It's the one thing you've always had but don't fully understand.
What is it? It's your body — a natural wonder that illustrator David Macaulay explores, draws, and explains in his book, The Way We Work.
Sure, you know you have systems for breathing, digesting food, moving your blood around, and thinking. But you might be surprised to learn that, in Macaulay's view, your body is also home to raging rapids, rollercoaster dips, mysterious caverns, and bustling industrial zones. And occasionally, some muscle cells dance under a glittery disco ball, but that's another story.
Macaulay, 62, became well known by describing — with drawings — how things work. He's written much-loved books about buildings, such as pyramids, cathedrals, and mosques. And he's written about all sorts of machines, explaining stuff we use every day but don't understand, like how keys open locks.
But nothing beats the body, he said.
"It's the most wonderful collection of things we've every encountered," Macaulay said of his 6-year project to understand the human body in all its detail.
That's right: 6 years. Stop a minute and figure out what you were doing 6 years ago. If you're 8, you were a toddler who was probably learning to use the potty. If you're 11, you were just a kindergartner!
So it was that long ago that Macaulay started work on the book. An architect by training, he said he started out at square one, knowing very little about what goes on inside the body. Macaulay got going by doing a lot of reading and research. And he did sketch after sketch to get the drawings right.
"I don't believe I understand something until I draw it," he said.
To explain how the body gets and distributes oxygen, Macaulay created "Ride of a Lifetime," taking oxygen molecules on a rollercoaster ride. They drop from the trees (thanks to photosynthesis) and then these very important passengers ride around the body in red blood cells, getting dropped off everywhere they're needed.
In the book, Macaulay begins with your smallest body part — the super-tiny atoms in your tiny cells. Unseen unless you're looking through a powerful microscope, there's a whole world of activity going on in each of those cells. All that is you was built cell by cell, from the moment you existed. So how many cells is that? Oh, many trillions, Macaulay writes.
He closes the book by looking at the reproductive system — once again back to a single cell. This time, it's one cell that divides until there are just too many to count. In other words, a baby who will grow up to have trillions of cells.
Macaulay's research began with books like Gray's Anatomy, a famous and not-very-easy-to-read guide to the body. But he also took a long look at the Anatomy Coloring Book. In fact, he encourages kids to draw and color the parts of the body. It's a great way to learn what they look like and how they all fit together, he said.
But Macaulay did far more than read and draw to create the 336-page book. He talked often with doctors and researchers and attended several surgeries to better learn what these body parts look like in real life. Macaulay even held a spleen in his hand!
What's a spleen? It's part of your infection-fighting lymphatic system, a small organ in the belly that also traps red blood cells when they're worn out. That's another example of how the body finds a way to solve problems, in Macaulay's view.
Red blood cells wear out, so they need somewhere to go. To the spleen! There, the spleen breaks them down, keeps iron and some amino acids. Then, the rest becomes bile pigment — coloring for the yellow-green digestive fluid called bile. For all the majesty of the human body, Macaulay found there's plenty of dirty work that needs to be done.
"Your body is an oxygen and nutrition highway system that also needs to carry garbage away," Macaulay said.
By describing your body as a highway system, Macaulay makes something very complicated easier to understand. He does the same thing when he dips into the human head. A cross-section of the head looks like a slice into the Earth with its layers, from crust to core. Down deep, there's the cerebral cortex and white matter. Closer to the surface, there are layers of protective membrane and skull bone. Up top, your scalp spreads out like a farmer's field, sprouting hair instead of wheat.
Bits of humor, Macaulay says, get people interested and let them know there's some fun to be had here. Remember the dancing muscle fibers? But he doesn't take shortcuts when it comes to describing the complicated processes that keep a body working and alive. One look at a page full of his spider-webby neurons — your brain cells — will tell you that.
Another page — describing the cells inside pancreatic islets — envisions them as part of an industrial park that manufactures hormones and then pours them into a capillary. Like puzzle pieces, glucagon, insulin, and glucose flow by, on their way to the liver.
Because the books are illustrated, some people think Macaulay writes children's books. But look inside and they don't seem like typical kids' books. So what gives? Macaulay is happy to appeal to both kids and adults. In fact, he says he approaches them the same way. When he talks to groups about his books, he gives the same talk whether the audience is full of kids or grownups.
"If I do this right, I'll get them excited about it," he said.
He likes that kids have a forceful curiosity — something people say Macaulay has, too. Ask the question that pops in your head, he says, and don't stop until you understand. One girl recently followed this principle, asking him, "Does pee and poop come out of the same place?"
It's a good question and it deserves an answer, which happens to be no, Macaulay said. Pee flows through the urinary system and poop is the end of the line for the digestive system.
He can think of two big reasons to learn about the body: The first is that if something goes wrong, you'll be better able to understand it, and hopefully get it fixed. The second is pure enjoyment. It's a missed opportunity to be walking around inside this work of art, this feat of engineering, and not appreciate it.
"It's almost incomprehensible," he said. "The more you know, the more impressed you are."