Bats are the pinnacle of animal evolution. They play a crucial role in the ecosystem and are considered a scientific marvel.
Not everyone is fond of bats.
However, those who appreciate them tend to be deeply enamored.
During her early career as a scientist,Sharon Swartz initially focused on studying gibbons but became captivated by the complex skeletal structure of bat wings and the evolutionary need for flight in mammals. This fascination led her to pivot from primate research and travel to Australia to study a large bat species known as the fox bat.
Sharon recalls a particular evening spent at a suburban golf course where bats roosted in the trees. As the sun set, one bat took flight, followed by a few, and then hundreds, creating what she describes as a “river of bats in the sky.” The following night, Swartz, now a biology and engineering professor at Brown University, along with a colleague, used nets to capture the bats. For the first time, she held a fox bat with an impressive wingspan of nearly six feet. “My heart was racing. I had never seen anything so beautiful before.”
A more common reaction to bats could be an involuntary shiver. In Western culture, bats have long been linked to darkness and malevolence, making them challenging to describe in simple terms. They are not classified as birds, yet they can fly. Additionally, they are not exactly like mice.
Some individuals simply find bats unsettling. Others fear the diseases they may carry, including one similar to the virus that has sparked the COVID-19 pandemic worldwide. It’s worth noting that rabid dogs are responsible for more human deaths than bats, and the flu virus can be transmitted by pigs and ducks, yet these animals don’t evoke such frightening associations.
For bat enthusiasts—or even die-hard fans—nobody surpasses biologists like Swartz and her colleagues. Many are so passionate about bats that they have turned away from studying other mammals to delve into a realm filled with scientific enigmas, such as bats’ acrobatic flight, remarkable lifespan, and their extraordinary resistance to nearly all forms of cancer. Researchers across the globe are working to unveil these mysteries. Some aim to transform our understanding of these creatures into practical applications for humans, while others are simply intrigued by their remarkable diversity and evolutionary lineage. They wish to convey that bats are far more than just winged, mouse-eared animals.
Bats exemplify this. They are one of the greatest evolutionary success stories. Their ancestors were small, four-legged mammals likely feeding on insects, similar to most modern bats. However, the exact method by which those ancestors learned to fly remains a mystery. The oldest known bat fossils were discovered in the Green River Formation in Wyoming and date back over 50 million years, showcasing forearms and fingers that evolved into a rudimentary framework for attaching the bat’s delicate wing muscles. This is the origin of the term Chiroptera, the Latin name for bats, meaning “hand wing.”
Once capable of flight, bats adapted to various ecological niches found in bird communities, spreading across the globe. Bats constitute one-fifth of all mammal species, ranking second in number only to rodents. They have a varied diet, consuming insects, fruit, nectar, blood, and fish. They range in size from the blue-toothed bat, which weighs less than two grams, to the greater harlequin fruit bat, which can reach 1.8 meters (5.3 feet) in length and weigh up to 3.1 pounds (1.3 kg). Some bats are solitary, while many are social, living in large colonies or small groups, roosting in tree branches, caves, attics, and behind shutters. They play an essential role in nearly every ecosystem, feasting on mosquitoes and agricultural pests, as well as aiding in the pollination of crops like bananas, mangoes, avocados, and durians—not to forget the agave plant, a crucial ingredient in the production of tequila, Mexico’s renowned local spirit.
Their flight is unparalleled, which was the initial reason Swartz visited that golf course in Australia over 30 years ago. At that time, she was examining the mechanics of movement in primates, exploring how skeletons evolved to balance the necessary strength against the drawbacks of heavier bones. “It became evident that weight posed a challenge for flying animals in a different way than it does for other species,” she remarks.
Bat wings are composed of skin stretched over lightweight bones and feature numerous joints, enabling them to interact with the wind in ways that less flexible birds and insects cannot. A bird’s wing has three points of articulation, which can be likened to the human shoulder, elbow, and wrist. “A bat wing has many of the same joints found in a human hand,” Swartz clarifies. “And there are all these fascinating muscles hidden beneath that skin.” Bat wings are covered with countless fine hairs that detect changes in air currents. They continuously interact with the wind, adjusting their shape, generating lift, and reacting to every gust or breeze with unique maneuvers. In a series of experiments conducted by Swartz and her team to illustrate the challenges of traditional flight, they discovered that when they introduced saltwater into the stomachs of bats to replicate the weight of a large meal, different bats reacted in their own ways. Dimitri Skandalis, a researcher focused on individual animal nuances from Johns Hopkins University, compared the intricacies of bat wing movement to human facial expressions. All smiles may indicate happiness, but no two smiles are exactly alike.
Paul Webala, a National Geographic Explorer and wildlife biologist from Maasai Mara University, along with Eric Keeter, a biology student from Eldoret University, captured bats in Three Sisters Cave in southeastern Kenya to document their vocalizations and gather genetic information.
Webala captured striped giant bats for Kenya’s bat sound library project; researchers could eventually identify and classify bat species based on their calls.
Every night, five to ten million straw-colored fruit bats leave their roosts in Zambia’s Gazanga National Park and travel nearly 50 kilometers in search of fruit. Gazanga serves as a stopover along one of the world’s largest mammal migrations.
Can machines replicate these intricate, instinctual movements? Alireza Ramesani, an assistant professor of engineering at Northeastern University, describes bat flight as “a kind of dance in the air.” He explains, “For me, it was thrilling to create a drone that mimicked a bat.” Drawing inspiration from Swartz’s findings, he aimed to build a robotic bat. With the flexibility of its hands and the stretchability of its skin, bat wings can adapt to rapid, complex changes in airflow, especially in confined spaces.
Ramesani explains that a key aspect of understanding and modeling bat flight is that they don’t make immediate decisions. The soft tissues of a bat’s wings change in reaction to air pressure without needing a signal from the brain’s control center. This phenomenon is an example of what engineers refer to as passive dynamics. When a bat moves a primary wing joint, the membranes convey the movement to smaller joints, and the wing flaps adjust to counteract the airflow. “Bats exhibit specific locomotion patterns similar to those of jellyfish and birds,” Ramesani notes.
How do bats achieve flight? Scientists at Brown University in Rhode Island are releasing winged mammals, such as this Egyptian fruit bat, into a laboratory wind tunnel to study the mechanics of flight.
A team of researchers at Muni University injected bats with components of the uninfected Ebola virus, a process akin to vaccination. They tested three bat species, each with a distinct history of Ebola infection, to observe their immune response variations.
For each bat examined, technicians collected over 20 blood and tissue samples and conducted a variety of measurements. These tests could uncover which genes grant some bats resistance to lethal viruses and potentially aid in developing treatments for humans.
Flapperoo, a bat-inspired robot, was developed to test flight mechanics at Brown University. Researchers could adjust the speed of its wings or the skin’s friction to observe the effects of each modification on flight. Such precision is unattainable with a living animal.
Ramesani adds that while the elegance and intricacy of bat flight initially captivated him, it was the practical potential of bat-like drones that propelled the project forward. Building upon Swartz’s discoveries, he and his team are creating soft-bodied robots capable of navigating environments that conventional quadcopter drones, widely used in military and civilian contexts, cannot access. He notes that in the U.S. alone, there are over a million miles of sewage pipes that are hard or hazardous for humans to inspect and monitor. There are also caves to explore, whether for archaeological, paleontological, or mining purposes.
Emma Teeling functions like a colleague. Many of her findings regarding bats occurred “by sheer chance.” She is a co-founder of Bat1K, a project aimed at sequencing the complete genomes of approximately 1,400 bat species, and an early advisor to Paratus Sciences, a startup determined to gather data on bat biology to help address human diseases. “We believe that bats hold the key to a safer world and healthier people,” claims the company’s website.
Flapperoo, a bat-inspired robot, was created to test flight mechanics at Brown University. Researchers adjusted the speed of its wings or the friction of its skin to see how each change impacted flight. This level of precision is unachievable with a living animal.
PhD student Bibek Gupta demonstrates the Aerobat, a robot being developed by Northeastern University in Boston, intended for exploring urban sewers, caves, and other confined spaces that drones cannot access.
After her experiences working with foxes and deer, Teeling quickly became captivated by the unique biology of bats. While many mammals have a relatively short lifespan, bats the size of mice can live for decades. “They are remarkably long-lived,” she states. They also rarely develop cancer. “They host a variety of viruses without becoming ill,” Teeling, now a lecturer at University College Dublin, is keen to uncover the reason.
She has come to increasingly believe that the answer lies in a seemingly elusive concept: their ability to fly. She hypothesizes that flight has granted bats uniquely robust immune systems that contribute to their longevity and resistance to cancer.
subject James Gorman
photo Nicole Sobecki
translate Sarawarisa Mekpaiboon
Read more at: Ancient City of Sri Thep “The glory of the Lord”
“Bats” are the Pinnacle of Animal Evolution. They Are Vital to Our Ecosystem and Considered a Scientific Wonder.
Not everyone falls in love with bats.
But those who do often find themselves enchanted.
When I was a young scientist, Sharon Swartz studied gibbons but became fascinated by bats’ intricate skeletal structure and evolutionary necessity for flight among mammals. This led her to shift from primate research to studying large bats—specifically, the fox bat—in Australia.
She recalls a memorable evening at a suburban golf course where bats roosted in trees. As the sun set, one bat took flight, quickly followed by hundreds, creating what Swartz described as a “river of bats in the sky.” The thrill of holding a nearly six-foot wingspan fox bat for the first time left her with a pounding heart, captivated by its beauty.
While the beauty of bats enthralls some, many people in Western cultures associate them with darkness and fear. Bats are not exactly birds, yet they can fly; they’re also not mice but often elicit similar reactions of fear. Concerns about germs, such as the viruses they may carry (like the ones causing COVID-19), make them less liked. Interestingly, rabies and flu infections from dogs and pigs respectively pose greater risks to humans, but these animals don’t share the same scary image.
The community of bat enthusiasts, including scientists like Swartz, are captivated by bats’ remarkable capabilities: acrobatic flight, impressive longevity, and extraordinary resistance to various cancers. Researchers globally are unraveling these creatures’ mysteries, hoping to apply this knowledge for human benefit and to highlight the incredible diversity and evolutionary significance of bats—as more than just winged, mouse-eared creatures.
The Evolutionary Success of Bats
Bats epitomize one of the greatest evolutionary success stories. Their ancestors were small, quadrupedal mammals likely feeding on insects, resembling many modern bats. The evolutionary leap to flight remains intriguing; the oldest-known bat fossil, dating over 50 million years back, reveals that forearms and fingers had evolved into frameworks that support wings. This is where the term Chiroptera—meaning “hand wing” in Latin—originates.
Once capable of flight, bats filled various ecological niches, spreading across the globe. Today, they constitute one-fifth of all mammal species, second only to rodents. Bats consume a diverse diet, ranging from insects to fruit, nectar, blood, and fish. Their size varies dramatically, from the blue-toothed bat weighing under two grams to the greater harlequin fruit bat, which can reach a length of 1.8 meters (5.3 feet) and weigh up to 3.1 pounds (1.3 kg). Bat behavior also differs, with some species leading solitary lives while others thrive in social colonies.
Bats play a crucial role in ecosystems, controlling mosquito populations and agricultural pests. Moreover, they help pollinate crops, including bananas, mangoes, avocados, and durians, and even agave, an essential ingredient for tequila, Mexico’s renowned liquor.
The Mechanics of Bat Flight
Bats exhibit unparalleled flying capabilities, demonstrated by researchers such as Swartz, who initially researched primate locomotion. She discovered that the mechanics of bat wings—made of skin stretched over lightweight bones with multiple joints—allow complex interactions with the wind, making their flight unique.
While birds possess three points of wing articulation (shoulder, elbow, wrist), a bat’s wing mirrors the joints found in a human hand, allowing for superior aerodynamic control. Bat wings are equipped with countless fine hairs that detect air currents, enabling them to consistently adjust their shape and generate lift, closely communicating with their environment. Swartz’s tests involving weight simulation revealed distinct variations in flight response among different bat species, comparable to the unique expressions found in human smiles.
Bat Research and Engineering Innovations
Innovations inspired by bats extend to robotics. Alireza Ramesani, an engineering assistant professor, observes that bat flight resembles a “dance in the air.” His team is creating robotic models that replicate bat flight mechanics, addressing challenges like tight spaces where conventional drones struggle.
Fundamentally, bat wings utilize passive dynamics. As major wing joints move, their soft tissues adjust automatically, transforming airflow interactions without conscious commands from their brain. This intricate wing structure permits rapid, complex movements, similar to patterns found in jellyfish and birds.
Bats and Human Health
Emma Teeling, a co-founder of the Bat1K project, aims to sequence the genomes of around 1,400 bat species. Her work highlights the potential of bats to unlock secrets about disease resistance, particularly in relation to human health. Bats, known for their long lifespans and remarkable immune responses, may hold keys to combatting diseases, given their ability to carry numerous viruses without succumbing to illness.
Subject: James Gorman
Photo: Nicole Sobecki
Translate: Sarawarisa Mekpaiboon
Read more at: Ancient City of Sri Thep “The Glory of the Lord”
