Contents

18 December 2015
Vol 350, Issue 6267

About The Cover

Cover image expansion

COVER Cheap, widely available, and easy to use, the genome editing system called CRISPR earned Science's 2015 Breakthrough of the Year laurels for many great feats and some controversial ones—including the alteration of DNA in human embryos. See page 1456.
Illustration: Davide Bonazzi/@SalzmanArt