In this episode of Longevity By Design, Dr. Gil Blander interviews Dr. Emma Teeling, a leading bat researcher from the University of Dublin. They delve into the extraordinary world of bats, discussing how these mammals hold the key to understanding disease resistance, immunity, and longevity. Dr. Teeling explains the unique immune system of bats and their ability to suppress inflammation—which is considered one of the primary drivers of aging. Many lessons from bats can be applied to humans, including how bats manage the immune response to viruses.
In this conversation, Dr. Teeling also explores the impressive DNA repair mechanisms bats possess and its contribution to bats’ healthspan. Dr. Teeling shares insights into her groundbreaking research, which has the potential to uncover innovative treatments for aging and various health conditions. Listen to the full episode to discover how understanding bats can help improve human health and longevity.
About Dr. Emma Teeling
Dr. Emma Teeling is an international leader in the cross-cutting fields of mammalian phylogenetics and comparative genomics. Dr. Teeling has particular expertise in bat biology. She established the Laboratory of Molecular Evolution and Mammalian Phylogenetics and is a Founding Director of the genome consortium Bat1K and the Full Professor of Zoology at University of College Dublin. Dr. Teeling has also been awarded numerous prestigious personal grants.
Bats are defying normal aging patterns
Bats challenge the conventional process of aging in many ways. While most animal species adhere to a pattern where longevity can be predicted based on body size—known as the longevity quotient—bats deviate from this norm. Smaller organisms typically have shorter lifespans, while larger organisms tend to live longer. For instance, the Bowhead whale can live over 220 years compared to shrews which rarely live longer than six months.
However, bats stand out as an exception to this norm. Despite being amongst the smallest mammals on Earth, they can live up to ten times longer than expected based on their body size. Dr. Teeling points to a study published in 2010 that revealed that out of the 19 mammal species living longer than humans when considering body size, 18 of which were bats.
Key takeaway: Bats experience exceptional longevity compared to what’s expected based on their body size, and their unique biological characteristics challenge our understanding of the aging process. There are lessons to be learned about how humans age from understanding bat biology.
How do bats delay aging?
Considering their body size, bats outperform humans when it comes to aging and healthspan. They remarkably excel without any medical interventions or treatments, thriving in the wild amidst predators. By studying bats, we gain valuable insight into their exceptional abilities and apply them to uncover strategies to enhance human well-being.
A look at their genome
Dr. Teeling introduces the topic of bat longevity by highlighting the connection between the bat genome and the human genome.
As mammals, humans and bats possess a similar number of genes. However, bats have significantly smaller genomes compared to humans. To put it simply, if we were to compare the amount of genetic information in bats and humans, bats have around 2GB of genomic data, while humans have approximately 3GB. This means bats possess less non-coding DNA compared to humans.
While bats contain all the necessary genes to function as mammals, their genome size seems to approach the lower limits.
Key takeaway: Overall, the genomes of humans and bats exhibit significant similarities, despite varying in size.
Flight: A possible answer to bats' exceptional longevity
Bats are the only mammal capable of flight. And the secret to bats' longevity may lie in their unique ability to take flight.
Flight is a metabolically costly process. Free radicals are produced during flight, which are molecules that break up DNA, cause constant sterile inflammation, and excite the immune response. Because of their ability to fly, bats expend three times more energy over the course of their lifespan compared to a similar-sized mammal. Oxygen consumption during bat flight can reach levels 30 to 300 times higher than mammals of the same size.
In this context, Dr. Teeling presents a thought-provoking argument connecting the relationship between bat longevity and their ability to fly. She suggests that in order to successfully evolve flight capabilities, ancestral bats had to also evolve mechanisms for DNA repair, cellular damage removal, and protein aggregation mitigation. In essence, bats may have developed highly effective strategies for damage resistance and tolerance.
DNA repair mechanisms in bats
In the quest to understand how bats cope with elevated levels of reactive oxygen species (ROS), researchers have examined their DNA repair mechanisms. Surprisingly, despite generating high levels of ROS, bats also possess robust anti-ROS machinery and multiple mechanisms to combat free radicals.
To assess oxidative damage, Dr. Teeling’s team conducted comprehensive sequencing of the mitochondrial population in bat cells. Their results revealed that bats exhibited lower levels of oxidative damage than expected, considering their high ROS production observed in the wild. This suggests that bats have developed mechanisms to either prevent or repair the damage caused by ROS, potentially through antioxidants or efficient repair pathways.
Dr. Teeling and her team further investigated genes that show distinct evolution in bats compared to other mammals. They identified selection processes related to protective mitophagy pathways—mitophagy being a process which selectively removes damaged mitochondria from cells. These mitophagy pathways could explain bats' ability to eliminate the damage from ROS production. Additionally, bats showcased significant selection in DNA repair genes, not limited to mitochondria but encompassing overall DNA repair processes.
Another noteworthy experiment conducted by Dr. Teeling involves examining bats’ blood transcriptomes across different age groups. Her team found that bats' DNA repair capacity increased with age, contrasting with humans whose ability to repair DNA diminishes with age.
In summary, Dr. Teeling suggests that bats possess exclusive control over DNA replication and repair processes, which appears highly advantageous. These adaptations likely evolved as a response to the damage associated with flight, ensuring bats can effectively manage and repair DNA damage caused by ROS.
Future directions: Better understanding of DNA repair mechanisms in bats may help improve healthspan interventions in humans.
Flight and the immune response
Continuing the thread of bat adaptations, Dr. Teeling moves to their immune response. Bats possess a distinct immune response to pathogens, characterized by a robust antiviral defense and a simultaneously aggressive anti-inflammatory reaction. They have evolved remarkable mechanisms to maintain homeostasis in the face of these challenges.
This unique immune response may have developed as a result of the detrimental effects of flight. Bats dampen their immune response to pathogens similarly to how they regulate constant sterile inflammation, allowing them to coexist with numerous viruses without falling ill.
The ability to repair cellular damage and regulate immune responses also significantly impacts bat healthspan. The typical hallmarks of aging are slowed down, leading to extended health and vitality.
Thus, the acquisition of flight may have driven these distinctive adaptations in bats, enabling them to effectively manage damage and disease. As a result, bats exhibit extraordinary longevity and the ability to combat viral infections.
Key takeaway: Dr. Teeling believes the combination of various evolutionary pressures has shaped bats into an extraordinary species with remarkable abilities to cope with damage and disease. The interplay between flight, immune regulation, and virus resistance likely contributed to their extended healthspan and longevity.
How did bats gain the ability to fly?
The evolutionary origin of flight in bats is a fundamental question in biology. By examining the phylogenetic tree and studying the closest ancestors of bats, researchers aim to understand the reasons behind this remarkable adaptation.
Findings from studying the phylogenetic tree
Before the advent of molecular phylogenetics, it was assumed that bats and flying lemurs were closely related. However, this has turned out to be incorrect, adding to the mystery surrounding the evolution of flight in bats.
The transitional stages that led to bats acquiring the ability to fly remain unclear. Examination of primitive bat fossils reveals the presence of claw-like structures at the ends of their fingers, suggesting the potential for climbing trees. However, the evolutionary process of wing development raises questions about the specific changes that occurred, such as the elongation of fingers, growth of wing membranes, modification of inner ears, and the co-evolution of flight and echolocation. Additionally, the origins of nocturnality in bats remain uncertain. These intriguing inquiries continue to be subjects of ongoing research and exploration.
Comparing humans to bats
When considering how bat longevity compares to humans, a crucial question arises: do bats experience age-related diseases? Dr. Teeling dissects this question, shedding light on the challenges of assessing this metric in bats.
- Tumor development: Notably, bats show no signs of developing tumors, which sets them apart from humans.
- Senescence and fertility: The longest-living bat species continues to reproduce year after year without a decline in fertility. This contrasts with the concept of senescence, and human female menopause.
- Gene expression changes: Dr. Teeling has been conducting long-term transcriptomic analysis, examining gene expression in bats and how it changes with age. Bats exhibit stable gene expression once they reach puberty (around age two). This suggests that the observed changes typically associated with aging are not present in bats.
- Telomere length: Telomeres, the protective caps at the ends of chromosomes that tend to shorten with age in many species, do not seem to shorten significantly in bats.
- Age-related conditions: The presence of age-related conditions like rheumatoid arthritis is challenging to determine in bats. However, studies have not detected significant changes in inflammatory cytokines, which are often associated with such conditions.
In summary, research is ongoing to better understand chronic diseases in bats, and thus far, evidence suggests that bats do not experience age-related diseases to the same extent as other species—especially humans.
Sex differences in bats
In many organisms, female life expectancy is longer than males. However, when it comes to bats, the research on age-related differences between the sexes is currently inconclusive. Further investigation is needed to determine if there are variations in lifespan between male and female bats. One of the research challenges is that it can depend on how the bats are captured and assessed, leading to differing results across studies.
Future directions—relating bat science to human healthspan
What does this all mean for human healthspan research? Future research focused on unraveling the DNA repair mechanisms possessed by bats may also extend the lifespan of humans.
By gaining deeper insights into the specific mechanisms that enable bats to efficiently repair DNA damage, scientists may be able to identify potential targets for interventions aimed at improving DNA repair capacity in humans. This knowledge can contribute to the body of knowledge on innovative therapeutic approaches to combat age-related DNA damage and preserve cellular health.
Understanding how bats regulate ROS production and manage oxidative stress may inform strategies for reducing the detrimental effects of oxidative damage in human cells. Insights from bat research may guide the development of antioxidant-based therapies or other interventions that mitigate oxidative stress and promote healthy aging.
Lessons from bats have the potential to inform and inspire innovative approaches for improving human healthspan interventions, enabling humans to live healthier, longer lives.
Top tip to improve healthspan
According to Dr. Teeling, a key recommendation for promoting healthspan is to optimize immune response by modulating inflammation. It is crucial to explore strategies that can effectively reduce and regulate inflammation in the body.