A flurry of squabbles about high-profile biological research is prompting scientists to revisit a perennially touchy subject: how should credit for scientific findings be assigned?

In recent months, a panel on research integrity at the University of Pittsburgh, Pennsylvania, scolded cloning expert Gerald Schatten for his limited contribution to papers he co-authored with a South Korean team. Ian Wilmut of the Roslin Institute in Edinburgh has been criticized for taking most of the credit in 1997 for the cloning of Dolly the sheep. And a co-author has accused Alison Murdoch, of the University of Newcastle upon Tyne, UK, of hogging the credit for an advance in cloning human embryos (see ‘Cloning clashes’).