Scholars have long believed that the first Americans arrived via land bridge some 13,000 years ago, when retreating glaciers created an inland corridor from Siberia. Jennifer Raff, an anthropological geneticist at the University of Kansas, Genetic-History-of-the-Americas-By-Jennifer-Raff.html">tells a different story in “Origin.” According to Raff, the path to the Americas was coastal rather than inland, and what we’ve thought of as a bridge was a homeland inhabited for millenniums. Raff talks about the book on this week’s podcast.

“In recent years, the ability to obtain complete genomes from ancient ancestors has really given us new insights — extraordinary new insights — into the histories not only of individuals and populations but also of our ancestors globally,” Raff says. “We can now identify the populations who originally gave rise to the ancestors of Native Americans. And we can identify extremely important evolutionary events in that process going back, starting about 26,000 years ago. So we can use genetics to identify biological histories, to characterize biological histories, and even identify populations which we had no idea existed based on archaeology alone.’

Ira Rutkow visits the podcast to talk about of-the-scalpel-ira-rutkow.html">“Empire of the Scalpel: The History of Surgery.” Rutkow says the idea for the book evolved over the course of 50 years, and that he wrote it for the general public and surgeons alike.

“I was dismayed, over the course of my surgical practice, at how little patients understood about the whys and wherefores of what a surgeon did, or how a surgeon becomes a surgeon,” he says. And he was “shocked” when he would ask colleagues historical questions — “When did anesthesia come about? When did Lister discover antisepsis?” — and “they would have no idea.”

Also on this week’s episode, Alexandra Alter has news from the publishing world, and Elisabeth Egan and John Williams talk about what they’ve been reading. Pamela Paul is the host.

Here are the books discussed in this week’s “What We’re Reading”:

days-of-afrekete-asali-solomon.html">“The Days of Afrekete” by Asali Solomon

child.html">“A Word Child” by Iris Murdoch

examined-life-by-stephen-grosz.html">“The Examined Life” by Stephen Grosz

true-american-by-anand-giridharadas.html">“The True American” by Anand Giridharadas

We would love to hear your thoughts about this episode, and about the Book Review’s podcast in general. You can send them to books@nytimes.com.

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