Shulou(Shulou.com)11/24 Report--

Birth, aging, sickness and death is a natural law that can not be avoided by all living things. For wild animals, it is difficult to live to death, and injury, infection or being eaten is a more common outcome.

For some very large animals, although they are less likely to be eaten in adulthood, it seems difficult to die of old age. Elephants are such animals. In the wild, with the exception of poaching, elephants who die of natural causes mainly die of unexpected causes: hunger.

People and elephants are very similar in many ways, for example, they are both social animals and their lifespan is close. In theory, the lifespan of an elephant is 70 years old, but few elephants live to that age. They do not die of all kinds of diseases like human beings, but most of them starve to death.

But why do most elephants who die of natural causes starve to death?

This is because of their special teeth. The teeth mentioned here are not the "ivory" loved by poachers. In fact, the tusks of elephants are their upper incisors. Although many elephants die because of these two beautiful incisors, elephants die of natural causes because of their molars, another kind of tooth.

African elephant molars (Photo: wikimedia) Elephant teeth are very special in mammals. Almost all mammals have only three sets of molars, which cannot be renewed in adulthood and grow in a manner similar to the tip of a bamboo shoot.

But elephants are different. Elephants have no canine teeth, only incisors and six sets of molars. However, their upper and lower jaws are relatively short and cannot hold 6 sets (a total of 24) molars at the same time, so these six sets of molars appear in turn. Elephant molars, like conveyor belts, are gradually moved forward from the back of the mouth.

Elephants usually have only two sets of molars in their mouths, and the back one will slowly push the one in front of them out. (photo Source: Amboseli Trust for Elephants) at birth, the baby elephant carries four mini-molars. By the time they are 2 years old, these deciduous teeth will fall out, followed by larger and more lasting molars.

The relationship between six sets of molars and the stage of life in an elephant. (photo Source: doi.org/ 10.1016 / j.mambio.2018.12.004) these molars fall off with wear and are replaced by new molars. The service life of the new set of molars is often longer than that of the previous set and a little longer than the previous set. When a new tooth is grown, the root of the old tooth is absorbed by the upper and lower jaw. This process is quite uncomfortable, so elephants who change their teeth are usually grumpy.

Sadly, every time a new set of molars appears, the elephant's life countdown advances by one frame. By the time the sixth set of molars appears, their lives enter the final stage.

The 1st to 6th sets of molars of elephants. (photo: doi.org/ 10.1111 / j.1469-7998.1988.tb03760.x) this last set of molars appears in their heyday, about 30 years old.

The shape of the sixth set of molars is obviously different from that of the other sets. The end surfaces of the first five sets are smooth or smooth, but the end of the sixth set is sharp. The sixth set of molars takes 20 or 30 years, so elephants will lose life if they eat too much food that is hard to chew, such as bark and thorns.

The elephant had used up all its molars before he died because there were no replacement molars in the back row. (photo source: Amboseli Trust for Elephants) EleAid, a charity for elephant rescue, says this is why most older elephants die of hunger. Considering the special physiology of elephants, some zoos or rescue organizations provide special food for captive elephants. For example, Wildlife SOS, a wildlife rescue nonprofit, feeds old elephants that have reached the sixth set of molars with semi-liquid food.

In addition to elephants, only three species of manatees, one species of kangaroo (Petrogale concinna), and frost rodents (Heliophobius argenteocinereus) push their teeth from back to forward.

Frost Mouse (Heliophobius argenteocinereus) (Photo: wikimedia) that is, of the 5500 known mammals, fewer than 10 can constantly renew their molars.

But why do elephants have such progressive teeth?

Biologists Oscar W. Johnson and Irven O. Buss pointed out that the last three sets of molars in elephants are generally believed to correspond to the molars of other mammals in adulthood, but no one knows the origin of the first three sets of molars in elephants.

Some researchers believe that the first three sets are equivalent to deciduous molars. In other words, elephants still have baby teeth when they are in their teens.

Researchers have yet to figure out why elephants slowly teething with age.

Some researchers speculate that the secret of elephant teeth may be hidden in their bones.

This is because, although the lifespan of elephants is comparable to that of humans, their bones mature very late. The backbone of the elephant does not merge with the epiphysis until it is about 40 years old, which means that the elephant does not stop growing until the age of 40, and their last set of molars appear at about this stage.

The second reason is that there is a strong positive correlation between elephant tooth stage and bone length, which is also puzzling to researchers. Some people speculate that this may be because bone growth promotes tooth renewal, or vice versa.

Comparison of molars between adult elephants and young elephants. (photo Source: Amboseli Trust for Elephants) does this mean that elephants can live to "die of old age" as long as they protect their teeth? In any case, the outcome of elephants in natural conditions is almost certain.

Older elephants tend to be more pink and tender as they get older, because their ears and noses fade with age. On their deathbed, hungry elephants tend to look for water, so you can see pink elephants dying near the water.

Tikiri, an elephant engaged in animal shows in Sri Lanka, lived to the age of 78, which was her deathbed. (photo: Save Elephant Foundation) the location of the water source is shared in the same elephant family, so elephants of the same race tend to die together. And this may be the origin of the so-called elephant graveyard.

After watching the natural ending of elephant life, I don't know whether to envy them or feel sorry for them.

Enviably, they didn't have any serious illness except hunger before they died. Unfortunately, even if they escape poachers, they will inevitably die because of their unique teeth.

Human: stand at thirty.

Elephant: thirty shudders.

Reference:

Https://docs.qq.com/doc/DVHZ4aFBZWWFEcHdi

This article is from the official Wechat account: take Science Home (ID:steamforkids), written by Seven Jun

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