Bp J

11,000 - 8600 BP-S600 - 7000 BP -7000 - 5-000 BP -5000 - 3000 BP -3000 - 500 BP -350 BP-

DECIDUOUS FOREST SEMi-EVERGREEN EVERGREEN EVERGREEN OLD CLEARING

Figure 7.2. The frequencies of early successional phytoliths and burnt successional and arboreal phytoliths in modern tropical forests and through time at Lake La Yeguada. The data profiles from the Late Pleistocene period at El Valle, where human disturbance was not detected, are also displayed for comparison. At c. 12.9 kcal. yr bp at La Yeguada, charcoal levels also increase by several orders of magnitude, and pollen and phytoliths from grasses and other invasive taxa increase substantially. Reprinted from Piperno and Pearsall (1998, fig. 4.4). Description of modern vegetation in the figure:

DECIDUOUS FOREST SEMi-EVERGREEN EVERGREEN EVERGREEN OLD CLEARING

FIELD

Figure 7.2. The frequencies of early successional phytoliths and burnt successional and arboreal phytoliths in modern tropical forests and through time at Lake La Yeguada. The data profiles from the Late Pleistocene period at El Valle, where human disturbance was not detected, are also displayed for comparison. At c. 12.9 kcal. yr bp at La Yeguada, charcoal levels also increase by several orders of magnitude, and pollen and phytoliths from grasses and other invasive taxa increase substantially. Reprinted from Piperno and Pearsall (1998, fig. 4.4). Description of modern vegetation in the figure:

Evergreen forests are from El Cope, Panama (hatched symbol) and north of Manaus, Brazil (black symbol). Semievergreen forest is Barro Colorado, Panama. Deciduous forest is Guanacaste Province, Costa Rica. Old clearing (cleared from forest and planted with banana 50 years ago) is from Guancaste, Costa Rica. Fields are present day slash and burn agricultural plots from Panama planted in manioc and maize. Phytolith frequencies for each modern site are averages from a series of soil transects or "pinch samples" taken from the upper soil surface at the sites (see Piperno, 1988 for details). Circa 23.9-12.9 kcal. yr bp records are from El Valle and La Yeguada. Circa 12.9-0.35 kcal. yr bp records are from La Yeguada. + = Observed at a frequency of less than 1%.

Piperno et al., 2000 a, b; Pope et al., 2001; Mora and Gnecco, 2003; Pearsall et al., 2003, 2004; Piperno and Stothert, 2003; Dickau, 2005; Piperno, in press a and b).

Interestingly, joining the evidence from archeology, molecular biology, and botany also tells us that most important lowland crops in both Central and South

America were originally brought under cultivation and domesticated in the seasonal tropical forest (e.g., Piperno and Pearsall, 1998; Olsen and Schaal, 1999; Matsuoka et al., 2002; Sanjur et al., 2002; Westengen et al., 2005; Piperno, in press a). Figure 7.3 provides a guide to the geography of origins for various crops and shows the locations of archeological sites with early—c. 11.4-5.7 kcal. yr bp (10-5k14CyrBP) —remains of domesticated plants. Particularly important were regions such as the Balsas River Valley, southwestern Mexico (domesticated there were maize and quite possibly the lowland Mesoamerican squash Cucurbita argyrosperma, the cushaw and silver-seeded squashes); the Cauca and Magdalena Valleys of Colombia and adjacent mid-eleva-tional areas (for sweet potato, liren, arrowroot, and possibly the South American lowland squash, Cucurbita moschata); southwestern Brazil/eastern Bolivia (the probable birth place of manioc and probably other crops), and southwestern Ecuador and possibly northwestern Peru (for a species of Cucurbita [C. ecuadorensis], South American cotton [Gossypium barbadense], and probably the South American jackbean [Canavalia plagiosperma]).

The Amazon Basin has long been an area of interest for crop plant origins. However, although some crops like manioc were domesticated on the fringes of the Basin, few to no others that would become staple foods with the exception of the peach palm (Bactris gasipaes) appear to have been domesticated within its core area (Piperno and Pearsall, 1998). And as Harlan (1971) predicted, there appears to be no single, major center of agricultural origins in South America at all. Even after plants were domesticated and dispersed out of their geographic cradles of origin, peoples in other regions continued to experiment with, modify them, and significantly change them phenotypically. One prominent example of this is maize. There are hundreds of different varieties adapted to a wide range of ecological conditions. Paleoecological and archeological evidence indicates that the crop had been well-dispersed and established in South America by c. 6.3 kcal. yr bp (Monsalve, 1985; Bush et al., 1989; Mora et al., 1991; Piperno and Pearsall, 1998; Pearsall et al., 2003, 2004; Iriarte et al., 2004).

A significant number of investigators interested in the origins of agriculture, including this one, believe that changing ecological circumstances at the end of the Pleistocene combined with a consideration of how efficiently (in calories obtained per person per hour) full-time hunters and gatherers could exploit their post-glacial landscapes, may provide satisfactory answers for why and when agriculture arose. These end-Pleistocene transitions have often been depicted as a kind of environmental amelioration for human populations in the literature on cultural adaptations during this period. In all likelihood, however, subsistence options for low-latitude hunters and gatherers, and perhaps those of other areas of the world, became a great deal poorer when the ice age ended.

For example, during the Pleistocene more than 30 genera of now-extinct, large-and medium-sized grazers and browsers—including horses, mammoths, and giant ground sloths—roamed the tropical landscape, and it is clear that humans routinely hunted some of them (Cooke, 1998; Piperno and Pearsall, 1998; Ranere and Cooke, 2003). The animals were gone by c. 11.4 kcal. yr bp, at which point hunting and gathering became a far different enterprise. When compared with the Pleistocene

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Figure 7.3. Domestication areas for various lowland crop plants as indicated by present molecular, archeological, and ecological evidence. Also shown are the locations of archeological and paleoecological sites in Central America (a) and South America (b) with early (11.4-5.7kcal. yr bp) domesticated seed and root crop remains. Detailed information on the sites can be found in MacNeish (1967), Pearsall (1978), Monsalve (1985), Flannery (1986), Bush et al. (1989), Mora et al. (1991), Cavelier et al. (1995), Smith (1997), Piperno and Pearsall (1998), Piperno et al. (2000a, b), Pope et al. (2001), Pearsall et al. (2003, 2004), Piperno and Stothert (2003), and Piperno (in press a). Domestication areas for Mesoamerica:

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Figure 7.3. Domestication areas for various lowland crop plants as indicated by present molecular, archeological, and ecological evidence. Also shown are the locations of archeological and paleoecological sites in Central America (a) and South America (b) with early (11.4-5.7kcal. yr bp) domesticated seed and root crop remains. Detailed information on the sites can be found in MacNeish (1967), Pearsall (1978), Monsalve (1985), Flannery (1986), Bush et al. (1989), Mora et al. (1991), Cavelier et al. (1995), Smith (1997), Piperno and Pearsall (1998), Piperno et al. (2000a, b), Pope et al. (2001), Pearsall et al. (2003, 2004), Piperno and Stothert (2003), and Piperno (in press a). Domestication areas for Mesoamerica:

Mexico: maize (Zea mays) and squash (Cucurbita argyrosperma); also possibly jicama (Pachyrhizus spp).

Domestication areas for South America:

D1. Sweet potato (Ipomoea batatas), squash (Cucurbita moschata), arrowroot (Maranta arundinacea), achira (Canna edulis—lower, mid-elevational in origin); also possibly sieva beans (Phaseolus lunatus), yautia, or cocoyam (Xanthosoma saggitifolium), and liren (Calathea allouia). D2. Yam (Dioscorea trifida); also possibly yautia (Xanthosoma saggitifolium), liren (Calathea allouia), and chile peppers (Capsicum baccatum). D3. Manioc or yuca (Manihot esculenta), peanut (Arachis hypogaea), chili pepper (Capsicum baccatum), and possibly squash (C. maxima). D4: Cotton (Gossypium barbadense), Cucurbita ecuadorensis, possibly jack bean (Canavalia plagiosperma).

Notes: Probable areas of origin for other lowland, pre-Columbian cultivars include the wet forests of the northwestern Amazon Basin (Bactris gasipaes [the peach palm] and possibly Sicana odorifera [cassabanana]), eastern Mexico (chili peppers), and the Yucatan Peninsula (G. hirsutum [cotton]).

Explanation of modern vegetation:

(a) 1. Tropical evergreen forest (TEF). 2. Tropical semi-evergreen forest (TSEF). 3. Tropical deciduous forest (TDF). 4. Savanna. 5. Low scrub/grass/desert. 6. Mostly cactus scrub and desert.

(b) 1. TEF. 2. TSEF. 3. TDF. 4. Mixtures of TEF, TSEF, and TDF (TSEF and TDF grow over substantial areas of the southern parts of the Guianas and south of the Orinoco River). 5. Mainly semi-evergreen forest and drier types of evergreen forest. Floristic variability can be high in this zone. 6. Savanna. 7. Thorn scrub. 8. Caatinga. 9. Cerrado. 10. Desert.

fauna, animals that were available to human hunters between c. 12.5 kcal. yr bp and 11.4 kcal. yr bp occurred at much lower biomass and were also typically small-sized. Moreover, because tropical forest was expanding into the considerable areas where tree cover had previously been sparse or more discontinuous, hunters and gatherers had to more routinely exploit forest plants, but would find them to be a generally poor source of calories and widely dispersed in space. The most starch-dense examples (roots, rhizomes, tubers) often contained high amounts of toxic chemicals and other defenses that made them time-consuming and difficult to convert into food (Piperno and Pearsall, 1998).

Empirical data generated recently on how modern hunters and gatherers choose their diets from the resources available to them, and on the relative efficiencies of foraging and farming in various modern tropical habitats, have also proved to be significant illuminators of subsistence change at the transition to agriculture (Kennett and Winterhalder, in press). These data can be used to predict that, in contrast to the situation that existed during the Late Pleistocene, plant cultivation in the Early Holocene forest was probably a less labor-intensive and more energetically-efficient strategy than full-time hunting and gathering (Piperno and Pearsall, 1998; Piperno, in press). Thus, nascent farmers were very likely at a competitive advantage over people who were not growing their food, a factor that led to the establishment and rapid spread of agricultural systems (for a complete discussion of these issues and the utility of using evolutionary ecology, especially foraging theory, as an explanatory framework for agricultural origins, see Piperno and Pearsall, 1998, Piperno, in press a, and Kennett and Winterhalder, in press). Explanations such as these for agricultural origins and other major transitions in human lifeways are not environmental determinism, at least not the form of it that a fair number of anthropologists are prone to deriding. They are acknowledgments that ecological factors and evolutionary biology matter deeply in human affairs, and that scientists need not shy away from nomothetic explanations for human behavior if available empirical evidence indicates that such kinds of generalizing explanations are supportable (see Piperno and Pearsall, 1998, Piperno, in press a, and Kennett and Winterhalder, in press, for further discussions).

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