonomists to understand how such a large fish could have evaded discovery all this time," she said in a press statement. "Overall, we felt science had been repeatedly tricked by this cheeky species, which is why we named it the 'hoodwinker.'"

Japanese researchers first detected genetic differences between previously known sunfish and a new, unknown species 10 years ago, and this confirms the existence of a whole different type from species like the Mola mola or Mola ramsayi.

Mola tecta looks a little different from other sunfish, with a more slender body. As it grows, it doesn't develop the protruding snout or bumps that other sunfish exhibit. Similarly to the others, though, it can reach a length of 8 feet or more. 

Based on the stomach contents of some of the specimens studied, the hoodwinker likely feeds on salps, a jellyfish-like creature that it probably chomps on (yes, sunfish have teeth) during deep dives. The species has been found near New Zealand, Australia, South Africa, and southern Chile.

[h/t Smithsonian]

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