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  • Go to Brilliant.org/SciShow to learn more.

  • [ intro ]

  • There's a lot written about how early animals transitioned

  • from living in water to living on land.

  • But you rarely hear how /plants/ did it.

  • That's kind of a shame,

  • because plants reached land first,

  • and they conquered the planet way faster than animals.

  • Also, without them, you and I really wouldn't be here.

  • Unfortunately, the earliest land plants didn't leave much fossil evidence behind,

  • so their story isn't that clear.

  • To know what these plants were like,

  • scientists have to hunt for clues in the DNA of today's plants.

  • And last week in the journal Cell, one team shared an exciting new finding.

  • They analyzed all of the genetic material in two species of algae

  • that are closely related to land plants.

  • And by doing so, they might have discovered how early plants managed to survive in the

  • open air.

  • Sidenote, I just want to emphasize how hard it is to go from living in the water,

  • where all chemistry happens -

  • This research focused on a class of algae called, wait for it,

  • Zygnematophyceae.

  • Put it on the screen there for ya, didn't I do a good job?

  • Recently, scientists found that this type of algae

  • shares a lot of genetic material with the first land plants,

  • so they're probably closely-related.

  • This is early work, though, so in this new paper,

  • the first thing researchers did was look for more evidence that it's true.

  • To do this, they sequenced the genomes of two early types of Zygnematophyceae.

  • In other words, they analyzed and created lists of the stuff in the algae's DNA.

  • Then, they compared those lists to the genomes of land plants

  • and a handful of other algae species.

  • The team found that the early algae shared a bunch of genes with land plants:

  • a whopping 902 of them.

  • But the other algae species didn't have these genes.

  • That suggests those genes evolved before Zygnematophyceae and land plants

  • branched off from each other about 580 million years ago.

  • And it all but confirms that this class of algae represents the closest living relatives

  • to land plants.

  • And That's great news,

  • because it's super satisfying to figure out how things are related to each other.

  • I mean, who doesn't like a nice, complete family tree?

  • But the team also found something else in their data

  • something that might explain how early plants managed to survive on land at all.

  • They noticed something weird about two families of genes in that list of 900.

  • They were the genes responsible

  • for helping plants cope with the stresses of living in the open air,

  • like drought or pests.

  • But they didn't just appear in land plants and those two species of algae.

  • After searching a large database,

  • the scientists also found these genes in one other group

  • just one.

  • Soil bacteria.

  • That might feel like it comes out of nowhere,

  • since bacteria, algae, and land plants aren't that closely related.

  • But the team had an explanation for how it might have happened.

  • Bacteria are big fans of exchanging their DNA

  • through something called horizontal gene transfer.

  • It's where they pass genetic information not from parent to offspring,

  • but from one organism to another, unrelated one.

  • Bacteria do this fairly frequently.

  • So the team proposed that at some point,

  • soil bacteria passed the genes for surviving on land to the common ancestor of land plants

  • and Zygnematophyceae algae.

  • And eventually,

  • that may have given plants the adaptations they needed to survive and take over the world.

  • Or at least the land parts of it.

  • Now, this hypothesis isn't bulletproof,

  • and the idea of bacteria transferring genes to more complex organisms

  • is kind of controversial.

  • Any positive results are often blamed on contamination.

  • But among other things,

  • this team took safeguards to avoid that.

  • So at least for now,

  • their results are getting some researchers pretty excited.

  • After all, now that we've spotted these bacterial genes,

  • we can learn more about how they got there and how they evolved to help land plants.

  • And as a result,

  • we can learn how the Earth became all beautiful and green and leafy and stuff.

  • In any other news,

  • Caltech researchers announced on Monday that they discovered a skill in honeybees that's

  • never been seen in any other insect.

  • And honestly, it's pretty cute.

  • Apparently, honeybees can surf on water.

  • At least, in a sense.

  • If you're an insect with wings, water can be dangerous.

  • With one touch, your wings can be trapped by the water's surface tension,

  • and that takes a huge amount of force to overcome.

  • Often, insects just end up drowning.

  • But for honeybees, going for a dip is not a death sentence.

  • The Caltech researchers found that,

  • when honeybees fall into water,

  • they can carefully alter their wingbeats to surf their way to safety.

  • They confirmed this by setting up a shallow pool of water illuminated by filtered light,

  • so that any waves cast visible shadows.

  • Then, in went the honeybees.

  • Thirty-three bees each took their turn surfing.

  • And they did something super cool.

  • They used their wings as hydrofoils

  • surfaces that can generate lift in water, kind of like what airplane wings do in the

  • air.

  • With the underside of their wings stuck to the water,

  • they flapped against the surface with slow, shallow strokes.

  • To illustrate, an average flying honeybee flaps its wings between 90 and 120 degrees

  • and about 250 times per second.

  • But in water, most of these bees moved their wings about ten degrees,

  • and less than a hundred times per second.

  • Almost like a honeybee doggy paddle.

  • That created a pattern of waves behind the bee that propelled it forward.

  • The insects couldn't do this forever, of course.

  • In the experiment, they flapped around for a few minutes,

  • and then the researchers scooped them out and gave them some well-earned rest.

  • But in nature, one scientist estimated

  • that a honeybee could probably keep this up for about ten minutes.

  • And that could be enough for it to get to safety.

  • This research is super adorable,

  • but the team behind it is hoping to take a page from the insect's playbook, too.

  • They're already applying the bee's surf style to robotics research

  • in hopes of creating a robot that can navigate both air and water.

  • So, thanks, bees!

  • Just another reason to appreciate you.

  • If you want to learn more about some of the science topics we talked about in the video,

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  • They have a few quizzes about things like hot air balloons and rockets,

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  • [ outro ]

Thanks to Brilliant for supporting this week of SciShow!

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