How The hedgehog Got Its Name
This week’s episode of It’s Okay To Be Smart (below) focuses on a very special chunk of DNA and the things that it does, part of a family of genes that help sculpt complex body shapes across the animal kingdom, from fruit flies to fish to humans to hedgehogs. Sonic hedgehogs, to be exact.
Sonic hedgehog is a gene that every vertebrate carries that, working in beautiful concert with dozens of other developmental genes, helps guide and shape everything from your spinal cord to your face (as Emily showed us in the recent Two-Faced Calf episodes on The Brain Scoop). It helps the developing embryo determine which is the front side of the hand and which is the rear. And coolest of all, it helps precisely five fingers sprout, not four, not six, and determines which will be the thumb and which will be the pinky.
It also has something to do with the evolutionary biology of The Simpsons, but we’ll have to save that for another post.
Sonic hedgehog isn’t the only hedgehog gene we carry. We also carry inside our DNA an indian hedgehog and desert hedgehog. So what’s up with the names? Our array of hedgehogs (that’s the official term for a group of hedgehogs, as it happens) are all related to a gene from fruit flies.
In the late 1970’s Christiane Nüsslein-Volhard and Eric Wieschaus randomly mutated fruit flies and (quite literally) combed through them by the tens of thousands looking for interestingly deformed mutant embryos. Pretty macabre stuff, if it wasn’t flies, eh? Based on this screen (which won them the Nobel Prize), they discovered a swarm of genes that affect how the fly’s body decodes its form (read their original paper). And they gave those genes funny names based on funny patterns or phenotypes in the mutant embryos.
Why? Well, it’s possible that Germans have some hidden sense of humor that they aren’t telling the rest of the world about, but it’s more likely that they named the genes this way because that’s how Thomas Hunt Morgan, master of mutant flies, did it.
How do you get a hedgehog from a fruit fly? Let’s start with a normal fly embryo. Usually these tiny worm-beasts display an elegant, banded pattern of “denticles”:
Well, one of the random mutations that Christiane and Eric identified resulted in a scrunched up embryo with completely bunched denticles. The reasons for that scrunchiness are complex, but if you want to know more, read up on the treasures that lie within pair-rule genes and gap genes. Anyway, since fruit fly folks name genes based on what the mutant looks like (e.g. wingless, yellow, curly) they named it hedgehog!!
Relatives of that gene in other animals were discovered in the following years in many other species, and thanks to the finely tuned comedic skills (and long nights at the pub) that biologists are known for, we ended up with Indian, Desert, Sonic, and in fish, even Tiggywinkle hedgehogs. And that hedgehog lives in every cell, brought out of its burrow with careful genetic choreography to make you the thumbed wonder you are today. Ain’t biology adorable?
If you could visit anywhere in the universe, in time and space, to witness something wonderful and scientific, where/when would you go?
That’s one of the questions I answered in this week’s Ask Joe video:
My answer? I’d go back to the single day, approximately 2 billion years ago when one cell gulped up another one, and instead of eating it, created the mitochondrion. Our little cellular energy factory, formerly a free-living organism, is the key to the evolution of quite literally all complex life on Earth, plant or animal. As Ed Yong writes in his history of the mighty mito, it happened only once. I’d just want to watch it happen under a microscope, so I could say “Yep, that’s why I’m here.”
Oh man. But what if I sneezed or something? I could ruin the whole universe. On second thought …
Apparently telling people they are distantly related to fish is not a popular thing to say?
That’s the impression I get from reading the comments on this week’s It’s Okay To Be Smart video, anyway. If you haven’t watched it, check it out. And if you have a strong forehead and feel like smacking hand, check out the comments (just wait 30 minutes after eating and be polite before jumping in). I knew it would get some anti-evolution reactions, but wow.
The funny thing is, as evolution goes, the video I made this week is pretty tame. I mean, I could come up with a LOT more controversial topics to talk about if that was my goal (which it isn’t… my goal is to inspire people to learn and help them connect to the beauty of the natural world around them).
While it certainly doesn’t make us happy to do it, I think it’s important that we regularly remind ourselves how many people out there still think that their beliefs, whatever they may be, mean that they aren’t allowed to make science part of their life.
There’s as many points along the line connecting science and spirituality as there are people on that line, and there’s views hitting every extreme in all directions. We may never all be able to find common ground on what we believe in in the spiritual sense, but there’s one thing I’m sure of when it comes to the science: There is magic in reality, and understanding the world we live in, and how we came to live in it, and all the science that informs that story, it can only enrich your life… no matter what you believe.
Also, we have fossils and stuff. So there.
Even Enrico Makes Mistakes…
In my "How The Elements Got Their Names" video, I dropped this little rhyme about element 93 (Neptunium), Enrico Fermi, and how his Nobel(ium) helped him get to Americ(ium):
There’s a crazy story behind 93, it was named for Italy by Enrico Fermi.
But his science was wrong, and when his Nobel came along, he snuck off to the States to be free.
Confused? Well, the full story behind element 93 is a fascinating tale of bad PR, fascism, and laboratory screw-ups.
Uranium, element number 92, is the largest element (in terms of number of protons) found in nature. Every element above 92, a club known as the transuranium elements, is unstable, decaying into smaller elements and subatomic particles. In the mid-1930’s, element-hungry scientists knew that the transuraniums theoretically could exist, but didn’t have a way to make them.
Enrico Fermi, then working in Rome, figured that pummeling uranium atoms with slow-moving neutrons might birth elements 93+ thanks to a process called β- decay, where the new neutron enters the nucleus, converts into a proton, releasing an electron and antineutrino in return. The result? Uranium+1 or Uranium+2, or elements 93 and 94… theoretically, at least.
In 1934, Fermi shot some neutrons at some uranium, saw the beta decay he was looking for, and figured he had done it! Elements 93 and 94, in the proverbial bag. Time to pack his bags for Stockholm, right?
Like a cold neutrino pudding, the plot thickened. At the time of Fermi’s experiment, Italy was under the control of Benito Mussolini's fascist regime. Sensing a good PR opportunity for “Italian science” and “fascist cultural supremacy”, Mussolini's government widely publicized the finding, much to Fermi’s chagrin, who wanted to, you know, check his work and stuff.
The first name proposed for Fermi’s #93 was Mussolinium (can you imagine if that had been approved?!) but since the element was short-lived, it was thought that Il Duce would take offense to its frailty. Instead they proposed that the new names for 93 and 94 honor ancient and poetic names for Italy: Ausonium and Hesperium.
In 1938, as these names were being considered, Fermi was awarded the Nobel Prize in Physics for his discovery. Scientific national pride swelled in pre-WWII fascist Italy. But there was just one catch. Enrico Fermi was wrong.
Soon after his Nobel, it was shown that Fermi instead split uranium by nailing it with neutrons, which produced beta decay and energy, but resulted in lighter elements, not heavier. So did Fermi get credit for discovering fission? Nope. That honor goes to Otto Hahn and Lise Meitner, who split uranium (on purpose) in 1938.
So Fermi not only lost out on discovering what would be named neptunium (thanks to Edwin Macmillan and Philp Abelson’s work in 1940), but he also missed out on discovering fission, because he didn’t know that he did it.
After his 1938 Nobel Prize ceremony (for the faux-discovery), fearing for his family’s safety in Mussolini’s Italy, Fermi emigrated directly from Stockholm to the United States, where he worked on the Manhattan Project, using his prize money to set up a new life in a new home.
Fermi had many scientific accomplishments and many successes, but the story of elements 93 and 94 show that there’s a whole lot of history, humanity, and drama behind those little boxes on the periodic table.
Ok, so now that SXSW is winding down and I have my city and my sanity back … I owe you guys some science!
Last week’s It’s Okay To Be Smart video looked at where the elements of the periodic table got their names (check it out here if you haven’t watched it yet!!!) AKA “awesome elemental etymology”. Of course, I couldn’t fit all the weird, wacky, drama-infused histories in just three and a half minutes of YouTube, and there’s a lot of cool element-name stories that I didn’t get to share.
So I’ll be posting some of the strangest tidbits today and tomorrow.
Sit back, relax, and allow yourself to be hypnotized by this microscopic time-lapse video of snowflakes as the are born and evolve their emergent hexagonal complexity.
This video, embedded below, is the fine work of Vyacheslav Ivanov:
And if you’d like to know more about the science of how snowflakes form and why they look that way, check out this video, from … me:
Neil’s message perfectly encapsulates the feeling of yugen, an awareness of the universe that triggers emotional responses too deep and powerful for words.
Next weekend I’m running a marathon, in the name of science!
I’ll be making an episode of IOTBS about it, so what do you guys want to know about the science or evolution of running? Let me know!
What can I say? I’m method.
Monday’s video is quickly turning into Saturday night’s entertainment.
Interested to see what you guys think of this one. I don’t know if everyone knows this, but I film and edit the occasional IOTBS episode all by myself (it should be pretty obvious which ones those are), as opposed to the director/editor/etc on the “bigger” vids. That’s where we can play around, hang out, and experiment. Monday is an experiment. A fun one :)