It all started with a summer pool party and a Harvard neuroscientist who prefers to be called Bob. Bob—aka Sandeep Robert Datta—was splashing around the pool with his kids when science writer Carl Zimmer noticed an image of DNA inked to his shoulder. It was not a surprising choice for a tattoo, since Bob studies the DNA of fruit flies. But it turned out there was more to it. In an excerpt from the introduction to his latest book, "Science Ink: Tattoos of the Science Obsessed," Zimmer explains the science and story behind his friend's tattoo:

"DNA stores information for making proteins in its rung-like units called bases. There are four different bases: adenine (A), cytosine (C), guanine (G) and thymine (T). It takes three consecutive bases to code a single amino acid, the building block of protein. There are 20 different kinds of amino acids in humans, each abbreviated with a letter. The letter E, for example, stands for glutamate. Bob explained to me that the tattoo spelled out the initials of his wife, Eliza Emond Edelsberg."

Was there a subculture of other scientists sporting body art, Zimmer wondered, intrigued. The question led to a query on his blog, The Loom. Pictures began pouring in, a torrent of tattoos. He received roughly 1,000 over the next four years—so many that he turned them into the book.

Proof again that scientists are a creative, edgy tribe, eager to express themselves beyond the conference lecture and the journal abstract. (For other examples, see this and this.)

This week, Carl Zimmer spoke with PBS NewsHour correspondent Hari Sreenivasan about Zimmer's entry into this world of body art, the process of researching this book and some of the surprises he encountered along the way. Bonus extra: Zimmer reveals the kind of tattoo he'll get if he ever succumbs to the needle himself.

The tattoos in the book are wildly varied.

» Click here to see a slide show of selections from the book

Some of the tattoos are simple and clean, some are old and fading, some are big and colorful and wild. They tell stories of galaxies and molecules and disease research and mathematical equations and unusual species. And they delve into the history of science. One scientist has a tattoo of the original drawing from the patent for Thomas Edison's first phonograph. A neuroscientist whose father died of Lou Gehrig's disease has the neuron that gets destroyed by the disease inked onto her foot.

How many science writers can boast an art book that digs so deeply into personal stories while celebrating such a broad spectrum of scientific research? Then again, how many science writers have a tapeworm named after them? (Hari asked Zimmer about that, too.)