Phytolith Evidence for Early Holocene Cucurbita Domestication In
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R EPORTS amined 18 fruits from 18 different popula- tions of wild and semi-domesticated varieties Phytolith Evidence for Early from the only known Cucurbita native to Ecuador, Cucurbita ecuadorensis (10–12). Holocene Cucurbita Domestication We dated archaeological Cucurbita remains using refined methods of phytolith 14C study in Southwest Ecuador (8) (figs. S1, A and B). All archaeological sediment samples yield- Dolores R. Piperno1* and Karen E. Stothert2 ed spherical scalloped phytoliths specific to the fruit rinds of the genus Cucurbita (7, 9, 13, 14). Cucurbita (squash and gourd) phytoliths recovered from two early Holocene An increase in mean and maximum size above archaeological sites in southwestern Ecuador and directly dated to 10,130 those recorded in modern wild plants is a stan- to 9320 carbon-14 years before the present (about 12,000 to 10,000 cal- dard criterion for separating wild from domes- endar years ago) are identified as derived from domesticated plants because ticated macrobotanical remains (such as seeds they are considerably larger than those from modern wild taxa. The be- and peduncles) of Cucurbita archeologically ginnings of plant husbandry appear to have been preceded by the exploi- (2). Our data show that size criteria are useful in tation of a wild species of Cucurbita during the terminal Pleistocene. These phytolith studies, because mean and maximum data provide evidence for an independent emergence of plant food pro- phytolith length and thickness in modern wild duction in lowland South America that was contemporaneous with or slight- species are substantially smaller than in domes- ly before that in highland Mesoamerica. ticated varieties (Fig. 1, A and B). There is also a clear relation between phytolith size and fruit The transition from hunting and gathering to site located 15 km further inland than site 80 size (Fig. 1C). The sensitivity of phytolith size agriculture was one of the most important (6). Midden contents (chipped stone tools, to domestication can also be seen in individual economic and social passages of human pre- shells, fish bones, and deer bones) support the fruits from wild taxa (C. argyrosperma ssp. history, and the topic has long been a focus of idea that this is a habitation site. 14C dates sororia and C. pepo ssp. fraterna) that exhibit archaeological research. Studies in dry high- range from ϳ10,800 to 7250 yr B.P. (Table 1 signs of introgression with domesticated spe- land regions of Mesoamerica show that plant and table S1) and indicate that occupations at cies, such as nonbitter flesh. These fruits have domestication had occurred by 9000 years sites 67 and 80 were contemporaneous (8). somewhat larger phytoliths than do wild ex- before the present (yr B.P.) (about 10,000 Although seeds, roots, and nuts were not amples, with no such evidence of domesticat- calendar years ago) (1, 2). However, empiri- preserved at sites 80 and 67 and pollen grains ed germ plasm (Fig. 1, A and B, arrows). cal research in the lowland Neotropics, long are rare, phytoliths were abundant. Moreover, fruits from different wild species hypothesized to have been another indepen- At site 80, we found the presence of Cu- and populations sampled over wide geo- dent center of agricultural origins (3), has curbita fruit phytoliths throughout the Las graphic areas have similar sizes. been impeded by the poor preservation of Vegas occupation, and we suggested that Phytoliths with a mean length of about 82 plant remains. Here we describe early plant wild Cucurbita was exploited during the to 86 m or longer and a mean and maximum domestication in Ecuador using an analysis of latest Pleistocene and domesticated by thickness of at least 68 and 90 m, respec- phytoliths: microscopic siliceous remains of ϳ9000 yr B.P. (6, 7, 9). However, our tively, are contributed only by semi-domesti- plants that survive in humid environments interpretations hinged on this single site, cated C. ecuadorensis fruits at least 14 cm in over long periods of time (4). and our chronology was based on dating the height or 16 cm in diameter. A maximum The early Holocene Las Vegas preceramic carbon isolated from tens of thousands of phytolith thickness of 100 m or more was culture of coastal Ecuador is known from 34 phytoliths of different sizes and taxonomic seen only in a C. ecuadorensis fruit that was sites on the Santa Elena Peninsula (5, 6). classes occurring in the same samples with 14 cm in height and 18 cm in diameter, and Excavations at the type site, OGSE-80 (here- Cucurbita (7–9). The dates were closely similarly in the largest fruits of C. moschata after site 80) have produced evidence for a comparable to those from associated shell and C. ficifolia studied, with diameters of 17 broad-spectrum subsistence strategy involv- and charcoal but were not as precise as 14C to 25 cm and heights of 21 to 36 cm (15). ing terrestrial, estuarine, and mangrove envi- analysis of individual macrofragments of Phytoliths of such sizes also distinguish all ronments, and fairly sedentary occupations domesticated plants might have been. other domesticated from wild taxa and pro- dated from about 10,000 to 6600 14C yr B.P. In the present study, we isolated and stud- vide a secure baseline for identifying domes- (about 11,300 to 7300 calendar years ago) ied Cucurbita phytoliths in three additional ticated varieties of archaeological Cucurbita (5–7). Traces of a terminal Pleistocene hu- sediment samples from the terminal Pleisto- in Ecuador. man presence are found stratified underneath cene occupation at site 80, as well as 12 In three different terminal Pleistocene a part of the Las Vegas midden. Cultural samples representing the earliest to latest cul- samples from site 80, where 14C ages on materials are sparse in these deep levels, but tural activity at site 67 (4, 8). Ten samples charcoal and shell range between 10,840 Ϯ three 14C determinations on shell and char- from site 67 were from a column sample 410 yr B.P. and 10,300 Ϯ 240 yr B.P., phy- coal from this zone range from 10,840 Ϯ 410 removed from a deep stratigraphic cut, Unit tolith size is indicative of a wild species of yr B.P. to 10,300 Ϯ 240 yr B.P. (about 1, which was located well away from burials; Cucurbita (Table 1 and table S1). In the three 13,800 to 11,000 calendar years ago) (5, 6). the remaining two were recovered from un- deepest samples from Unit 1 at site 67 [be- M5 A4-67 (site 67) is another Las Vegas disturbed contexts in other portions of the site tween 70 and 100 cm beneath the surfa- as the excavations proceeded. To assess the ce(b.s.)], where phytoliths are dated at or status of the Cucurbita remains as wild or somewhat before 10,820 Ϯ 250 yr B.P., phy- 1 Smithsonian Tropical Research Institute (STRI), Bal- domesticated, we used a large modern refer- tolith size likewise falls within or close to the boa, Panama. 2Center for Archaeological Research, The University of Texas at San Antonio, San Antonio, ence collection comprising 157 mature fruits upper ends of the means and ranges of wild TX 78249, USA. from 115 different populations, land races, species. Because no other wild species of *To whom correspondence should be addressed at and varieties from most known wild and all Cucurbita has been located in Ecuador, the STRI Unit 0948, APO AA 34002–0948. domesticated species of Cucurbita.Weex- evidence suggests that a wild form of C. 1054 14 FEBRUARY 2003 VOL 299 SCIENCE www.sciencemag.org R EPORTS ecuadorensis was present on the landscape are present. We were thus able to segregate micromovement of phytoliths of different sizes and used by the pre–Las Vegas people. about 70% of all the Cucurbita phytoliths in sediments. Because a previous age determi- Previous analyses of site 80 indicated that from Unit E8-9, 110- to 120-cm level. Car- nation of 9740 Ϯ 60 yr B.P. on phytoliths from Cucurbita phytoliths with sizes substantially bon isolated from approximately 550 domes- Unit F8-9, 110- to 120-cm level, was carried exceeding those found in modern wild spec- ticated-sized Cucurbita phytoliths and 3200 out on fine and coarse silt phytoliths (here 90% imens made their first appearance near the large grass phytoliths concentrated from the of Cucurbita phytoliths occur in the coarse silt), base of the Las Vegas–phase midden in the sand yielded a date of 10,130 Ϯ 40 14Cyr the true age of the Cucurbita in this level near 110- to 120-cm level of Unit E8-9 (6, 7, 9). B.P. (Table 1, box) (8). the base of the midden is probably older, an Our initial determination of phytolith age in Another date on an isolate of coarse silt inference which is suggested by their size as this sample from a phytolith extract over- phytoliths from this sample, in which the re- well (Table 1). whelmingly represented by grass phytoliths mainder of the Cucurbita occur, was 9320 Ϯ The results from site 67 are similar. In isolated from the fine (5 to 20 m) and coarse 250 yr B.P. Hence, an age of between ϳ10,100 the Unit 1 column samples, the earliest (20 to 50 m) silt was 9080 Ϯ 60 yr B.P. (7, and 9300 yr B.P. can be assigned to the appear- Cucurbita phytoliths that are identifiable as 9) (Table 1, box). Our new results indicate ance of a domesticated Cucurbita. A new date derived from a domesticated species occur that this date is somewhat too young.