The broken pieces of ostrich egg shells (often abbreviated OES in the literature) are commonly found on Middle and Upper Paleolithic sites throughout the world: at the time ostriches were much more widespread than they are today, and indeed were one of several megafaunal species which experienced mass extinctions at the end of the Pleistocene.
Ostrich egg shells offered protein, a palette for artwork, and a way to carry water to our ancestors over the past 100,000 years, and as such, they are well worth considering a raw material of interest.
The Qualities of an Unbroken Egg
The ovate eggshell of an ostrich averages 15 centimeters long (6 inches) and 13 cm (5 in) wide; with its contents intact an egg weighs up to 1.4 kg (3 pounds), with an average volume of 1 liter (~1 quart). The shell itself weighs about 260 grams (9 ounces). Ostrich eggs contain about 1 kg (2.2 lbs) of egg protein, equivalent to 24-28 chicken eggs. An ostrich hen lays between 1-2 eggs each week during the breeding season (April to September), and in the wild, hens produce eggs for some 30 years during their lives.
Ostrich eggshell is composed of 96% crystalline calcite and 4% organic material, mostly proteins. The thickness (averaging 2 millimeters or .07 in) is made up of three different layers that vary in structure and thickness. The hardness of the shell is 3 on the Mohs scale.
Since it's organic, OES can be radiocarbon dated (typically using AMS techniques): the only problem is that some cultures used fossil eggshell, so you have to have additional data to back up your dates, always a good idea anyway.
Ostrich Egg Shell Flasks
Historically, ostrich egg shells are known to have been used by African hunter-gatherers as a light-weight and strong flask or canteen to store and transport various fluids, usually water. To make the flask, hunter-gatherers puncture a hole in the top of the egg, either by drilling, punching, grinding, cutting or hammering, or a combination of techniques. That's been difficult to identify in archaeological sites, which typically include only a few eggshell sherds. Intentional perforations could be considered a proxy for the use of eggshell as a container, and based on the perforation, an argument has been made for flask use in southern Africa at least 60,000 years ago. That's tricky: after all, you have to open an egg to eat what's inside anyway.
However, decoration on eggshells has recently been identified which supports the use of flasks in Howiesons Poort contexts in South Africa at least as long ago as 85,000 years (Texier et al. 2010, 2013). Refits of the decorated OES fragments indicate that the patterns were placed on the shell before the shell was broken, and, according to these papers, decorated fragments are only found in context with evidence for purposefully cut openings.
The decorated fragments research is from the Middle and Later Stone Age Diepkloof Rockshelter in South Africa, from which has been recovered over 400 pieces of engraved ostrich eggshell (out of a total of 19,000 eggshell fragments). These fragments were deposited throughout the Howiesons Poort phase, especially between Intermediate and Late HP periods, 52,000-85,000 years ago. Texier and colleagues suggest that these markings were intended to indicate ownership or perhaps a marker of what was contained in the flask.
The decorations identified by the scholars are patterns of abstract parallel lines, dots, and hash marks. Texier et al. identified at least five motifs, two of which spanned the entire length of the HP period, with the earliest decorated eggshell fragments from 90,000-100,000 years ago.
The bead-making process was recently documented archaeologically at the Geelbek Dunes site in South Africa, dated between 550-380 BC (see Kandel and Conard). The bead-making process at Geelbek began when an OES breaks, purposefully or accidentally. Large fragments were processed into preforms or blanks or made directly into discs or pendants.
Processing the blanks into beads involves the initial drilling of angular blanks followed by rounding, or vice versa (although Texier et al. 2013 argue that the rounding process almost always follows the perforation).
Mediterranean Bronze Age
During the Bronze Age in the Mediterranean, ostriches became quite the rage, with several occurrences of elaborately decorated eggshells or eggshell effigies. This came at the same time as state-level societies in the fertile crescent and elsewhere began keeping lush gardens, and some of them included imported animals including ostriches. See Brysbaert for an interesting discussion.
Some Ostrich Egg Shell Sites
- Diepkloof rockshelter (South Africa), decorated OES, possible flasks, Howiesons Poort, 85-52,000 BP
- Mumba rockshelter (Tanzania), OES beads, engraved OES, Middle Stone Age, 49,000 BP,
- Border Cave (South Africa), OES beads, Howiesons Poort, 42,000 bp
- Jarigole Pillars (Kenya), OES beads, 4868-4825 cal BP
- Geelbek Dune Field (South Africa), shell bead processing area, Later Stone Age
- Ikhe-Barkhel-Tologi (Mongolia), OES, 41,700 RCYBP (Kurochkin et al)
- Angarkhai (Transbaikal), OES, 41,700 RCYBP
- Shuidonggou (China), OES beads, Paleolithic, 30,000 BP
- Baga Gazaryn Chuluu (Mongolia), OES, 14,300 BP
- Chikhen Agui (Mongolia), OES, terminal Paleolithic, 13,061 cal BP
Bronze Age Mediterranean
- Nagada (Egypt), OES, predynastic
- Hierankopolis (Egypt), engraved OES, 3500 BC
- Ur royal tombs, 2550-2400 BC, gold ostrich egg effigy, and painted OES
- Palaikastro (Crete), OES, Early Minoan Bronze Age IIB-III, 2550-2300 BC
- Knossos (Crete), OES, Middle Minoan IB, and IIIA, 1900-1700 BC
- Tiryns (Greece), OES, Late Horizon IIB
- Aseyev IV. 2008. Horseman image on an ostrich eggshell fragment. Archaeology, Ethnology, and Anthropology of Eurasia 34(2):96-99. doi: 10.1016/j.aeae.2008.07.009
- Brysbaert A. 2013. 'The Chicken or the Egg?' Interregional Contacts Viewed Through a Technological Lens at Late Bronze Age Tiryns, Greece. Oxford Journal of Archaeology 32(3):233-256. doi: 10.1111/ojoa.12013
- d'Errico F, Backwell L, Villa P, Degano I, Lucejko JJ, Bamford MK, Higham TFG, Colombini MP, and Beaumont PB. 2012. Early evidence of San material culture represented by organic artifacts from Border Cave, South Africa. Proceedings of the National Academy of Sciences 109(33):13214-13219. doi: 10.1073/pnas.1204213109
- Henshilwood C. 2012. Late Pleistocene Techno-traditions in Southern Africa: A Review of the Still Bay and Howiesons Poort, c. 75-59 ka. Journal of World Prehistory 25(3-4):205-237. doi: 10.1007/s10963-012-9060-3
- Kandel AW, and Conard NJ. 2005. Production sequences of ostrich eggshell beads and settlement dynamics in the Geelbek Dunes of the Western Cape, South Africa. Journal of Archaeological Science 32(12):1711-1721. doi: 10.1016/j.jas.2005.05.010
- Orton J. 2008. Later Stone Age ostrich eggshell bead manufacture in the Northern Cape, South Africa. Journal of Archaeological Science 35(7):1765-1775. doi: 10.1016/j.jas.2007.11.014
- Texier P-J, Porraz G, Parkington J, Rigaud J-P, Poggenpoel C, Miller C, Tribolo C, Cartwright C, Coudenneau A, Klein R et al… 2010. A Howiesons Poort tradition of engraving ostrich eggshell containers dated to 60,000 years ago at Diepkloof Rock Shelter, South Africa. Proceedings of the National Academy of Sciences 107(14):6180-6185. doi: 10.1073/pnas.0913047107
- Texier P-J, Porraz G, Parkington J, Rigaud J-P, Poggenpoel C, and Tribolo C. 2013. The context, form and significance of the MSA engraved ostrich eggshell collection from Diepkloof Rock Shelter, Western Cape, South Africa. Journal of Archaeological Science 40(9):3412-3431. doi: 10.1016/j.jas.2013.02.021