The tusks of elephants are actually just enormous teeth that grow out of the elephant’s upper jaws.  As each individual elephant matures, it lays down a new layer of dentine (and other compounds) within the tooth cavity where the tusk grows.  Each new growth segment is created as an inverted cone at the base of the tusk and in this way the enormous tooth grows longer and longer. 

photo M. Noonan

Because the rainy/dry seasonal cycles bring periods of varying nutrition, it is not unusual for tusks to grow more at certain times of the year than at others.  As a result, cross sections through many tusks reveal faint lines for each passing year.  In this way, they are a little bit like the rings that are visible in the trunks of some trees, and the number of successive growth cones can reflect the age of the individual elephant.

photo M. Noonan

Ordinarily, the tusks of male Asian elephants grow to three or four feet in length.  But depending on the age and size of the elephant, they can sometimes be much longer than that.  For example, there is a 60 year old elephant living in Sri Lanka (pictured at right) whose tusks are nine feet long.

photo M. Noonan

Female Tusks

Often it is said that female Asian Elephants do not have tusks.  However, that is not really true.  It is just that the tusks of the female Asian Elephants are much smaller than those of males -- so small that they are often not visible unless the elephant opens her mouth.  Most female Asian Elephants actually  have tusks that are about one inch thick and six inches long.  Female elephants can, and do, use their tusks to prod other elephants during social interactions and also to rip away bark while feeding on trees. 

photo M. Noonan

Tuskless Males

photo M. Noonan

In Asian Elephants, it has almost always been the tusker males that have been killed for the ivory trade.  In fact, the relentless pressure from hunters has been so great, it has created an enormous artificial selection pressure in many areas.  In the distant past, a tuskless male was a very rare thing.  However, when they did occur, they were almost always passed over by ivory hunters.  Because of this, tusk-less males were much more likely to survive, and therefore had a better chance of breeding.  Over time, this meant that more and more of the male offspring of each successive generation inherited the trait of being tuskless too.  As a consequence, in some modern populations of Asian elephants, tuskless males have come to predominate in terms of numbers.  In effect, the selective pressure created by mankind’s relentless hunting has altered a natural trait of the species.