From maggots to viruses, this book is a celebration of the creepy-crawlies that live off your body. When Craig Venter, one of the mappers of the human genome, set out on a sailboat cruise to map DNA in seawater all across the globe, he found that a teaspoon of seawater contained on average 50m viruses. That sounds terrifying until you learn most of them are phages that infect marine bacteria and have no interest in you. Small comfort, but we'll take it.

Viruses are parasites, and like all their parasitic kind, they get a free ride from living organisms. The whole point of multicellular life is to create a cozy environment for cells to live in, and evolution has invented all manner of stowaways that want this comfort and manage to get on board. While it's not generally in a parasite's best interest to kill its host and be forced to find a new home, some come dangerously close. Most diseases in the developing world are connected in some way to parasitic infections. So next time you enjoy a swim, remember: you're bathing in a viral soup. You're welcome.