Extra digit (IMAGE) University of California - San Diego Caption Changing the instructions for development: Single-letter changes to genomes led to the formation of an extra digit (right). Credit Fabian Lim and Genevieve Ryan, Farley Lab, UC San Diego Usage Restrictions Must be used in conjunction with Nature paper on enhancers and development. 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.