What is ivory? Is it just elephants that have ivory? JV Chamary explains all you need to know about ivory <\/p>
Traditionally used to create ornaments and art of cultural value, humans have turned ivory into everything from piano keys<\/a> to hip replacements. But it\u2019s also a rare commodity that\u2019s been harvested to finance wars, cutting African elephant<\/a> numbers from 3-5 million in the 20th century to around 400,000 today. <\/p> Commercial trade in the ivory of African elephants is banned under CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora<\/a>), yet illegal poaching persists. Why is ivory still so highly prized?<\/p> Any mammal with tusks, which are elongated teeth. Elephant tusks are what a dentist might call \u2018maxillary lateral incisors\u2019. They\u2019re located between the front teeth and canines of the upper jaw, and grow continuously (over 3cm in length per year) throughout a lifetime. Tusks can also grow from the lower jaw, as seen in hippos<\/a> or warthogs. They typically occur in pairs, but a narwhal<\/a>\u2019s spiral tusk is a single canine.<\/p> Tusks are sheathed in cementum, the substance that covers the root of a tooth. But the bulk of a tusk is dentine, the material below a tooth\u2019s crown of enamel and above its pulp (containing nerves and blood vessels). Pulp deposits layers of dentine, pushing a tusk outward to make ivory. Dentine itself is a composite made of roughly equal amounts of water, collagen and a mineral, hydroxyapatite, that forms solid crystals on a scaffold made by the fibrous collagen proteins.<\/p> As adults tell kids, you need calcium for strong teeth and bones! That\u2019s because the mineral contains calcium ions in both structures. In dentine, some crystals contain magnesium instead, altering ivory\u2019s chemical and mechanical properties.<\/p> Mainly for fighting and foraging. As weapons, for instance, ivory absorbs impact and stress \u2013 a common occurrence when males clash in a competition for mates.<\/p> Elephant tusks are multipurpose tools used to dig soil for nutrients, clear vegetation and strip bark from trees. In African elephants, tusk size influences social hierarchy: the female with the longest tusks is often a herd\u2019s matriarch.<\/p> Why does the desire for elephant ivory exceed the demand for ivories from other \u2018large tuskers\u2019? One reason is the material\u2019s workability. Unlike timber, which can crack or splinter when you work against the wood grain, ivory\u2019s microscopic structure allows craftsmen to carve or chisel fine details from almost any angle.<\/p> Another desirable feature is aesthetics. In cross-section, ivory\u2019s structure has a unique checkerboard pattern that appears to the naked eye \u2013 once the surface has been polished \u2013 as beautifully stacked chevrons known as Schreger lines.<\/p> While bone is twice as tough (resists fracture), ivory has double the strength (withstands breaking completely). Ivory is harder (resists scratches and wear) and stiffer (less flex) than bone, which is relatively lightweight because it contains more pores. Ivory is heavy and dense: an elephant tusk\u2019s mass can reach over 35kg.<\/p> Several substitutes have been proposed. Jarina seeds \u2013 also known as tagua nuts or vegetable ivory \u2013 from palm trees have comparable properties, but have limited applications as they\u2019re only plum-sized. Artificial plastics with similar qualities have (so far) proven inferior to ivory.<\/p> Iconic as they are, tusks may not be necessary for survival. While females from African species (forest and savannah) are normally tusked, an Asian female might only have short protrusions called tushes. Human-mediated selection is driving the evolution<\/a> of tusklessness, as animals without tusks will be favoured by natural selection if tusked individuals are killed by poachers for their ivory before they are able to reproduce.<\/p> Time will tell whether they go extinct or go tuskless. Either way, the world would lose a versatile material. To elephants, even if ivory isn\u2019t vital, it\u2019s incredibly valuable.<\/p>Which animals produce ivory?<\/strong><\/h2>
What\u2019s ivory made of?<\/strong><\/h2>
How are tusks used?<\/strong><\/h2>
What makes elephant tusks special?<\/strong><\/h2>
Are there alternative materials?<\/strong><\/h2>
Do elephants need tusks?<\/strong><\/h2>
Will humans drive African elephants to extinction or force them to adapt?<\/strong><\/h2>