Scientific Evidence for Pre-Columbian Transoceanic Voyages to and from the Americas
by John L. Sorenson and Carl L. Johannessen
Introduction
This paper is an expanded version of a presentation given at a conference, "Contact and Exchange in the Ancient World," held at the University of Pennsylvania, Philadelphia, May 5, 2001. The conference was organized by Victor H. Mair of the Department of Asian and Middle Eastern Studies at the University of Pennsylvania. He is also editor of the volume of papers from that conference in press at the University of Hawaii Press in 2004.
Since our initial paper was submitted for inclusion in that volume, we have made further discoveries. The present book incorporates the new materials, constituting a revision and extension of the original paper. Because much of the literature that enters into our argument in the extended paper is interpreted here in ways other than biologists conventionally do, for readers' convenience we give in the Appendix précis of our reference materials on each species discussed. Selected illustrations and a bibliography for both the text proper and the Appendix follow.
Support for the preparation and presentation of the original paper was provided by the Institute for the Study and Preservation of Ancient Religious Texts, at Brigham Young University, and the Center for Ancient Studies of the University of Pennsylvania. We express gratitude to those organizations, but, of course, we authors alone are responsible for the views expressed and for any errors. Our appreciation also goes to Linda S. McElroy for her helpful editing of the present manuscript.
Abstract
Examination of an extensive literature has revealed conclusive evidence that nearly one hundred species of plants, a majority of them cultivars, were present in both the Eastern and Western Hemispheres prior to Columbus' first voyage to the Americas. The evidence comes from archaeology, historical and linguistic sources, ancient art, and conventional botanical studies. Additionally, 21 species of micro-predators and six other species of fauna were shared by the Old and New Worlds. The evidence further suggests the desirability of additional study of up to 70 other organisms as probably or possibly bi-hemispheric in pre-Columbian times. This distribution could not have been due merely to natural transfer mechanisms, nor can it be explained by early human migrations to the New World via the Bering Strait route. Well over half the plant transfers consisted of flora of American origin that spread to Eurasia or Oceania, some at surprisingly early dates.
The only plausible explanation for these findings is that a considerable number of transoceanic voyages in both directions across both major oceans were completed between the 7th millennium BC and the European age of discovery. Our growing knowledge of early maritime technology and its accomplishments gives us confidence that vessels and nautical skills capable of these long-distance travels were developed by the times indicated. These voyages put a new complexion on the extensive Old World/New World cultural parallels that have long been controversial.
The Problem
In general, scholars concerned with the ancient culture history of the Americas believe that there were no significant connections by voyaging between the Old World and the New World before 1492. To the contrary, our data from an extensive literature that hitherto has been inadequately searched demonstrate that fauna and flora were extensively shared between the Old and New Worlds before Columbus' discovery of the Americas. The only plausible explanation for this bi-hemispheric distribution is that those shared organisms moved across the oceans via intentional voyages that took place during the eight millennia or more immediately preceding Columbus' discoveries. This book presents and documents the evidence for our position. We believe students of the human past are obliged to adopt a new paradigm for the role of long-distance sea communication in history and culture.
In the past, arguments for transoceanic contacts have relied mainly on evidence from cultural parallels (Sorenson and Raish 1996). Some of those parallels are indeed striking, but scholars generally have rejected their value as evidence that significant pre-Columbian contacts took place with the Americas across the oceans (see, e.g., Kroeber 1948, 538-71; Rands and Riley 1958). Over a century ago, Tylor (1896) compared details of the Aztec board game, patolli (e.g., the board's layout, the sequence of moves, and cosmic associations of the pieces and moves), with the game called pachisi in India. Even Robert Lowie, an influential anthropologist who was usually critical of diffusionist (voyage-dependent) explanations for such similarities, accepted that in this case "the concatenation of details puts the parallels far outside any probability [of having been invented independently]" (1951, 13). Still, tentative acceptance by some influential observers, like Lowie, of the possible historical significance of the cultural parallels has always ended up being rebutted by a demand from critics for 'hard,' or 'scientific' evidence for voyaging. Often, the sort of evidence demanded was demonstration that numbers of plants were present on both sides of the oceans before Columbus' day (Kidder et al. 1946, 2).
Data from the life sciences now provide that desired evidence, not only for the flora, but for fauna as well. The largest body of data is on plants. (See Tables 1, 2, and 3, below.) We will also deal with shared infectious organisms as evidence for voyaging (see Tables 4 and 5), as well as some larger animal forms (see Tables 6 and 7).
An example from the history of health-damaging organisms demonstrates our approach while illustrating the power this kind of evidence can provide in the study of human history and prehistory. The hookworm Ancylostoma duodenale causes one of the most widespread human ailments. The long-term prevalence of the hookworm in East and Southeast Asia makes that area the obvious source from which the organism reached the Americas.
A. duodenale was at first assumed to have been introduced by slaves brought from Africa. Early in the 20th century, Fonseca (not fully published until 1970) discovered the parasite in an isolated Amerindian population in the Amazon basin. Shortly afterward, microbiologist Samuel Darling (1920) pointed out that the hookworm apparently had infested South American tropical forest peoples since before Columbus arrived. If a date for the parasite in the Americas before European discovery could be proven, he observed, then the only explanation for the parasite in the New World would have to be that it arrived anciently via infected humans who had crossed the ocean -- "storm-tossed fishermen," he ventured.
His reasoning sprang from facts about the life cycle of this worm. In one stage it must inhabit warm, moist soil (in a climate no colder than that of North Carolina today). At a later stage, the worms from the soil penetrate a human host's body and settle in the digestive tract. Immigrants who came to the New World in slow stages via Beringia would have arrived hookworm-free because the cold ambient conditions would have killed the parasite in the soil (Soper 1927; Ferreira et al. 1988).
The hookworm's pre-Columbian presence in the Americas was established authoritatively by Allison et al. (1973), who found traces of the pest in a Peruvian mummy dated about AD 900. Evidence from other mummies and human coprolites has since repeatedly confirmed the initial find (Araújo 1988; Reinhard 1992). In 1988, Brazilian scientists identified this parasite from remains excavated in eastern Brazil. A series of radiocarbon dates fixed the age at about 7,200 years ago. Given the inland remoteness of the site, the organism's arrival on the coast of the continent must have occurred centuries earlier.
Can these findings be said to establish conclusively that early human voyagers crossed the ocean to the Americas? Is there some explanation for the presence of the worm in the New World due to natural forces, independent of human beings? Absolutely not. There is no alternative explanation. Modern microbiologists continue to assure us that Darling's assessment was correct. Ferreira, Araújo, and Confalonieri (1982) say, "Transpacific migrants from Asia by sea must be one component of the ancient American population." Fonseca (1970) asserts, "shared species of parasite ... make it inescapable that voyagers reached South America directly from Oceania or Southeast Asia." Ferreira and colleagues (1988) agree: "We must suppose that [the human hosts for the parasite] arrived by sea." Araújo (1988) confirms, "The evidence points only to maritime contacts" (emphases added).
This kind of fact, or secure inference, is vital in our present study. First, since A. duodenale could have arrived in the Americas only in the bodies of (presumably) Asians who came by sea, we can be certain that elements of some particular culture, as well as a set of Asian genes, arrived with them. Second, vessels capable of crossing or skirting the Pacific were already in use by the 6th millennium BC, and at least one of those craft actually reached South America, where its occupants passed the hookworm on to subsequent inhabitants.
A second species, Necator americanus, also called 'hookworm,' has been found in Brazil in prehistoric human remains of the same age (Ferreira et al. 1980, 65-7). Its reproductive cycle is similar to that of A. duodenale. Presence of this second organism confirms the fact that millennia ago nautical technology that would allow successful voyages across or around the Pacific existed in Asian waters.
Subsequently, archaeologists and paleo-pathologists have found decisive evidence in the Americas for the presence of 18 other infectious organisms from the Old World (see Table 4). Most of them could not have come with early Bering Strait migrants, and the others very likely did not. They include additional parasites, bacteria, viruses, fungi, and other micro-predators. Beyond the primary 20, there is enough evidence of transfer across the ocean of another 18 disease-causing organisms to call for further research on their pre-Columbian distribution.
The zoological literature also identifies six animal forms (see Table 6) documented as present in both hemispheres, and possibly 6 more (see Table 7).
The volume of evidence about plants obviously greatly exceeds that on fauna. We will first present salient data on the former, after a short methodological orientation.
Organisms, whether plant or animal, have special significance for the history of long-distance human movements. Biologists believe that a given species arises only once in the course of evolution because any new species develops within a unique set of environmental parameters that is found in only a single geographical location (see Zohary 1996, 156; for changes in thought on this topic, see Blumler 1992; 1996). Plant geographer N. Polunin (1960) stated the governing principle very clearly: "The chances that two isolated populations will evolve in exactly the same way are incalculably low," since, as Wulff (1943, 56) put it, "no two localities on earth are exactly alike in all ... physico-geographical conditions" governing the evolutionary process. Stephen Gould (1994, 3) echoed the thought: "I regard each species as a contingent item of history .... [A] species will arise in a single place [and time] ...."
When the same species is found to have lived before Columbus in the New World as well as an ocean apart in Oceania, Asia, Europe, or Africa, that departure from the norm demands rational explanation. One might hurriedly conclude that certain seeds moved inter-continentally by the actions of winds or waves; however, few seeds are equipped to survive long while floating or to move great distances via wind (and no disease organism spreads in such a way). The odds for successful natural transport of plants are so slim (Guppy 1906, following De Candolle; Fosberg 1951) that anyone who claims a passive, natural mode of transport is obliged to demonstrate the possibility in the immediate case rather than merely to assume or assert it. By the same token, the explanation that humans transported some plant overseas requires empirical and logical support.
The Plant Evidence
Table 1 lists 98 plant species for which there is what we consider decisive evidence that the organism was present in both Eastern and Western Hemispheres before Columbus' first voyage. Table 2 gives 19 more species for which the evidence is significant, though less than decisive, and Table 3 adds 18 more species that deserve further research to determine their possible bi-hemispheric presence.
What do we consider decisive evidence? It can come from the discovery through archaeology of actual plant remains -- macrofossils, pollen, phytoliths, DNA -- manifesting the presence before AD 1492 of a particular species in the hemisphere where, according to botanists, it did not originate. A second source of evidence is historical documents -- references to or descriptions of plants in ancient texts, explorers' reports, or lexicons of appropriate date that show knowledge of the species in the hemisphere where it did not originate. Detailed representations of plants in ancient art can be determinative also. Conclusive information may also come through well-informed inferences by botanists, based on such data as where a plant's relatives and possible wild ancestor grew (Zohary and Hopf 1993, chap. 1).