When we think of slow and steady, the image of a tortoise often comes to mind. But behind that unhurried gait lies a remarkable creature capable of defying time itself. The tortoise is among the longest-living animals on the planet. Their extraordinary lifespan has fascinated biologists and storytellers alike, leading us to wonder: how do these creatures live so long? Is it the giant tortoises of the Galápagos or the smaller, land-dwelling species that hold the key to longevity? Let’s take a deeper look.

A Life of Patience and Persistence

The tortoise’s slow walk is not just a quirky trait — it’s a life philosophy, ingrained in their very survival. These creatures are not in a race against time, they are its patient conquerors. Some species of tortoises can live well over a century, and in the case of the Giant Tortoise (known for its immense size), individuals have been documented living for more than 200 years. But why is it that these ancient reptiles live so long, while their cousins, the turtles, tend to have shorter lifespans?

In terms of lifespan, tortoises—especially the giant tortoises—lead the pack. A giant tortoise can outlive many other creatures, including their ocean-dwelling cousins, the turtles. While turtles generally live between 50 to 100 years, giant tortoises surpass this, sometimes even living beyond 150 years. In fact, Jonathan, a Seychelles giant tortoise living on Saint Helena Island in the South Atlantic, holds the record as the world’s oldest living land animal at 189 years old. Jonathan, who was born in 1832, has outlived all of his peers, continuing to thrive on the island where he was discovered.

The Science Behind Their Longevity

The secret to the tortoise’s longevity lies deep within its biology. While there are several factors that contribute to their long lives, two of the most significant are evolutionary adaptations and cellular processes that are finely tuned to conserve energy and maintain health over decades.

From an evolutionary perspective, tortoises face fewer natural threats in their environment compared to faster, more vulnerable animals. For many species of tortoises, survival has been less about outpacing predators and more about outlasting them. Many tortoises lay multiple eggs, often many more than a single clutch, and they continue to reproduce over several decades. This “quality over quantity” approach to reproduction ensures that their genes continue to thrive, while their individual lifespans stretch out.

Moreover, tortoises tend to have slower metabolic rates compared to other animals. Their bodies conserve energy by keeping their metabolic processes at a steady, slow pace. This “slow burn” strategy is key to their extended lifespans. A slow metabolism means that fewer cellular processes are damaged by the wear and tear of daily life, which translates into fewer health issues in old age.

One of the most fascinating aspects of tortoise longevity is the role of their telomeres. Telomeres are the protective caps at the ends of chromosomes that prevent them from fraying and tangling. Every time a cell divides, the telomeres shorten slightly. In most organisms, as the telomeres shorten, cells lose their ability to divide, eventually leading to aging. However, in tortoises, the telomeres wear down at an unusually slow rate, allowing their cells to divide without the usual detrimental effects seen in other animals. This slower rate of telomere shortening helps them avoid age-related diseases such as cancer and ensures that their cells remain healthier for longer.

Furthermore, some studies have revealed that tortoises are capable of a process called apoptosis—a form of programmed cell death—where damaged or dysfunctional cells are destroyed before they can cause harm. This controlled form of self-destruction in damaged cells helps prevent the formation of tumors and other age-related diseases, which is another reason for the tortoise’s impressive lifespan.

The Giants of the Tortoise World

When we talk about longevity in tortoises, we cannot overlook the giant tortoises of the Galápagos Islands and the Seychelles. These remarkable creatures have not only captured our imagination but have also become living symbols of resilience and endurance.

The Galápagos Giant Tortoise, for instance, can live over 150 years, and some individuals have even outlived the scientists who studied them. They were once thought to be heading for extinction, but thanks to conservation efforts, their populations have stabilized.

In India, a rare breed of tortoise known as the Aldabra Giant Tortoise has been known to live up to 255 years. This species, although not as well-known as the Galápagos counterparts, is another testament to the wonders of nature’s design.

Turtles, which are often found in aquatic environments, tend to live shorter lives, averaging about 30 to 50 years

But what about other, lesser-known giants? In Kasaragod, Kerala, India, a giant soft-shell turtle species was discovered in May 2021, which lives in freshwater, weighing over 100 kilograms! These giant creatures are living proof of the astonishing adaptability and longevity that nature has to offer.

The Mystery of Tortoises and Turtles

While all tortoises are technically land-dwelling creatures, there is an interesting distinction between tortoises and turtles. Turtles, which are often found in aquatic environments, tend to live shorter lives, averaging about 30 to 50 years. Tortoises, on the other hand, tend to have larger bodies, longer necks, and more robust shells. Their heavy, often plant-based diet plays a role in the additional years they add to their lifespan.

A surprising discovery made in the Seychelles in recent years has sent shockwaves through the scientific community: certain tortoises, once thought to be herbivorous, have been seen eating birds and other small animals. This has raised questions about the adaptability of tortoises in changing environments and has piqued the interest of researchers studying their survival strategies.

What Lies Ahead?

Despite all that we know about these extraordinary creatures, there is still much to discover. Researchers continue to study tortoises, particularly the giant species, to learn how their unique biological traits could benefit human medicine, particularly in the fight against aging and diseases like cancer. The discovery of their telomere dynamics, coupled with the ability to prevent cell damage through apoptosis, could one day revolutionize the way we approach longevity and healthcare.

For now, we can only marvel at the tortoise’s timeless existence, its slow, steady journey through the ages, and the lessons it teaches us about patience, resilience, and the secrets of life’s most enduring creatures.

In a major development for knee rehabilitation, researchers at Indian Institute of Technology (IIT) Ropar have introduced a revolutionary, low-cost solution to make Continuous Passive Motion (CPM) therapy more accessible to patients. The team’s newly patented innovation, the Completely Mechanical Passive Motion Machine for Knee Rehabilitation, is set to transform post-surgical recovery, especially in resource-limited areas.

Unlike traditional motorized CPM devices, which are expensive and reliant on electricity, the new machine operates entirely through mechanical means. Utilizing a piston and pulley system that stores air as the user pulls a handle, the device enables smooth, controlled knee motion to aid in rehabilitation. This design eliminates the need for electricity, batteries, or motors, making the machine lightweight, portable, and environmentally friendly.

The mechanical CPM machine addresses a key barrier to knee therapy: the high cost and power dependence of conventional electric machines. It offers a viable alternative for patients, particularly in rural and off-grid areas, where access to electricity is often unreliable. Its portability also enables patients to continue their therapy at home, reducing the need for frequent hospital visits or prolonged stays.

Knee rehabilitation is crucial for patients recovering from surgeries, as CPM therapy helps improve joint mobility, reduce stiffness, and speed up recovery. With this new device, IIT Ropar’s researchers are offering a cost-effective, sustainable option that could improve the lives of countless patients, especially in India, where advanced medical technology can be scarce in rural regions.

Lead researcher Dr. Abhishek Tiwari, along with his team members Suraj Bhan Mundotiya and Dr. Samir C. Roy, expressed optimism about the machine’s potential. “This device has the power to revolutionize knee rehabilitation, particularly in areas where access to sophisticated medical equipment is limited. It’s designed to be an affordable and eco-friendly solution that not only aids in recovery but also minimizes environmental impact,” said Dr. Tiwari.

The introduction of this innovative mechanical CPM machine marks a significant step toward democratizing healthcare and improving rehabilitation outcomes globally.

In an enlightening conversation with EdPublica, Sajikumar Sreedharan, Associate Professor at the NUS Yong Loo Lin School of Medicine, Singapore, shares his research insights on memory formation and the transition from short-term to long-term memory. His areas of research include aging and neurodegeneration, the neural basis of long-term memory (LTM), and synaptic tagging and capture (STC) as an elementary mechanism for storing LTM in neural networks. He also explores metaplasticity as a compensatory mechanism for improving memory in neural networks. With a career spanning over two decades, Prof. Sreedharan discusses his key findings, innovative methodologies, and the significance of receiving the “Investigator” award from the International Association for the Study of Neurons and Brain Diseases. Join us as he reflects on his journey and the collaborative spirit that drives his research.

Edited Excerpts:

Your research has been recognized for significantly advancing our understanding of memory formation. Could you elaborate on your key findings related to the transition from short-term to long-term memory?

I have been working in the field of learning and memory since 2000. My first mentor in neuroscience was Prof. T. Ramakrishna, the founder and first head of the Life Sciences Department at the University of Calicut, Kerala, India. He was a great motivator, and we often had insightful discussions about learning and memory in the evenings. I had the chance to work with him for my master’s dissertation, which was my first real research experience. Prof. Ramakrishna encouraged me to expand my knowledge further, and he connected me with Dr. Shobi Valeri, a senior researcher in Delhi at the time.

Dr. Shobi soon left for Germany to pursue his Ph.D. and recommended me to DRDO (Defence Research and Development Organisation). Dr. Shobi is now a senior scientist at the National Institute of Nutrition in Hyderabad. I worked at DRDO for a year before moving to Magdeburg, Germany, where I began my Ph.D. under Prof. Juletta Frey. She is well-known in the field of learning and memory, particularly for her research on the cellular mechanisms involved in forming associative memory.

In Prof. Frey’s lab, I discovered how different pieces of information can link together to form long-term memories. This work later inspired the development of many computational models of memory. After completing my Ph.D., I did my postdoctoral studies with Prof. Martin Korte in Braunschweig. There, I discovered how activating neurons before learning could enhance memory formation in the future, a process known as metaplasticity—an exciting and emerging area of neuroscience.

“Using animal models, we have uncovered the role of specific brain regions, like CA2 and CA1, in forming social and spatial memories—both of which are significantly affected by aging, neurodegenerative diseases, and mental health conditions

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Since 2012, I have been working at the National University of Singapore, where I have focused more on aging, neurodegeneration, and mental health. Using animal models, we have uncovered the role of specific brain regions, like CA2 and CA1, in forming social and spatial memories—both of which are significantly affected by aging, neurodegenerative diseases, and mental health conditions.

How do you approach the study of molecular mechanisms in memory, and what methodologies do you find most effective?

In my lab, we approach research questions by examining them from different angles—molecular, cellular, behavioural, and system-level. We choose the most appropriate method depending on the specific question we’re investigating. I can’t say that one method is better than the others because each plays an important role in confirming our findings.

Recently, we’ve been using optogenetic and chemogenetic tools, which allow us to target and stimulate specific neurons. These methods are particularly helpful because they ensure precision in how we activate or deactivate brain cells.

Congrats on receiving the “Investigator” award from the International Association for the Study of Neurons and Brain Diseases. What does this recognition mean to you personally and professionally?

Thank you for your kind words. As a researcher, I feel proud and happy that my work is being recognized internationally. Professionally, this recognition is a significant motivation to continue pursuing my research.

This achievement is not just mine alone—I owe it to all my Ph.D. students, postdocs, and research technicians who have worked with me over the past 20 years. This award is for them as well.

How do you feel your work contributes to the broader scientific community, especially concerning memory impairments related to aging and mental health?

I am the Research Director of the Healthy Longevity Translational Research Programme at the School of Medicine, National University of Singapore, where we have more than 36 scientists working on various aspects of healthy aging. One of our key areas is brain health. Living a long life is not meaningful without a healthy brain.

I am one of the principal investigators studying how neural networks are impaired during aging and neurodegeneration. My wife, Dr. Sheeja Navakkode, is also a neuroscientist, focusing on Alzheimer’s disease using animal models. Neural networks undergo tremendous changes during aging and in various mental health conditions. Our goal is to correct or rewire neural network activity so that memory can be preserved with minimal damage, especially during conditions such as aging, Alzheimer’s Disease, and mental health disorders.

(Read the full interview in the upcoming December 2024 issue of EdPublica magazine.)