In life, two things are certain: death and taxes. While taxes are a societal construct, death is a universal truth, affecting everything from stars to humans. This inevitability is governed by the Second Law of Thermodynamics, which dictates that everything eventually breaks down over time. Living organisms, unlike inanimate objects, actively resist this breakdown—at least temporarily. But ultimately, entropy wins.
Death is a natural law, but dying of old age isn’t officially recognized as a cause of death in many countries, including the U.S. Instead, we succumb to “age-associated diseases” like cancer, Alzheimer’s, heart attacks, and strokes. As we age, our bodies accumulate disorder—mutated genes, malfunctioning cells, and tissues. This is where entropy plays its part.
Even the act of breathing poses risks. Oxygen, essential for breaking down food and powering our bodies, releases free radicals—reactive molecules that can damage tissues and organs. Our DNA also contains transposable elements, which can disrupt our genetic code as we age, leading to diseases like cancer.
Leonard Hayflick, a biogerontology pioneer, suggests that good health merely slows down the inevitable decline toward death. In the U.S., the average life expectancy is 79 years, with Japan leading globally at 84 years. If we could eliminate age-associated diseases, scientists estimate life expectancy could reach 89 years. However, our cells have a “maximum expiration date” encoded in our DNA, specifically in our chromosomes.
Each cell contains 46 chromosomes, capped by telomeres. These protective regions shorten with each cell division, eventually halting cell division altogether. This marks the beginning of cellular decline and, ultimately, our demise.
Why don’t we have longer telomeres? Evolution and natural selection play a role. Once an organism reproduces and ensures its offspring’s survival, its evolutionary role is fulfilled. Human telomeres don’t lengthen with age because evolution hasn’t optimized us for longevity beyond reproduction. As a result, entropy eventually overpowers our repair mechanisms.
While evolution may not help us defeat entropy, some animals have developed resistance to aging. The naked mole rat, for example, can live up to 32 years by occasionally slowing its metabolism and reducing free radicals. Some people mimic this by practicing caloric restriction, though its effectiveness in humans is debated.
Lobsters offer another intriguing example. They never stop growing because their cells continue dividing, thanks to an enzyme called telomerase that rebuilds their telomeres. However, while telomerase can make cancer cells immortal, it doesn’t extend human life.
The freshwater hydra, which may be immortal, keeps its transposable elements in check, preventing genetic disruption. With further research, these simple creatures might offer insights into extending human life.
Humans have made progress against entropy through better diets, medicine, and public health, but the battle isn’t won. Our bodies have a built-in expiration date due to evolution. However, understanding how entropy affects aging could help us repair ourselves faster than we break down.
If we conquer aging, we’ll face new challenges, like supporting a potentially immortal population. Will these advancements be accessible to all, or just a privileged few? And how will we spend our extended lives? These questions remain unanswered, but the pursuit of longevity continues.
As we explore these possibilities, it’s essential to remain curious and inspired. KiwiCo, a supporter of PBS Digital Studios, aims to inspire the next generation of innovators through hands-on projects that make learning fun and accessible. Whether you’re a curious learner or know someone who is, KiwiCo offers educational experiences that spark creativity and curiosity.
Engage in a structured debate on the ethical implications of extending human life expectancy. Consider questions such as: Should we strive for immortality? What are the societal impacts of significantly longer lifespans? Prepare arguments for both sides and participate in a class discussion.
Conduct a research project focused on telomeres and their role in aging. Investigate current scientific studies and breakthroughs related to telomere lengthening and its potential impact on human longevity. Present your findings in a detailed report or presentation.
Analyze the biological mechanisms that allow the naked mole rat to resist aging. Explore how these mechanisms could be applied to human aging research. Write a case study report that includes potential applications and limitations of these findings.
Design a small-scale experiment to understand the effects of caloric restriction on metabolism and aging. Use available data or simulations to predict outcomes. Discuss the potential benefits and drawbacks of caloric restriction as a strategy for extending lifespan.
Write a short story imagining a day in the life of an immortal human. Consider how daily routines, relationships, and societal roles might change with the absence of aging. Share your story with classmates and discuss the potential realities of such a future.
Thank you to KiwiCo for supporting PBS Digital Studios. In this world, nothing can be said to be certain except death and taxes. Taxes may not be a law of the universe, but death is, whether you’re a star, a car, or a human. That’s because the Second Law of Thermodynamics ensures that we inevitably break down over time. Life is a struggle against entropy. That’s what makes living things different from cars and burning balls of gas: our bodies actively fight against entropy—at least for a while. Sooner or later, the Second Law gets us all.
Can we shift the balance of power to beat entropy and live longer? Or is life a battle that we’re all doomed to lose in the end?
Death is a law of nature, but dying of old age isn’t— in fact, dying of old age is not recognized as an official cause of death in the U.S. and many other countries. If an accident or trauma doesn’t kill us, we actually die of “age-associated diseases.” These are diseases that become more common as we age, such as cancer, Alzheimer’s, heart attack, and stroke. But why do we become more vulnerable to these diseases as we get older? That’s where entropy comes in. The longer we live, the more we accumulate disorder: mutated genes, warped molecules, and cells and tissues that no longer function properly.
Even breathing has risks. When we take in oxygen to break down food and power the body, we release highly reactive molecules called free radicals that can damage our tissues and organs. Another ticking bomb our bodies harbor are transposable elements. These are regions in our DNA that can jump out of their correct location and insert themselves in different parts of chromosomes, potentially scrambling our genes. Transposable elements make up nearly half of our genome, but luckily, our cells usually keep them under control. However, as we age, we lose control over these elements, leading to various problems, including cancer and degenerative diseases.
All of this starts happening in your body long before you realize you’re on the slow decline toward death. As entropy runs its course, it’s just a question of which cells, tissues, or organs will fail first and which age-associated disease will affect us. Leonard Hayflick, a pioneer in the field of biogerontology, puts it this way: “Good health is merely the slowest possible rate at which one can die from an age-associated disease.”
In the U.S., the average life expectancy is 79 years, and globally, Japan tops the list at 84. So what if we could eliminate all those age-associated diseases that kill people today? Scientists believe the average human life expectancy could reach 89 years. Why not longer? Even without age-associated diseases, our cells have a sort of “maximum expiration date.” In other words, we have biological programming that determines our maximum lifespan, which is written in our DNA, or more specifically, in our chromosomes.
Each of our non-reproductive cells contains 46 chromosomes, and at the end of each chromosome is a cap called a telomere. These protective regions don’t code for anything, but we need them because every time our cells divide, a bit at the end of each telomere gets lost in the process. Eventually, the telomeres become too short, and the chromosomes can’t be copied anymore, leading to no more cell division. When our cells can no longer divide to grow and heal, this marks the beginning of the end for our cells and eventually for us.
The length of your telomeres is like your life line—except it actually works. Leonard Hayflick found that normal human cells will only divide 40 to 60 times before they enter senescence, a state where cells no longer grow, mainly due to shortened telomeres. So why didn’t nature give us longer telomeres? It’s all down to evolution and natural selection. Once an organism passes on its genes and ensures its offspring survive, it has essentially fulfilled its role in natural selection. That’s why human telomeres don’t get longer as we age. We’re products of evolution, which didn’t optimize us to function well after we can have children. Eventually, entropy overpowers our ability to repair ourselves.
I know this is disheartening, but don’t blame me—blame evolution. Take it up with Darwin! So evolution isn’t going to help us win the fight against entropy. However, there are other animals that have evolved resistance to aging, and perhaps they can teach us how to stack the odds in our favor. For example, the naked mole rat can survive up to 32 years, making it the longest-living rodent. It’s thought that the naked mole rat achieves this by occasionally slowing down its metabolism and reducing free radicals in its body—essentially slowing down entropy.
Some people are mimicking naked mole rats by restricting their caloric intake in hopes of lowering their own free radicals. This practice, known as caloric restriction, involves eating fewer calories than recommended for one’s age. Research has shown that caloric restriction can prolong life in many laboratory species, but it carries significant risks for humans, and the effectiveness is still debated. According to science, humans are not actually naked mole rats.
If we can’t beat entropy, maybe we can strengthen ourselves by looking to lobsters for inspiration. Unlike us, lobsters never stop growing because their cells never stop dividing. The oldest lobster ever caught weighed 20 kg—the weight of a medium-sized dog. It’s likely that lobsters only die because they get eaten or grow so large that they can’t safely regrow their shell. Lobsters have telomeres like we do that shorten with each cell division, but they also possess an enzyme called telomerase that constantly rebuilds their telomeres, allowing their cells to continue dividing indefinitely.
So let’s pump ourselves full of telomerase! Right? In fact, adult humans already have some cells that produce telomerase—like special cells lining our intestines. But you know what else produces a lot of telomerase? Cancer cells. This means that while telomerase can make cancer cells immortal, it doesn’t extend the life of the person who has them.
What about those disruptive jumping elements in our genes? Can we control those? The freshwater hydra can. Hydras don’t seem to age, and scientists think they may even be immortal. They appear to keep their transposable elements in check, preventing their genome from becoming scrambled. Who knows? With more research, one of Earth’s simplest animals could teach us a trick or two for extending our own lives.
Humans have made some progress against entropy, thanks to better diets, modern medicine, and public health, but no one has ever won the war. Our bodies may have a built-in maximum expiration date due to evolution. However, if we can learn more about how entropy affects our bodies as we age, we might be able to build ourselves back up faster than we break down. But if we do conquer aging, we’ll also need to figure out how to support the billions of newly immortal people. Will this advancement be accessible to everyone or just a privileged few? And what will we do for fun in a world where most of our lives are no longer spent working? Would we run out of YouTube videos? Nah.
If we can answer these questions, as we age, we’ll be living better too. Or perhaps, by pursuing this dream, as the great architect Michael once put it, we’re just setting ourselves up to “attempt something futile with a ton of unearned confidence and fail spectacularly!” Stay curious!
A big thank you to KiwiCo for supporting PBS Digital Studios and It’s Okay To Be Smart. Some people say that the first person to live to be 150 years old has already been born. I don’t know if that’s true, but if you’re out there, can you keep me from getting older too? Problems like beating aging will require creative science and engineering solutions. KiwiCo’s mission is to inspire and educate the next generation of innovators. KiwiCo delivers monthly projects designed to make learning about science, art, math, and more fun and accessible. They have six different crates for kids from 0 to 16 and beyond. My son just turned one, and the Tadpole crate is full of fun and educational toys that don’t play annoying songs. In each crate, you receive an educational magazine, all the supplies you need, and detailed instructions written just for kids. These are hands-on projects that are super fun but also educational in a really cool way. Whether you are a kid or know a curious kid who might enjoy this, you can go to KiwiCo.com/Okay or click the link in the description below.
Entropy – A measure of the disorder or randomness in a system, often associated with the second law of thermodynamics, which states that entropy tends to increase over time in an isolated system. – In thermodynamics, the entropy of a closed system will increase until it reaches equilibrium.
Aging – The biological process of becoming older, characterized by the gradual decline in the functional capacity of cells and organisms. – Researchers study the molecular mechanisms of aging to understand how to extend the healthy lifespan of organisms.
Evolution – The process by which different kinds of living organisms develop and diversify from earlier forms during the history of the earth, driven by natural selection, mutation, gene flow, and genetic drift. – The evolution of antibiotic resistance in bacteria is a significant concern in medical biology.
Telomeres – The protective caps at the ends of chromosomes that prevent the loss of genetic information during cell division, their shortening is associated with aging and cellular senescence. – Telomeres shorten with each cell division, which is why they are often linked to the aging process.
Longevity – The length of time that an organism is expected to live, often influenced by genetic and environmental factors. – Studies on longevity aim to uncover the genetic factors that contribute to a longer lifespan in certain species.
Cells – The basic structural, functional, and biological units of all living organisms, often referred to as the building blocks of life. – Stem cells have the unique ability to differentiate into various cell types, making them crucial for regenerative medicine.
Cancer – A disease characterized by the uncontrolled division of abnormal cells in a part of the body, often forming malignant tumors. – Understanding the genetic mutations that lead to cancer is essential for developing targeted therapies.
DNA – Deoxyribonucleic acid, the molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. – DNA sequencing has revolutionized the field of genomics by allowing scientists to read the genetic code of organisms.
Metabolism – The set of life-sustaining chemical reactions in organisms that convert food into energy, build cellular structures, and eliminate waste products. – Metabolism plays a crucial role in maintaining the energy balance and overall health of an organism.
Radicals – Highly reactive atoms or molecules with unpaired electrons, often involved in chemical reactions that can cause damage to cells and tissues. – Antioxidants are important because they neutralize free radicals, preventing cellular damage.
