vanessa cell lineage (IMAGE) Johns Hopkins Medicine Caption Illustration: Mutations that act as barcodes help scientists look back in the developmental timeline to trace the origin of cells in a fully-grown organism. Credit Johns Hopkins Medicine Usage Restrictions -- License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.