The history of the domestication of turkeys is one of those great questions in archaeological science. While archaeologists are certain Meleagris spp was domesticated in North America probably at least as long ago as 100 BC-100 AD, there are still difficulties in identifying a domestic bird. Simply put, the skeletons of domesticated precolumbian turkeys aren't physically different from those of wild turkeys. Archaeological evidence for turkey domestication has thus far relied on the identification of pens, or healed long bone fractures in turkeys, or weird blips in demographic tables, such as an abundance of juvenile bird bones in a site assemblage.
Ocellated Turkey at Tikal
Photo Credit: Lilac Breasted Roller
But recent work identifying the calcium absorption rate in eggshell may prove another route of investigation. Researchers Bradley Beacham and Stephen Durand (reported in a recent article in the Journal of Archaeological Science) have been able to identify eggshell that came from hatched birds, as opposed to eggs which were eaten before they were hatched. Most amazingly, this cellular level of evidence exists in archaeological samples, as shown in their recent work at the pueblo site of Salmon Ruins in New Mexico.
The process relies on the calcium absorption rate that occurs during the gestation process. Bird embryos use their eggshells as a source of calcium throughout gestation. As the embryo gets ready to hatch, it takes out more and more calcium out of its shell. The amount of calcium taken out of the shell is quantifiable under a microscope, and the range of alteration is clearly visible even in archaeological samples.
The ability to identify hatched birds when your evidence is simply a pile of egg shell fragments has a strong potential to shed light on this very interesting problem.
Source and More Information
- Beacham, , E.B. and S. Durand. (2007). Eggshell and the archaeological record: new insights into turkey husbandry in the American Southwest. Journal of Archaeological Science, 34(10), 1610-1621. DOI: 10.1016/j.jas.2006.11.015
- Domestication of the Turkey
- Marks of Domestication
- Table of Animal Domestication