Stephen Jett is one of a handful of dedicated (mostly) geographers who have sought to keep dialogues about prehistoric transoceanic contacts with the Americas within the realm of scholarly discourse for historians, anthropologists, archaeologists, or anyone else who might listen. Jett's first major contribution on this topic was the opening chapter in Man across the Sea: Problems of Pre-Columbian Contacts (Riley et al. 1971, University of Texas Press), a volume composed of 24 essays presented at the Society for American Archaeology annual meeting in 1968. In it, Jett and others considered an eclectic array of evidence for and against transoceanic diffusion based on a range of commodities and styles from a wide variety of source cultures. Like Jett, many of the authors in that book (e.g., Gordon Eckholm, David Kelley, George Carter, John Sorenson, and Alice Kehoe) continued to publish on this topic in the intervening decades, some more successfully than others. The current volume at a minimum represents the capstone of Jett's long scholarly career devoted to the issue of transoceanic contacts, and it could well be considered the culmination of the collective effort of all these scholars (although perhaps more so when considered in tandem with Alice Kehoe's 2016 book Traveling Prehistoric Seas: Critical Thinking on Ancient Transoceanic Voyages, Left Coast Press).

If the 1971 volume was eclectic in its coverage and thinking, the current book is methodical, well organized, and exceptionally well researched. In the first 12 chapters (142 pages) Jett considers the many varied arguments that have been made over the years against precolumbian contacts from across the sea. He approaches this by tackling seemingly every single idea that has ever been expressed to raise doubt about the likelihood of Old World contacts with the New prior to Columbus. The scholarship here is thorough and meticulous. Jett begins by addressing the “myth of the oceans as uncrossable barriers” and continues to consider related topics such as “why most domesticated plants and animals stayed home” and “the supposed silence of the historical record.” In this first third of the book, Jett seeks to establish circumstantial or contextual cases for contact before focusing on actual physical evidence. Here it can be said that Jett is possibly overthorough—attempting to thwart every imaginable objection to prehistoric transoceanic contacts. This is a tendency common among transoceanic diffusionists who have long suffered from quick, unthoughtful dismissals from archaeologists. Nonetheless, overthoroughness does not necessarily lead to greater credibility. Being given an explanation for “the mystery of the missing artifacts” before being exposed to the actual artifactual evidence itself does not necessarily help to build a stronger case.

The second third of Jett's volume is an exceptionally thorough consideration of the history and archaeology of watercraft, navigation, and sails. These 10 chapters are by far the strength of the volume. Jett's scholarship here is solid, and his case that various forms of watercraft, sails, and effective navigation were present in world areas other than the Mediterranean thousands of years before Columbus seems sound. He certainly establishes that the requisite technology was in place to enable transoceanic precolumbian diffusion to the New World.

In the final third of Jett's magnum opus, the actual physical evidence for contact is presented, and it is here where I was and most other archaeologists will probably be disappointed, because of the tendency for transoceanic theorists to grab onto every single minuscule transoceanic stylistic similarity or other questionable scrap of possible evidence—and consider all of them on equal footing. Jett and others seem convinced that every set of evidence is indicative of a separate independent contact event, implying therefore that there were many such events in the past. But instead of creating a powerful overall case, this shotgun approach—combining the odd, incredible evidence with the more compelling—only serves to raise questions about the whole enterprise. For example, Jett (p. 287) points to apparent depictions of turkeys on tenth- to thirteenth-century signet rings in Hungary—a landlocked country—which he implies (with no illustrations or citations) had some kind of connection with precolumbian Mesoamerica, where the turkey was domesticated. In the very next paragraph he considers the profoundly more compelling case of the chicken, for which there are clear mitochondrial DNA data and radiocarbon dates indicating its transport by Polynesians to coastal South America before Columbus (Storey et al. 2007, PNAS 104:10335–10339). In my view, “evidence” like Hungarian signet rings borders on ridiculous, while the Polynesian chicken dating and DNA evidence is compelling. Transoceanic theorists must convince the scientific world of one significant case of prehistoric transoceanic contact first by concentrating on the more powerful lines of evidence and distinguishing them from the spurious ones that are easily dismissible as chance convergent stylistic developments. Despite such misgivings, I think that the possibility of intercivilizational contacts across the oceans connecting Asia, Malaysia, South America, and/or Mesoamerica continues to be worthy of consideration, and I appreciate Jett's monumental efforts in trying to keep that possibility alive in the minds of American scholars.