Diversity of management strategies in Mesoamerican turkeys: archaeological, isotopic and genetic evidence

Abstract

The turkey (Meleagris gallopavo) represents one of the few domestic animals of the New World. While current research points to distinct domestication centres in the Southwest USA and Mesoamerica, several questions regarding the number of progenitor populations, and the timing and intensity of turkey husbandry remain unanswered. This study applied ancient mitochondrial DNA and stable isotope (δ¹³C, δ¹⁵N) analysis to 55 archaeological turkey remains from Mexico to investigate pre-contact turkey exploitation in Mesoamerica. Three different (sub)species of turkeys were identified in the archaeological record (M. g. mexicana, M. g. gallopavo and M. ocellata), indicating the exploitation of diverse local populations, as well as the trade of captively reared birds into the Maya area. No evidence of shared maternal haplotypes was observed between Mesoamerica and the Southwest USA, in contrast with archaeological evidence for trade of other domestic products. Isotopic analysis indicates a range of feeding behaviours in ancient Mesoamerican turkeys, including wild foraging, human provisioning and mixed feeding ecologies. This variability in turkey diet decreases through time, with archaeological, genetic and isotopic evidence all pointing to the intensification of domestic turkey management and husbandry, culminating in the Postclassic period.

Keywords: ancient DNA analysis; animal domestication; archaeology; isotope analysis; turkey (Meleagris gallopavo).

Figure 1.

Historic distribution of North American wild turkey subspecies (Meleagris gallopavo) and the ocellated turkey (Meleagris ocellata) (after Schorger [5]) with the location of the sites analysed in this study and the regions mentioned in the text. 1, Texcoco (Estado de Mexico); 2, Teotihuacan (Estado de Mexico); 3, Terremote-Tlaltenco (Estado de Mexico); 4, Oaxtepec (Morelos); 5, Xochicalco (Morelos); 6, Huixtoco, Ixtapaluca (Estado de Mexico); 7, Santa Ana Teloxtoc (Puebla); 8, El Tigre (Campeche); 9, Calakmul (Campeche); 10, Champoton (Campeche); 11, Chichen Itza (Yucatan); 12, Malpais Prieto (Michoacan); 13, Vista Hermosa (Tamaulipas); 14, El Calderon (Chihuahua).

Figure 2.

Median-joining network displaying the relationships between the obtained sequences and existing archaeological [19] and modern [35,42,43] sequences, obtained from GenBank. Mexican turkeys (in black) are compared with archaeological samples from the SW USA (in grey), modern breeds (in white) and wild subspecies (according to the colours). Mesoamerican samples are primarily grouped in the mHap1 and mHap2 haplotypes, whereas North Mexican individuals fall within the aHap2e haplotype.

Figure 3.

Scatter plots of carbon and nitrogen isotopic values. (a) Mesoamerican turkeys analysed in this study, grouped according to site location and genetic identification. (b) Means of isotope values for the Mesoamerican turkeys analysed here, according to chronological and geographical distribution; error bars represent 1 s.d. (c) Turkeys from Chihuahua, Northern Mexico, analysed in this study. (d) Published isotopic data for the nuclear Puebloan region [7,15,17,18] and marginal areas [16] of the SW USA used as comparison with Mexican turkeys.

Figure 4.

Scatter plot of carbon and nitrogen isotopic values of turkeys from Teotihuacan, from this study (haplotype mHap1, triangle; haplotypes mHap2/mHap2a, circle) and previously published specimens ([69], square). Data compared with ellipses (0.95 confidence interval) calculated for modern wild common turkeys ([7,16,48], plain grey line, n = 44), archaeological free-range common turkeys ([16], dotted blue line, n = 18) and other archaeological common turkeys from Mesoamerica (this study, [30], dashed red line, n = 49).

Figure 5.

Intensification of common turkey husbandry during the Postclassic period, seen through stable isotope and zooarchaeological data. (a) Stable isotope ratios of carbon and nitrogen from this study and Thornton et al. [30], showing significant differences between Preclassic/Classic (n = 14) and Postclassic (n = 30) birds. (b) Relative proportions of turkey, leporids, dog and deer in Mesoamerican archaeological corpus from the Early Classic to the Middle/Late Postclassic period, considering the archaeological sites where common turkeys have been identified (electronic supplementary material, table S3).