Recent research highlights the power of the canine nose to uncover buried remains from ancient human history. On a sunny summer day in Croatia several years ago, an archaeologist and two dog handlers watched as two dogs, one after another, slowly worked their way across the rocky top of a wind-scoured ridge overlooking the Adriatic Sea. Bodies had lain in beehive-shape tombs on this necropolis, part of the prehistoric hill fort of Drvišica, since the Iron Age. The two dogs, trained to detect human remains, were searching for scents that were thousands of years old. Panda, a Belgian Malinois with...