quaternary Review Human Discovery and Settlement of the Remote Easter Island (SE Pacific) Valentí Rull Laboratory of Paleoecology, Institute of Earth Sciences Jaume Almera (ICTJA-CSIC), C. Solé i Sabarís s/n, 08028 Barcelona, Spain; [email protected] Received: 19 March 2019; Accepted: 27 March 2019; Published: 2 April 2019 Abstract: The discovery and settlement of the tiny and remote Easter Island (Rapa Nui) has been a classical controversy for decades. Present-day aboriginal people and their culture are undoubtedly of Polynesian origin, but it has been debated whether Native Americans discovered the island before the Polynesian settlement. Until recently, the paradigm was that Easter Island was discovered and settled just once by Polynesians in their millennial-scale eastward migration across the Pacific. However, the evidence for cultivation and consumption of an American plant—the sweet potato (Ipomoea batatas)—on the island before the European contact (1722 CE), even prior to the Europe-America contact (1492 CE), revived controversy. This paper reviews the classical archaeological, ethnological and paleoecological literature on the subject and summarizes the information into four main hypotheses to explain the sweet potato enigma: the long-distance dispersal hypothesis, the back-and-forth hypothesis, the Heyerdahl hypothesis, and the newcomers hypothesis. These hypotheses are evaluated in light of the more recent evidence (last decade), including molecular DNA phylogeny and phylogeography of humans and associated plants and animals, physical anthropology (craniometry and dietary analysis), and new paleoecological findings. It is concluded that, with the available evidence, none of the former hypotheses may be rejected and, therefore, all possibilities remain open. For future work, it is recommended to use the multiple working hypotheses framework and the strong inference method of hypothesis testing, rather than the ruling theory approach, very common in Easter Island research. Keywords: islands; discovery; settlement; colonization; Easter Island; Rapa Nui; Pacific Ocean; Polynesians; Native Americans 1. Introduction Due to their remoteness and physical isolation, oceanic islands are particularly well suited to study discovery and settlement processes [1]. Easter Island, located in the South Pacific, has been included among the most remote inhabited places on Earth (Figure1). This, together with its more or less intermediate position between the Polynesian Pacific archipelagos and the South American continent, of contrasting cultural traits, has fostered the interest on when, how, and by whom this tiny island was discovered and initially settled and whether it has experienced significant cultural turnover since then [2–5]. This paper briefly reviews the classical literature on the subject to present the main hypotheses that have been erected and the archaeological, ethnological, and paleoecological evidence used to test them. The paradigmatic outcomes of these studies are then checked against new multidisciplinary evidence collected during the last decade, including genomics, the results of which have challenged and/or enriched former views. The focus is on the discovery and settlement phases and, eventually, on the occasional occupancy between these two events. Postsettlement cultural developments and their possible drivers have already been reviewed by the author elsewhere [6,7]. Finally, it is recommended Quaternary 2019, 2, 15; doi:10.3390/quat2020015 www.mdpi.com/journal/quaternary Quaternary 2019, 2, 15 2 of 16 Quaternary 2019, 2, x FOR PEER REVIEW 2 of 16 thatFinally, further it is studiesrecommended adopt athat multiple further working studies hypothesesadopt a multiple framework working combined hypotheses with framework the strong inferencecombined method with the of strong hypothesis inference testing method to adequately of hypoth tackleesis thetesting inherent to adequately complexity tackle of the the topic inherent under studycomplexity [8]. of the topic under study [8]. Figure 1.1. GeneralGeneral map of the PacificPacific Ocean with indication of the main archipelagos including those mentioned in the text. Easter Island (EI) is displayed as a red dot and some significantsignificant islands in the context ofof thisthis paperpaper are are highlighted highlighted as as blue blue dots dots (M–Mangareva; (M – Mangareva R–Rapa; R – Iti;Rapa T–Tahiti). Iti; T –The Tahiti). distance The betweendistance between Easter Island Easter and Island some and relevant some islandsrelevant is islands expressed is expressed in km [3]. in km [3]. 2. The Island Today Easter IslandIsland is calledcalled RapaRapa NuiNui byby itsits aboriginalaboriginal inhabitants,inhabitants, thethe Rapanui.Rapanui. The namename EasterEaster Island (Paasch(Paasch Eyland, Eyland, in in Dutch) Dutch) was was coined coined by theby the first first Europeans Europeans who who arrived arrived to the to island, the island, a Dutch a expeditionDutch expedition commanded commanded by Jacob by Roggeveen,Jacob Roggeveen, on Easter on Easter Sunday Sunday (5th April) (5th April) of 1722. of The1722. name The name Rapa NuiRapa (Big Nui Rapa) (Big originatedRapa) originated later in the later 1860s, in andthe was1860s, used and by was the Tahitianused by sailors the Tahitian to differentiate sailors theto islanddifferentiate from a the smaller island one from called a smaller Rapa (nowone called Rapa Rapa Iti, meaning (now Rapa Small Iti, Rapa) meaning (Figure Small1). AccordingRapa) (Figure to the1). According indigenous to tradition, the indigenous the first nametradition, of the the island first wasnam Pito-o-te-Henuae of the island (thewas NavelPito-o of-te the-Henua World (the or theNavel End of of the the World World, or dependingthe End of the on theWorld, source) depending but this on term the issource) rarely but used. this In term Spanish—the is rarely used official. In ChileanSpanish— languagethe official (the Chilean island belongslanguage to (the Chile island since belongs 1888)—the to Chile name since is Isla 1888) de Pascua.—the name Easter is Isla Island de 2 isPascua. very smallEaster (164 Island km is) andvery of small triangular (164 km shape,2) and owing of triangular to the coalescence shape, owing of threeto the volcanic coalescence cones: of Terevakathree volcanic (the highest cones: elevationTerevaka of(the the highest island withelevation 511 m),of the Poike, island and with Kao 511 (Figure m),2 ).Poike The, islandand Kao is ◦ 0 00 ◦ 0 00 located(Figure at2). about The island 27 07 is09 locatedS and at 109 about21 29 27ºW, 07’ more 09” S than and 2000 109º km 21’ apart29” W from, more the than nearest 2000 Polynesian km apart islandsfrom the (Picairn) nearest and Polynesian >3500 km islands far from (Picairn) the South and American >3500 km Pacific far from coasts the (Figure South1 ).American Pacific coasts (Figure 1). Quaternary 2019, 2, 15 3 of 16 Quaternary 2019, 2, x FOR PEER REVIEW 3 of 16 FigureFigure 2. Google Earth view of of Easter Island Island indicating indicating the main features mentioned in the text. ◦ The climate is subtropicalsubtropical oceanic with annual average temperatures of 20 20–21–21 °C and small ◦ seasonal variations (2 (2–3–3 °C). Total annual precipitation is 1200 mm on average, with a moremore humidhumid period between AprilApril andand JuneJune (120–140(120–140 mm/month)mm/month) and a drier phase between NovemberNovember andand January (70–90(70–90 mm/month).mm/month). There There are are no no permanent permanent water water courses courses on on the the island island due to the high porosity of its its volcanic volcanic rocks rocks;; the the only only freshwater freshwater reservoirs reservoirs are are the the ranos ranos,, an an indigenous indigenous name name to todesignate designate a volcanic a volcanic crater crater with with permanent permanent water water inside, inside, in the in form the form of a oflake a lakeor a ormarsh a marsh [9]. The [9]. Thebiggest biggest one is one Rano is Rano Kao, Kao,with witha lake a of lake >1 km of >1 diameter km diameter and ca. and 10 m ca. depth, 10 m followed depth, followed by Rano by Raraku Rano Raraku(300 m diameter (300 m diameter and up to and 3 m up depth) to 3 m and depth) Rano and Aroi, Rano with Aroi, a marsh with of a ca. marsh 150 m of diameter ca. 150 m (Figure diameter 3). (FigureThe3). vegetation is entirely anthropogenic and dominated by grasslands (85–90% of the surface), forestThe and vegetation shrublands is are entirely scare anthropogenic (5% each), and and~1% dominated corresponds by to grasslands crops and (85–90%ruderal vegetation of the surface), [10]. forestThe flora and is shrublands not very rich are scareand most (5% each),species and are ~1% introduced. corresponds Indeed, to crops of the and >200 ruderal species vegetation of vascular [10]. Theplants flora known, is not less very than rich a andquarter most are species autochthonous are introduced. and only Indeed, four ofare the endemic >200 species to the island of vascular [11]. plantsThis situation known, contrasts less than with a quarter palynological are autochthonous reconstructions and onlythat have four aredocumented endemic toan the island island mostly [11]. Thiscovered situation by dense contrasts and extensive with palynological palm-domi reconstructionsnated forests during that have the last documented ~40 kyr BP an [12 island–14]. mostly These coveredforests would by dense have and been extensive totally removed palm-dominated in 1400–1600 forests CE during by