Learn about the science of sourdough starters; and why identical twins aren’t so identical after all. Then, play along at home as we test your podcast knowledge with this month’s Curiosity Challenge trivia game.
Learn about the science of sourdough starters; and why identical twins aren’t so identical after all. Then, play along at home as we test your podcast knowledge with this month’s Curiosity Challenge trivia game.
Study of sourdough from around the world shows location doesn't matter for its microbes by Cameron Duke
Identical twins aren't so identical after all by Steffie Drucker
Episodes referenced in Curiosity Challenge Trivia game:
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/identical-twins-arent-as-identical-as-we-thought
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about the science of sourdough starters; and why identical twins aren’t so identical after all. Then, play along at home as we test your podcast knowledge with this month’s Curiosity Challenge trivia game.
CODY: Let’s satisfy some curiosity.
If you started a sourdough bread hobby during the pandemic, you probably learned that your sourdough starter is unique to your location in the world. A sourdough starter is the flour and water mixture bakers use to grow the yeast that makes their bread rise, and some of that yeast comes from the surrounding air. So if your bread is particularly good, you probably live in a location with particularly good sourdough microbes. That’s the claim, anyway. However, a new study has revealed that while there’s tons of diversity among sourdough starters, geography has nothing to do with it.
A team of microbiologists, probably inspired by their own pandemic bread baking, decided to tease apart what gives sourdough its character. Scientists have known that particular types of yeast and bacteria feeding on flour can form unique communities, but they haven’t known much about the structure or diversity of those communities.
The team had bakers from all over the world send in samples of their sourdough starters. They ended up with 500 samples from across the US, Europe, Asia, and Australia. After sequencing the DNA in the starters, the team did several things. First, they employed “sensory professionals,” who are people literally paid for their smelling abilities, to sniff out the individual aromas from the starters. Then they chemically analyzed the volatile organic compounds from the dough that contribute to smell. Finally, they measured how quickly the dough from each starter rose.
In the end, they learned that there is much more diversity among sourdough starters than we had realized. For instance, they found more than 700 different species of yeasts, but 30% of the starters didn’t contain the kind of yeast we traditionally associate with bread baking. The scientists were also surprised to find that acetic acid, or vinegar,-producing bacteria was way more common than they realized. Starters with lots of this bacteria produced slower rising bread with a vinegary smell.
But the big, maybe disappointing finding is this: geography has absolutely nothing to do with the bacterial communities in sourdough starters. The team says the differences between starters come down to lots of tiny things, like the starter’s age, how often it’s replenished with new flour, and where people store it.
If you’re a baker like me, I know — it’s pretty lame [LAHM]. Try not to be too sour now that you dough. After all, we’re still in a pandemic — bread research is the yeast of our problems.
Hollywood has a fascination with identical twins. [Ad-lib all the twins we can name - Jimmy and Jey Uso, THE PROPERTY BROTHERS Drew and Jonathan Scott, Tia and Tamara, The Bella Twins Brie and Nikki Bella] But science is just as enamored with them. That’s because identical twins are said to have identical DNA. And when you’ve got two people with the same DNA, that means any differences between them probably aren’t genetic.
Well new research has broken that spell: It turns out identical twins aren’t as identical as we thought.
The scientific term for identical twins is “monozygotic,” meaning they came from a single fertilized egg that split into two. So it was long assumed that identical twins were a carbon copy of one another, even at the genetic level. But it wasn’t until recently that scientists could verify that claim, since they didn’t have the tech to compare twins’ genomes. But now they do! So for a study published in January, scientists analyzed the DNA of 381 identical twin pairs. They found that the pairs differed by an average of 5.2 mutations.
That seems tiny when you consider there are 3 BILLION letters in a genome. But remember, that was an average. 10 percent of the pairs differed by more than 100 mutations, while another 10 percent had no differences at all. The rest were somewhere in the middle.
This discovery has huge implications for science. That’s because, like I said, identical twins have been popular study subjects for questions of “nature vs. nurture.” Researchers would study identical twins who had been raised in different households. If there was a major difference between them, researchers could conclude that it was due to their upbringing; if they had some unusual similarity, it was probably genetic. This new study casts some doubt on work based on that assumption.
Even cooler is that scientists were able to pinpoint when these mutations happened — down to the stage of embryonic development. Sometimes, mutations happen when the enzyme copying our DNA makes a mistake that goes uncorrected. In twins, that can happen before or after the egg splits, and that can affect whether one or both twins gets the mutation. Other times, the differences aren’t in the genes themselves but in which genes are turned on, or expressed. That’s called epigenetics, and it can change over a twin’s life. Sequencing the genomes of the twins’ parents, partners, and children helped scientists narrow down where each genetic difference came from.
This study is just more proof of the fact that nothing is really nature or nurture. Both interact in complicated ways to make us, us.
It’s time once again for the Curiosity Challenge! Every month, I call up a listener and put them to the test by asking three questions from stories we ran on Curiosity Daily in the previous month. For this Curiosity Challenge, I talked to Stephanie, who's an engineer and a longtime listener. I started by asking her where she's from — and getting acquainted with her dog. Take a listen!
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100%! Can't get better than that. How did YOU do? If you’d like to play next month, OR if you have a question you’d like us to answer on the show, shoot us an email at curiosity at discovery dot com, or leave us a voicemail at 312-596-5208!
CODY: Before we recap what we learned today, here’s a sneak peek at what you’ll hear next week on Curiosity Daily.
ASHLEY: Next week, you’ll learn about a simple fix to reduce your carbon footprint while using the internet;
That time giant sandworms roamed the ocean floor;
Why lakes freeze from the top down instead of the bottom up;
And more!
CODY: We’ll also learn about the future, from award-winning producer and “Flash Foward” host Rose Eveleth. Super exciting! Okay, so now, let’s recap what we learned today.
[ad lib optional]
CODY: Today’s trivia segment was produced and edited by Ashley Hamer. Today’s stories were written by Cameron Duke and Steffie Drucker, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Today’s episode was produced and edited by Cody Gough.
CODY: RISE from your grave. Have a great weekend, and join us again Monday to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!