If the Arctic is no longer cold in the future, will polar bears become brown bears? If not, what animal can a polar bear evolve into?
This is a super problem, because it uses existing knowledge to create a new field. Studying biology is not like studying physics, but more like studying history. In other words, biological evolution follows specific laws. As long as we figure out these laws, it is possible to predict the future.
The ancestors of polar bears are brown bears, so how did brown bears become polar bears? If you answered that it was because the brown bear arrived at the North Pole and snow fell on it, it became a polar bear. Then next time it snows, you must not let the snow fall on you, otherwise you will become an “Arctic”.
If your answer is that the brown bear becomes a polar bear in order to obtain a protective color, then the explanation seems good. To prevent ultraviolet rays when you go to the beach, what a good example is that your skin will turn black! The beauty of this explanation is that you can do whatever you want, but if you want to fly every day, can you really grow wings? In any case, as long as you justify yourself, it’s not wrong! What is self-justification? That is, there are no loopholes or contradictions in your explanation.
We now propose a hypothesis. You can judge whether we can justify ourselves.
Long ago, the Arctic region had a warm climate and was covered by forests. Brown bears lived here and used young leaves and berries as their main food. Maybe you will ask, isn’t it honey? Do you think they are as comfortable as Winnie the Pooh? Sweets are very rare in the wild, and it is even more difficult to obtain high-energy foods such as honey. Maybe you would say that bears eat fish. Unfortunately, only a few brown bears receive this treatment. Every year, only in the season of salmon flow, the brown bears near the river gather here to enjoy the feast. Let’s talk about the story of the brown bear in the North Pole: Later, the temperature in the North Pole dropped, the forest disappeared, and the way back was flooded by the sea, and a group of brown bears were trapped here. Of course, this is a very slow process.
It became more and more difficult for brown bears to find food. At this time, a little bear with albinism appeared. Its fur was white. This is a genetic mutation that also occurs in forests. The difference is that the albino bear cub is a different species in the forest. It looks like a monster to other bears. It is almost impossible for it to reproduce. However, the white hair becomes an advantage in the snow-covered North Pole. It becomes a protective color, but not to prevent natural enemies. The bear has only one natural enemy, and that is human. The role of this protective color is similar to that of a lion color that can be incorporated into the grassland, in order to get close to the prey.
What is the prey of the brown bear? seal. Why are there seals? Because there are many fish in the water. There is very little life on the snow-covered land. Why are there fish in the water? Because there are many plankton in the water. Why are there plankton in such cold water? Because the water temperature is low, there is more oxygen dissolved in the water. This is a typical process of discovering the essence of things through in-depth questions. Usually, you can find the root cause by asking 3 to 5 questions.
Since it can catch prey and obtain high-energy food, little white bears have an advantage. They can not only survive, but also reproduce, and their offspring will also have albinism genes. This is the ancestor of the polar bear. Do you find this hypothesis a bit familiar? By the way, it is evolution. In fact, human society is similar to the natural ecosystem in many places.
Animals can reproduce in a suitable environment, and people can obtain achievements if they find their own domain. Even if your grade is the last in the class, it is like an albino bear in the forest, but once you find your own field, you can be king in this field. What you are good at in this field can be playing building blocks, drawing, writing, playing football…
Maybe you already believe this hypothesis, because it can justify itself. But don’t believe it easily, you need to find loopholes. We are constantly looking for loopholes to improve our model, so as to better predict the future. Remember what we are going to do? Predict the future of polar bears after the Arctic warms. It’s actually very simple. As long as you compare the polar bear with the brown bear, you will find the problem.
The weight of an adult polar bear can reach more than 600 kg, while the weight of a brown bear can only reach more than 300 kg. The polar bear is much heavier! why? Obviously not the result of albinism. You might say that polar bears eat meat and brown bears eat leaves and berries, so polar bears are big. This explanation seems pretty good. Europeans and Americans mainly eat meat, and Asians mainly use vegetables and food, so Europeans and Americans are taller than Asians.
Let’s look at another hypothesis to explain the problem of body shape. Ask everyone a simple question: A bowl of hot water and a bathtub of hot water have the same temperature, which one is slower? The answer is the bathtub. Because the bathtub has a large heat dissipation area, but more water. Therefore, in cold regions, it is very challenging for animals to maintain their own body temperature. The larger the figure, the slower the heat dissipation, which has an advantage in keeping warm. Europeans and Americans are larger than Africans because their ancestors lived in the cold regions of Northern Europe. The same is true for polar bears that are larger than brown bears.
Because the polar bear can keep warm by getting bigger, so the little white bear has grown up, right? If you understand the previous hypothesis, maybe you can perfect the process of polar bear evolution. The offspring of the little white bear have larger individuals. They have more offspring because of better heat preservation and advantages. Is it a bit familiar? Much like the evolutionary theory of the giraffe’s neck. In the end, the polar bear became what it is today.
The history is almost understood, we can predict the future. Global warming is a particularly real problem. The glaciers in the Arctic are melting and the polar bear habitat is destroyed. You might say that polar bears can swim and hunt seals in the water. Polar bears can indeed swim, but letting polar bears hunt in the water is as difficult as letting you catch dolphins in the water.
How do polar bears hunt? It must be on land. By the way, we must use our own advantages to deal with the disadvantages of others. Why do seals go to land? Because it is a mammal, it breathes through its lungs. The main job of the polar bear is to wait at the landing of the seal, because it has enough time to do nothing anyway.
In the future, the glaciers will melt and the area of ice will decrease. Polar bears will not be able to sit on the ice and wait for a delicious meal. You might say that seals burrow in the ice to give birth and must come on the ice. Polar bears still have food to eat. I have to admire you as “half polar bear expert”, but unfortunately, “half expert” is not enough to save polar bears.
The time for seals to give birth is very short each year. Can you spend one month each year for eating and other time for walking? Remember, polar bears walk in the North Pole at minus 50 degrees Celsius with strong winds, which consume a lot of energy.
Well, it seems that there is no way to stay on land, only going to the sky or going to the sea. Let’s talk about God first, how wonderful the “flying bear” is, it can fish like a bald eagle. Imagine a bear with wings flying over its head, then you are in danger!
It can grab you at any time. Are there any loopholes in this hypothesis? The ability to fly has evolved independently in nature many times, including birds, flying fish, insects, bats, and so on. Few mammals can fly, except for bats and flying squirrels. The thin films under their upper limbs serve as wings, which seems to indicate that flying is not suitable for mammals.
The bones of birds are hollow, very light, and have strong chest muscles. The bones of mammals are heavier because they have to support the body, and the breast muscles of mammals are like nothing compared to birds. The largest flying squirrel is tens of centimeters long, but it is still too “pediatric” compared to the huge polar bear. What a strong chest muscle a polar bear needs to fly!
In addition, the ancestors of bats and flying squirrels seem to have started gliding high, but there are no trees in the North Pole. Moreover, the polar bear first needs to get smaller before it can begin to glide. You may remember that large animals have an advantage in the Arctic, but now that the temperature is rising, it is no problem for animals to be smaller. In this way, it seems to be justified.
Of course, this process requires genetic mutation and then natural selection. In any case, even success will be a long process. However, imagine flying over the North Pole with a mammal that resembles a flying squirrel. It seems cool!
Flying is always a difficult task, because most animals on the earth cannot fly because gravity must be overcome. It seems to be much easier to live in the sea. Even life originated in the sea. What mammals live in the sea all year round? Whales, dolphins, dugongs (often known as mermaid, if you have seen its true face, you will very much doubt the aesthetics of the sailor who named it back then).
Here we also need to study history. The ancestors of whales and dolphins were land mammals, living near the water, and gradually evolved into what they are today. It looks good, at least polar bears don’t have to lose weight.
Nature is like a master of ingenuity, removing everything it doesn’t need. This is equivalent to doing subtraction, and genetic mutation is doing addition. Yes, it is possible to have today’s biodiversity because of the wrong copy. This particularly reminds us that we should treat mistakes with courtesy and maintain a tolerant attitude. In the process of evolution, these errors will lead you to places that are hard to reach. So as long as the conditions are met, it is entirely possible for a polar bear to evolve into a whale or dolphin look.
Remember, this is an extremely long process. It takes a long time to go to the sky or go to the sea, because the speed of gene mutation is very slow, so as long as the speed of climate warming is slow enough, it is enough. In the history of the earth, climate change is a long process, and organisms have enough time to evolve and adapt. But since the rise of mankind, our influence on nature has accelerated, and organisms have not had enough time to adapt to this mutation, and many have been eliminated. Climate warming is related to carbon emissions after the industrial revolution. This is the reason why we want to reduce carbon emissions now.
To sum up, first of all, this is a particularly good question, because it opens up a new field using the theory of evolution. Secondly, when we try to explain a phenomenon, we should try our best to justify ourselves, try to find loopholes, and then improve it, you can get a better explanation. Finally, we also asked questions in depth. This is a way to discover the essence of things, and it is also a very effective way of thinking.