Editing Humanity explores the history, biology, sociology, and ethical import of CRISPR (“clustered regularly interspaced short palindromic repeats”), the major new DNA technology indicated in the book’s subtitle, “The CRISPR Revolution and the New Era of Genome Editing.”  Using CRISPR, researchers can manipulate the DNA of animals, plants and microorganisms with extremely high precision. In particular, scientists now have the potential to customize the human genome.  

What is CRISPR? To quote Davies, “CRISPR is a small subsection of the bacterial genome that stores snippets of captured viral code for future reference, each viral fragment (or spacer) neatly separated by an identical repetitive DNA sequence.” (p. 23) When the cell is reattacked by a virus, an RNA copy of that virus’ stored “signature” forms a DNA-splitting complex that destroys the incoming virus. In 2012, Jennifer Doudna, of the University of California, Berkeley, and Emmanuelle Charpentier, of the Max Planck Institute, Berlin, demonstrated that CRISPR could be engineered to edit any gene. One could, for example, replace a disease-causing mutation in any DNA segment with the healthy variant, thus preventing genetic disease.  

The author, Kevin Davies is a geneticist and science writer whose previous books include Cracking the Genome and DNA: The Story of the Genetic Revolution.  In Editing Humanity, he discusses an array of actual and potential applications of CRISPR technology, including human disease prevention by altering susceptibility of animal vectors, improving farm productivity, and even resurrecting extinct species. However, the most powerful and controversial topic is genetic manipulation of the human embryo. Davies devotes several chapters to the cautionary tale of the young Chinese scientist He Jiankui who engineered the world’s first gene-edited babies, and the scandal and disgrace that followed. (He was convicted in China of “illegal medical practice” and sentenced to prison.)