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How to Regrow a Limb
Once they’re gone, mammalian arms and legs can't ever be restored. But if you cut off a salamander's leg it will reappear in just a few weeks. The enigma of amphibian organ regeneration has long puzzled scientists. Now, a new wave of scientists hopes to put it to use.
What's the Big Idea?
The loss of a human limb is a tragedy. We know that once they’re gone, mammalian arms and legs can't ever be restored. But if you cut off a salamander's leg - or tail - it will reappear in just a few weeks. The enigma of amphibian organ regeneration has puzzled scientists since it was first recorded by Aristotle, reaching its strangest and most scientifically-accepted heights in the 1700’s, when Voltaire decapitated a snail just to see if the head would grow back. (It did.)
Now, a new generation of longevity-seekers hopes to apply the power of amphibians like the salamander, the axlotl, and the worm to human medicine. Sonia Arrison, policy analyst and author of 100 Plus, believes that tissue engineering will revolutionize the treatment of chronic illnesses: “In the future, if we had the ability to grow a brand new heart or parts of hearts with that person’s very own adult stem cells, then when we know that they have heart disease, we could just replace the heart. All of those [costly] visits to the hospital, all of the drugs, won’t be required.” Better tools will enable us to repair people rather than just sort of patching them up for a little while until they get sicker and sicker, she says.
What's the Significance?
This idea is more practical than it sounds. Over the past few decades, scientists have begun to understand exactly how the regeneration process works in nature. When a salamander is injured, a clump of cells called a blastomea forms at the site of the wound. Like embryonic stem cells, the blastomea are especially plastic. These cells are then triggered to de-differentiate and re-initiate growth. (Debate remains over whether they're fully pluripotent, meaning that they have the ability to form any type of tissue, or whether the cellular dynamics merely have to be reprogrammed, as in recent studies by Doug Melton of the Harvard Stem Cell Institute.)
The trick, of course, is applying this knowledge to human anatomy. Arrison explains, "Since we all evolve from the same place, humans must have a set of genes that can allow for growing back new limbs - it’s just that they’re 'turned off' right now ." If we could figure out how to turn them back on, or to add new genes based on the salamander model, then it could be possible to create new organs from scratch. In fact, one of the biggest spenders in this story is the Pentagon, which has put at least $250 million in to the search to find a way to create new human organs in the lab.
“They’re funding work in terms of growing all sort of organs - bladders and windpipes and hearts and lungs, livers," says Arrison, "but also in hopes of figuring out how to regrow arms and legs" for soldiers wounded in combat. Thanks to this influx of public money, the field has moved forward much quicker than it would have otherwise. So far, researchers have succeeded growing hearts, livers, breast tissue, and bone in the lab. The brain remains elusive - but Arrison is optimistic: "The brain is much tougher than other organs in the human body, but work is moving along."
There are, however, two things that she's worried about. The first is that technology won’t move quick enough for those alive today. "We’ve made a lot of progress in terms of reverse engineering the human code, we’ve made a lot of progress in tissue engineering and gene therapy, but it’s that we still have a ways to go." she says. The second is that, if we do see organ regeneration applied to medicine, the distribution of benefits like faster healing and increased longevity will be inequitable:
How long will the gap be between the wealthy getting it and the poor getting it? Because we’re already starting from a point of inequality. If you look around the world, life expectancy in Monaco in the South of France is around 90 years. Life expectancy in Angola is around 38 years. That’s like a 50-plus gap of an entire lifetime, really. And then within the United States, there’s a pretty decent gap as well. An Asian-American woman living in New Jersey has a life expectancy of around 91 years. A Native-American man living in South Dakota has a life expectancy of about 58 years.
There's already a fifty year difference in what it's like to be rich and poor in the world, which may or may not be alleviated by technology, she says, depending on how we choose to use it.
Image courtesy of Shutterstock.
What is human dignity? Here's a primer, told through 200 years of great essays, lectures, and novels.
- Human dignity means that each of our lives have an unimpeachable value simply because we are human, and therefore we are deserving of a baseline level of respect.
- That baseline requires more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose.
- We look at incredible writings from the last 200 years that illustrate the push for human dignity in regards to slavery, equality, communism, free speech and education.
The inherent worth of all human beings<p>Human dignity is the inherent worth of each individual human being. Recognizing human dignity means respecting human beings' special value—value that sets us apart from other animals; value that is intrinsic and cannot be lost.</p> <p>Liberalism—the broad political philosophy that organizes society around liberty, justice, and equality—is rooted in the idea of human dignity. Liberalism assumes each of our lives, plans, and preferences have some unimpeachable value, not because of any objective evaluation or contribution to a greater good, but simply because they belong to a human being. We are human, and therefore deserving of a baseline level of respect. </p> <p>Because so many of us take human dignity for granted—just a fact of our humanness—it's usually only when someone's dignity is ignored or violated that we feel compelled to talk about it. </p> <p>But human dignity means more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose—a freedom that can be hampered by restrictive social institutions or the tyranny of the majority. The liberal ideal of the good society is not just peaceful but also pluralistic: It is a society in which we respect others' right to think and live differently than we do.</p>
From the 19th century to today<p>With <a href="https://books.google.com/ngrams/graph?year_start=1800&year_end=2019&content=human+dignity&corpus=26&smoothing=3&direct_url=t1%3B%2Chuman%20dignity%3B%2Cc0" target="_blank" rel="noopener noreferrer">Google Books Ngram Viewer</a>, we can chart mentions of human dignity from 1800-2019.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0ODU0My9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY1MTUwMzE4MX0.bu0D_0uQuyNLyJjfRESNhu7twkJ5nxu8pQtfa1w3hZs/img.png?width=980" id="7ef38" class="rm-shortcode" data-rm-shortcode-id="9974c7bef3812fcb36858f325889e3c6" data-rm-shortcode-name="rebelmouse-image" />
American novelist, writer, playwright, poet, essayist and civil rights activist James Baldwin at his home in Saint-Paul-de-Vence, southern France, on November 6, 1979.
Credit: Ralph Gatti/AFP via Getty Images
The future of dignity<p>Around the world, people are still working toward the full and equal recognition of human dignity. Every year, new speeches and writings help us understand what dignity is—not only what it looks like when dignity is violated but also what it looks like when dignity is honored. In his posthumous essay, Congressman Lewis wrote, "When historians pick up their pens to write the story of the 21st century, let them say that it was your generation who laid down the heavy burdens of hate at last and that peace finally triumphed over violence, aggression and war."</p> <p>The more we talk about human dignity, the better we understand it. And the sooner we can make progress toward a shared vision of peace, freedom, and mutual respect for all. </p>
Scientists find that bursts of gamma rays may exceed the speed of light and cause time-reversibility.
- Astrophysicists propose that gamma-ray bursts may exceed the speed of light.
- The superluminal jets may also be responsible for time-reversibility.
- The finding doesn't go against Einstein's theory because this effect happens in the jet medium not a vacuum.
Jet bursting out of a blazar. Black-hole-powered galaxies called blazars are the most common sources detected by NASA's Fermi Gamma-ray Space Telescope.
Cosmic death beams: Understanding gamma ray bursts<div class="rm-shortcode" data-media_id="cu2knVEk" data-player_id="FvQKszTI" data-rm-shortcode-id="c6cfd20fdf31c82cb206ade8ce21ba3f"> <div id="botr_cu2knVEk_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/cu2knVEk-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/cu2knVEk-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/cu2knVEk-FvQKszTI.js"></script> </div>
Researchers dramatically improve the accuracy of a number that connects fundamental forces.
- A team of physicists carried out experiments to determine the precise value of the fine-structure constant.
- This pure number describes the strength of the electromagnetic forces between elementary particles.
- The scientists improved the accuracy of this measurement by 2.5 times.
The process for measuring the fine-structure constant involved a beam of light from a laser that caused an atom to recoil. The red and blue colors indicate the light wave's peaks and troughs, respectively.
Scientists at Washington University are patenting a new electrolyzer designed for frigid Martian water.
- Mars explorers will need more oxygen and hydrogen than they can carry to the Red Planet.
- Martian water may be able to provide these elements, but it is extremely salty water.
- The new method can pull oxygen and hydrogen for breathing and fuel from Martian brine.