Online chapter

Las sociedades originarias
(The Indigenous Societies)

Director
Teresa Rojas Rabiela (Mexico)

Codirector
John V. Murra (United States of America)

Chapter 2: The Original Peopling of Latin America
Alan L. Bryan

Introduction

The distant ancestors of the first people who entered Latin America originated in Northeast Asia, traversed what is now known as Beringia (the region including extreme eastern Siberia, Alaska and Yukon) before moving through western Canada and the United States. Most likely, these earliest Americans entered what is now Alaska by traversing a land bridge now submerged under the Bering Sea, although they could have crossed short bodies of water with simple watercraft, or on winter ice. The land bridge appeared whenever the world-wide sea level was lowered 48 meters by the retention of precipitation on land in the form of glacial ice that accumulated in polar and mountainous regions of the world. At its maximum extent, when sea level lowered about l00 m below present, the Bering Land Bridge extended from Cape Navarin south of the mouth of the Anadyr River in western Siberia, south-westward to skirt the Pribilof islands and reached mainland Alaska near the tip of the Alaska Peninsula south of the mouth of the Yukon River. At such times the bridge extended northward about 500 km beyond the Bering Straits. Despite the cold temperatures, the climate north of the southern coast of the land bridge was arid and continental, so glaciers accumulated only on the high mountain ranges of Siberia, Alaska, and Yukon.

Whenever the land bridge existed the south shore remained mild relative to the interior because Arctic ocean currents were cut off. During the maximum glacial advance of the Last Glacial, between about 25,000 and 15,000 years ago, the shores of the Gulf of Alaska and the west coast of British Columbia as far south as Puget Sound in Washington State were covered with glaciers because of heavy snow precipitation in the adjacent mountains. During that time glaciers covered essentially all of Canada, except most of the Yukon, which like the rest of Beringia, remained too arid for accumulation of glacial ice. However, between about 50,000 and 35,000 B. P. (before present) the climate was much as it is now. This warm interval within the Last Glacial is called an interstadial.

Except during the glacial maximum, an ice-free corridor existed in the precipitation shadow east of the Rocky Mountains in the Mackenzie River Valley and Alberta. Before about 25,000 B. P., the corridor was open between the Laurentide glacial sheet centred over Hudson Bay and the Cordilleran ice, but closed for some time between then and about 18,000 B. P., after which time the presence of proglacial lakes and strong winds continued to impede habitation by large mammals until after about 12,000 B. P.

Despite these impediments, the ice free corridor continues to be the most popular route assumed to have been traversed by early Americans moving between Beringia and sub-glacial America. These earliest people are assumed to have been pedestrian hunters who pursued large herbivores onto the Great Plains of the central United States. The major basis for this assumption is because the earliest generally recognized cultural manifestation in North America is the Clovis technology, easily recognized by highly sophisticated fluted projectile points used to kill mammoth and bison between 11,200 and 10,900 B. P. (Haynes l980; Haynes, et al. l984). The model that the earliest Americans were specialized big game hunters with a specialised Upper Paleolithic-like technology has been developing ever since l927, when fluted points were confirmed to be in definite association with extinct bison at the Folsom site in New Mexico. Subsequent excavations at a dozen sites on the Great Plains and in south-eastern Arizona confirmed the presence of Clovis fluted projectile points which evidently had been used to dispatch mammoths.

The Great Plains has long been a vast grassland ecosystem which continued to support herds of grazing herbivores since the Last Pleistocene. Consequently, prehistoric occupants of the Plains have always emphasized hunting large herbivores as an economic base. Several sites containing fluted points have been found east of the Mississippi River dated between 11,000 and 10,500 B. P. Fluted point sites have also been dated to the same time range north of the Plains in north-eastern British Columbia, in arid central Washington State, and at a high altitude site in Guatemala; but these sites have not yielded extinct fauna, so we do not know what animals they may have hunted. Nevertheless, the model has gained popularity that Upper Palaeolithic big game hunters from Siberia and ultimately from Europe were the first Americans who later moved through the ice-free corridor onto the Great Plains, where they developed their distinctive Clovis technology, and then rapidly expanded in all directions to populate the entire New World within a few centuries.

There are now major problems with this model. The Clovis sites are not the earliest dated in the New World, and the Clovis complex was not distributed in vast areas of the Americas. As we shall see, the evidence of Pleistocene sites in South America is causing archaeologists to change their views.

In its full flower the model is based on two postulates and several assumptions, not all of which have been stated by the advocates (especially West l98l; Fagan l987, l990; Lynch l983, l990). The basic postulates are (l) the rapid and complete replacement of all primitive (non Homo sapiens Sapiens populations) in the Old World, including Neanderthal, by anatomically modern man with an advanced (Upper Palaeolithic) technology between about 40,000 and 35,000 years ago; and (2) the requirement of an advanced Upper Palaeolithic technology in order for human populations to inhabit the cold Arctic and sub-Arctic regions of Siberia and Beringia. Assumptions include:

(l) that people with a hunting/gathering economy can completely replace other hunters and gatherers who have built up and long maintained a body of intimate knowledge of their environment in order to sustain an effective adaptation to their ecosystem;

(2) that the earliest sites in Siberia were occupied by fully modern Homo Sapiens Sapiens who had developed a standardized Upper Palaeolithic technology which included the use of advanced hunting weapons, tailored skin clothing, and artificial shelters in European Russia, and then migrated eastward to inhabit Siberia;

(3) that Siberian hunters with an advanced technology crossed the Bering Land Bridge about 15,000 B. P. before it submerged, and traversed the ice free corridor as soon as it became habitable, perhaps by 14,000 B. P. These specialized big game hunters soon developed Clovis technology either in Alaska or south of the continental glaciers, and after about 11,500 B.P. they expanded rapidly in all directions to populate the rest of the New World;

(4) that there was a universal stage when people emphasized big game hunting throughout Eurasia as well as the Americas; in other words, that an economy emphasizing big game hunting and a technology including bifacially flaked stone projectile points were part of the earliest adaptations people made to all regions of the New World, including Central and South America;

(5) that it is highly unlikely if not impossible for hunters and gatherers with a Middle Palaeolithic level of technology independently to develop bifacially flaked stone projectile points as part of economic adaptations to local ecosystems that present the opportunity to hunt herd mammals with predictable habits.

(6) that human groups who had adapted to hunting mammoths on the Great Plains of central North America as early as 11,200 years ago were able to adapt to the many disparate intervening ecological zones, including deserts and tropical forests in Mexico, Central America, and South America; and to already be well adapted to southern Patagonia near the Straits of Magellan within two centuries.