In a paper published this week in PNAS, University of Edinburgh scientists show that "the majority of S. aureus isolates from broiler chickens are the descendants of a single human-to-poultry host jump," which they believe happened about 38 years ago, by a subtype of a lineage from Poland. This ST5 clade has adapted to its new host through acquiring new mobile elements and inactivating several important human disease genes, they say.