Ivory is a natural, osseous raw material, that is part of the dentition of a wide variety of animals: elephant, rhinoceros, walrus, hippopotamus, pig, sperm whale, killer whale and narwhal, as well as their extinct counterparts, including woolly mammoth (Mammutus primogenius) and woolly rhinocerus. True "ivory" usually refers to elephant (and mammoth) ivory, which has a distinct chemistry and internal architecture. Analyses of trace chemicals (magnesium, fluorine, strontium) have been used with some success to differentiate the different forms of ivory, as well as bone and antler (Müller and Reiche 2011).
Speaking chemically, ivory is a rigid biological composite, made of a matrix buttressed by a crystalline lattice of hydroxyapetite, a calcium phosphate which makes up most human and animal bone. About 10 percent of the calcium in ancient mammoth and mastodon bone has been replaced by magnesium, and as a result, the hydroxyapatite crystals are small and well-formed. Mammoth tusks, the main source of ivory in the past, have been known to grow to lengths of up to four meters (~13 feet), weighing up to 400 kilograms (~880 pounds).
Ivory as Artifact
Ivory is prized today (and likely prehistorically) for its malleability in working it into shapes, as well as its density, fineness of grain, luster when polished, weight and warmth of texture. Unlike stone and bone, ivory has a combined strength and elasticity, the ability to bend under pressure and rebound when the pressure is released.
Ivory is best known among students of the past as a raw material for the production of symbolic or representational sculptured objects, beginning in the early Upper Paleolithic of Europe. The earliest worked ivory objects are small, uniform beads made from mammoth tusks found in the Swabian Jura of of Baden-Wurtemberg, southwestern Germany at sites such as Vogelherd, Hohlenstein-Stadel, Geißenklösterle, and Hohle Fels. Basket-shaped beads and small pendants in ivory have also been recovered from Aurignacian contexts in the French cave sites of Abri Castanet, Abri Blanchard, Isturitz and Brassempuoy.
The oldest three-dimensional portable art objects in Eurasia, discounting beads, are ivory figurines, dated to the Aurignacian of 35,000-30,000 calendar years BP (cal BP), also in the Swabian Jura. Among the earliest are representations of woolly mammoths, including Aurignacian examples from Vogelherd and Geißenklösterle.
Middle Upper Paleolithic Gravettian (29,000-22,000 BP) examples are more numerous, including examples from Dolní Vestonice, Pavlov, Predmostí, Kostenki, Avdeevo, Eliseevitchi, Sungir, and Ust' Kova. Some mammoth figurines are carved from rock or built from fired clay.
Mammoth carvings on ivory and stone are later than the sculptures, dating to the Magdalenian (18,000-12,500 BP) at the Gönnersdorf site, where 76 carvings have been found. All the mammoths drawn at Gönnersdorf are tuskless: scholars believe the Gonnersdorf mammoths were the last population of mammoths in western Europe, who lost their tusks as a result of starvation cased by habitat loss at the end of the last glacial maximum. (Braun) Some scholars have tied the end of the mammoth as a source of ivory to the innovation of microblades (Pitulko and Nikolskiy).
Elephant Ivory Poaching and Archaeology
Today, ivory objects are still very highly prized, and a massive trade in poached ivory has developed in the past 150 years. Poaching ivory was such a lucrative business that it ultimately led to the decimation of modern elephant populations, for example, reducing the African elephant poulation from 1.3 million to 600,000 individuals between 1979 and 1987. In 1970, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was instituted, and its members eventually provided legal protection for elephants in the developed world, by restricting ivory trade to "antique" objects, those made at least 50 years before the EC Wildlife Trade Regulations came into effect in 1997 (i.e. June 1, 1947).
South African archaeologists led by van der Merwe and Vogel developed stable isotope research methods in the 1970s, and turned their attention to using the new techniques to identify the place of origin of illegal elephant ivory. Newer research (such as Wasser and colleagues and Wozney and Wilson) has turned to DNA to continue this important research.Determining whether a particular piece of ivory is older than 1947 has been difficult. Although ivory is an organic material, and thus can be dated using conventional radiocarbon (c14) methologies, these studies do not work well after the atmospheric nuclear weapon tests between 1945 and 1980. The bomb tests dramatically increased the amount of carbon in earth's atmosphere, making conventional radiocarbon tests unusable after they began. New methods (Brunnmeier et al., Schmied et al.) match the high active carbon content in a piece of ivory to the known nad changing percentage of modern carbon in the atmosphere, allowing researchers to identify dates within four years between 1945 and the present.
Braun IM, and Palombo MR. 2012. Mammuthus primigenius in the cave and portable art: An overview with a short account on the elephant fossil record in Southern Europe during the last glacial. Quaternary International in press(0).
Brunnermeier MJ, Schmied SAK, Müller-Boge M, and Schupfner R. 2012. Dating of ivory from 20th century by determination of 14C by the direct absorption method. Applied Radiation and Isotopes 70(8):1595-1602.
Heckel C. 2009. Physical Characteristics of Mammoth Ivory and their Implications for Ivory Work in the Upper Paleolithic. Mitteilungen der Gesellschaft für Urgeschichte 18:71-91.
Müller K, and Reiche I. 2011. Differentiation of archaeological ivory and bone materials by micro-PIXE/PIGE with emphasis on two Upper Palaeolithic key sites: Abri Pataud and Isturitz, France. Journal of Archaeological Science 38(12):3234-3243.
Pitulko VV, and Nikolskiy PA. 2012. The extinction of the woolly mammoth and the archaeological record in Northeastern Asia. World Archaeology 44(1):21-42.
Schmied SAK, Brunnermeier MJ, Schupfner R, and Wolfbeis OS. 2011. Age assessment of ivory by analysis of 14C and 90Sr to determine whether there is an antique on hand. Forensic Science International 207(1–3):e1-e4.
van der Merwe NJ, Lee-Thorp JA, Thackeray JF, Hall-Martin A, Kruger FJ, Coetzee H, Bell RHV, and Lindeque M. 1990. Source-area determination of elephant ivory by isotopic analysis. Nature 346(6286):744-746.
Vogel JC, Eglington B, and Auret JM. 1990. Isotope fingerprints in elephant bone and ivory. Nature 346:747-749.
Wasser SK, Joseph Clark W, Drori O, Stephen Kisamo E, Mailand C, Mutayoba B, and Stephens M. 2008. Combating the Illegal Trade in African Elephant Ivory with DNA Forensics. Conservation Biology 22(4):1065-1071.
Wasser SK, Shedlock AM, Comstock K, Ostrander EA, Mutayoba B, and Stephens M. 2004. Assigning African elephant DNA to geographic region of origin: Applications to the ivory trade. Proceedings of the National Academy of Sciences 101(41):14847-14852.
Wozney KM, and Wilson PJ. 2012. Real-time PCR detection and quantification of elephantid DNA: Species identification for highly processed samples associated with the ivory trade. Forensic Science International 219(1–3):106-112.