Around 4,000 years ago, on the wind-swept island of St. Kilda, Scotland, people started creating a food storage of sorts. They moved a population of sheep to the island, likely as a back-up food resource for when times were tough. Little did they know that their actions would affect 21st century science. Today, rather than ending up as a meal, sheep from this isolated population are the subjects of research on immune function. Ecologist Andrea Graham takes Dr. Biology on a trip of exploration through the dangerous cliffs, windy conditions, and wormy world that the Soay sheep deal with on St. Kilda.