What was early Earth like? How did life start on Earth? And what’s up with plate tectonics?
In part one of this two-part episode, we meet NASA scientist and Blue Marble Space Institute of Science founder Dr. Sanjoy Som. We learn about early Earth, stromatolites and how we can care for the planet that gave us life.
As always, submit burning questions at askdruniverse.wsu.edu.
Ask Dr. Universe is a service of Washington State University curated for an 8- to 13-year-old audience. Listeners working on the Middle School History of Earth Next Generation Science Standards may particularly enjoy this episode:
| MS-ESS1-4. | Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth's 4.6-billion-year-old history.
| MS-ESS2-2. | Construct an explanation based on evidence for how geoscience processes have changed Earth's surface at varying time and spatial scales.
| MS-ESS2-3. | Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.
What was early Earth like? How did life start on Earth? And what’s up with plate tectonics?
In part one of this two-part episode, we meet NASA scientist and Blue Marble Space Institute of Science founder Dr. Sanjoy Som. We learn about early Earth, stromatolites and how we can care for the planet that gave us life.
As always, submit burning questions at askdruniverse.wsu.edu.
Ask Dr. Universe is a service of Washington State University curated for an 8- to 13-year-old audience. Listeners working on the Middle School History of Earth Next Generation Science Standards may particularly enjoy this episode:
| MS-ESS1-4. | Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth's 4.6-billion-year-old history.
| MS-ESS2-2. | Construct an explanation based on evidence for how geoscience processes have changed Earth's surface at varying time and spatial scales.
| MS-ESS2-3. | Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.
Dr. Universe
Welcome back, young scientists. I'm Dr. Universe, and if you're anything like me, you've got lots of big questions about our world.
In an earlier episode, we met an astrobiologist and talked about life on earth and the possibility of life on other planets. That got me thinking about what Earth was like in the beginning—four and a half billion years ago.
This episode is the first part of a two-part conversation about early Earth. Let's get started.
I met Sanjoy Som after I recorded a podcast episode with my friend Afshin Khan. Dr. Som is an astrobiologist. One thing he studies is the way very, very old rocks tell the story of early Earth. Dr. Som is a NASA scientist and he founded the Blue Marble Space Institute of Science to bring the mystery and wonder of astrobiology to people of all ages.
I'm so excited to talk to you. Can we start out just by talking about what early Earth was like?
Dr. Som
The early earth was a very different planet compared to the earth we live and work in today.
Why? One, the planet was spinning faster, so the days are a lot shorter than they are today.
And the moon was a lot closer. And as the moon is slowly moving away, the planet's rotation is slowing down. So back in the early days when the moon was closer, the planet was spinning faster. So days were 12, 14 hours, depending on how far back in time you go.
The sun was also different. It was much younger. It was fainter than it is today. The sun is slowly, slowly, very slowly getting brighter. If you go back far in time—we're talking billions of years, so that's a one followed by nine zeros, a long, long, long time ago—the sun was fainter. So, you have a fainter sun, a planet that's spinning faster, a closer moon.
And if you somehow took a time machine and went there, and took a deep breath, you would die. There was no oxygen either. The air was different. It was much more volcanically active. There was no grass, no animals, no trees. All that comes way, way, way down the road. So, for all intents and purposes, the early earth is essentially—we like to think of it as an exoplanet.
So, a planet that has nothing to do with our own planet, that orbits a star that's different than ours. That's how different early Earth was.
Dr. Universe
Wow. That's incredible. If there was no grass and no animals, what did it look like? What would I see if I stepped out of my time machine?
Dr. Som
Imagine that you would step out on a field of black volcanic rocks. There are national parks out there—like in Hawaii and in Idaho—that are just this kind of field full of black volcanic rock. It would look a little bit like that.
There would be no tall mountains. So, you had volcanoes with very shallow slopes, kind of like in Hawaii. As I mentioned, you couldn't breathe. There was no oxygen. There was probably a haze in the atmosphere. So, the sky will probably not be blue. It’ll probably be like an orange—pale orange, butterscotch type color.
Dr. Universe
Kind of like when we have wildfires, what the sky looks like?
Dr. Som
Yeah, exactly right. So, I live in the San Francisco Bay area, and a year and a half ago the sky completely turned orange because of the wildfire. It was very eerie. Something similar I think. Yeah, exactly right.
That doesn't mean there was no life. There was a lot of life, and you could see that evidence of life in the rocks as well, which is incredible. But it was microbes, so single cellular organisms that lived and formed colonies. Those colonies, some of them are called stromatolites—and still today you find stromatolites in certain specific locations. The most famous one is in Shark Bay in Australia. And they've been alive as far back as time goes. I've seen evidence of those that are 3.5 billion years old.
It's cool because it's like: these are your ancestors.
Dr. Universe
So, they're like colonies of bacteria?
Dr. Som
Yep. And they kind of baffled the water with their filaments, which traps the sediments, and the sediments fall on top of them. And then they climb on top of what's fallen on top of them and do the same. So, over time, they accumulate kind of this mound of sediment. And that shape cannot be produced with processes that are not linked to biology. So that's why we know it's a biological remnant of life.
Dr. Universe
So, I know there are a lot of theories about how that life started, do you have a favorite?
Dr. Som
Yeah, so, the origin of life is an active area of research, but unlike a lot of my colleagues, I don't think it started in a single location. Because, a single location, there's a lot of things that need to happen in this one geochemical setting for life to arise. And it's hard to appreciate that that could happen.
I think all the different complexities that we have now as an evolved life form probably happened in different environmental settings on our planet. For example, hydrothermal vents or a beach where you have water that comes and goes. So, you have dehydration and hydration.
Many different chemistries happening in different environments and somehow—and that's the weakness in my argument—somehow, they found each other and kicked in a new form of chemical reaction.
A lot of information about how life evolved is encoded in our genetic code. It’s encoded in the molecules that do all their things in our bodies, but that can only go so far back. And so there's a big gap of knowledge between this last universal common ancestor that links you and I and all the animals and all the bacteria up to our common ancestors. There's a big gap between that and the origin of life. And it's unclear how to tease out that information. It's an active area of research, but I don't think we'll ever know.
But I'm leaning towards that life is actually a product of different chemistries happening in different weird environments that the earth produces.
Dr. Universe
I love that, that makes so much sense to me.
Dr. Som
We are definitely a product of rocks, right? I mean, we have so much iron in our bodies that, if you go back far enough, an environment that was rich in iron probably generated some of those early molecules that are incorporated in our modern bodies.
I mean, at the very basic level, biology is just a clever way of transporting electrons from different chemical species to extract energy. The transporters of electrons in our cells all have iron in it. Right? That weird. Why? Why iron? It's a fantastic element, but it's most likely was an early electron capturer because it formed in an environment when life was very young and not even being able to be defined as life. But iron was prevalent—and you have that in the deep sea and there's different settings but there are other metals in our body that do important things, and maybe there they reflect other environments where those metals were rich.
So, we are definitely a product of the geochemistry of our planets, which is good to think about. You know, in our modern day-to-day lives, we don't feel necessarily attached to the planet. But we are from it. And if one is more aware of that, I think becomes easier to be like, “Now that I have the opportunity to help the planet out now—after it has nurtured me and my ancestors for billions of years—I have the privilege of being able to help that planet out. Maybe I should do something about it. It's a different frame of mind of thinking about being a product of the earth than just living our lives, doing our work, eating our food.
Dr. Universe
That is a completely different mindset than I've ever heard before, and it's so beautiful, and it makes so much sense, and it does make me feel more connected to rocks and the earth.
Dr. Som
It's humbling, I find. And a good message to take care of our parent planet.
Dr. Universe
Are there things that kids can do at an individual level that can make a difference?
Dr. Som
Of course. We can all play a part to make a difference. What I recommend the kids to do is work with their parents to write letter to their local representatives and to Washington DC and make them aware that these are issues that matter to them.
Ultimately, the people who represent us in government will fight for what their constituents want fought for. And so, if the environment is something that matters to you and to your children—or if you are a child, it matters to you—take a pen, take a pencil, write it down. Tell your congressperson—which your parents can help you find—that this is something that matters to you, and I am pretty confident you will get a response.
Dr. Universe
That's amazing. I love that. I have loved every part of this conversation. I feel like I've learned so much.
Dr. Som
Yeah. I think the planet has a lot to teach us in terms of how to be better humans and how to be better custodians of the planets.
There's a lot more that brings us together as humans than what differentiates us. I'm sure you've seen those cave painting. You know, where they have the hand prints with the red ochre around it. These are the ancestors to all of us, right? You don't have to go back billions of years.
You only have to go back thousands of years to find ancestors to every single human being present. So, you and me, we are related. Not going that far back, both of us had ancestors that built the pyramid, right? And that's true of all the kids that are hopefully listening. You and I are brothers and sisters, are cousins.
It seems like today the world is designed for us to be afraid of people who don't believe like us, speak like us, eat like us, look like us. But the truth is I think we are able to be a lot stronger and appreciate the diversity of thought if we embrace the differences and learn from them. I think that makes us better humans.
Dr. Universe
Yeah, that's a powerful message.
That's all for this episode, friends. Big thanks to Sanjoy Som for giving us a window into astrobiology.
As always, if you've got a science question tickling your brain, you can submit it at https://askdruniverse.wsu.edu/. Who knows where your questions will take us next.