Why, I wonder, are both these things true? There is an animal, a wee little thing, the size of a poppy seed, that lives in lakes and rivers and eats whatever flows through it; it's called a gastrotrich. It has an extremely short life.
Hello, Goodbye, I'm Dead
It hatches. Three days later, it's all grown up, with a fully adult body "complete with a mouth, a gut, sensory organs and a brain," says science writer Carl Zimmer. In 72 hours it's ready to make babies, and as soon as it does, it begins to shrivel, crumple ... and usually within a week, it's gone. Dead of old age.
Sad, no? A seven-day life. But now comes the weird part. There's another very small animal (a little bigger than a gastrotrich) that also lives in freshwater ponds and lakes, also matures very quickly, also reproduces within three or four days. But, oh, my God, this one has a totally different life span (and when I say totally, I mean it's radically, wildly, unfathomably different) from a gastrotrich.
It's a hydra. And what it does — or rather, what it doesn't do — is worthy of a motion picture.
So we made one. Well, a little one. With my NPR colleague, science reporter Adam Cole, we're going to show you what science has learned about the hydra. Adam drew it, animated it, scored it, edited it. My only contribution was writing it with him, but what you are about to see is as close as science gets to a miracle.
I have so many questions. Why the hydra? If nonsenescence, or biological immortality, is an option in nature, how come this particular mini-bit of pond scum got the big prize? Why not the gastrotrich? Why not (excuse me for asking) ... us? Evolution is such a random, casinolike affair; it's startling to learn that longevity varies without regard to size. I know Daniel Martinez's hydras were cleaned, fed, protected. They didn't live in the wild. But still, they have lasted and lasted and lasted. I expect sequoias, redwoods and whales to last longer than mayflies, daisies and clover. Big things go on, but when two little freshwater animals have such drastically different life expectancies, all I can think is ... whoa! Life is a puzzlement.
Robert Krulwich is co-host of Radiolab, WNYC's Peabody Award-winning program that examines big questions in science, philosophy and the human experience through compelling storytelling. Today, Radiolab is one of public radio's most popular shows. Its podcasts are downloaded over 4 million times each month and the program is carried on 437 stations across the nation. In addition to Radiolab, Krulwich reports for National Public Radio. “Krulwich Wonders” is his NPR blog featuring drawings, cartoons and videos that illustrate hard-to-see concepts in science.
This is probably one of the coolest things I have ever seen. Learning about cells and biology always seems to blow my mind. There are so many things that occur in such small amounts of time. The fact that the hydra can pretty much renew itself after twenty days seems a little like it's cheating death. These are the kind of discoveries that make me want to know more about how the world works and why things happen the way they do.
Mortality is one of a suite of a strategies to improve adaptability. We tend to be biased by those things around us which have clearly defined lifespans because they're big, like us. But most life on Earth is immortal. All the single-celled organisms just keep on dividing. Even some big lifeforms are (potentially) immortal. Plants that survive by cloning are effectively immortal. All the navel oranges in the world are one tree which is to all intents and purposes immortal. I'm pretty sure daffodils will never die so long as you keep cutting off their flowers. Deep sea sponges live for thousands of years, but can grow entirely new sponges from bits broken off and can repeat this indefinitely, making them potentially immortal.
I've read that our brains' neurons are immortal when cultured appropriately in a lab, so we have the seeds of immortality within us, but genetic turnover is more valuable to our species than any individual life, so we are programmed to die.
We are approaching a time when our brains can be modelled inside a computer. When that time comes immortality will be genuinely accessible to us -- perhaps to all of us.
Hydras reproduce in a much different manner than all the other species mentioned in the film (by budding). It seems possible that this very different method of reproduction may be why the hydra's overall lifespan doesn't relate to the age at which it's able to reproduce the way it does in all the other species mentioned.
Because Robert though you (and the rest of us) look at this as THE big prize, for nature it's just another option in the mixing of the chemicals of the DNA. We are just accidents of nature so this option is no different. It is only different to us because we have a skewed perspective, the anal one! :)
I'm surprised that no one pointed out to Robert that we die because dying imparts an evolutionary advantage. If members of a species die of old age, then the younger members of that species (more evolved, by definition) don't have to compete with the older individuals for resources. This speeds evolution. We acquired mortality a long time ago and it propelled us to the stars. Hydra don't have this advantage, which is why they are far less advanced and diverse than, for example, mammals.
If we had lucked into negligible senescence and replaced the bulk if not all of our cells completely, how might that affect the 'soul' debate? Or if we could revert to polyp stage an inordinate amount of times like Turritopsis, I wonder how differently we may have shaped our ideals. If humans could be perpetual motion machines?
Another way to view the Hydra is to compare one to another species. Until extinct, a species appears immortal. The difference is that each individual has a distinct beginning and end. Hydra cells die but the demarcation between individuals is fuzzy, as seen with one collection of cells splitting into two. This is not to diminish the amazing strategy of the Hydra genus, which reproduces both sexually and asexually. I'm just suggesting a different philosophical perspective.
Comments [12]
This is probably one of the coolest things I have ever seen. Learning about cells and biology always seems to blow my mind. There are so many things that occur in such small amounts of time. The fact that the hydra can pretty much renew itself after twenty days seems a little like it's cheating death. These are the kind of discoveries that make me want to know more about how the world works and why things happen the way they do.
Isn't the big difference in the telomeres?
Mortality is one of a suite of a strategies to improve adaptability. We tend to be biased by those things around us which have clearly defined lifespans because they're big, like us. But most life on Earth is immortal. All the single-celled organisms just keep on dividing. Even some big lifeforms are (potentially) immortal. Plants that survive by cloning are effectively immortal. All the navel oranges in the world are one tree which is to all intents and purposes immortal. I'm pretty sure daffodils will never die so long as you keep cutting off their flowers. Deep sea sponges live for thousands of years, but can grow entirely new sponges from bits broken off and can repeat this indefinitely, making them potentially immortal.
I've read that our brains' neurons are immortal when cultured appropriately in a lab, so we have the seeds of immortality within us, but genetic turnover is more valuable to our species than any individual life, so we are programmed to die.
We are approaching a time when our brains can be modelled inside a computer. When that time comes immortality will be genuinely accessible to us -- perhaps to all of us.
Hydras reproduce in a much different manner than all the other species mentioned in the film (by budding). It seems possible that this very different method of reproduction may be why the hydra's overall lifespan doesn't relate to the age at which it's able to reproduce the way it does in all the other species mentioned.
Because Robert though you (and the rest of us) look at this as THE big prize, for nature it's just another option in the mixing of the chemicals of the DNA. We are just accidents of nature so this option is no different. It is only different to us because we have a skewed perspective, the anal one! :)
It's fascinating
> Who wants to live forever ? <
Freddy Mercury - Queen
(He, for one, evidently didn't.)
This Queen song is featured in the soundtrack for the 1986 movie 'Highlander' about a Scottish warrior from the 16th century who can't die.
Hey Robert: This song should be playing in the background for your clip.
Check it out on YouTube ...
I'm surprised that no one pointed out to Robert that we die because dying imparts an evolutionary advantage. If members of a species die of old age, then the younger members of that species (more evolved, by definition) don't have to compete with the older individuals for resources. This speeds evolution. We acquired mortality a long time ago and it propelled us to the stars. Hydra don't have this advantage, which is why they are far less advanced and diverse than, for example, mammals.
If we had lucked into negligible senescence and replaced the bulk if not all of our cells completely, how might that affect the 'soul' debate? Or if we could revert to polyp stage an inordinate amount of times like Turritopsis, I wonder how differently we may have shaped our ideals. If humans could be perpetual motion machines?
Somebody should make a skin rejuvenation product or food supplement with it.
Doesn't matter if it works - but it will sell.
Reminds me of Turritopsis dohrnii, the immortal jellyfish.
Another way to view the Hydra is to compare one to another species. Until extinct, a species appears immortal. The difference is that each individual has a distinct beginning and end. Hydra cells die but the demarcation between individuals is fuzzy, as seen with one collection of cells splitting into two. This is not to diminish the amazing strategy of the Hydra genus, which reproduces both sexually and asexually. I'm just suggesting a different philosophical perspective.
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