On the Dispersal of Hominini by Sea-Rafting
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On the Dispersal of Hominini by Sea-Rafting A Non-Thesis—Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Master of Arts with a Major in Anthropology in the College of Graduate Studies University of Idaho by Ann Godoy Piersol Major Professors: Lee Sappington, Ph.D and Don Tyler Ph.D Committee Members: Leslie L. Baker, Ph.D and Laura Putsche, Ph.D May 2016 2 ABSTRACT Floating islands have been accepted as an effective means of dispersal of a large variety of organisms across narrow and wide sea gaps. Here I explore the hypothesis that hominins may also have been conveyed on natural rafts across sea gaps and able to survive long enough to reproduce and establish a population, or add their genetic signature to already established inhabitants of the site upon which they disembark. A review of the colonization of several locations; South America by platyrrhine monkeys and caviomorph rodents, Sulawesi by the macaques and tarsiers monkeys, and Flores by Homo floresiensis, and the wide distribution of bottle gourds, reveals evidence that water barriers existed suggesting rafting as a mode of conveyance. Rafting substrata is composed of almost any material, including wide sections of coastlines and pumice rafts, typically a byproduct of natural disasters, and can be large enough to convey and sustain rafters across sea gaps, carried by wind and sea current to near or distant landforms. Throughout history there have been many reports of people rescued adrift at sea, demonstrating that as a species we are resourceful and will survive or adapt to any environment. The investigation of cranial morphology and genetic variation of initial populations of the Americas demonstrate that South American Paleocene remains are more similar to extant Australian, Melanesian, and Sub-Sahara populations, this variation is absent in North American remains. And finally, higher amount of Denisovan DNA is found primarily in Oceanic populations but missing from Eurasians suggesting possible rafting situations. All evidence supports the plausibility that rafting events have contributed to variation in the genetic mix of peoples around the world. 3 Acknowledgments I am indebted to Lee Sappington, Don Tyler, Leslie Baker, and Laura Putsche for their support and encouragement throughout this adventure. Special thanks to Don Tyler for his role in planting the seed that led to my thesis. My thanks to all for their reviews and comments which significantly helped to improve this paper. I would also like to thank Linda Robison for her friendship, encouragement and review during this process. 4 Dedication To my children Benjamin, Keith, and Sara, my life, my reason for being, and to Mark William Piersol, the love that completes my life and my happily ever after 5 Table of Contents Abstract 2 Acknowledgement 3 Dedication 4 Table of Contents 5 Introduction 6 Colonization Across Sea Gaps 7 Hominin Colonize Flores 12 Rafting Substrata 16 Oral Tradition of the Maori People of New Zealand 24 Pumice Colonization by Vegetation and Arthropods 26 Current, Wind and Glaciers 27 Drifting Scenarios 31 Human Specific Parasites 33 Survival at Sea 34 The Archaeological Record of the New World 38 Cranial Morphology and Genetic Variation 45 Summary 46 Conclusion 48 References 51 Figures Floating Pumice from the submarine eruption in 2012 of the Havre Caldera 1 in the Pacific Ocean 20 2 Global Tectonic and Volcanic Activity of the Last One Million Years 23 3 Volcanic Explosivity Index 24 Appendix A Archaeological sites of North and South America discussed in this paper 50 and vessel drift crossing times in days as discussed by Montenegro et al. (2005) 6 INTRODUCTION For decades scientists have been engaged in debate over the peopling of many isolated locations, for example, North and South America and the island of Flores in Indonesia. The findings of research conducted in regions of South America demonstrate that the genetic data and cranial morphology of the earliest South Americans are more similar to Australians, Melanesians, and Sub-Saharan Africans of today, than to Eurasians and Native Americans (Menendez et al. 2015; Neves and Hubbe 2005; Skoglund et al. 2015). By 880,000 years before present (BP) there is evidence of hominin occupation of Flores and in order for this island to be reached a wide sea gap had to be crossed (Morwood et al. 1998). Many varieties of fauna and flora are and have been transported across water for short or extended distances by rafting (Bauer and Schreiber 1996; Bond et al. 2015; Bryan et al. 2004 and 2012; Bryan et al. 2012; Fraser et al. 2011; Houle 1998; Metcalfe et al. 2001, 409-416; Poux et al. 2006). The term “rafting” is an expression used to describe the dispersal of land organisms across water on floating objects, a term coined by Alfred Russell Wallace in the early nineteenth century (Houle 1999; Wallace 1998). Rafting has also been used to explain the colonization by organisms in locations separated by water from their place of origin. Examples are the New World monkeys and caviomorph rodents of South America with proposed origins in Africa, and the macaques and tarsiers of Sulawesi with proposed origins in Southeast Asia (Smith 2001). The purpose of this paper is to explore the hypothesis that hominins may have sporadically been carried away from shore, clinging to debris created by natural disasters, and conveyed across sea gaps surviving long enough to reproduce. Occupation of riverine and coastal environments by hominins is well documented in the archaeological record. These inhabitants exist in an environment prone to natural disasters that can create rafts upon which people may be swept out 7 to sea and set adrift. My investigation includes an overview of the archaeological record of the New World genetic data and cranial morphology of early Americans and Melanesians. Also discussed in this paper are the different types of natural rafting media, the survival possibilities of primates for long distance trans-oceanic transport, and global tectonic and volcanic activity. COLONIZATION ACROSS SEA GAPS New World monkey fossils, with a presumed African palaeogene ancestry, are found in South America with an approximate entrance during the Late Eocene. The accepted hypothesis for the appearance of Platyrrhini, the New World monkey in South America, is by rafting (Bauer and Schreiber 1996; Bond 2015; Houle 1999; Poux et al. 2006). The paleontological evidence suggests that Africa is the most likely continent of origin (Takai et al. 2000). However, South America and Africa have been separated since the late Cretaceous, approximately 90 to 100 million years ago (Mya), leaving South America an island continent until its reconnection with North America in the Pliocene 3 to 3.5 Mya (Bond et al. 2015; Bauer and Schreiber 1996; de Queiroz 2014; Poux, et al. 2006). Platyrrhini is the formal name for New World monkeys that are distinct from other living monkeys. The distinguishing characteristics, thought to be primitive retentions in New World monkeys when compared to monkeys and apes of Africa and Asia, are three premolar teeth instead of two and ear canals that are not enclosed in complete bony tubes (Rosenberg and Hartwig 2001). The earliest known New World monkey arrival, Perupithecus ucayaliensis, found in Amazonian Peru resembles an Eocene African anthropoid Talahpithecus which existed approximately 38 to 39 million years ago (Bond et al. 2015; Bauer and Schreiber 1996). Talahpithecus, found in Dur At-Talah in central Libya, is among the oldest African anthropoids found in three late middle Eocene sites of Libya, Algeria, and Egypt (Chaimanee et al. 2012). Bond et al. (2015) suggest that 8 the Perupithecus may be members of a pre-platyrrhine anthropoid stock that differentiated in Africa from anthropoid ancestors and that Talahpithecus may be an early representative of their radiation. An estimated timeframe for the divergence between catarrhini and platyrrhini is said to have occurred some 41 Mya in Africa, or possibly Asia (de Queiroz 2014). This scenario suggests a trans-Atlantic dispersal of primates by approximately 40 Mya (de Queiroz 2014; Houle 1999; Poux et al. 2006). Several hypotheses have surfaced that attempt to explain a transatlantic migration of New World monkeys and rodents. One of these, the Gondwanan vicariance model, which refers to the break-up of the supercontinent Gondwana and propose a vicariance-mediated diversification via continental drift, the ocean becoming the physical barrier to gene flow, is problematic because approximately 2600 km separated South America from Africa since well after the breakup of Gondwana and before the earliest fossil record of primates discovered in Amazonian Peru (de Queiroz 2014; Bondoni de Oliveira et al. 2009). Other scenarios include the island hopping model, a “mode of dispersal in which organisms migrate across large water bodies through sets of islands,” and the land bridge model, a “mode of dispersal in which two land masses were connected in the past, but not anymore” (Bondoni de Oliveira et al. 2009:57). Bondoni de Oliveira et al. (2009) reconstructed the position of the African and South American continents between 20 and 50 Mya to evaluate the paleogeography of the region during the period of possible crossing of caviomorphs and platyrrhines. They modeled three factors, horizontal plate motion, thermal subsidence of the oceanic lithosphere, and global sea level fluctuations during the Cenozoic, at 20, 30, 40, and 50 Mya, in order to reconstruct a tenable scenario that would support an overseas migration to South America. De Oleveira et al. (2009) report that based on their study, there is no complete connection between South America and Africa at 50 Mya, negating the land bridge model. They state that the 9 shortest distance between Africa and South America, in a straight line at 50 Mya was 1,000 km found between Sierra Leone and Paraiba state, in Brazil.