Why Do Giant Tortoises Live So Long?

iStock
iStock

Sorry hares, but giant tortoises are still winning the race of life by treating it like a marathon and taking each lap slow and steady. The oldest living giant tortoise known to science (and the oldest animal in the world) is Jonathan, a 184-year-old that lives on St. Helena Island. Unofficially, there have been claims of older tortoises, including one believed to have been 255 when it died in 2006. Researchers have not been able to pin down exactly what keeps them around for so long, but their slow-motion lifestyle may have something to do with it.

Giant tortoises have very slow metabolisms, which means they burn energy at a slower rate than smaller and faster animals. In 1908, physiologist Max Rubner introduced the rate of living theory, which suggested an inverse correlation between metabolism and lifespan (the faster the metabolism, the shorter the life). Scientists have had some issues with the theory over the past century (some argue that metabolism is a “poor measure of energy expenditure”), and it has largely been discredited, but it did spawn the phrase “Live fast, die young,” and it serves as the basis for expanded research on the topic.

The link between metabolism and longevity is still not understood, but some scientists believe that metabolism is linked to the creation of free radicals, unstable molecules that damage cells and that increase as more energy is burned by the body. According to this theory, tortoises live longer because their slow metabolisms burn less energy, which means less harm to the cells in their bodies.

Theories on aging alone don’t fully explain how tortoises live much longer than humans, but their reproductive lives and size may hint toward an explanation. Because of their built-in home security system (the massive hard shells) and their geographic isolation (they only live on a few specific islands), giant tortoises have very few predators to worry about. Besides simply not becoming prey, this means that giant tortoises don’t have to rush into reproduction to keep their species alive. The tortoises essentially reserve their biological resources to keep themselves alive—they needn't rely on them to aid procreation while they’re young.

Each theory has its flaws and unanswered questions, but scientists believe that some combination of biological and evolutionary factors is what keeps giant tortoises alive for so long. There is no magical gene that humans can harvest and exploit, but that hasn’t stopped us from looking.

Looking to Downsize? You Can Buy a 5-Room DIY Cabin on Amazon for Less Than $33,000

Five rooms of one's own.
Five rooms of one's own.
Allwood/Amazon

If you’ve already mastered DIY houses for birds and dogs, maybe it’s time you built one for yourself.

As Simplemost reports, there are a number of house kits that you can order on Amazon, and the Allwood Avalon Cabin Kit is one of the quaintest—and, at $32,990, most affordable—options. The 540-square-foot structure has enough space for a kitchen, a bathroom, a bedroom, and a sitting room—and there’s an additional 218-square-foot loft with the potential to be the coziest reading nook of all time.

You can opt for three larger rooms if you're willing to skip the kitchen and bathroom.Allwood/Amazon

The construction process might not be a great idea for someone who’s never picked up a hammer, but you don’t need an architectural degree to tackle it. Step-by-step instructions and all materials are included, so it’s a little like a high-level IKEA project. According to the Amazon listing, it takes two adults about a week to complete. Since the Nordic wood walls are reinforced with steel rods, the house can withstand winds up to 120 mph, and you can pay an extra $1000 to upgrade from double-glass windows and doors to triple-glass for added fortification.

Sadly, the cool ceiling lamp is not included.Allwood/Amazon

Though everything you need for the shell of the house comes in the kit, you will need to purchase whatever goes inside it: toilet, shower, sink, stove, insulation, and all other furnishings. You can also customize the blueprint to fit your own plans for the space; maybe, for example, you’re going to use the house as a small event venue, and you’d rather have two or three large, airy rooms and no kitchen or bedroom.

Intrigued? Find out more here.

[h/t Simplemost]

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The 10 Best Shark Movies of All Time, According to Rotten Tomatoes

MCA/Universal Home Video
MCA/Universal Home Video

If the ongoing popularity of shark films has taught us anything, it’s that we simply can’t spend enough screen time with these predators, who can famously ruin a beach day with one swift gnash of their teeth. And even if shark attacks are far less common than Hollywood would have us believe, it’s still entertaining to watch a great white stalk an unsuspecting fictional swimmer—or, in the case of 2013’s Sharknado, whirl through the air in a terrifying cyclone.

To celebrate Shark Week this week, Rotten Tomatoes has compiled a list of the best shark movies of all time, ranked by aggregated critics' score. Unsurprisingly topping the list is Steven Spielberg’s 1975 classic Jaws, which quite possibly ignited our societal fixation on great white sharks. The second-place finisher was 2012’s Kon-Tiki, based on the true story of Norwegian explorer Thor Heyerdahl’s harrowing voyage across the Pacific Ocean on a wooden raft in 1947.

If you did happen to write off Sharknado as too kitschy to be worth the watch, you might want to reconsider—it ranks sixth on the list, with a score of 78 percent, and its 2014 sequel sits in ninth place, with 61 percent. The list doesn’t only comprise dramatized shark attacks. In seventh place is Jean-Michel Cousteau’s 2005 documentary Sharks 3D, a fascinating foray into the real world of great whites, hammerheads, and more.

But for every critically acclaimed shark flick, there’s another that flopped spectacularly. After you’ve perused the highest-rated shark films below, check out the worst ones on Rotten Tomatoes’ full list here.

  1. Jaws (1975) // 98 percent
  1. Kon-Tiki (2012) // 81 percent
  1. The Reef (2010) // 80 percent
  1. Sharkwater (2007) // 79 percent
  1. The Shallows (2016) // 78 percent
  1. Sharknado (2013) // 78 percent
  1. Sharks 3D (2004) // 75 percent
  1. Open Water (2004) // 71 percent
  1. Sharknado 2: The Second One (2014) // 61 percent
  1. Jaws 2 (1978) // 60 percent

[h/t Rotten Tomatoes]