How Earth’s Tides Gave Us Life As We Know It

How Earth’s Tides Gave Us Life As We Know It


{♫Intro♫} For hundreds of years, “Are we alone in
the universe?” has been the ultimate question for science. And while astronomers are busy searching for
life beyond Earth, they’ve also started asking another question: If life seems so difficult to find, then why
is our world so full of it? One answer might be overhead right now: the
Moon. Moons are all over the solar system—bigger
ones and smaller ones—but there’s something unique about ours. All of Jupiter’s moons combined are just
two hundredths of a percent as massive as Jupiter. A similar ratio holds for Saturn and Neptune’s
moons, while the Uranian and Martian moons are even less massive compared to their planets. In comparison, our single moon is a whopping
1.2% of the Earth’s mass—which means its effects aren’t exactly subtle. In particular, the Moon’s gravity causes
tides that affect huge swathes of the planet. And while it’s hard to know anything for
sure when you’re talking about billions of years in the past, there are good reasons
to suspect that those tides played a large role in shaping life as we know it. For one, tides likely played a key role in
creating the basic conditions for life. That’s because tides don’t just affect
water. Even though we think of tides as rising and
falling ocean levels, tides actually affect the entire surface of the Earth. For example, New York City can rise and fall
more than 35 centimeters in a day. But while water can simply flow to its new
shape every time the tides go up and down, the Earth’s crust is full of rock that twists
and grinds on itself, creating friction that releases heat. Earth already gets a lot of heat from radioactive
decay in the mantle, and all of this heat helps move around the pieces of the crust
we know as tectonic plates. As these plates move around, creating earthquakes,
volcanos, and new mountains, they also release elements critical to life, like phosphorus,
copper, and zinc, that come from the Earth’s mantle. And as old land gets pulled back into the
mantle, it traps the greenhouse gas carbon dioxide underground, which helps keep the
planet cool. What’s left is a delicate balance of temperature
and nutrients that sets the stage for life to arise. And the tides may have had a role in that
next step as well. We don’t know for sure how life got its
start, but one of the most famous models describing the origin of life is the primordial soup
theory. In this scenario, Earth’s early oceans were
full of the basic building blocks of life, like amino acids. Under just the right circumstances, a very
lucky combination of these ingredients could have created the first life. In particular, that cocktail would have had
to include one important ingredient—a way of copying itself, or making more life from
life. Today’s replicating molecules are DNA and
RNA, and the backbone of these structures is made of phosphate. To make copies of genetic information, they
have to come together and separate—a process that’s sometimes described as zipping and
unzipping. Early life likely had replicating molecules
that worked similarly and were also made of phosphate. The catch is, in normal, low-salt ocean water,
phosphates repel each other and block one strand of phosphates from connecting to another. But in water with higher concentrations of
salt, that effect is neutralized. Strands of phosphates can suddenly come together
and replicate. And the ebb and flow of the tides could have
helped make that possible. As the tides wash out, seawater gets trapped
in tidepools where it can start to evaporate, leaving behind its salt and creating an extra
salty environment where the miracle of molecule replication can occur. Once life got started — however it did — tides
continued to shape its development. Researchers debate whether tides would have
helped stabilize or destabilize the Earth’s climate over time, but the one thing they
agree on is that tides definitely would have influenced it. See, while tides might seem like a simple
in-out motion from any one point on the shore, their movement around the globe is actually
pretty complex. Tidal motion helps set up enormous ocean currents
that can redistribute the equator’s warm water across the planet and have profound
effects on the climate. It’s hard to predict exactly what happened
in the past because the motion of tides and currents depends a lot on the location of
the continents and the shape of the ocean floor, Like, just the appearance of a strip of land
connecting North and South America—the Isthmus of Panama—a few million years ago was enough
to cut off circulation between the Atlantic and Pacific Oceans and completely change the
shape of ocean currents. Because of that change, a new, Gulf Stream
current started carrying warm water up north, making Northern Europe as much as 10 degrees
Celsius warmer than it used to be. And there’s no doubt that shifts in the
climate, affected by the tides, drove much of life’s evolution. Even today, tidal motion is increasing the
melting of ice in the Arctic by carrying warmer water up and under the sheets of sea ice. Of course, Earth isn’t the only place that
experiences tides, and tides have actually become a signpost in the search for life. Tidal heating has created an ocean twice the
size of Earth’s under the surface of Jupiter’s moon Europa. [en-SEHL-uh-duhs]
And tides from Saturn inject enough heat into its moon Enceladus to create giant geysers
that shoot hundreds of kilometers into space. Places like these—rather than dry, dusty
Mars—might be our best hope for life in the solar system. After all, if the tides helped get life started
once, maybe it could happen again. Thanks for watching this episode of SciShow
Space! And thanks to this month’s President of
Space, SR Foxley, for helping us bring you this episode! SR is one of our patrons on Patreon, and if
you want to find out more about how to join the amazing community of supporters who help
make SciShow happen, you can find out more at patreon.com/SciShow. {♫Outro♫}

100 thoughts on “How Earth’s Tides Gave Us Life As We Know It”

  1. Could something as large as the great pacific garbage patch have an impact on tidal motion or does the impact exclusively come from changes in the land mass underneath the ocean as opposed to a large surface level obstruction?

  2. 5:45 Can you use Miles as well as a unit of measurement for your American fewers? Even simple parenthesis on screen would do well at delivering the info more clearly to your viewers.

  3. Surprised he didnt mention how in the past the tide would have been way stronger. The moon was much closer, orbited much quicker, and the earth days were shorter(spun faster). So there would have been a lot of mixing as the area of tide pools would have been huge

  4. Hank as well as other people who think life just happened should be ashamed of themselves. There is a design behind everything and thus, a designer behind the design. Life did not just happen. Life was designed and there is a designer behind life. The designer behind life itself is none other than God himself. This is why it is comical to watch scientists waste millions of dollars to answer the question of where life originated from when the answer is painfully obvious and free.

  5. SciShow (2 days ago): We have no idea how or why tectonic plates are here.
    SciShow Space (Today): The moon doesnt just affect water, land also moves and twists creating tectonic plates.

  6. Didnt PBS Spacetime doing a video on what really casues tides is surface tension not the moon????? Look it up

  7. For some reason, this makes me think about Mars and it's dead core.
    Could you just put an equally proportionately sized moon around Mars and gravitational flex its solidified iron core back into a magnetic field producing existence?
    Hey…Elon..get on that.
    Beats nuking the poles.

  8. Tides at the time life first formed where a lot bigger and more violent than they are today, because the Moon was much closer and Earth itself rotated faster, so I don't know if they would actually have helped life form of if they would have made things too turbulent to allow anything interesting to happen.

  9. All I can say is that, if we manage to find life anywhere else in the solar system, then life is just something very common in the universe, then all we can say is… we are really lucky to have survived (as living organisms) until now.

  10. Also, lava tides might be what create our magnetosphere, important for life. (But I think this is just theory nowadays and ice shell moons won't need this anyway)

  11. 1:52 He: "Earth already gets a lot of heat …"
    Me: "from political groups clashing against each other."

  12. Panama: Yeah, Ill just pop up right here, blocking the currents and allow the new ones to warm Europe and enable the western civilization to form.
    The western civilization: Oh look, theres Panama. Lets dig a hole in that.

  13. If you are looking at tides, there is no nastier tide in our solar system than the tide on Io because it has a very big "moon" called Jupiter.

  14. Nope, as life on earth is the only randomness that is possible on its settings, you can't say that the surroundings are a condition for life, but rather that these settings drive this form of life. So the title, including the phrase "as we know it" is more correct than the conclusion of the video.

  15. Don't forget that the tides were MUCH larger in the past because the moon was considerably closer to the planet.

  16. Wow I was thinking this exact question yesterday! Especially since the moon used to be closes and have stronger tidal forces.

  17. Life existed with much higher concentrations of, "those gases" and almost died when they were replaced. Can you just put your agenda aside for like 5 minutes to give actual historical facts? Or maybe mention life started in an environment we assume had little to no Oxygen.

    Winning people over to the importance of climate doesn't happen by just ignoring alternative facts. You'd learn that if you got out of your bubble.

  18. Our world is full of life? I didn't know that, I thought life primarily just lives on the surface of it and some in the crust, which is only a very tiny portion of the entire planet.

  19. "It's hard to predict what happened in the past…"
    Actually, I would assert that it's darned impossible.
    I know, I know, and I get his meaning, but perhaps "discern" would have been a better word choice.
    I did get a giggle out of, though.

  20. Wooooow… so with Charon being ~10% of Pluto's mass, is Pluto pretty much one giant rainforest of biodiversity?

  21. Doggo is the best friend of Hooman
    Moon is the best friend of Earth.
    Thank you, you shiny roundy cheese in the sky!

  22. Somewhere in the universe, two planets are orbiting eachother as if they were eachothers moons, you can guarantee the species living on those planets are fighting eachother and blame eachother for tidal damage.

  23. Interesting aspect! Especially when I think about specialised life in tidal areas. That's not uninterrupted chains of tidal life since day one, but the idea of life at the oldest life generators is always interesting. Just like chemically interesting lightnings and underwater vulcanoes, the initial potential to change things is unbroken.

  24. We have life. We have tides. Therefore, life needs tides.

    Such is the self-justification of evolution in a closed loop system.

  25. I know that even the simplist form of life is too complicated to be formed by chance. One molocule of protine is so complex I heard a scientist say if you have the ociens filled with amino acids we don't have time to form one functional protien molocule by chance.

  26. Just yesterday, someone in your comments section called me a liar for saying exactly these things about the moon.
    Do more videos about the moon, many people seem baffled that it's actually important, or even does anything at all.

  27. 5:10 you need to look no further than Europe to see that. London, which gets fed warm air by ocean currents, is fairly warm and livable. While Moscow, at a similar latitude, is notoriously cold.

  28. And we recently learnt that phosphorus, which is produced by a certain type of supernova seems to be only common in our small neighbourhood. If phosphorus, which of course is part of the very important phosphate molecule, is absolutely essential for life and ours is the only form of life, than we are definitely living in a very dead universe. Oh, and if we ever get FTL travel, we're going to have problems going beyond that small sphere unless we can find a way of easily synthesising phosphorus.

  29. This is quite the discovery. I really wonder the possibilities we have with our own artificially made moon. Maybe we can even revive Mars?

  30. Videos like this all make the "perfect conditions" fallacy. Life is stupidly resilient, and adapts to the environment in which it's in. Life isn't fragile.

    If there were no tides, would life look different? Yeah probably. A lot different? Not likely.

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