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Hi, I'm Emily Graslie of The Brain Scoop, filling in for Hank Green. Sorry! I know you really liked Michael Aranda last week, but it's my turn now. And you are indeed in the right place, because this is SciShow News.

And there's a lot we have to lay on you today: an effort to classify every organism on Earth, a fight among scientists about what happened in the 8th century, and a whole new look for your DNA. Oh, and did I mention the dung beetle?

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Let's start with an ambitious and, if you ask me, inspiring call to action that was made on Thursday. In this week's issue of the journal Science, Australian and British biologists write that if we put our minds to it, we can catalog all of the living things on Earth by the end of this century.

Now, you're probably thinking, "Aren't we already trying to do this?" Well, yeah, in a way. There's a whole discipline of biology dedicated to classifying organisms. That's taxonomy. But many scientists have thought that it'd never be possible to actually find and name every single living thing.

For starters, some think that there are just too many species for us to discover. Some estimates go as high as 100 million species, whereas there only about 1.9 million known to science so far. It's also been argued that of all the unknown species out there, so many could be going extinct so fast that we could never possibly catch all of them in time. And finally, who's gonna do all of this catching and classifying? I mean, taxonomy isn't exactly the sexy discipline that it was back in the day of Carl Linnaeus.

Well, biologists Mark Costello, Robert May, and Nigel Stork have answers for all of that. First, they argue, there probably aren't nearly as many unknown species out there as we think. About 20% of known species are likely what they call synonyms: organisms that are mistakenly classified as separate species. Duplicates in the tree of life, basically. So the team estimates that there are probably no more than 5 million species on Earth, not 100 million. They also point out that the extinction rate for known species so far averages less than 5% per decade. Not great, but there's still no reason to believe that the extinction rate would be any higher for unknown species, so they say species probably aren't disappearing as fast as we fear. Finally, they want you all to know that the science of taxonomy is alive and well, thank you very much. There are more taxonomists in practice today than ever, and in the past six years alone, they've discovered and classified an average of 18,000 new species per year. We're talking all over the world and all up and down the tree of life: plankton species in Antarctica, deep-sea lobsters in the Indian Ocean, right down to a very tiny Venezuelan snail no bigger than a grain of sand.

Most of the scientists classifying these finds, as you might expect, work in some of the world's hottest biodiversity hot spots, especially in South America and the Asia Pacific region, like this one conducting a fish count in the Philippines. Counting fish? Sounds like a fun job!

So, the way the biologists in Science magazine this week figure it, if there are, say, 3.5 million species on Earth to be classified and the taxonomists of the world could I.D. 20,000 species a year, then we'd have a complete catalog of all the world's organisms by 2100.

And I say we do it! Count me in. Where in the world would you want to go to discover new species to science? And what kind of creatures would you hope to find there? Let us know in the comments below.

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Next, here are three surprises.

First, dung beetles aren't stupid. Okay, no one said they were, but they have tiny brains, and let's face it: they make their living by hoarding poop. But scientists from South Africa and Sweden have found that they are the first animals known to navigate by the light of the Milky Way.

See, when collecting food, dung beetles' main objective is to gather as much poop as they can from the nearest pasture pie and roll it in a straight line as far away as possible from competing beetles. As one researcher in the new study, Marcus Byrne, puts it, "dung beetles don't care which direction they're going in, they just need to get away from the bun fight at the poo pile."

It's how they do it that's the tricky part. Scientists have known that beetles can orient themselves by the sun and moon and have suspected that they could also navigate by the stars because the beetles are often found to lose their way on overcast nights. So Byrne and his colleagues at Wits University in South Africa and Lund University in Sweden put the bugs to the test under simulated night skies in a planetarium. They found that the beetles are able to stay on a straight path under starry skies, and they did just as well under simulated skies where no stars were visible other than the distant fog of the Milky Way.

This makes sense, considering that the beetle's tiny compound eyes are probably better at detecting the diffuse light of galaxy rather than individual stars or constellations. The team published their findings Thursday in the journal Current Biology.

Next, more than 1,200 years ago, Earth was struck by a massive burst of radiation, leaving traces that can still be found today, and scientists are fighting about what caused it. Science fight!

The bombardment apparently took place around 774 or 775 CE. Charlemagne was trampling over Western Europe, the biggest city on Earth was Baghdad, and everyone was minding their own medieval business. But then some celestial barrage took place that left telltale signs all over the world.

Last year, researchers studying ancient cedar trees in Japan noticed unusually high levels of radioactive carbon 14 in its inner layers dating back to 775, and this coincided with other oddities, like weird levels of the isotope beryllium-10 detected in ice cores drilled in Antarctica.

Scientists agree that these signs are likely the result of unusually intense radiation blasting Earth's upper atmosphere, but what could've caused it? Last November, a team of U.S. researchers suggested that it was the result of a really historically ginormous coronal mass ejection, when the sun's corona emits huge plumes of solar material.

This week, however, a pair of German physicists said it was likely the result of an even more dramatic but more distant event: the collision of two supermassive objects in our galaxy, like a neutron star crashing into another neutron star or possibly a black hole that unleashed unholy amounts of gamma radiation.

The American scientists argue that such an event would be unlikely, but one thing everyone agrees on is that if a 775 event were to happen today, we'd be up dung beetle creek, if you know what I mean. It might not wipe us out or even cause any extinctions, but it would probably fry our whole satellite and communication systems, and if it were any closer, it'd frazzle the ozone layer that protects us from U.V. radiation. So, try not to think about that.

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Instead, think about this. Your DNA doesn't always look like you thought it did. You might've heard this already, but it bears repeating. We typically associate our DNA with the double helix, the structure that was first theorized 60 years ago by Watson and Crick. But researchers at the same institution where they worked -- Cambridge University -- have discovered what they call DNA quadruplexes -- four intertwined strands of DNA -- throughout the human genome.

They seem to be most common in cells that are in the process of rapid cell division, and cell division is great. It happens about a quadrillion times in your body throughout your lifetime as you replace old cells with new ones. But "rapid cell division" is kind of a polite term for "cancer," so these quadruplexes may provide us with yet another way to track and potentially stop the growth of cancer. But that's still pretty far down the road. For now, I'm just amazed that we're still learning about even the most basic blocks of life.

Too bad Hank's not here to enjoy this.

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