Today, let's talk about vampire bats. This rare and mysterious creature.
There are many bloodthirsty creatures in nature, but only vampire bats are given the most misunderstandings and prejudices by humans. They are also the longest exaggerated and interpreted existence in literary and artistic works. In movies, novels, and games, they often play a negative role, and often serve as a background to set off a strange atmosphere, which further deepens people's fear and suspicion of them.
Today, we will follow a vampire bat research expert to understand these so-called small vampires, this seemingly insignificant biological group, in fact, in their own way, affecting our lives. It is only at your and my interest in how you perceive it.
In this Frankenstein feast, you'll learn some interesting questions:
For example, how did early naturalists describe vampire bats?
How do they relate to vampire legends?
Why did bats evolve into vampires?
Birds with richer varieties and a longer history, why don't they suck blood?
First, let's talk about the leader, Bill Schutter, associate professor of biology at Long Island University. He is a graduate of the American Museum of Natural History, specializing in the field of vertebrates, and is also an iron fan explorer for various types of bats.
In 2002, Professor Bill came to the Eastern Caribbean, where there is a small island called Trinidad. The purpose of his trip was rather simple — to take a good look at vampire bats.
Satellite photographs of Trinidad
The first stop is a farm outside Trinidad. No sooner had he arrived there than Bill saw a strange sight. Under the grapefruit tree in the corner of the farm, two chickens were mooring the ground, their movements stiff, nervous, as if they were very frightened, and there was a pool of blood on the ground around them.
This blood stain, which was already half dry, was probably left over from last night from time. Bill stared at the chickens, hoping to find one from the group of creatures that looked alike, kissed by vampire bats, and surely had blood on its body.
The vampire bat coiled in this place is also the first kind we want to introduce - the white-winged vampire bat. It is a relatively rare and special branch of the entire population.
Bats are the only type of mammal that can fly. They are found all over the globe, accounting for one-fifth of mammals, have lived on Earth for nearly 90 million years, and are ancient creatures that have fought with dinosaurs. Bat populations are extremely large, about 1100 species, but most of them feed on plants and insects. There are only three kinds of real blood suckers.
In this small family with only three members, the white-winged vampire bat is even more maverick. It uses trees as its habitat and basically eats only the blood of poultry.
White-winged vampire bat
It's like the scene Professor Bill speculated from this pool of blood. The white-winged vampire bat hunts in a very special way. Like spiders, they crawl across the farm and slowly approach the fat hens. The hen in the egg stage is unusually alert, and it keeps an eye on the guys who want to get close to her. But bats, on the other hand, can rely on silent crawling, lurk in front of the hen, and gently rub the hen's chest with the protruding tip of the nose. In this way, the hen can quickly relax. Because, it's the same thing a chicken would do to its mother.
Then, the white-winged vampire bat plunged its head under the hen's feathers, a sensitive spot called the egg-holding point, where the blood vessels are dense, where the chicks are used for warmth and the bats for feasting. Its chick-like demeanor, and almost painless nibbling, made the hen shake its feathers and crouch down. Obviously, this imitation of chickens is not innately engraved in the genes of bats, so how do they learn it?
To answer this question, we have to continue with the professor, deep into the forests of the Trinidadian frontier.
In August in South America, the climate was humid and sweltering, and Bill and his partner, riding a jeep, bumped all the way to the edge of the dense forest. There is almost no sign of human activity, only a few clearings and dilapidated slab houses looming from the bushes. There was no running water, no cell phone signal, just an old-fashioned diesel generator, buzzing.
Bill chose an extraordinarily stout grapefruit tree and pulled up a large net on it, ready to catch the lost bat. Locals also know that every night, there are domestic chickens and guinea fowl entrenched in the trees to hide from predators on the ground. But they did not expect that there was another kind of aerial hunter who would covet their own blood. This caused many chickens to fall weakly to the ground due to excessive blood loss. These mysterious guys are vampire bats.
Trinidad
Indeed, the indigenous people of Trinidad are familiar with the countless bats that inhabit it. They will light lamps with the grease of ordinary bats, but they are still full of awe and fear for the vampire bats in them. Vampire bats also bring a lot of trouble to people and animals here. The bitten animals, which may continue to bleed for a long time, attract swarms of flies, spread a wide variety of microorganisms, and then infect and die.
It is also believed that the biggest threat of vampire bats to humans is the spread of rabies. The local Department of Virus Control, for many years, has been working to eliminate vampire bats. In local legends, the threat of vampire bats is more specific and absurd, and it is believed that it will transform into a dry and thin old woman, and at night, it will shed its human skin and turn into a ball of fire to attack humans. The only way to face this monster is to sprinkle rice on the door of the house, and the blood-sucking old woman will be addicted to counting the grains of rice and will not bother to invade people's homes.
In fact, there are 58 species of bats native to Trinidad, of which only two are blood-sucking. But vampire bats are not the natural hosts of rabies, which means that unless they have been infected with rabies first, it is difficult to say that they are rabies transmitters.
Bats entrenched in caves
The camera goes back to Professor Bill. The big nets they laid soon reaped. In the flashlight, three black figures struggled in the tough mesh, all vampire bats, obviously much stronger than their vegetarian counterparts. "It's the White-winged Vampire Bat!" Professor Bill was overjoyed, and he put on his thick leather gloves and carefully removed the captives from the net. Soon, they will be sent to the Institute of New Mexico, where they will no longer have to prey on the hapless hens themselves.
At this time, in the night sky of South America, the full moon rises. Professor Bill said that the real vampire bats are actually very afraid of the moonlight, and the bridges in the movie are all deceitful.
So why is the professor so fond of vampire bats, seemingly ugly and weird creatures? This has to start with an expedition 9 years ago.
That's when Professor Bill first came to Trinidad. The destination of the trip is a ruin in the northern part of the city, the long-abandoned Wallerfield Air Force Base. It was originally the South Atlantic command center of the U.S. Military during World War II, and was the largest and busiest air base in the world at that time. Now, all that's left is a rubble.
The professor, approved by trinidad's Ministry of Agriculture, would spend two weeks on the island collecting all the information about vampire bats. His friend, on the other hand, introduced the abandoned fortress, which is now just as infamous, not only with local gangsters and criminals, but also with countless bats.
Arriving at Wallerfield, Bill discovers that the massive buildings that once stood here have been eroded and covered by Trinidad's unique prairie vegetation, like a green steel jungle. The only relatively intact preservation is a concrete-poured bunker that stands out among the tangled plants. And its owner is thousands of bats.
Professor Bill and his wife carefully walked through the narrow passages of the bunker. The ceiling has collapsed there, and there is a hidden risk of collapse at any time. In the doorway, in the corridors, there were large, sticky, unidentified substances everywhere, but it was not a trace left by some nameless monster, but only bat droppings.
Fortunately, the dungeon is not pitch black. There are also small windows that allow for daylight. Light shot in obliquely through the gap, illuminating a three-meter-high cement pier. With the footsteps of the living, countless dusts were stirred up and danced. They cut through the dense web of dust and went deeper into the shadows. In front of him, there was a fairly spacious space, and in the corner of the room, Professor Bill found a mysterious small room with a radius of less than two square meters. He had planned to go inside to have a look, but was stopped by his companions. When I lit the headlamp, I found that the floor of the cubicle reflected an eerie glow.
It turned out that it was not a hidden treasure trove at all, but an elevator shaft. Bill kicked over a piece of rubble, only to hear a pop, and the stone actually crossed the floor of the room and disappeared in front of his eyes. At first, people thought it was the surface of the water, but when they looked closer, they realized that it wasn't water at all. The floor of the elevator shaft is actually a swamp full of debris and debris, filled with a viscous black oily liquid. It is a mixture of bat urine, bird droppings and rain. Fragments of the ceiling floated on this layer of black oil, looking like the ground that a group of people had just walked through, but more dangerous than traps.
The partner told Bill that a squad had come here to watch bats. One of the women, halfway gone, was gone, and it was here that they finally found her. This elevator shaft, in fact, is several stories deep, and once it falls, the consequences are unimaginable.
In addition to bats, there are a large number of toads living in elevator shafts. They feed on bat cubs. The partner suggested that the bat should be clearly seen from the stairs next to the elevator shaft to the high place. A group of people climbed up the stairs and swept the walls with the light of the headlamps, and in the top corner of the room, there were three black shadows lying there, like Christmas trees, hanging upside down on the edge of the patio.
Suddenly, a black shadow turned sideways and spread its wings more than half a meter wide. Bill quickly recognized it as the second largest spear-kissed bat in the region, known for its long, pointed mouth. Bill assembles a net and prepares to show off, but his partner reminds him that with this rudimentary device, he can't catch a clever and flexible vampire bat.
Originally, there were three species of vampire bats, namely the common vampire bat, the white-winged vampire bat and the hair-legged vampire bat. These three types have large behavioral differences. For example, the white-winged vampire bat can make movements that many other bats dare not imagine, crawling like a spider on the ground is an example. The flight of vampire bats, especially the take-off action, is also different from the same family, because the blood sucker increases weight, they can not accelerate the body by flapping their wings, so they use a similar movement of standing up on the ground and catapulting from the ground. These maverick approaches lead to the conclusion about the evolution of species— vampire bats have roughly the same range of activity, and in order to reduce competition for resources, they must evolve these differences. But when the point of view is there, it still needs reliable evidence to support it. Scientific research must be rigorous and meticulous, stand the test, and speak with data facts. Therefore, the main purpose of this ruin expedition is to capture live vampire bats.
But this capture operation can be described as a bumpy road ahead. The ecology of vampire bats in the local area is already at stake. Since more than half a century ago, the U.S. military has tried to eradicate the bats that surround the base. They used explosives, navels and flamethrowers against bats hiding in caves. Thousands of creatures were killed, and more than 8,000 caves were destroyed around Brazil alone. Ironically, most of those killed are ordinary bats, and vampire bats hidden deep in caves are rarely actually affected. What's more, these extermination actions have made the modern vampire bat evolve into a species that is opportunistic, has a high IQ, and is tough and strong.
Pull your gaze back to the ruins. As the expedition team went deeper into the building, the pungent smell of ammonia in the air became stronger. They know they've come to the heart of the bats. Headlamps, footsteps and conversations awakened the mysterious inhabitants of the cellar, and hundreds of black shadows flashed by, emitting unrecognizable high-frequency cries.
Bill turned off his headlight, lifted the net, and waved it a few times into the sky. Soon, the weight was felt at the end of the net. Bill reached into the net and carefully grabbed a little guy. Unfortunately, this delicate little bat, with its wide snout and long tongue, is not a vampire bat, but a long-tongued bat that depends on nectar for its livelihood. There are about 500 species of tropical plants that rely on this hummingbird-like bat for pollination. Bats, like other animals, work in tandem with insects and plants.
Unfortunately, this expedition did not harvest vampire bats. It was past dusk, the sky was getting darker, and they had to leave the cellar before dark. Bill took one last look at the little bat, then flicked it to let it regain its freedom.
Before we start the next leg of our journey, let's talk about the image interpretation of vampire bats.
In various literary and artistic works, they always play some disgraceful roles. People are accustomed to projecting their fears and doubts onto these nocturnal animals. For example, in European vampire legends, bats are generally evil accomplices of their earl masters. There are also scenes where vampires take on bat forms and travel through the night sky, coveting the blood of mortals. Of course, these hypotheses are 18,000 miles away from reality, but they also lead to some interesting questions, that is, why do bats contact vampires as mentioned at the beginning? This has a lot to do with how early researchers viewed them.
To make a long story short, give the microphone to the 15th-century New World explorers.
These travelers, trekking all the way from the Americas, returned to Europe, naturally bringing with them countless stories and legends. Except for the strange talk about sea monsters and giants. It has been found that there is indeed a species of bat that can suck blood, and there are also records of attacking people and livestock at night. However, under the false rumors and processing rendering, the vampire bats in the story will be exaggerated into a giant beast with an abominable face and a body size of more than two meters. No one really takes the time to correct and figure out these stories, and according to the rule of thumb, the biggest and ugliest bat becomes the embodiment of a vampire. And this kind of rumor, if there is a scholar's support, it is even more difficult to distinguish between true and false.
In the case of Professor Bill's research, several naturalists who observed and documented bats in the early days were fully responsible for this misconception. Without in-depth research on bat ecology and eating habits, they used the blood-sucking word in Latin to name some poor guys who were completely vegetarian.
For example, a curator from the Bavarian Academy of Sciences, Johann Spiekers, made a fatal mistake. Beginning in 1817, he spent three years collecting thousands of bat specimens throughout Brazil. Many of them are unprecedented in Europeans. But he knew nothing about the bats he was snaring and often confused different species. For example, the long-tongued bat that Professor Bill caught before was regarded by him as a blood-sucking species, and Spixar judged only from its appearance that this bat would use its tongue to pierce the hunting body and feed their flesh and blood.
These misconceptions about bats continued into the 19th century and gradually reached a climax. At that time, the Industrial Revolution stimulated the curiosity and desire of the whole society to collect. Collectors of all kinds, turning their attention to the tropics, are in dire need of a large number of exotic special products. Naturally, being able to obtain a bat specimen, called a vampire demon, has also become a vanity that people are eagerly pursuing. People tend to believe that what is easily identifiable and distinguishable, coupled with the media, makes discrimination and misunderstandings worse.
Fortunately, scientific research also began at this time, and correct cognition did not stop advancing. In 1810, the Spanish cartographer, Felix Assara, searched for and fought the world's first and most common common vampire bat in Paraguay. A few years later, in Brazil, a hairy bat with a furry leg was found, that is, a hairy-legged vampire bat.
Hairy-legged vampire bats
In 1832, Charles Darwin, also on his own journey around the world, observed vampire bats, sucking the blood of horses. At that time, Darwin was camping in the Chilean mountains, and he noticed that a horse was unusually grumpy, so he asked the servant to go and watch, and without thinking, the servant reached out and groped on the horse's back, and caught a vampire bat. It is also this opportunity that the English-speaking world finally has the biological term of blood sucking.
The relatively unique appearance of these bats has also become the premise of misunderstanding. We now know that, depending on their appearance and range of activity, common, white-winged, and hair-legged vampire bats are all classified into the family Vampire bats, which also belong to the family Pterodactylidae. They all inhabit the American continent and have a protruding, spear-like nose that looks sharp and is actually soft.
This characteristic, of course, implies its aggressiveness to those who hold empiricism as a holy scripture. Some naturalists believe that the noses of vampire bats act like swords, and they will pierce their noses into the body of their prey to release blood. But in fact, these noses are tools used by bats to amplify ultrasonic waves, used to echolocate in dark environments. Vampire bats, although belonging to the family Manta, do not have a nose as prominent as that of their siblings. They are more used to assume the function of perceiving temperature changes, which is also an evolution to approach warm-blooded animals in a lightless environment.
Imagine a vampire bat, on a dark night without moonlight, relying on heat sensors hidden in the nasal lobes, like infrared imagers, to detect animals under the skin, where blood vessels are dense, and where temperatures are higher. They can even use sound to identify which animal has been sucked into blood before, and that's the preferred target.
And these shape records, however, let the early naturalists, come to the wrong conclusion, they simply according to the shape of the nose lobe, hundreds of non-vampire bats, wrongly classified as vampire bats. It was not until the end of the 19th century that these misconceptions were gradually clarified in the academic community, and the identities of the three vampire bats were recognized in turn. But the misconceptions left to the people have unfortunately become a footnote to vampire legends, reinforcing their artistic effects.
Blood-sucking process
So, let's go back to the origin of the vampire. The origin of the modern word vampire, probably a proper noun in Slavic, first appeared in the 11th century, in a Russian manuscript. In Russia, there are also many similar rumors. 600 years later, someone translated this Russian word into English to describe some horrible zombies hungry for the blood of living people.
All over the world, there are similar legends of blood-sucking creatures. From ancient Babylon to ancient Greek folklore, there is no shortage of similar records. Every culture will also give them a proper noun. And this legend, which arose in Europe, probably pushed back to the 15th century, and in the 18th century, it developed to the point of hysteria. At that time, people had a kind of "near-death panic", they were worried that the buried dead would suddenly come back to life, and even dig up the corpses in the cemetery and smash the wooden stakes into the heart.
Interestingly, vampire legends vary from place to place due to local influences. For example, the Slavs believed that vampires would not turn into bats, but into inanimate things like flames and smoke; gypsies living in the Balkans had a special fear of food, and they felt that pumpkins that were kept for more than ten days would become vampires. But how these toothless guys suck blood is really unimaginable.
Evolution of the image of the European vampire
The hatred of disease is also the driving force behind the vampire legend. Rabies can lead to schizophrenia, and in some ancient European cases, some criminals were so obsessed with blood that they may have been victims of rabies, devouring blood to get satisfaction.
Celebrities and vampires are probably related to the nickname "Bloody Mary", Countess Elisabeth Barthori of the Kingdom of Hungary. At first, she only had sadistic tendencies, but later gradually believed that blood was the effect of rejuvenating people and maintaining their youth forever. Thus began a tragedy of torturing and maiming hundreds of young girls.
Misrepresentations of some epidemics, in Professor Bill's view, may also be one of the sources of vampire legends. In ancient times, Europeans often pushed some sudden evil diseases to vampire attacks. For example, tuberculosis, the Black Death and so on. In the era of extreme medical backwardness, it is difficult for ordinary people to judge whether a person is really dead, and after a person is buried hastily, there is no shortage of so-called "resurrection from the dead" cases.
In this cultural atmosphere, a real vampire creature, a vampire bat, once discovered, will naturally be associated with vampires. People do not understand this creature, but rely only on empiricism to give them a cloak of mystery and unknown. As a result, many native European bats have also been attacked together and are regarded as accomplices of vampires. Imagination and speculation have replaced reason and science, and this kind of rare thing to see in the daytime, but at night, the little guy who flies with his wings becomes an excellent object of superstition and fear. In a sense, the discovery of vampire bats has even contributed to the spread of vampire legends. In 1897, the publication of a novel made the connection between the two even more permanent.
In Stoker's "Dracula", Count Dracula also has a prototype. He was the 15th-century governor of Romania and was named Vlad III. In his time, Vlad was a hero in the hearts of the locals against the Muslim army. But the grand duke treated his captives with great cruelty. His favorite puncture torture was to pierce a stake into the chest or navel of a captive's heart, and sometimes the stakes would be polished smooth, greased, and slowly inserted from the victim's anus. It is said that his territory is full of thousands of bodies that have been punctured and killed. Governor Vlad, it was for this reason that he earned the title of King of the Piercings.
The first edition of Dracula
In addition to these legends, there is a real problem that plagues bat researchers, including Professor Bill. That is, how did bats evolve into vampires? Why is it that there are more than 20,000 species of vertebrates living on land, and only three species of bats that inhabit the Americas can suck blood?
Professor Bill believes that to explain this problem, it is not enough to study the evolution of bats from ancient times to the present. We have to change our perspective and start with the emergence of another animal, the modern horse.
The ancestor of the modern horse, the Archaeopteryx, has gone through a long evolutionary road to its present appearance. There is a group of populations called the Order of the Strange Hoof, which occupied a large area of jungle vacated after the extinction of the dinosaurs on the North American continent 50 million years ago. In this population, the fox-sized Archaeopteryx, with its short limbs, lives in bushes and feeds on fruits and blades of grass.
After another 25 million years, the climate of the North American continent changed. The air gradually dried up, the forest area shrank, and the grassland territory became larger. The plants that grow there contain more silica, which is more difficult to digest for many herbivores. As a result, some small animals began to gradually become extinct, while populations that could adapt to the new environment survived. They have evolved special body structures, such as long, wide teeth, that can cope with tooth wear and tear caused by chewing hard plants for a long time.
But in the grasslands, there are not many vegetation that can hide. Then the slender limbs that are good at running become more important. Archaeopteryx's skull began to grow longer and longer, and its eyes grew farther and farther away from its mouth, allowing them to see approaching predators while eating. The prototype of the modern horse was gradually born.
And how do we know that this long evolutionary process is going on? To put it bluntly, it is to rely on speculation and physical evidence, that is, to study fossils. Modern horses leave a variety of fossil records at different stages of evolution. By comparing the differences between fossils from different periods, it is possible to arrange how a creature adapts and changes its own body structure in different historical stages and changing environments.
Unfortunately, the fossil evidence is indeed intuitive. Bats, on the other hand, did not leave much fossil. Their bones are too fragile and fragile, and because they inhabit the tropics, most of the bodies are more likely to decay or be eaten, and the hope of preserving them as fossils is even more slim. Therefore, researchers usually rely on the understanding of modern organisms to imitate bat evolution. Especially those modern creatures that have a close connection with paleontology, such as a parasite that is equally primitive and relies on blood for food.
Vampire bat skull
So, understanding this basis for derivation, let's look at the first hypothesis about the origin of vampire bats.
Since most bats feed on insects, their primitive ancestors may have tasted the first drop of blood when they enjoyed the blood-sucking parasite. Bats, as social animals, clean each other's bodies. Professor Bill hypothesized that bats would taste the blood of the parasites as they cleaned up. But this hypothesis, there is a next time, that is, blood-sucking parasites, widely distributed around the world, while vampire bats, only exist on the American continent, and are rare in number. This raises the question, why aren't there more vampire bats? This question, let's sell a close first.
There is also a hypothesis, from bat scientist Brock Fenton. He believes that the blood-sucking behavior may have evolved from primitive bats while preying on larvae on wounds of large mammals. It is well known that large animals such as cattle and horses are not as good as animals, and after being attacked by predators, the wounds on the body will soon attract large groups of insects that want to forage and lay eggs. The ancestors of vampire bats may have tasted the taste of blood while eating these bugs, and gradually became only eating blood.
But Professor Bill believes that this "wound feeding hypothesis" also has its own problems. He felt that the foothold of this hypothesis was that bats gradually evolved blood-sucking behavior in the face of environmental pressure.
But the problem is that if blood-sucking behavior is considered evolutionary, then at least it should be beneficial to the survival of vampire bats. But in fact, the main components of the blood of large mammals such as cows and horses are water and protein, and the calorie supply is minimal. Vampire bats, on their own, cannot rely on fat to store energy. This innate deficiency, coupled with eating food that is very cost-effective, causes vampire bats to eat half of their body weight every day to barely survive. According to modern research data, vampire bats have an average of three nights to go hungry one night, to put it bluntly, vampire bats have chosen a very difficult way to survive. In addition, this hypothesis requires that animals have open wounds, and the more conditions there are, the greater the probability of starvation. Not to mention, there is no evidence that modern vampire bats suck blood in wounds made by other animals. These theoretical flaws make the wound hypothesis somewhat untenable.
Further analysis, from the perspective of the population, the predation of modern vampire bats is not easy, so they should choose insects as food to be more efficient. Moreover, the echolocation ability of vampire bats is outstanding in the entire bat world, but this function is of little use for eating. If it is environmental pressure that forces bats to give up preying on insects, why did they evolve this useless function of blood sucking?
Others believe that the knife-like teeth of vampire bats were inherited from bats that eat fruit. The incisors, which were originally used to poke through the skin, have become sharp blades that can pierce the flesh. But the question remains, why switch from sucking juice to sucking blood? And, if this hypothesis holds, those little guys outside the American continent who also have front teeth should also evolve into vampire species.
Professor Bill argues that these arguments have their own merits and next time, but they are all whirled around on the premise that biological evolution is, to some extent, fully predictable. For example, if the American vampire bat changes from eating fruit to sucking blood, then this change should also occur on other continents.
But in reality, on the American continent, environments that can lead to blood-sucking behavior, such as habitats and prey, can also be found on other continents, but do not affect local bats. And if we copy a South America out of thin air, there is no guarantee that the bats there will also suck blood.
Vampire bat distribution area
According to paleontologist Stephen Gould. Even if we can reverse the history of the earth and let it repeat itself, there is no guarantee that the results of this evolution will be completely consistent with the present. This is because of a key factor, namely, the existence of chance events. Chance and coincidence have played a crucial role in the survival and evolution of organisms in the long river of history.
For example, the evolution of horses mentioned earlier. If climate change had not occurred at that time, resulting in the shrinking forest area of North America, it is difficult to say whether this would be the case for modern horses. If 65 million years ago, there was no disaster or accidental destruction of the dinosaur living environment, then small mammals had no chance to grow and grow, and instead of humans on the stage, it may be another group of creatures.
This kind of contingency, placed on the bat, makes sense. To take the perspective a little farther, perhaps, a long time ago, there were many kinds of blood-sucking animals around the world, not only bats, but also birds, and even blood-sucking you oh eating animals. Because of some contingencies and natural environmental influences, only one population on the North American continent, under the family Phylloscopidae, has undergone evolution and become the only stock of vampire vertebrates.
Based on this, Professor Bill also proposed his hypothesis on the origin of vampire bats, that is, the blood-sucking behavior did not evolve from 0 to 1, but these primitive bats, from the beginning, ate meat and preyed on small animals on trees, but for some reason, they gradually reduced their diets, giving up eating meat and drinking only blood.
With a point of view, how to prove that the point of view is valid? Studies have found that several modern vampire bats have the behavior of preying on trees. For example, white-winged and hair-legged vampire bats hunt in trees and prey on perched birds. The autopsy found that the hairy-legged vampire bats had fragile hind leg bones, proving that they had been predators perched on trees. The white-winged vampire bats, on the other hand, have strong hind leg bones, suggesting that they have recently returned to the trees, reducing competition with land rivals.
We can imagine such a scenario. 10 million years ago, on the North American continent, some leaf-mouth bats that were originally carnivorous, ushered in their own key moments. At that time, the vast forests of South America became grasslands, and some of the meat-eating bats that survived at that time suddenly found that the prey they could have bullied casually, such as possums and sloths, became larger and larger, and it was difficult to deal with the previous predation strategies.
Over time, some carnivorous bats underwent a change in behavior and began to curve to save the country, using these animals as a food warehouse rather than a disposable source of heat. They began to approach each other secretly, sucking their blood while they were asleep, and although the blood heat was not high, it was better than starvation. In order to avoid waking up the prey as much as possible, natural selection began to urge bats to make greater evolutions, gradually having teeth that could cause painless wounds, secreting anti-coagulated saliva that made the opponent's blood flow, and agile hands. Some further populations have also moved from trees to the ground, targeting larger terrestrial biota, such as cattle and horses.
Moreover, vampire bats have evolved this behavior, which is equivalent to learning a skill that other animals do not have. They can exploit an unprecedented resource, namely vertebrate blood. No one competed with them, and they didn't have any rivals on this new continent of food.
Of course, Professor Bill's view is still only a hypothesis. Whether it can stand the test of time, supplement itself with more evidence, and finally become an accepted theory remains to be seen. But neither Bill nor any other scholar. They all face a lot of controversy and counter-evidence when answering an interesting question. Perhaps, the origin of the vampire bat, there are several completely different scripts, which also leave a lot of room for the present, as well as for those who come after.
Finally, an interesting conjecture. Maybe even today, there are even larger vampire bats. It was a giant vampire bat that, in ancient times, was able to prey on glyptodonts that were several meters long. This oversized vampire monster does have a fossil record. But it is generally speculated that with the extinction of prey, they also followed suit. But others believe that at least one giant vampire bat escaped the attack. Witnesses claim that in some parts of South America, such as in the heart of the Amazon River, there are remnants of giant bats. Near the remains of modern creatures, the skeletons of large vampire bats have also been excavated. This gives scientists a glimmer of light: large vampire bats may still haunt the south American wilderness that has been neglected by humans.
I hope so.