In the world of scientific research, devoting one’s career to studying bats is a bit like following an echo in the dark — lonely and uncertain at times, but full of potential wonders.  

For HHMI Investigator Michael Yartsev and Freeman Hrabrowski Scholar Gerald Carter, the choice was easy. Yartsev studies the neural mechanisms of learning, memory and spatial behaviors in natural settings in both individuals and social groups — and Carter studies cooperative relationships and social bonds.  

They both found that the very traits that distinguish bats from other mammals also made them ideal for answering difficult questions — those that could help us better understand not just bats, but ourselves.

Why Bats Are Useful Models for Brain and Behavior Research 

“The more I got to know about bats, the more I appreciated their potential as a model to understand how the brain supports behavior in natural and social environments,” says Yartsev. “When I entered the field over 15 years ago, we understood a lot about their sonar and flight capabilities, but much less about their brains — especially in natural and social settings. That mismatch created great opportunities for discovery.”  

One of Yartsev’s recent studiesexternal link, opens in a new tab uncovered how the brain organizes experience and memory during natural behavior in freely flying bats. Using cutting-edge wireless neural recordings and high-speed 3D tracking, his team was able to monitor hundreds of neurons in the hippocampus, the brain’s hub for learning and navigation, while bats explored large flight environments.  

They found that the brain spontaneously “replays” a compressed version of the spatial experiences. These replays often occurred far from the original location or time of the experience, suggesting that the brain flexibly integrates events across contexts rather than merely reproducing recent actions.  

Mapping Navigation, Communication, and More 

More broadly, Yartsev’s labexternal link, opens in a new tab at the University of California, Berkeley, studies how the brain supports natural learning, memory, and social behavior, from individual navigation to complex group communication.

His team has shown that neural systems encode not only an animal’s position in space but also its social relationships, communication signals, and representations of others.  

These findings include stable neural maps of familiar environments over days and weeks, neural synchrony across interacting individuals, and representations of social dynamics within groups. The work highlights the value of studying animals under natural conditions, in which they are free to move, interact, and experience the world. 

The Social Lives of Vampire Bats 

As an evolutionary biologist, Gerald Carter approaches his research through a behavioral lens.  

Bats are generally social and communicative creatures, but his species, the vampire bat, is a particular standout. Because they subsist only on the blood of other animals — which is often an elusive form of nutrition — vampire bats have developed extraordinary social bonding and cooperative behaviors to help them survive.  

While many animals share food only with relatives, vampire bats regurgitate blood meals even to unrelated individuals — an altruistic act akin to friendship.  

By introducing bats to new colonies and observing how quickly they’re accepted, Carter’s labexternal link, opens in a new tab at Princeton University explores how individual bonds form and how these relationships shape their broader social networks.  

He is also studying how much an individual bat’s behavior will change depending on their context — for example, removing a highly aggressive bat from its social environment and evaluating whether it behaves equally aggressively amongst strangers. Like humans, their behavior is not based solely on the intrinsic qualities of the bat, but the influence of their community. 

The Challenges of Bat Research 

Devoting one’s career to an under-explored subject matter brings challenges. Even basic standards may be undefined.  

Carter’s lab has collaborated extensively with zoos and the few other experts in the field to develop basic guidelines on how best to care for the animals. He hopes that this work will help lower the barrier to entry for other scientists who might be interested in vampire bats.  

Studying bats also poses technical hurdles. To track neural activity and spatial navigation in animals that fly as powerfully as fighter jets, Yartsev’s team had to establish a variety of wireless systems capable of recording hundreds of neurons, regardless of the bats’ movements. They also established miniature data loggers that can store neural and behavioral information “on the fly” for later analysis — a major engineering achievement. Yartsev says the challenge is to bridge laboratory precision with ecological validity. 

Understanding Rhythmic Brain Activity in Bats and Beyond 

This insight about brains and behavior has important implications for other species, including humans. Yartsev’s study of memory in freely flying bats showed that, unlike in other mammals, the recorded neural sequences were not tied to traditional brain rhythms (termed theta oscillations) but instead synchronized with the bat’s wingbeats.  

This coordination between internal brain dynamics and natural motor rhythms offers a new perspective on how memories and spatial representations may be structured in other species during natural behaviors. 

Interestingly, many animals exhibit behaviors at this frequency: rodents whiskers’ sniff at eight hertz, monkeys’ eyes dart at eight hertz, and excited humans can speak at roughly that rate. Yartsev aims to explore whether rhythmic behaviors in bats drive the emergence of the brain activity or vice versa.  

Bats, Aging, and the Importance of Community 

Bats live remarkably long lives — up to 10 or 20 years on average — which also offers useful research opportunities for an evolutionary biologist like Carter. A new “epigenetic clock” allows his lab to study the bats’ DNA to determine how closely their physical aging aligns with their actual ages.  

Bats are highly social creatures, and Carter hopes to better understand the potential health consequences of bullying, isolation, or other adverse social conditions on their physical wellbeing. This work has clear implications for humans — another species that evolved to be highly social, but now often lives in relative isolation.  

Of course, studying bats is just one way to diversify our understanding of the natural world — and ourselves. Carter is inspired by the different approaches to curiosity-driven research he sees among his cohort in the Freeman Hrabowski Scholars program.

“Many of my peers are departing from convention,” he says. “It requires a lot of foundational work, but it will pay off as we explore the unknown.”