Modern scientific theory states that the human occupation of the American continents began around 12,000 years ago with the crossing of the northern land bridge of Beringia. Humans then moved south, filling North America with a culture referred to as Clovis, and then into South America. Although this model is commonly accepted, do the South American Paleo-Indian cultures represent a natural extension of the Clovis culture or do they represent a completely separate cultural complex?
It is commonly accepted that the New World was colonized rapidly (Anderson and Gillam 2000), but exactly how and why are still being debated. One theory makes the assumption that as hunter-gatherer bands grew in population, they split and the new group formed its territory adjacent to the original group. This sets up a chain of roughly circular territories that stretch throughout the continents. Using this “string-of-pearls movement scenario…[it] would have required 30 territories or ‘pearls’ to span North America, with another 24 required to reach the southern cone of South America” (Anderson and Gillam 2000:57). At that rate, it would have taken four to five thousand years to fill both continents, which Anderson and Gillam state as being much too long to fit the current archaeological data.
The next theory takes the accepted timeline into account as well as the scattered nature of Paleo-Indian sites. It is called the “frog-leaping” pattern and suggests that when hunter-gatherer bands split, the new group would move to a distant location instead of residing nearby. When looking at the archeological record in North America, the heavily clustered, but widely separated, locations of Clovis artifacts lends some credibility to the frog-leaping theory. There are, however, still those who are not convinced.
Moore and Moseley believe that the small numbers that Anderson and Gillam used in their population models cannot constitute a viable breeding pool for the colonization of two entire continents. The two major problems they identify as limited population expansion are incest taboos and sex ratio at birth (Moore and Mosely 2001). Within small populations, there is an increased chance that individuals are closely related to one another and unless the incest taboo developed recently in human cultures, which is not supported by anthropological studies, there would be a limited number of potential mates for any particular individual. Also, there is the possibility that the children born in a small community might all be of the same sex.
Using a mathematical model, they ran a simulation that “does not permit marriage between siblings, between child and parent or parents’ siblings, between child and grandparents, or between first cousins, but allows women to marry polygynously” (Moore and Mosely 2001:527). Even though they ran the simulation with different numbers of starting populations, in every case they lasted less than one thousand years. The largest determining factor was the number of males in each generation – the more males born, the shorter the population as a whole survived.
This being the case, Moore and Mosely are convinced that the frog-leaping model, which puts groups in relative mating isolation, is incorrect. In order for a population to survive, it must have contact with nearby groups to exchange mates, and thus they support the string-of-pearls method in spite of its shortcomings.
Anderson and Gillam responded with a very interesting observation: “The fact that isolated band-sized groups of 25 people could go extinct within a comparatively short time…may help explain why pre-Clovis archaeological remains are so uncommon in the New World – small numbers of people may have been present much earlier then traditionally thought, but prior to much before ca. 13,500 cal. B.P. most or all probably died out, representing ‘failed’ migrations, and hence leaving the spotty, varied, and somewhat ambiguous archaeological record that characterizes the pre-Clovis era” (Anderson and Gillam 2001:531). They also have a greater faith in the ability of human culture to overcome environmental challenges that widely separated communities might be faced with (Anderson and Gillam 2001:532).
But what would happen if humans were faced with barriers that culture could not overcome? The environments of North America are very different from those found in Central and South America. Could the human body adapt as quickly to the new environs as the current colonization models suggest? It is clear from the archaeological record that the Clovis culture was not only widely spread across North America, but also highly mobile due to the spread of raw lithic material from specific regions across the continent. But in South America, the Clovis tradition is conspicuously absent. One theory to explain this is called the “Disease Barrier Hypothesis” (Waguespack 2002).
Although the environment of Central and South America have changed over the past 13,000 years, archeological reconstruction “indicate that tropical rainforests extended across the northern portion of South America during the period of human colonization” (Waguespack 2002:230). While North America had its share of diseases, tropical regions generally have a higher concentration of pathogens and would have to be crossed in order for the colonization of South America to take place.
Highly mobile hunter-gatherer populations are more likely to encounter detrimental pathogens and, as they travel, spread that pathogen to others – especially if the populations are large enough to support frequent contact. However, we know from the historic record that diseases such as smallpox could not have had such a devastating effect on indigenous cultures if it wasn’t for the increase in population and decrease in mobility, therefore, “for pathogens to truly present a colonization barrier population growth and mobility must be significantly reduced from previously inhabited, less disease prone, originating environments” (Waguespack 2002:234). Whether or not the tropical zones created such a barrier is difficult to determine. The presence of modern pathogens does not automatically suggest a limiting factor to ancient colonization, but it does provide a plausible excuse for the lack of Clovis artifacts in South America.
As an alternative to travel through the tropics by land, evidence of early marine resource use in South America may imply the use of coastal/marine travel to bypass the tropical environments. Excavations at Quebrada Jaguay in southern Peru show that marine resources were being used around 11,000 – 13,000 YBP (Sandweiss 1998). This in conjunction with sites along the Pacific coast in North America, suggest “that some early inhabitants of the Americas migrated along the Pacific coasts of North and South America, separately from those who moved through the interior” (Sandweiss 1998:1832). Certainly by 10,000 years ago, the coastal regions of South America were colonized and heavily used for resources, as opposed to earlier where Sandweiss suggests that the human occupation might have happened only in seasonal rounds – living part of the time in the highlands and part of the time on the coast.
Within the tropical regions of South America, there is evidence for human occupation that is quite distinct from the northern Clovis culture. Sites in the Amazonian basin have been identified as possible Paleo-Indian artifacts that are contemporary with Clovis but fit neither a Clovis nor a pre-Clovis theory. Bifacial stone points have been found near Monte Alegre, although the dates for such finds are hotly debated. Roosevelt et al. (1996) contend that the Caverna da Pedra Pintada site near Monte Alegre are indeed of a Paleo-Indian age instead of from a later time as others argue (Haynes, Reanier, and Barse 1997). The debate continues as the implications of sites such as these may ultimately determine the longevity of the Clovis First hypothesis.
Discussion
For the Clovis culture to have colonized both American continents, they would have had to been highly mobile and have a high fertility rate. Todd Surovell (2000) looked at whether those two factors are incompatible. He looks at two types of groups. One he calls “high residential foragers” who move their base camp frequently, maximizing “the distances walked annually while moving base camps, but minimizes daily foraging distances” (Surovell 2000:498-499). The other type is “low residential foragers” who “move base camps infrequently, thus minimizing residential mobility and maximizing foraging distances. This strategy instead emphasizes moving food to people” (Surovell 2000:499).
At first it seems that high mobility and high fertility are at odds with each other. However, Surovell’s study shows that less distance is spent moving the base camp more frequently, since less distance is traveled on a daily basis. Therefore, groups that have a more mobile base camp can afford to spend more energy on childcare. This becomes more interesting when compared to modern hunter-gatherer in tropical locales. Those groups that “move most frequently (Ache, Hill Pandaram, and Hadza) are also characterized by the highest levels of fertility” (Surovell 2000:504).
Using this strategy, Surovell suggests that Paleo-Indian cultures could have traveled long distances, accessed the valuable lithic raw materials, and still have contact with neighboring groups for mate exchange. As these bands reached the tropics, they would have tried to retain their highly mobile and highly fertile lifestyle. Diseases reduced mobility and contact between groups spread the pathogens; those that survived then spread out into the South American continent. If this scenario took place in pre-Clovis times, perhaps those diseases were what reduced those populations and allowed for the spread of Clovis in the north while limiting it in the south.
The evidences to support or refute the connection between South American Paleo-Indian cultures and the Clovis culture of North America are not accepted by all parts of the community of archaeologists. All that can be safely said is that Clovis spread throughout North America by any number of means, and that the cultural remains stopped in the northern part of Central America. The result is that there are two areas that are separate and distinct from each other. As Jared Diamond first wrote in his book The Third Chimpanzee (1992) and later expanded upon in Guns, Germs, and Steel (1997), the New World lay in a north-south orientation with the tropics dividing it into two halves – something not seen in the Old World which lay on an east-west axis. While not commenting upon the relations between the two cultural complexes, he believes that the tropics produced a barrier (but perhaps not necessarily a disease barrier) to the movement of people and, more importantly, to the movement of plants and animals.
Llamas, alpacas, guinea pigs, and potatoes never spread into Northern America and even “many crops that were apparently shared prehistorically between North and South America [cotton, beans, lima beans, chili peppers, and tobacco] actually occurred as different varieties or even species in the two continents, suggesting that they were domesticated independently in both areas” (Diamond 1992:246). With such variation in flora and fauna, it should come as no surprise that human cultures that may or may not be in existence at the same time, have just as much variety regardless of common heritage.
Conclusion
With the current level of knowledge and archaeological sites, it is impossible to determine the exact nature of the South American Paleo-Indians. Changes in environment, geography, and human behavior place obstructions to recreating an accurate picture of human migration patterns. While the northern temperate plains show a relatively simple picture, the tropical zone creates a barrier of sorts and it is perhaps a moot point on whether or not Clovis peoples struggled their way through. Whether on foot or by boat, if some did get through they were, perhaps, so depopulated and isolated from those in the north that they would be, in essence, in a completely new New World and would be starting a new migration point from which to colonize it.
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