"Walking" to achieve great success! The secret of "Xiang" all the way to the north...

Recently, Asian elephants "strolled" and performed great deeds! Recently, police officers at the border of Xishuangbanna, Yunnan received reports from the public that wild Asian elephants were active near the highway. However, when the thermal image of the elephant was displayed on the screen, the police found suspicious figures nearby! Moreover, the Asian elephants were always moving in the direction of the suspected smugglers. With the help of the Asian elephants "leading the way", the police arrested the illegal immigrants on the spot! Netizens commented:

Image source: People's Daily

Speaking of Asian elephants "strolling", everyone should be familiar with it. On April 16, 2021, more than a dozen Asian elephants in Yunnan formed a "strolling and eating group" and migrated northward. After nearly 120 days and 1,300 kilometers of circuitous progress, 14 elephants "returned home" and returned to the nature reserve to continue their lives.

To this day, these Asian elephants migrating north are still a focus of attention. What is the truth behind these Asian elephants' "exodus"?

August 12 is World Elephant Day. Lin Jingxing, a researcher at the Institute of Geology, Chinese Academy of Geological Sciences, gave a popular science lecture titled "A New Understanding of the Elephant's Northward Migration" at the 715th Capital Science Lecture Hall , which brought us a new understanding of the elephant's northward migration from the perspectives of geological history and the evolution and migration of paleontology. Come and learn together!

Lin Jingxing

Researcher, Institute of Geology, Chinese Academy of Geological Sciences

Why did the Yunnan elephants migrate north?

The elephant migration started on April 16, 2021. Why did this group of elephants migrate north? There are three mainstream views : one is to find a new habitat. Some people think that it is because the elephant population has increased and the habitat is too small, so they migrate north to find a larger place. The reason for this view is that the number of elephants was 190 40 years ago, and now it is more than 300.

However, everyone who has been to Xishuangbanna knows that the place is too big. Let alone 300 elephants, such a good environment can easily support 600 elephants, so this view is not valid. The second view is to find new food. You should know that the primitive forest of Xishuangbanna belongs to the subtropical forest, and the food there is enough for 300 elephants to eat, so this view is also wrong. The third view is the influence of geomagnetic storms, which is even more untenable. Geomagnetic storms occur every few years. Why didn't they migrate north before? Therefore, there is no basis for the view that geomagnetic storms affect the elephants. The above three mainstream views are not correct, so what is the reason?

In the 4.6 billion years since the birth of the Earth, there have been many large-scale migrations of organisms: when the climate warms, tropical and subtropical animals migrate north; when the climate cools, organisms in cold zones migrate south... This phenomenon has occurred countless times.

Migration of ancient and modern elephants

In order to find evidence of elephant migration, we turned our attention to ancient elephants. Why did we turn to ancient elephants? Because they live in tropical and subtropical areas, they are very sensitive to the climate. When it gets cold, they will migrate south; when it gets hot, they will migrate north. So we want to see if ancient elephants in China actually migrated at that time.

There are some differences between ancient elephants and modern elephants. The easiest way to distinguish them is that the tusks of elephants are generally curved, while those of ancient elephants are straight. Of course, ancient elephants are the ancestors of modern elephants.

Ancient Elephant

So did the ancient elephants migrate?

Of course they did migrate, and they migrated northward. Between 100,000 and 40,000 years ago, the southernmost distribution of ancient elephants was north of the Huai River, between the Huai River and the Yellow River. There were also some in Jinan, but the northernmost distribution of ancient elephants was near Beijing, which was the northernmost limit of their distribution.

Why go near Beijing?

This shows that Beijing was already very warm at that time, much warmer than it is now. In a word, Beijing had a tropical or subtropical climate at that time. This was the result of climate change, which means that the temperature rose, so the ancient elephants migrated northward.

Moving forward to the present day, to the Spring and Autumn Period and the Warring States Period, we will look at the great migration of modern elephants. From more than 2,000 years ago to the present, there are very few fossil records. How can we study the migration of modern elephants?

There are many clues in relevant literature records. Various records show that there were still elephants in the Yellow River Basin during the Spring and Autumn Period and the Warring States Period. Elephants lived in Sichuan, Hubei, Hunan, Zhejiang and other places. However, the modern elephants distributed in China have been migrating continuously from north to south. In modern times, only some areas in southern Yunnan still have wild modern elephants in the country. This is due to climate reasons and human factors, but the main reason should be climate.

We study the past to understand the present, and we study the present to understand the future. If the climate changes in the future, whether it becomes colder or warmer, humans will have corresponding countermeasures, or at least we will be mentally prepared. This is why geologists around the world study climate change, because climate change is closely related to human life.

What are the factors behind modern elephant migration?

First of all, we need to know how they migrate, where they migrate to, whether they migrate to cold places or hot places. Elephants are typical large tropical and subtropical animals, also called macroscopic animals. Researching elephants is more credible, because where elephants migrate to indicates that the place must have become hotter, and studying other animals may not achieve this effect. So we must choose indicator animals, and elephants are an indicator animal of temperature and climate warming. They are standard tropical and subtropical animals, so only by studying elephants can people believe you and your conclusions can stand up.

Elephants may migrate north in the future

Historical data show that in the last 100,000 years, the average annual temperature in eastern China was 7 degrees higher than it is now during the warmest period, and 6 degrees lower during the coldest ice age. Based on this climate data, we can summarize the real reason for the northward migration of Yunnan elephants, which is simply global warming.

Regarding global warming, mainstream scientists have two opinions . One is that there are too many carbon dioxide emissions; the second is that it is a natural change in the geological history cycle , that is, the historical cycle changes in the rotation of the earth and the sun. If you admit that the first reason is that there are too many carbon dioxide emissions, then of course emissions must be reduced, but I am more inclined to believe that it is a cyclical change in the geological history climate, including changes in the rotation of the earth, changes in the speed, changes in the sun, etc.

So from the perspective of the 4.6 billion years of history of the earth and the development of organisms, the migration of elephants is caused by natural climate change, not by human factors, not by changes in food caused by human factors, not by insufficient land, and certainly not by magnetic storms. As the climate warms, tropical and subtropical organisms will definitely migrate north; as the temperature cools, polar organisms will definitely migrate south . This trend of change is unstoppable, so elephants will continue to migrate north in the future.

Produced by Beijing Association for Science and Technology Media Center