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

Not chasing stars and chasing pandas, recently, giant pandas such as "Menglan", "Huahua" and "Qizai" have been out of the circle, and various major Internet social networking platforms and short video platforms are shaking their lovely figures.

While the whole people pay attention to it, the doubts in many people's minds are magnified again: is a panda a bear, a cat, or a raccoon? Giant pandas and red pandas are both called pandas. Why do they look so different?

In fact, the seesaw battle over the classification of pandas has been going on for a long time, and there has been no winner so far, and efforts to find a more complete answer continue. In the Last Panda, George Shaler, an American biologist and environmentalist, traces the tug-of-war over the classification of pandas from the perspective of biological evolution.

By George Shaler, translated by Zhang Dingqi and translated by Hu Jinchu, at the end of the article, his passage is worth pondering:

Bear, raccoon and centrist all promote their views with the clearest logic, while giant pandas live peacefully in the mountains of Sichuan, never expecting to cause so much uproar in the animal community just because it is it.

The giant panda is still making faces at us with its false thumb.

A panda is a panda.

From "the Last Panda"

(us) George Shaler, Zhang Dingqi and Hu Jinchu

I pretended to disguise my true appearance.

Shakespeare's Othello

Is the giant panda a kind of bear? Is the red panda related to the giant panda? These two issues have been debated for a century.

Anatomists, behaviorists, paleontologists and molecular biologists have exerted great creativity and perseverance to direct this fascinating discussion to the evolutionary relationship between the two species. They constantly draw different conclusions based on different evidence and do not give up the pursuit of fast-changing answers. Their pursuit attitude is the best evidence of scientific logic and research methods, and only thorough investigation can bring intellectual satisfaction.

I have not put my energy into this matter, and the research in this area is not directly related to my interest, but I think the process of solving the riddle is very interesting.

Panda Huahua ©Tommyue the relationship between red panda and giant panda is extremely complicated. They are not only similar in name, but also quite similar in physique. Their heads, teeth and front claws have all evolved to be alike as a result of eating bamboo. The two also hold the bamboo in the same position, but the red panda lacks the sixth finger (or pseudo thumb) that the giant panda uses to control the bamboo stem. The similarities between the two kinds of pandas are obvious to all, but are they really related?

This has been the subject of scientific debate since Father Tam Weidao discovered the giant panda in 1869. He decided that the panda was a kind of bear, so he gave it the generic name "Ursus". The next year, Alphonse Mirnyi Edwards looked at the bone structure of the panda and thought it was not a bear, but related to a raccoon. Since then, two species of pandas have been moving in biological taxonomy in an increasingly mysterious and technical way.

Basically, it's a simple question. Some biologists observe the two kinds of pandas and think that there is no special relationship between them, and that their physical similarity is just the result of evolution caused by the same diet and lifestyle. They classify red pandas as raccoons, while giant pandas belong to the same family as bears.

Other biologists face the same evidence, but eventually insist that the two are relatives and live together on the evolutionary tree. They either set up another family for pandas or incorporate them into the raccoon family. Each family can come up with physical characteristics to support their story.

For example, the bear faction stresses that the physical structure of the giant panda is similar to that of the bear; the raccoon faction retorts that the giant panda's bones are too heavy. The Morris couple pointed out that the panda skeleton feels "like a 'fake' bear skeleton." The giant panda certainly looks like a bear, but is it a pure and simple bear? Or is it an animal that looks like a raccoon, but is too big and too heavy, so it needs strong legs to support it, so it looks like a bear?

To some extent, this long-delayed topic is actually a bit boring, which is enough to prove that science is uneasy about any uncertainty and is too attached to a radish, trying to put everything in a particular place.

If the giant panda is a bear, it is definitely an unorthodox bear. If the giant panda is a raccoon, it does have a large group of relatives who look out of place together, including the long-nosed raccoon (coati), the honey bear (kinkajou) with a strong tail grip, the living fossil covered-tailed raccoon (ringtail), which is exactly the same as its ancestors in the Oligocene 30 million years ago, and the raccoon with particularly flexible claws.

The long-nosed raccoon but the controversy also raises a basic scientific question-which characteristics are the most important and meaningful when it comes to animal classification? In an era when only the structure of the body needs to be considered, classification is no longer an easy task, but with the advent of molecular biology, there are more problems and conflicts, and all aspects of evidence must be included in the assessment. Surprisingly, the mystery of the origin of pandas is as fascinating as the question of why dinosaurs were wiped out.

When I give a speech, people often ask me at the end whether a panda is a bear or a raccoon. For the sake of brevity, I usually reply: "A panda is a panda."

When the Bear supporters were at their peak, it was clear that my view was in the minority. Taking a scientific review on this issue in the journal Nature in 1986 as an example, the author is obviously impatient with objections. He points out that some people still think that the two pandas are "closely related to each other. In fact, it seems quite obvious that all kinds of evidence almost refute this argument in unison." In his opinion, "there is irrefutable evidence that giant pandas have a close relationship with bears, and this dispute had better stop here."... there are only a small number of behavioral scholars who have not yet been convinced.

When you see the word "irrefutable evidence", you'd better be careful. Is this article promoting some biased dogma, or is it a close examination of existing evidence? The scientific community usually only absorbs and spreads the real conclusion quietly, and there is no need for any "almost unanimous voice" to transform heresy into the right one.

Giant panda cub "Liangyue" holds the keeper's leg during a naming ceremony at Yangjiaping Zoo in Chongqing. Photo by Chen Chao. Is it because I am lazy that I do not want to join the bear school, or am I unable to get rid of outdated ideas, or is there something questionable about the views supported by the majority?

I must admit that I was delighted to hear that giant pandas could not be classified even though they were dissected, observed, measured and treated by a series of advanced molecular technologies. Just as I hope the snowman (yeti) really exists, but never be discovered, I also hope that the giant panda will always keep its little secret. There is an intellectual pleasure in trying to solve such puzzles.

Molecular studies have provided important clues to the classification of pandas in recent years. DNA, which is composed of protein molecules, can closely reflect the heredity and evolution history of an animal. Proteins are made up of different amino acids.

According to the corollary, the degree of difference in the amino acids contained in any two proteins should be proportional to the time it takes for them to differentiate from different ancestors. Assuming that the process of molecular evolution is not affected by environmental factors, it is regular enough to act as a molecular clock to provide accurate information about the extent of genetic changes over the past millions of years.

Vincent Saric (Vincent Sarich) published a study in 1976. He used immunological techniques to compare the blood proteins of giant pandas, red pandas, bears and raccoons. The method is to inject the protein into the rabbit, and the antibody produced will produce a strong resistance to the protein, but the weaker the resistance to the similar protein contained in the more distant species.

He concluded: "there is no doubt about the relationship between giant pandas and other bears."... surprisingly, red pandas cannot be classified as other raccoons. " It seems to have differentiated from the same ancestor earlier than giant pandas and bears.

In 1985, Stephen O'Brien and his colleagues published an article called "using Molecular Science to solve the Mystery of the Origin of Giant Pandas" in the journal Nature. Giant pandas, bears and raccoons were compared using electrophoresis techniques (gel electrophoresis), which can classify proteins by charge and volume.

The researchers conducted a DNA mixing test to test the results of the experiment. Instead of comparing proteins, they compared the DNA that actually controls heredity in each species. The DNA obtained from one species is treated by radiation and mixed with the DNA of another species to measure the stability of the mixture. The conclusion of the study is as follows:

Red pandas were separated from raccoons and bears at about the same time, while the ancestors of giant pandas left the bear family quite late, just before the emergence of modern bears.

The differentiation of the panda Huahua Tuyuan network is said to have occurred 15 million to 25 million years ago. In other words, giant pandas are bears, while red pandas are raccoons. But less than a year after the study was published, another blood protein study showed that the two species of pandas were more closely related than giant pandas and bears or red pandas and raccoons.

Which blood protein should be used as the classification standard to identify the giant panda as the bear albumin (albumin) or the giant panda is not the bear hemoglobin (hemoglobin)? Molecular clocks are sometimes not as accurate as expected. Different proteins in the same tissue may mutate at different rates, and natural selection may have a greater effect on proteins such as hemoglobin than other proteins.

In 1989, David Goldman (David Goldman), Lassena Giri (Rathna Giri) and O'Brien joined the battlefield with a new study that included all seven genera of the bear family, plus giant pandas, red pandas and raccoons.

The study, published in the journal Evolution, "is based on the electrophoretic range of 289 radiation-marked fibroblast (fibroblast) proteins dissolved in two-dimensional electrophoresis among 44 isozymes (isozyme) dissolved in one-dimensional electrophoresis."

I have limited knowledge of molecular biology, and I don't understand what this kind of research is all about, let alone comment on their techniques or analysis. The experimental results generally affirm O'Brien 's report in 1985. The ancestors of raccoons and bears parted ways in the Oligocene, and 10 million years later, red pandas separated from raccoons. In the Miocene (Miocene), bears had three branches, the earliest was the ancestor of giant pandas, the second was the ancestor of present-day South American spectacled bear, and the last was the common ancestor of the other six genera of the bear family.

If the three of them try to use this set of research to resolve the panda debate, I am afraid they will be disappointed. According to the tradition of molecular research, the research that follows is bound to contradict their conclusions. If that's the case.

In 1991, Zhang Yaping and Shi Liming published a detailed analysis of the mitochondrial DNA of two pandas, Asian black bears and Malay bears in the journal Nature. They concluded that the giant panda has a closer relationship with the red panda than it has with the bear. They also pointed out: "there are 10, 000 to 10, 000 mitochondria in each cell; the pressure of natural selection on this DNA is very low. So the similarity of DNA between the two pandas is not necessarily the result of convergence and evolution."

The contradictory results of molecular research have taught us a very important science lesson. Complex and modern techniques do not necessarily explain what is puzzling. Morphology, paleontology and natural history continue to play an important role in solving the evolutionary mysteries of the two species of pandas.

Fossils often provide inspiration for the history of species, but there is often a big gap in the fossil record, especially pandas. The raccoon family is an early branch of the canine family, which originated in North America and later spread to Asia and Europe, where raccoon-like ancient raccoons (Sivanasua) were found in the Tertiary Miocene 2 million years ago. Bear is also a member of the canine family, which appeared in the genus Ursavus in the early Miocene. It is an animal that looks like a bear and is the same size as a medium-sized dog.

The first real panda (Parailurus), a small panda-like animal, appeared in southern Europe and North America in the early Pliocene (Pliocene), about 12 million years ago; it survived in Europe until the last ice age, when it was common in temperate forests. Some researchers believe that a bear-like animal called Agriarctos, which appeared in the middle Miocene, evolved from the genus Zuxiong and was the ancestor of the giant panda.

In 1989, Qiu Zhanxiang and his colleagues discovered a new fossil from the late Miocene in Yunnan, with teeth similar to those of giant pandas, but also with some primitive bear characteristics. The animal, named Ailurarctos lufengesis, is less than half the size of today's giant panda.

The giant panda suddenly appeared in the late Pliocene or early Pleistocene, probably no more than two or three million years ago. Panda fossils have been found in Myanmar, Vietnam, especially eastern China, as far north as Beijing, and are often unearthed along with Pleistocene Stegadon, so the two species are characteristic of local animal fossils. The pandas in the early Pleistocene were about half the size of today's pandas and were regarded as a separate species of mini panda (Ailuropoda microta).

New species are often created because a small number of ancient species are isolated, and these animals change their appearance and behavior patterns through natural selection until a considerable number of species with new characteristics are reached.

This process may be completed very quickly, leaving no species or so-called "lost links" in the fossil record that can be seen as intermediate transitions. It is not difficult for animals to achieve rapid evolution by rearranging and combining chromosomes, but evolution may also go through a single gene mutation, which is much slower. After the new species adapt to the environment, they may not change for millions of years, and at best make some small adjustments.

The time for giant pandas to acquire this form is not as long as many people claim, and it is still a newcomer to the earth. But its evolutionary history is still unknown.

Does the behavior pattern of the small giant panda provide clues to the evolution process? There are some problems with this research method. Species living in the same habitat may develop similar social structures and similar appearance, resulting in similar patterns of behavior without kinship.

When comparing species, we must first identify the ways in which behavior patterns are significantly affected by ecological conditions. For example, the quantity, quality and distribution of food can affect the action, activity cycle and social structure of animals. Similarly, two separate groups may behave differently, even if they belong to the same species. However, behavior patterns, such as using smell to mark or pronounce, can still operate in very different environments, so they are less likely to be changed by ecological pressure.

Giant pandas can make surprisingly rich sounds, some the same as bears, some the same as red pandas, and some all three. For example, bears also do the smack of anxiety, including teeth and lips, while red pandas and even long-kissed raccoons make similar sounds in slightly different ways.

Giant pandas make mournful cow barks, indicating that they are not very frustrated, similar to the grunts complained by bears or several raccoons, but for the latter, the sound has another function, which is for mothers to communicate with cubs.

The moan of Menglan, a giant panda, can be said to be unique to pandas, including howling, whining and long-stretched groans. Only giant pandas and bears send out such warning signals.

The most noteworthy is the call of giant pandas like sheep, which is used to show friendliness when they meet their own kind. As Gustav Peters of the Alexander Koenig Museum Museum in Alexandria in Bonn points out, the sheep call is equivalent to the squeak of red pandas and all raccoons, but bears do not have similar calls.

For an animal as big as a giant panda, we don't usually expect it to make high-frequency calls; in fact, the giant panda has several calls that are too high to match the status of a large carnivore like it.

The cubs who are still breast-feeding will make a strange sound, a continuous wow, sharp and rapid, almost a loud guttural sound. Although the role of this sound is not clear, it is obviously very important to the mother, probably asking her to lie still and secrete milk. Giant pandas don't make that sound. If the giant panda is a bear, I can't understand why the baby panda doesn't make such an important sound.

The act of marking is of course determined by the inherent glands of the species and the location of the glands. Giant pandas scratch the bark with their claws, pee, and rub objects with glandular sacs near the anus. Bears lack such glands, but they still stand up and rub the trunk with their shoulders, necks and heads. They also bite or scratch the bark to leave their body odor.

Red pandas will ride on tree stumps or other protrusions and use the action of drawing circles to leave the smell of anal glands, which is very close to that of giant pandas; male red pandas will also pee. Miles Roberts (Miles Roberts) of the National Zoo in Washington found that red pandas have small holes in the soles of their feet that secrete a transparent liquid, which is a way to leave special information when walking. Most raccoons use urine or anal glands as markers and behave like pandas, but with slightly different details.

The newborns of giant pandas and bears are both very small. Mothers of black bears weigh 250 times as much as their newborns, while giant pandas weigh nearly nine hundred times. (by contrast, a raccoon mother is only 55 times the weight of her baby. Why are the newborns of giant pandas so small?

Reproduction is affected by ecological conditions, especially depending on the amount of high-quality food available to mothers and babies in different seasons. Bears, like giant pandas, have delayed implantation of fertilized eggs. Bears in temperate regions mate and conceive in June, but the fertilized eggs do not attach to the uterine wall until about 60 days before the cub is born in January or February, allowing the embryo to develop, during which the mother is hibernating.

If the bear cub is large and active, the sleepy mother may not be able to meet its milk supply needs, and the fat hoarded by the mother may not be used to end hibernation. Giant pandas do not hibernate, and different pressures of natural selection make newborns particularly petite. The cubs of bears and giant pandas are both small, but that doesn't mean they are related. It's just that why the newborn giant panda is so small is a question that puzzles me.

I found some clues from observing the red panda. Red pandas also delay bed (but not in raccoons), and their average gestation period is 131 days, roughly the same as that of giant pandas. The daily weight gain of giant panda embryos is less than half that of bear embryos, but is closer to that of red pandas or raccoons. Red pandas give birth to one or two babies, and their newborns weigh about the same as giant pandas, about 113 grams. Female red pandas hide their children in tree holes. They grow slowly and don't leave the nest until they are three months old, which is longer than raccoons or long-nosed raccoons.

All these facts show that giant pandas reproduce more like small mammals such as red pandas than bears. Of course, there are some adjustments due to the size of the body. For example, giant panda cubs stay in the nest for a long time and need to be taken care of by their mother for more than 18 months, so that the mother's lactation period will be extended to the next mating season and will not be able to give birth every year.

Relatively speaking, red panda cubs can be independent when they are eight months old, so females can mate every year. I infer from this that in terms of reproduction, giant pandas also maintain the characteristics of many smaller panda-like ancestors, with only a small number of organs degraded to adapt to the current state.

Panda Huahua and Mom Tu Yuan Network judge from sporadic evidence. The relationship between giant pandas and red pandas is irrefutable: special structures of the head, teeth and front claws; various reproductive features; certain modes of sound; and the act of marking with smells.

If the two species are not related, we must admit that they converge to a greater extent than the evidence allows. But when did their differentiation begin? It is very likely that giant pandas and red pandas had the same ancestors in the Miocene.

So should the two pandas belong to the bear family or the raccoon family? Although the giant panda has a close relationship with the bear, I still think it is not just a bear. And even small genetic differences between the two species can have a profound impact on appearance and behavior. Chimpanzees share 99% of the same genes as humans.

There is no doubt that we should regard chimpanzees as a member of the family. But are chimpanzees human? There are several ways to classify giant pandas and red pandas. Should giant pandas be included in the bear family or another family, while red pandas should be placed in the raccoon family? Will each of the two pandas have a separate family? Will two kinds of pandas be combined into one panda family (Ailuridae)? I am more in favor of the last method. Science will one day overcome all contradictions and evolutionary difficulties and summarize the classification of pandas.

There is no winner in this tug-of-war for animal classification. The search for a more complete answer continues. "Bear, raccoon and centrist all promote their views with the clearest logic, while giant pandas live peacefully in the mountains of Sichuan, never expecting that just because it is it, it will cause so much uproar in the animal community." Edwin Colbert (Edwin Colbert) wrote in 1938. The giant panda is still making faces at us with its false thumb.

This article is from the official account of Wechat: non-fictional time (ID:non-fiction702), by George Shaler

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