The elephant’s trunk is almost omnipotent. It is not only used for breathing, you can compare it to a hand, a leg, a signal receiving device, a food catching device, a water pump, a dust collector, an excavator, etc. Specifically, elephants will use it to grab food and eat it, use it to drink water or take a shower, and use it as a weapon to kick down enemies.

Or you may use it to wipe your eyes, demonstrate to love rivals, use it to greet, walk, etc... Compared with the peculiar long trunk, many people don't know that elephants are the only animals other than humans. A mammal with a jaw. What's even more strange is that the elephant's ability to evolve such a long trunk has a deep connection with its chin. And all this starts with the ancestors of elephants who became extinct in prehistoric times.

When it comes to the ancestors of elephants, many people may think of the ancestor elephants that appeared 47 million years ago. From its appearance, it looks like a cross between a tapir and a hippopotamus, only as big as a pig. It did not have the long trunk of modern elephants, but the nostrils and lips were connected together, and it could also search for food dexterously. Therefore it is considered to be the prototype of the elephant trunk.

And because some of the characteristics of its teeth are similar to those of modern elephants. Therefore, people initially mistakenly thought it was the most primitive ancestor of modern elephants, but in fact, it was just an extinct branch of ancient elephants.

*Note: There are currently only three types of elephants left in the world, namely the Asian elephant, the African savanna elephant and the African forest elephant. Apart from this, all other elephants mentioned in this article are extinct.

Another 12 million years later, an ancient mastodon appeared that had sprouted deciduous teeth. Scientists currently believe that the ancient mastodon is the true ancestor of elephants. At that time, this elephant lived near what is now the Sahara Desert in North Africa. However, at that time, the desert areas with no trace of water were actually large tracts of swamps.

This means that most of the earliest ancestors of elephants lived in the water. On this basis, there is the theory of diving breathing to explain the reason for the existence of elephant trunks. In order to facilitate swimming in swamps, elephants evolved forward-protruding trunks to reach out of the water for ventilation.

However, with the changes in the forest climate, such as the disappearance of forests, the gradual drying up of oceans and rivers and other geographical factors. These ancient elephants were forced to live on land, but their trunks remained.

This hypothesis is currently considered the most reasonable explanation, but it still does not solve a problem. That is, why did the elephant's trunk become longer and longer later?

Judging from the fossil restoration pictures, the trunk of the ancient mastodon, the ancestor of the elephant, was relatively short. On the contrary, its flat lower teeth are like a huge shovel, very sharp. Scientists speculate that their lower teeth are used to help them scoop up plants from the water when foraging in swamps.

In fact, when ancient elephants moved to live on land, the situation changed. Generally speaking, land herbivores need to be much taller than carnivores. Because this helps pick leaves and other plants from higher places. In order to survive, elephants also have to make appropriate changes. As a result, the elephant grows bigger and taller, and its head gets further and further away from the ground.

But what should you do when you want to eat the delicious grass on the ground? Can't you just give up? Many animals, such as horses, cows, giraffes, and camels, do this by extending their necks. Because their long necks ensure that their mouths can reach the ground and prevent them from lying on the ground to eat grass. In this way, food can be enjoyed well whether it is high or low.

Compared to other animals, the elephant’s head is relatively heavy. No matter how long your neck is, you need strong neck muscles to lift your head. Adding its sharp teeth, the head would weigh several hundred kilograms. If it always has to move its neck a lot, it will have to have a crane on its shoulders. Since this road was blocked, those ancient elephants had to find another way.

Let’s first take a look at how those extinct elephants evolved? They chose a very simple and crude method. If your neck is not good, then try to lengthen your chin. So, they gradually elongate their mandibles to be able to reach food on the ground. Some elephants have long and wide mandibles and a pair of thick tusks.

One of the extreme examples is the very strange elephant species that appeared in the Miocene Era. Its lower jaw is extremely elongated, with a pair of flat lower incisors growing side by side at the front.

Because its shape resembles a large shovel, it was named the spade-toothed elephant. Its strange beak looks like a cross between a duck, a boar and a geoduck. At first, it was thought that spadedons foraged in mud and swamps. However, research has found that spadedons, like modern elephants, ate from trees.

Looking at the teeth of this type of food shoveler through a microscope, scientists found that there were no traces of shoveling the ground with teeth. On the contrary, there are many marks on it that look like they were rubbed against bark and branches.

When you see this, do you think of a creature with protruding teeth chewing a branch with its pouting mouth? This weird picture may make people lament the difficulty of survival. This side shows that the elephant's chin was still very useful at that time. The dinosaur Elephantus, which was about the same period as the spade-toothed elephant, evolved in another direction.

That's right, it's an elephant with only two long lower teeth. The genus lived in Asia, Europe and Africa from the Miocene to the Pleistocene. The largest individual could reach 12 tons and its body length was nearly 8 meters.

Unlike modern elephants, the tusks on its body did not grow forward, but curved toward the ground like hooks. So what is the use of this short, curved ivory?

In the final analysis, it is still to solve the problem of eating elephants. Scientists speculate that the tusks may have been used to push branches to eat leaves or dig bark. For the ancient mastodons, the ancestors of modern elephants, their increasingly longer jaws began to affect their flexibility of movement. The thick head, long tusks, and short trunk move the elephant's center of gravity forward.

In order to keep the head vertical, they often need to consume a lot of energy. The chin that grew bigger and bigger began to become useless, unable to support the weight of the elephant.

What’s even more troublesome is that the elephant’s head is too heavy to reach the leaves on the tall trees. At the same time, their huge jaws also prevent them from eating grass on the ground. Seeing that there is no way to survive, they have to find a way to reduce the weight of their heads and move their center of gravity back. So, over many generations of evolution, the elephant's head and chin became shorter and shorter. The nose connected to the upper lip becomes longer and longer and more flexible.

Those elephants that did not have time to evolve long trunks lost their competitive advantage, and climate change made their living environment worse and worse, and they became extinct one after another.

In any case, the elephant's trunk roughly goes through a process from scratch, from short to long. This gave rise to the slender and well-developed trunk of modern elephants. Even though an elephant's trunk is very soft and flexible, it contains 40,000 muscles. And because the maxillary nerve and facial nerve form the unique proboscis nerve, it becomes the organ with the most functions in the elephant. An elephant's trunk is capable of many things through precisely coordinated muscle contractions. It can lift hundreds of kilograms of weight and wipe its eyes very gently.

So, who can answer the lyrics in Crayon Shin-chan: "Elephant, elephant, why is your trunk so long?" A paper published in 2015 believed that the long trunk is responsible for maintaining the elephant's size. key.

Generally speaking, the energy consumed by metabolism is also positively correlated with body size. The larger the body, the more it needs to eat a lot, otherwise it will easily starve to death. Researchers believe that the elephant's trunk is equivalent to a soft mouth, which can increase the elephant's food intake at one time and make its food intake commensurate with its body weight. Not only that, it also greatly improves the quality of elephant food. Because of their huge size, elephants generally choose larger plants. However, as the plant grows in size, the proportion of leaves and the proportion of nitrogen will decrease. If you just eat it all at once, the efficiency of nutrient intake will be very low. This requires them to use their noses to select the most nutritious leaves before eating.

For this, the elephant’s mouth alone cannot do it. Only a flexible organ like the trunk that acts as a soft mouth can do it. Because soft tissue is difficult to fossilize. Therefore, there is still insufficient evidence to prove that it determined the evolution of elephant trunks. But it is also the most reliable hypothesis so far, and scientists are working hard to study it.

The article is reprinted from Zhihu@SMEInformer