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Age Determination in Elephants

by Leslee Maasdorp

(Writing for Zimbabwe Hunters’ Association’s Rifa Conservation Camp)

Introduction

Age determinations of elephant are important in population studies. This information is needed for e.g. in management programmes.

Though the increase in size and mass of tusks have always interested people, their growth only provides a limited guide to the age of the elephant. These famous front teeth are sought after and used in the making of carvings, piano keys and nowadays chop sticks. For fashioning these trinkets, elephants are harassed and poached. Though Zimbabwe has a healthy population overall, poaching activity from the north in the mid-Zambezi Valley is reaching alarming proportions especially in the Rifa Section.

Ponder the following extract of a note written in Wildlife Conservation by W. Conway. “Today, there are about 548 million people living in Africa and 400,000 to 600,000 elephants. If demographers are right, there might be 2,900,000,000 people there by 2050. What will be left for the elephants? For how many elephants? and where? By 2100, most of Earth’s large land animals will survive only with your agreement. They must become the pride and treasures of human beings.”

The main technique discussed below is based on molar wear and replacement using lower jaws obtained from legally hunted or poached elephant. Such data has been used to construct growth rates of elephant and have helped in refining field methods of estimating age.

Consider the elephant’s future over the next sixty years, your lifetime. Can you help to make its very existence more tenable?

Methods of determining the age of an elephant

1. Body Size

The relative sizes of elephant in a family unit compared with that of an average lead cow, can provide a rough estimate of the age of the members of the group.

 It is easy enough to determine the age of a young baby – if it can walk under its mother then it is less than a year old – but aging on size is an increasingly inaccurate method of determining age as the elephant grows.

For instance, if you saw these three elephants in the bush how would you decide on their age?

In the following slide show there are some suggestions about things to look for that would give you an idea of the age of an elephant.

https://www.elephantvoices.org/multimedia-resources/how-to-identify-african-elephants.html?view=article&id=808

2. Ageing elephants from teeth on the lower jaw

This is the most accurate method for determining the age of an elephant (but unfortunately the elephant is usually dead when this method is being applied).

The following age group structure was researched by Laws (1966)[i] and is related to the progress of eruption and wear of the six molar-like teeth in each side of the lower jaw. (24 in all).

Successive teeth grow forwards from the back of the jaw, replacing earlier teeth as these wear, move forward and drop out. Never more than two are in use as space is limited in the mouth. Wear is more advanced in the lower than in the upper jaw.

Of the molar teeth, the first three M1, M2 and M3 are easy to recognise because of their

(i) small size,

(ii) their thinner enamel and

 (iii) their slightly wavy enamel.

M6 is also easily distinguished, because it comes into wear as the bony capsule enclosing the tooth becomes solid and flattened.

Eventually the last molar, M6, is worn down to the last remaining fragments. When very little of the last teeth is left, the elephant cannot chew its food properly, it loses condition and finally dies of starvation. So the wearing down of the M6 places an upper limit of about 60 years for its life span. (At this point it will have large undigested fibres in its droppings and only small fragments of M6 remaining in its top and bottom jaws.)

Tooth Structure Vocabulary

This diagram shows the measurements and terms used in identification of the age of an elephant’s molar tooth. The hard enamel ridges have a characteristic pattern of lozenge shapes, also described as “loxodont” ridges (from which the scientific name Loxodonta is derived). These ridges are bonded together by cementum. Most of the tooth material is hard dentine.

Checks on tooth identification and ageing estimates

You might mis-identify a tooth and so assign the elephant to the wrong age group. To avoid this Laws introduces a number of checks to set record straight. These checks include measuring some features of the tooth to obtain data. These criteria are:-

(i) tooth size

(ii) laminary index

(iii) number of lamellae (a lamella is a thin layer, membrane, or plate of tissue).

Laws also recommended making comparisons with known-age lower jaws and considering the height and weight of the elephant and footprint size.

3. Aging elephants on tusk size and weight

As the introduction to this post suggests, the elephant “teeth” that are their most notable feature are their tusks. The largest tusks on record measured 338 cm in length and the heaviest tusk weighed 102.7 kg (222 lb) (males). Nowadays tusk weight of 45.5 kg is considered very good.

The bigger an elephant’s tusks are the older they are likely to be but this is not a very accurate method of determining elephant age.

4. Aging elephants on the weight of the eye’s lens

Another method of age determination involves the weighing lens of the elephant’s eye. (This obviously involves the age determination of a dead elephant.) During life, the lens continues to grow and becomes heavier, and there is a good relationship between the eye lens and age. This method is tedious and is not as reliable as looking at tooth wear and replacement.

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Conservationists need to have an accurate idea of the ages within an elephant population. Are the elephants in a given area breeding heavily, giving rise to a burgeoning population or is the population dwindling into a small group of aged individuals.


[1] Laws, R.M., “Age Criteria for the African Elephant, East African Wildlife Journal, Volume 4,  August, 1966


Leslee Maasdorp

Leslee Maasdorp devoted a huge proportion of her long and immensely productive life to writing educational material related to wildlife, the environment and conservation.

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