The role of the Panamanian land bridge during the initial colonization of the Americas

Abstract

Since 1999, an on-going survey project inPanamahas succeeded in locating traces of late Pleistocen~arly Holocene hlUllans who colonized the Americas. To date, our investigation has focused on three environ- mental zones found on the Pacific side of the continental divide -the highlands, the interior and the coast. The goal of this project is to link the early ar- chaeological records ofNorth and South America which still remain isolated on many levels. Although some Palaeoamerican Iithic assemblages from North and South America show clear technological similarities, the his- torical, genetic and even chronological relationships between these early populations are still the subjects of debate. Fortunately, the narrowness ofthe Isthmus of Panama and its axiallocation between the conti- nents afford an uncommon advantage for archaeolo- gists trying to understand north-south relationships between the larger land masses. Our main objective was to find stratified occupations containing diagnos- tic tools normally associated with either north or south Palaeoamerican groups and determine how these com- pared, both technologically and chronologically, with their respective homologues on opposite continents. The survey began around Lake La Yeguada, at an elevation of 650 m (FIGURE 1). This area was chosen for study based on the results of pollen cores taken from the lake, which contained large amounts of particulate carbon dating around 11,000 BP and attrib- uted to human disturbance (pipemo et al. 1990; Bush et al. 1992). The survey identified several early sites around the lake's shore as well as 10 quarry/workshops, various Iithic raw material sources and rock-shelters in the immediate area. Diagnostic artefacts included scatters ofbifacial thinning tlake, finished points and broken performs. Next, we located an ancient quarry/workshop in the middle of the Azuero Peninsula. The Nieto site is associated with a large quartz"Vein that juts out of a small hilltop. Both surface collections and excavations were carried out at the quarry (FIGURE 2). O1arcoal sam- ples were not recovered due to the shallowness ofthe deposits and the risk of contamination from on-going slash-and-bum cultivation next to the site. Neverthe- less, Clovis-like point performs (FIGURE 3a) and other diagnostic tools found among the manufacturing de- bris indicate that Palaeoamericans frequently visited this source to procure translucent stone. Finally, we excavated at Cueva de Los Vampiros which is situated on an inselberg, approximately 3 km from the mangrove-lined coast ofParita Bay. The cave appears to be part of a complex of cavities and inter- connecting tunnels that have dug into this isolated geological feature. The site was first discovered 20 years ago during the Proyecto Santa Maria survey (Cooke & Ranere 1984). Although initial test pits did not find any diagnostic artefacts, the discovery ofbifacial thinning flakes associated with a date of 856O:t160 (Beta- 5101) showed promise. New excavations between January and May 2002 have now revealed the existence of a fluted point oc- cupation at the base of its cultural deposits (FIGURES 3b, 4). Thus far, onlya few charcoal samples have been analysed. hútial radiocarbon results from above and immediately below the fluted point assemblage have bracketed this occupation between c. 11,500 and 9ooo BP. It is interesting to note that, although the cave was later used during Precolumbian times as a fish -processing locality, its Pleistocene occupants would have had to wa1k over 80 km to reach the Pacific. Recent discoveries at Cueva de Los Vampiros mark the third ocCUn'ence of diagnostic early Palaeoamerican artefacts found in a buried context between the Rio Grande and Columbia (an area encompassing 2,509,000 sq. km).lndeed, before we initiated this survey project only two localities, the Los Grifos cave in Mexico (Santamaria 1981) and the Los Tapiales site in Guate- mala (Gruhn & Bryan 1977), claimed similar findings. Current research on the Isthmus of Panama is at- tempting to build an information bridge to join the early archaeological records ofNorth and South America. Future excavations at Vampiros cave will help us un- derstand if the Isthmian region acted as a cultural fil- ter, a zone of contact or simply a springboard for rapid cultural diversification. Ultimately, continued inves- tigations into the Pleistocene period ofMiddle America will help provide a Pan-American perspective on the peopling