A Tick From a Prehistoric Arizona Coprolite (Galley Proofs)

Ticks have never been reported in archaeological analyses. Here, we present the discovery of a tick from a coprolite excavated from Antelope Cave in extreme northwest Arizona. Dietary analysis indicates that the coprolite has a human origin. This archaeological occupation is associated with the Ancestral Pueblo culture (Anasazi). This discovery supports previous hypotheses that ticks were a potential source of disease and that ectoparasites were eaten by ancient people. Nearly 1,000 coprolites from the desert west of the United States have been analyzed for parasite remains (Reinhard, 1990, 1992). Although arthropod parasites are rare, they are occasionally found in coprolites. The discovery of lice in human coprolites led Fry (1977) to conclude that arthropods were consumed to control infestation. In 2005, we commenced the dietary and parasitological analysis of coprolites from Antelope Cave in the northwestern corner of Arizona. At this site, we discovered a tick from a coprolite. This discovery has health, behavioral, and ecological implications for the Puebloan people that once occupied the cave. Antelope Cave is a large limestone cavern sunk into the gently rolling terrain of the Uinkaret Plateau some 40 km southeast of St. George, Utah. Prehistoric Native Americans occupied it, probably intermittently, for at least 3,000 yr (2028 B.C. to A.D. 1100). The most intense habitation of the cave is attributed to Ancestral Puebloan peoples (Anasazi) who lived there 1,300 to 1,000 yr ago. Antelope Cave lies within the Virgin River Branch of prehistoric western Anasazi territory, and the great majority of artifacts (for example, woven fiber sandals, plaited basketry, Virgin series pottery) in the cave reflects Puebloan (Kayenta) affiliation. There is scant evidence of Fremont cultural influence from the north in Utah. Cultural debris left in the cave by its prehistoric inhabitants forms a 1.52-m-thick layer and contains mostly perishable artifacts, including wooden arrow shafts, basketry, string, netting, sandals, needles and thread, etc., as well as painted pottery and various lithic tools. The Pueblo people used the cave for shelter, and in the surrounding area, they grew corn and beans, gathered wild plant foods, and hunted game, mostly rabbits. Professional archaeologists have conducted excavations in the cave, off and on, since 1954 (Janetski and Hall, 1983; Janetski and Wilde, 1989). The most extensive excavations were undertaken by the University of California–Los Angeles (UCLA) in 1959–1960 (Johnson and Pendergast, 1960). The coprolite specimen discussed here was recovered by UCLA and came from 1,000-yr-old Pueblo deposits at the rear of the cave. The date is based on cross-dated Anasazi artifacts pending C14 assay. In 1959, archaeologists from UCLA excavated five 2 2 m pits into the midden deposit of Antelope Cave. The excavation units were designated AC59-1 through AC59-5. The coprolite of concern here was recovered from the 60–76-cm level below the surface in pit AC59-2. Along with the coprolite, this level yielded a wide variety of cultural debris, including fragments of Pueblo pointed-toe sandals, sandal ties, a net bag, fiber cordage, feather cordage, and pottery. No features, such as fire hearths, storage pits, latrines, etc., were exposed in this or any other level. Eight Antelope Cave coprolites have been analyzed to date. Five are consistent with humans and 3 are consistent with canids, probably dogs. Laboratory sample 2 is the focus of this report. Its field context is AC 1516, pit AC 59-2, 60–76 cm below surface. After contextual information was recorded, the coprolite was cleaned of extraneous dirt, photographed, and weighed. Its weight, 2.67 g was then recorded. Observations relative to biological origin were made. The coprolite was then rehydrated in 0.5% trisodium phosphate for 48 hr. It was placed in a 300-ml beaker, and rehydration solution was added until the coprolite was completely immersed. Parafilm was used to cover the beaker to prevent potential modern airborne pollen contamination. Observations were made after 24 hr of rehydration. Rehydration fluid color is sometimes useful in verifying human origin (Reinhard and Bryant, 1992). Human coprolites tend to turn the rehydration solution dark brown or black, although this is not always the case. In addition, the rehydrating coprolite was examined for a mucilage coat, which sometimes forms on dog coprolites after rehydration (Reinhard et al., 1988). After 48 hr of rehydration, 3 Lycopodium sp. spore tablets were added to the coprolite to facilitate quantification (Warnock and Reinhard, 1994; Sianto et al., 2005). For this analysis, Lycopodium sp. spore batch 212761 was used. Previous analysis has shown that approximately 12,500 spores are present in each tablet (values presented from different analyses of tablets are 12,432, 12,489, and 12,542). The tablets were dissolved in a few drops of hydrochloric acid and added to the rehydrated coprolite. The coprolite was then disaggregated. It was transferred to a 600-ml beaker along with the rehydration solution and dissolved Lycopodium sp. tablets. A magnetic stir rod was added to the beaker, which was placed on a stir plate. The coprolite in the solution was then stirred for 45 min until it was completely disaggregated. Microscopic remains were separated from macroscopic remains by pouring the disaggregated coprolite through a 300m mesh screen. A stream of distilled water under pressure was used to thoroughly wash the microscopic remains through the screen and into a 600-ml beaker. The macroscopic remains on top of the screen were dried on cotton filter paper. The microscopic remains were sedimented by centrifugation in 50-ml tubes. The microscopic remains were then analyzed for parasite eggs and microscopic dietary evidence such as plant cells, phytoliths, and starch grains. Nine microscope preparations were made for helminth eggs or protozoan cysts. The dietary residues were categorized and counted. Next, using the following formula, the numbers of each category of dietary residue per gram of coprolite were calculated: concentration ([i/m] n)/w, where i is items counted, m is marker Lycopodium spores counted, n is marker Lycopodium spores added, and w is weight of