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  • This episode of DNews is brought to you by Subaru.

  • I'm pretty tall, a six-two or so, but there are people who are smallerAmy for instance

  • but there are also HUGE in comparison. Just HOW BIG can we get?

  • Height is a big deal. It affects every aspect of a person's life from their own perception

  • of the world to how they're perceived. It's a pretty common misconception that people

  • were shorter back in the day, but it's simply not true. 1,000 years ago people were as tall

  • as we are today, but during the 17th or 18th century, nutritional deficits during youth

  • caused humans to shrink 2 and a half inches on average. Dietary hardship, climate, and

  • disease throughout history all affect height. People were NOT shorter in the past, but had

  • the potential to be as tall as we are now; though, humans do seem to have some kind of

  • unofficial upper limit.

  • The tallest known person in history was Robert Wadlow. He stood 8 feet 11.1 inches (2.72M)

  • and was almost 200 kilos when he died at 22 in 1940. The man was massive. The current

  • "world's tallest man," is Sultansen from Turkey, and he has the same disorder as Wadlow,

  • a tumor on his pituitary that causes it to squirt human growth hormone into his body;

  • increasing his height abnormally.

  • The reason we don't just keep getting larger is, we have to live in the world. Gravity

  • is constantly pulling us down, requiring our bodies to create bones which counteract that

  • force. It's all about balance. We're reaching the upper limit for human height because more

  • weight requires larger bones, which requires more bodily resources to maintain. As an animal

  • grows, its support structure must grow with it; which means bones and muscles must thicken;

  • which can only happen so much. Plus, seven to eight percent of your body weight is blood,

  • so if you weigh 200 kilos, like Wadlow, you'd have 14 kilograms of blood. That blood needs

  • to be pressurized, and pumped, which as size increases, it gets more difficult for the

  • heart; so it needs MORE muscle, and there's only so much room in the human body. Elephants

  • and giraffes have highly pressurized circulatory systems, to keep their blood flowing!

  • Whales can grow larger than us because they don't live on land! The buoyancy of the water

  • around them helps support their weight; while their bones give structure to their body.

  • Air buoyancy is extremely low, only about zero point one two percent of your weight

  • at sea level, where the air is thickest. If our air was thicker, it would help hold us

  • up, allowing us to grow larger, but it would have to be a LOT thicker, which could affect

  • our ability to breathe it in at all.

  • In space astronauts gain a little height, growing as much a 3 percent taller because

  • the fluid in between the vertebrae relaxes and expands when not under the load of gravity.

  • For someone like me that could mean adding another 2 or more inches. On Mars, where gravity

  • is only 38 percent of Earth, you'd also get taller. But if children were sent to Mars,

  • they'd get big, but Earth gravity would be a struggle of real proportions. So they'd

  • kind of be stuck. If we lived under the water could we grow larger due to the buoyancy?

  • Maybe? But we couldn't walk on land at all because our bones would break due to the lack

  • of support. This is also why insects are limited in size; exoskeletons can only grow so large

  • before they're too heavy to support themselves!

  • If you could be a giant safely, would you want to be? What's your ideal height?

This episode of DNews is brought to you by Subaru.

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