Michael Specter, MIT professor, science journalist, and author of “Higher Animals: Vaccines, Synthetic Biology, and the Future of Life,” explains the enormous impact that new technologies like mRNA, CRISPR, and A.I. are having on our lives, particularly when it comes to medicine. New Yorker staff writer and author of “Future Sex: A New Kind of Free Love” Emily Witt talks about some of the latest research into reproduction and women's fertility.