Rafting: A Post-Flood Biogeographic Dispersal Mechanism

Although biogeography has contributed important data to the debate on biological origins for centuries, global biogeographic models have had poor success at explaining biogeographic data. Heretofore, the best models (evolutionary biogeography models) have neither successfully explained the multi-taxon concurrence of trans-oceanic range disjunctions nor why areas of endemism exist where they do. Here a creationist dispersal mechanism is suggested. It is proposed that plants and animals rafted across oceans on and among masses of logs, plant debris, and vegetation mats in the immediate post-Flood world. United with post-Flood models of geology, climatology, and biology, a uniquely young-age creationist model of biogeography is generated which seems to explain not only the data explained by the best evolutionary models, but also data which such models fail to explain. Also introduced are eighteen biogeographic tests of the model. HISTORY OF BIOGEOGRAPHY Biogeography has contributed important data to the debate on biological origins for at least five centuries. A brief history of those debates is included here to familiarize the reader with the relevant discussions and data. The categories of biogeographic data and their relationship to historically important biogeographic theories are summarized in Table 1. Fixity/Dispersal Model Before the discovery of the New World, most western thinkers believed that biological organisms were unchanging and generated by a non-physical intelligence (usually either the Greek logos and/or the Christian God). With the Renaissance, the Western world returned (for a time) to accepting the Bible literally. As this happened, a global flood came to be taken seriously [6 pp. 2-3, 12]. Many believed that the land organisms got to their present positions by dispersing from the mountains of Ararat where the ark landed. By rejecting a global Flood, Carl Linnaeus (1707-1778) advocated a variation on this model [6 pp 18-20]. He maintained God created all the organisms on a single mountain in a global ocean, and as sea level dropped the organisms migrated to their present locations. Unchanging species dispersing from a single point of origin can be called a ‘fixity/dispersal model’ of biogeography. One of the earliest biogeographic observations – environmental specificity of species (Row 1 in Table 1) – is explained in this model by species dispersing to the environments for which they are best designed. Given the continuity of the known land masses and the limited number of known species, the fixity/dispersal model was not challenged by pre-Columbian biogeographic knowledge. Although the fixity/dispersal model was held by many into the 18 Century (e.g., Linnaeus), 16 and 17 Century explorations of the New World produced substantial challenges to this model. Since only one set of organisms dispersed from only one location, a simple fixity/dispersal model would predict that similar environments in different locations should be inhabited by the same creatures. As early as 1500, however, Amerigo Vespucci noted differences in primates between the Old and the New Worlds [13]. Further explorations – especially in tropical regions of Africa and South America – revealed similar environments on opposite sides of the Atlantic were populated by very different creatures (Row 2 in Table 1) [13]. As more and more species were discovered, there was attendant concern that all the species could not fit onto the ark [6 pp 8-9, 16-18]. As more and more distant lands and islands were discovered, there was further concern that many of the organisms could not traverse the great distances to their present locations [6 p 23] (without, for example, passing through environments in which they couldn’t survive) (Row 3 in Table 1). In 1589, for example, José da Acosta struggled with these issues as he considered South American species [13]. He wondered how the animals could fit on the ark. He discussed but rejected humans transporting the species, organisms swimming the separating oceans, and the post-Flood creation of species. In the end he