Why do elephants have tusks and we have hair? From Valentina, 6 years old, London
Elephant tusks are actually teeth. They are elongated incisors. We have incisors too – they’re the teeth at the front of our mouths, which we use for biting food. In elephants, these incisors continue to grow throughout their lives, extending from deep within their upper jaw.
The tusks are one of the most noticeable features of elephants, along with their massive body size and long trunk (one of the most amazing and versatile appendages in the animal world – but that is another story). In African elephants both males and females have tusks, while in Asian elephants only the males do.
While our incisors are used only for biting food, elephants use theirs for a whole range of activities, from digging holes and stripping bark from trees to fighting. They’ll even rest a weary trunk upon their tusks.
Generally speaking, male elephants use their impressive size to intimidate rivals and impress females. Size is so important in attracting mates that adult males have evolved to be twice as large as adult females, reaching a whopping seven metric tonnes. This is the weight of four family cars – with passengers. As part of the package, male elephant tusks are often five to seven times as large as those of adult females.
Some of the largest tusks ever recorded belonged to an old elephant called Ahmed, who lived in Kenya until the ripe old age of 65. His tusks were 3m in length and weighed 67kg each. That is 5kg more than the average weight of an adult human. Ahmed’s tusks were so big that it was rumoured he had to walk backwards uphill – a great story, but unlikely to be true.
Thanks to protection from the president of Kenya at the time, Ahmed got to live out his life in full, dying of old age in 1974. Sadly this is not the case for many elephants.
The cost of ivory
Humans have long been attracted to the beautiful tusks of elephants. Ivory remains one of the most highly prized materials in the natural world. Unfortunately, this demand has led to the deaths of thousands of elephants across Africa, because the only way that humans can get hold of the elephant’s tusks is by killing them. Those targeted are often the oldest and largest animals – because they have the biggest and therefore most valuable tusks.
This is not only tragic for individual animals, but also for the wider elephant population, as the oldest and wisest elephants play a key leadership role in elephant society. In fact, we conducted experiments showing that the oldest elephant matriarchs – the female leaders of the family groups – were much better than younger matriarchs at distinguishing more dangerous male lions from female lions using just the sound of their roars.
The killing of elephants for ivory has actually resulted in elephants having smaller tusks now than they did just a few decades ago (a 2015 study noted a 21%-37% decline). Plus, particularly in the areas where illegal killing has been most common, there is a huge increase in the number of elephants that don’t have any tusks at all. In a normal population you might expect two or three out of every hundred elephants to be tuskless, but in one population in Mozambique this has reached 32%.
Now, these elephants are likely to be at an advantage as they are much less likely to be targeted by poachers. A greater chance of surviving and breeding might explain why these tuskless animals have become more common in the population. (Studies are underway) to determine whether that is the case. What we don’t know is how not having tusks affects the day-to-day lives of these elephants when it comes to feeding and interacting with others in the population.
The good news, however, is that when protected and given space to roam, elephant populations can flourish. There are many excellent conservation projects across Africa and Asia working hard to ensure that elephants – and their tusks – are a part of the natural world for many years to come.
Indeed, by greatly reducing the number of elephants killed for their ivory, we can protect remaining populations, and potentially halt, or even reverse, the decline in tusk size. Who knows, maybe there is a young elephant in Africa who is destined to one day rival Ahmed and his mighty tusks.
As for hair …
Interestingly, elephants and humans both have hair. In fact, all mammals have hair at some point in their lives, even whales and dolphins. It is just present in differing amounts, which generally depends on how useful it is to the animal for keeping warm.
Elephants for example, have a very sparse covering of wiry hair across their bodies, which is only noticeable from very close up. Compare this to sea otters, which have some of the most densely packed hair in the mammal world: 130,000 hairs per sq cm.
The human head, by comparison, has between 124-200 hairs per sq cm. For sea otters, the value of that dense fur is to keep them warm in chilly seawater. Elephants commonly face the opposite challenge of needing to stay cool in hot environments, and therefore have very little hair.
Graeme Shannon does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
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This content was originally published by The Conversation. Original publishers retain all rights. It appears here for a limited time before automated archiving.By The Conversation