They seem to have been a bit of a luxury treatment, too expensive for the poor. The use of leeches to treat all sorts of ailments goes back to at least 1500BC, appearing in Egyptian tomb decorations.

Mark tells the story of some captive leeches that escaped and ended up in the back of a pickup truck in the hot sun for a day and a half before being found. The poor shriveled things were plopped ...

But leeches aren’t just useful at crime scenes. These creatures’ sanguineous appetites have also come in handy for scientists, who are hoping to use them to solve another mystery: the diversity of ...