Kind: captions
Language: en
Once you realize that life is constantly
and always evolving, you basically turn
on life and then you turn on this
endless story. The universe is too big
for my brain, but I'm really interested
in the story of our planet. When did it
start behaving like Earth? When did life
itself start? When did the oceans form?
When did the continents form? When did
the first fish evolve? I mean, this is
all heavy stuff for a paleobotist. I
want to tell you right now.
[Music]
[Applause]
[Music]
Hi everyone. Today I got to talk to Dr.
Kirk Johnson. He is s director at the
Smithsonian Institution National Museum
of Natural History, which is home to one
of the biggest natural history
collections on the planet. He's also a
paleobotonist and has hosted a bunch of
Nova documentaries like Polar Extremes
and Making North America. I love this
dude. We got into some really cool stuff
like how fossils form and where Earth's
oceans actually come from. You know,
stuff we all talk about right before
bed. So, if you get as much of a kick
out of this conversation as I did, I
need you to do me a favor and rate us.
or you can leave us a review or drop us
a comment and make sure you subscribe so
you never miss an episode because we got
more amazing stuff like this coming and
your support means everything. It helps
us to reach more curious minds just like
yours. So, let's jump into the
conversation.
Kirk, welcome to Particles of Thought.
Hakee, great to meet you.
>> Yeah, man. So listen, when I looked you
up, I saw two words, geology and
paleobatney.
I hadn't heard paleobatney before, but
when I think paleo, I don't think about
the diet. I think about paleontology,
which makes me think about dinosaurs.
Tell me about paleobatney. I've never
heard of paleobatney.
>> It's one of the obscure sciences for
sure. It's fossil plants. And the reason
I became a paleobotonist was I when I
was a kid, I loved finding stuff. Like
I'd find coins and egggots and rocks and
fossils. And once you have a thing you
can do as a kid and you find that it
works more than once, you do more of it.
And I became like my childhood
superpower was finding things.
>> Wow.
>> So I go on hikes with my dad. I'm like,
"What's this rock? What's that? Hey,
here's a fossil." And when we're driving
somewhere, I was like, "Mom, can we stop
here? I know there's some good stuff to
find here." Yeah. So, I started being
like this search kid detective. And
there were fossils around where I lived.
And there was a fossil site about a
15-minute drive from my house that had
cool things. It had fossil clams and
snails, but there was also fossil wood.
And then there was uh I found a fossil
walnut. And then I found a vertebrae
from a dolphin. I'm like, what's going
on?
>> Wait a minute, man. A fossil walnut.
>> Yeah.
>> So, it looked like a walnut, but it was
rock
>> even. Yeah. It was it was soft rocky,
but the shell was black and the meat was
white.
>> It looked like a walnut.
>> So I um I went to the museum in town,
the Burke Museum in Seattle, and the guy
said, "Yeah, there's a walnut specialist
you can mail this thing to,
>> a fossil walnut specialist." I'm like,
"Okay." So I mailed it to this guy. He's
like, "Hey, it's a walnut. You found a
fossil walnut." And then you know the
the part of the porpus, I found one
porpus vertebrae. It's like what where
in the world do you find walnuts and
porpuses together,
>> right? Well, at the edge of the sea
where there's walnut trees and purposes
swimming,
>> it's like a beachy deposit and it was
like 15 minutes from my house.
>> Sounds like you were set up to be a
paleontologist like young right out of
high school. You didn't need to get a
degree.
>> Like a paleobotonist even.
Yeah. Yeah. So, what what what separates
the um fossilized plants from I imagine
everything doesn't get fossilized,
right?
>> Yeah. Yeah. So, here's the key thing
that you have to know about fossils is
that in order to become a fossil, you've
got to die.
>> Yeah.
>> And you got to get buried.
>> Okay?
>> Right? And if you don't get buried, say
you just fall over in the forest
somewhere, you're going to rot away.
>> So, it's death plus burial. So, if
you're a dinosaur, you fall over and you
die, chances are you're not going to
become a fossil unless you live in a
place where stuff gets buried. And what
are those places? They're places like
Louisiana for instance, right? Right. If
you Louisiana, the whole landscape is
sinking slowly and the stream is always
dumping out sediment and putting more
layers on it. So an area that's sinking
is what I call DO or deposition world.
>> Ah, right.
>> And if you were to drill a hole beneath
New Orleans, you would go down almost
20,000 ft in layered mud that's only 25
million years old.
>> What?
>> That's literally miles of thickness.
Yes.
>> Miles. So if if a fish died in New
Orleans
>> 10 million years ago, it would be 10,000
feet down.
>> Wow.
>> And in the sediment it was buried in is
being compacted into rock.
>> So I've seen this p this image ge
geologically of the Gulf of Mexico and
how it goes out underwater. Then there's
like this big giant cliff. Yep. So all
of that stuff is from the river.
>> Yeah.
>> Whoa.
>> Yeah. And from rivers dating back to
millions of years. So the earth is as it
erodess mountain ranges all the sediment
ground up mountain ranges end up at the
edge of the continents and piling up in
thick layers of sediment or limestone or
other kinds of stuff and that's where
you create the fossils. You an animal
dies or animal plant dies is buried in
an area that's sinking which buries it
deeply and that turns the sediment into
rock. Yes.
>> And they're at depth and then eventually
what happens is some other first
phenomenon pushes that area back up. M
>> so areas that were depositional areas or
D world
>> right
>> become lifted up into what is called Eld
or erosion world.
>> So if you can look at North America for
instance most of North America right now
is erosion world or Eld.
>> It's getting eroded away.
>> Mountains. Anytime you see a hill or a
mountain you know that stuff's eroding
away. Look at the Mississippi River
time.
>> You see a river right?
>> Exactly. Yeah.
>> Some areas. And so there are are, think
about this, there are rivers in erosion
world like the Colorado River is cutting
the Grand Canyon. Yeah. Not a good place
to become a fossil. That's just grinding
away and taking it out to the sea.
>> And it goes side to side and meanders
and Yeah.
>> But that same river like Mississippi
when it gets down to New Orleans, great
place to make a fossil.
>> Ah,
>> so that's the Eld D world difference.
And the best place to find fossils and
like maybe the best place in the world
to find fossils is western United States
because most of the last 500 million
years that landscape was sinking. It was
D.
>> But then when the uplift of the Rocky
Mountains started, it pushed that area
back up and exposed those rocks in
EWorld.
>> So you want D.
>> So you bury them.
>> Bury them.
>> Then lift them and erode the stuff off
the top of them and now they're exposed.
>> Exactly. and and sometimes you uplift
them in an irregular way. So in one
place you might be able to see a
cross-section of the entire stack.
>> Oh,
>> and there's a place near Cody, Wyoming
where you can see from 2.5 billion years
to 60 million years in one spot.
>> Geez.
>> It's better than the Grand Canyon.
>> That is
And so because they've been lifted and
turned now, it's it's it's more
horizontal or at an angle rather than
Exactly. It used to be flat and then
turned up and they're almost vertical
and you just count the pages like this
all the way through.
>> Wow. And each layer has its
representative fossils.
>> Exactly. There like always there's sort
of local D world like the immediate area
around you like you're standing next to
a mud bluff and it it slumps down and
buries you. You just got buried in a
little narrowest piece of DO.
>> I see. But if you want to look at it at
the continental scale,
>> there most of North America is E-World,
but they're little local ponds and
little local lakes. But those local
things are not going to get preserved.
They'll eventually fill up in a roadway
too.
>> So the fossils are going to be in those
places where the whole landscape is
sinking.
>> Whole landscape. So what places would
that be on Earth today?
>> The edges of the continents primarily or
the shallow low elevation parts of the
margins of the continents.
>> Okay. Is that generally true throughout
history? Yeah. So, as a result, we
really don't have much of a fossil
record for mountains or hills.
>> Wow. So, so for example, right now,
humans are distributed primarily along
coastlines. So, so would it be the case
that land animals, even though it's a
it's it's geographically limited, it's
still a good representation because uh
that's where most life is going to
concentrate anyway. Is is that fair?
>> It's true. Probably the case, but like
you know, you're still going to miss the
mountain goats and stuff like that,
right?
the things that live only at high
elevations or you know even on the great
plains some of those things do get
preserved like the the animals of the
great plains are preserved because the
Rocky Mountains came up and all the
sediment coming off the Rocky Mountains
shed and buried things under river
sediments and then that area is still
coming up so those rivers are now being
exposed. Oh,
>> and so you have that kind of local D
world um is a source of good fossils on
continents. And we found an amazing site
in Colorado in 2012 that was a lake on
top of a hill at 9,000 ft.
>> Wow.
>> And it filled up with
>> Lake Tahoe. No,
>> no. Was at Snow Mass Skiary Snow Mass.
It's right 700 yards from the base of
the ski area. There's a little 12acre
lake that turned out to have been an ice
age lake
>> that filled up between 120,000 years ago
and 50,000 years ago. And we found 50
mastadons and 12 mammoths in this one
little lake in 70 days of digging.
>> It was an amazing thing. But that was a
a little tiny lake on top of a hill that
was a little temporary bit of deorld.
>> Yeah.
>> And in the future that'll erode away and
go away. But we got it before eroded
away.
>> Wow.
>> We just our timing was very good.
>> Good timing. But but over geological
history, a lot of those have come and
gone.
>> Yeah. Oh, yeah. Cuz that's at the top of
the hill. It's going to go,
>> right? It's going to go.
>> Hills go away. Mountains go away.
>> They're temporary.
>> Yeah. Never trust mountain ranges.
They're undependable. They rode away.
>> All right. All right. You can't depend
on them.
>> Yeah.
>> You know, later, man, we're going to get
back to this because one of the things
that I feel like as science
communicators, we don't do quite often
is we tell what the results are, but we
don't tell how we get them.
>> Yep.
>> But we'll get to that. But what I want
to go to first, man, is sort of like an
ultimate fossil.
>> A fossil from the foundation or the
formation of our solar system. I hear
you got an asteroid.
>> Well, we all share that asteroid. It's
asteroid Bennu, which is, you know, it's
a 550 meter diameter blob of rocks. It's
actually like a gravel pile that's all
held together by loose gravitation. And
NASA had the vision to send a a little
Osiris Rex out there to go take a look
at this thing. And they got there and
they orbited a whole bunch of times and
made a geologic map of the surface of
this thing and it's got boulders and
pebbles and things and then they had
this they moved the spaceship into
position and punched a little sampler
can the size of a tuna fish can
>> into this thing and it and it went way
in further than they thought. They like
they were they were when they got close
they're really scared because all these
huge boulders the size of buildings on
it and and they're like oh what if we
hit on a rock? They they they landed it
right where there's a spot and they just
punch it in and it was kind of like just
loose gravel in the air and they brought
back I think 150 grams okay
>> of samples that you know the spaceship
then left those Bennu flew back over
Earth they dropped it out it parachuted
down landed in the desert in Utah in
this little capsule was about this big
around and then they took off the lid of
this thing and here's like 150 grams
that look just like granola little
pieces little chunks of stuff
>> and those samples are untouched by
Earth's atmosphere.
>> So, they're subsurface of of the
asteroid. So, it's not is it surface
material or did they actually like cuz
you said it went in deeper than
anticipated?
>> Yeah, I think they it went in like I
don't know maybe the length of my arm
deeper. It wasn't a huge depth of my but
it was more than they expected. They
expected a hard surface but it was
really just loose material kind of
loosely held together. Yeah. And
>> so you have this all these particles
that they came back and at the
Smithsonian Natural Museum where I work
um we have Tim McCoy who was on the
Bennu team. So one of the very first
samples you know Tim was there when they
opened the can he got to bring home some
samples and we had acquired this great
analytical device so we could actually
look at these samples and within minutes
of these sample being in the building
and he had it under the equipment. We're
looking at this thing and he's like
there's hydrated minerals here. There's
all this incredible.
>> Wait a minute. Hydrated. Yeah. Water.
>> Yeah.
>> On a dry asteroid pile of gravel in it
system.
>> So there you go. Says water is the first
thing you're looking at. And what's cool
about rocks are that rocks are made up
of minerals and minerals are made up of
various things and some minerals have
water in them.
>> Well, that's what I was going to get at.
Right. There's a difference between
waterbearing minerals and there was
liquid water here.
>> Yeah. But but the water bearing minerals
has H2O in it.
>> Yeah. But it could be ice
>> or or in the molecular structure.
>> Molecular structure, right? Yeah.
>> So, but it's there. It's water. It's not
It wasn't a glass of water on the
>> Bennu did not have glasses of water.
>> Well, here's what I'm getting at. So, a
lot of uh asteroids are the remnants of
protolanets that collided and got broke
broken apart. That's why we get chunks
of iron out there, right? Exactly. Yeah.
And so I can imagine that could it have
been possible that one of those
protolanets actually had liquid water
and somehow that got incorporated into
Bennu or is it just the everyday kind of
space water?
>> So this was the big surprise on Bennu is
that the first glimpse is like wow we've
got these minerals we've got hydrated
minerals um other researchers in other
labs like hey we're getting some amino
acids out of this stuff. Wow. But what
our team discovered which was so amazing
was they they're uh museumbased
researchers. So we have the this amazing
collection of the world's minerals and
there's thousands of different kinds of
minerals on planet earth and a lot of
those minerals are med were formed in
conditions that formed on planet earth.
Some of them are mediated by life. For
instance, there's minerals that are
deposited by living organisms like
shells and clams and things like that or
humans and our bones. Those are
minerals, right? So life creates
minerals. So earth has a high diversity
of minerals because it has life.
>> So there's a, you know, it used to be
that whole animal, mineral, vegetable
kind of thing,
>> that's a little bit touching because
animals have minerals. So
>> they're like, "Let me wrap myself in
rock then you can't eat me."
>> Exactly. And some things do that like
right like turtles and things like that.
So, um, as they were inspecting these
grains, literally micron by micron with
their instruments and analyzing the
grains, they started noticing some
minerals that were familiar to them.
They're like, I've seen this mineral
somewhere before. And what they were
finding, they were finding evaporate
minerals. And these are the kind of
minerals that form when you take a lake
in a very warm area and you evaporate
the water like the Dead Sea or the Death
Valley
>> where there's a lot of sun, it's very
hot and the river is coming out of the
mountains carrying minerals and then it
evaporates and leaves those minerals
behind and think about the borax trains
of California,
>> right? Yeah. There's a whole sequence of
minerals that formed in Death Valley. As
the water comes off of the Sierra
Nevada, it evaporates, more water goes
back, you get a series of different
evaporate minerals. And they started
finding these minerals in the Bennu
sample.
>> So, is it that they come in a particular
combination? So, so it's sort of like a
signature of this.
>> Yeah. There's an evaporative series like
you evaporated off one kind of mineral
that leaves a different composition of
the water. The next time you evaporate,
you get a different mineral.
>> Oh.
>> So, it's actually an evaporative
sequence.
>> Yeah. and they start finding the
evaporative sequence which means that
you know Ben Venu was probably rubble
from some exploded planet.
>> Yeah.
>> Uh but on that planet there had to be a
sequence where water was evaporating and
creating evaporative minerals.
>> So that means a collection of liquid
water.
>> Yeah. So you got water now you have all
these different minerals. You have the
um amino acids and stuff like all the
things you need to make life are right
there
>> man. That's that's amazing because you
know one of the ideas that I've seen
about life you know where it might be
found. So we typically look at planets
and moons but there's this one scientist
who said comets if you have some
radioactive nuclides inside the comet
that could create enough heat to melt
the ice and create little water
reservoirs. But this is very different
because you have water that's liquid
then it dries then it's liquid then it
dries then it's liquid then it dries.
Now you think about Bennu. It's like
it's it's out there and it's exploded
from somewhere which means that and it's
from the beginning of our solar system.
>> Yeah. What's the age? Did it get an age
on it?
>> Well, I don't know. It's probably 4.567
billion more or less the age of our
solar system. Right. Right.
>> So you've basically got um debris out in
the solar system on a asteroid sitting
out there. That's a signal of what was
in the solar system when the solar
system founded. Which means that at the
beginning of our solar system, even
before Earth cooled,
>> you've got evidence for the conditions
for life before you have Earth, because
Earth, remember, it was a molten ball
and then it got hit by the body that
became the moon. So the the moon,
Earth's a bad place to be for his first
100 or 200 million years, right? You
starting to enjoy life, things are
cooling down, then bam, you get this
thing and then the moon forms. So the
rest of the solar system maybe has a 200
million year head start on the Earth. M.
>> So you've got conditions that could
maybe form life somewhere else,
>> right?
>> Out there. And then how does life get
onto Earth? Well, maybe some of that
stuff that was blown from somewhere else
lands on Earth.
>> Yes. Yes.
>> And you start the process.
>> Wow. So not necessarily from out. So
essentially what this suggests
potentially is that you don't even need
fully formed planets to get life. You
can at the protolanet stage, you can
have water. You're doing this complex
chemistry that results in amino acids.
So
>> what's to stop you?
>> What's to stop you? So So my
understanding of Oh, this is a good
question for you. So we look at the
origin of life
>> and the origin of the oceans. Yep.
>> Right. So what are the theories of where
the oceans originated? How did how did
we get them?
>> So So you don't have many options,
right? Because right now you've got the
planet where 70% of it's covered by salt
water, right?
>> And the you know it's it's even an
amazing question to ask or imagine what
the Earth didn't have oceans,
>> right? Amazing.
>> But you got to figure if it started out
as a molten thing, there was no ocean
there then. You have a giant blob of
molten water boiled away, right?
>> Yeah. So you've had that problem and
Earth's a big thing, too. Like it's got
a big diameter. It's got a lot of
volume.
>> So you got to you got to ask yourself
what's in the middle of that. And how
does how does the structure of the earth
itself form? How does its core and its
mantle and its crust form?
>> Yeah.
>> Where do the continents come from?
>> And where does the ocean come from?
These are like fundamental questions
about how our earth became this amazing
place it is today with lovely oceans and
great mountain ranges and all that kind
of stuff.
>> So, uh, you know, as you pointed out,
one idea is you have this molten blob.
It cools down and then it gets hit by a
bunch of comets which deliver truckloads
of water because the comet's got a lot
of ice. And so you come, it delivers the
water. Um, and there's ways to test
that. I don't really know how rigorous
those tests are. But the other option,
really the only other option is
>> the water was already there in the in
the rock of the planet and it was
inhydrated minerals that then somehow
outgassed and the water started to
accumulate on the surface. And the
question there is how do you keep the
water on the planet? Like what keeps
what holds the atmosphere and the oceans
to the planet? Obviously there's there's
gravity but
>> you know so you you basically have is
either was delivered or it was already
there. Those are your two options.
>> So I guess the question is you know if
you have a situation like Mars where the
atmosphere is incredibly thin because
it's been eroded by solar radiation. Y
>> so Earth's atmosphere doesn't erode as
quickly. My understanding from Jim Green
who's the um the uh who who who was the
chief uh scientist at NASA
>> is that it's being eroded but
geologically it's being replaced as
rapidly as it's being eroded away.
Right. But the the magnetic field of
Earth slows down the the erosion of our
atmosphere.
>> Do we know how early our magnet our
magnetic field kicked on the Earth's
magnetic field? I certainly don't know
the answer to that question, but I mean
that's you're you're basically asking
all the right questions, which is how
how does when does Earth start acting
like Earth? This is all heavy stuff for
a paleobotist. I want to tell you right
now,
right? Oh my goodness. Well, I would
imagine it's all mixed together, right?
So, you got the the planet's evolution
and life's evolution. So, it's almost
like life becomes its own geological
process that you know works together
with the planet.
>> Absolutely. And once you realize that
life is constantly and always evolving.
>> Yeah.
>> You basically turn on life and then you
turn on this endless story that we're
part of right now.
>> Yeah.
>> What things are and what's so cool I
think what I I kind of uh there's so
much cool stuff here that I kind of
restrict my knowledge to the planet
because I'm like the universe is too big
for my brain. But I'm really interested
in the story of our planet. How did it
start? How did the pieces come together?
When did it start behaving like Earth?
When did life itself start? When did the
oceans form? When did the continents
form? Right? When did the first forests
form? When did the first fish evolve? I
mean, in every one of those things, it's
got its own tale. But if you put it in
the context, we've got 4.5 billion years
to tell the story and then you just
start chipping away at every aspect of
the story.
>> Well, let's go back to that Earth
without water.
>> Yeah.
>> Sort of image because we do have
continents. So if you had an earth
without water, so I imagine that the the
you know the ocean is deep.
>> So do you imagine a world that's pretty
much you know if you look at
>> other bodies that don't have water
>> on them?
>> They appear to be more or less smooth if
you get rid of the cratering. It's not
like these giant, you know, you have the
places with volcanism like Mars and
Venus that have giant volcanoes, but
other than that, you don't have like big
basins and then huge continents sticking
up. Is that what we imagine?
>> Well, think about what you just said
because when you say the ocean's deep,
it's only 36,000 ft deep at its deepest
point. Most of the ocean is maybe only
8,000 ft deep. That's only a mile and a
half deep.
>> That's pretty damn deep if you ask me.
That's
>> Well, compared to the size of the Earth,
it's nothing. I'm like, if you look at
the Earth, if you drained all the water
off the planet right now, your highest
points Mount Everest, your lowest points
the Mariana's Trench, what's that?
29,000 ft and 36,000 ft. So like 60,000
ft. What's that? 10 miles only.
>> So that would from space, Earth would
look like a polished bowling ball.
>> Yeah.
>> And so there's really no topography
there to speak of at the the scale of
the planet.
>> And then you have to ask yourself, well,
how do you get that topography anyway?
How did you get the deeps in the ocean?
And how do you get the highs of the
mountains? Yeah,
>> that all happens because we have plate
tectonics and the continents are moving
and the plates are colliding with each
other and these deep part of the oceans
are where two oceanic plates come
together and make a deep subduction
zones. So the trenches are
>> Oh, the trenches are subduction zones.
>> Those are those are platetoplate
collisions and when you get a continent
colliding in a continent like India hits
Asia, you get the Himalayas. That's
where you get your high points. So you
can't even have um topography we have
until you turn on plate tectonics.
>> Yeah.
>> And then you you think about plate
tectonics that's ocean crust and
continental crust. It's like what came
first chicken or the egg
>> continents or the ocean
>> right? Do they form there?
>> And I guess another question is does the
weight of the water sort of segregate
the continents from the cont from the
oceanic crust? I'm just swagging here.
Scientific wild ass guesses. Well, the
thing about it is water weighs a lot
less than rocks and different rocks have
different um relative densities and
masses. So, you have a heavy rock and a
light rock.
>> The light rock's going to float on the
heavy rock.
>> Yeah.
>> Right. So, you have and also rocks
themselves, we think of rocks as really
hard things you throw out windows,
>> right?
>> But the reality is that rocks are the
pro like the products of any other
cooked item, right? Like they start out,
some of them start out liquid and they
cool to hard rock. Some of them start
out as sand, which cements become
sandstone.
>> Man, you're triggering me. I remember
elementary school, you had to learn
metamorphic, ignous, sedimentary.
I don't remember what's what anymore.
>> I'll tell you using a food analogy. How
about that?
>> The simplest one is sedimentary. Those
are just like particles of sediments,
sand grains, and things. So, the food
analogy there is salad. It's just a
bunch of stuff thrown in a bowl.
>> Got it?
>> You know, whatever is coming downhill,
it's just a bunch of stuff. That's
salad. Is it always in association with
water?
>> Uh, no. It can be blown in wind too.
Okay. Yeah. Wind dunes, sand dunes for
instance. So water or wind, both. And
you have Mars, you have
>> dunes. Oh, they have
>> they have wind. Right.
>> Right. So there and there's also on Mars
evidence of waterborne sedimentary
rocks. So you have both kinds. Then
there's the um the ignous rocks which
are the rocks that started out their
life melted. Ah
>> right. Yeah.
>> And the food analogy there is a fondue.
>> Melted cheese.
>> Melted cheese is a molted thing and it
cools to a blob and you eat it when it's
a little bit harder, but you know
whatever. So that's it. And then the
tricky one is the third kind, the
metamorphic rocks. These are rocks that
got heated and squeezed, but they didn't
melt.
>> They didn't go all the way back to being
fondue, but they were heated and pressed
enough that their crystal structure and
even its content changed. And so the
food analogy for a metamorphos is a
lasagna.
>> You start out with, you know, your
noodles and your sauce and your burger
and all that stuff and then you cook it
>> and it changes a bit. You can recognize
it a little bit. Um but since we only
cook lasagna to a certain temperature,
you only get lasagna looks like that. If
we cranked up the temperature in
lasagna,
>> Yeah.
>> Um you know, it might have a different
form even still. So all three states can
turn into the other state depending on
what happens to them. And this is why we
don't have the oldest rocks on planet
Earth because Earth is always baking
itself, melting itself, and grinding
itself up.
>> Wow.
>> It's like its own factory that's
churning away.
>> Yeah.
>> And cranking away on that thing.
>> The other piece is that we have a lot of
unique minerals on planet Earth because
they're formed by interactions with
living
>> organisms,
>> right? Yeah. Yeah. My mind went there as
you were saying that that life must play
a role also.
>> Yeah. And this is this took surprisingly
long to figure out for people, but like
this whole idea that that there are lots
of minerals that wouldn't exist if they
didn't have some living organism that
was mediating the formation of those
minerals. The study of the earliest life
forms really only got going in 19 the
1950s when they started looking at
>> precamprian rocks and slicing them open
and finding little things that look like
cells or little filaments and things. So
so much of what we know has been acred
in about the time that you and I have
been alive.
>> Wow.
>> I mean the understanding of our planet
is leaping forward in great bounds all
the time. But so much of it um if we'd
had this conversation when we were 5
years old.
>> Yeah.
>> There's a whole bunch of stuff that we
wouldn't have known collectively. Right.
So that's the thing that always blows me
away is if depends on when you stop
paying attention to science. Uh, don't
do that because science moves forward
moves fast every day. Every day.
>> It absolutely does.
>> This podcast is from the producers of
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[Music]
So, you've been chasing these fossils
since you were a kid. Where has that
taken you on the planet? and tell me
some of the coolest surprises that
you've encountered.
>> So, I have found about a thousand fossil
localities in my time on all continents.
>> Um, and my favorite continent is North
America because I'm from North America,
but because the western part of North
America, the Rocky Mountain region was
for a very long period of time primarily
deorld. So it accumulated layers and
layers and layers um from the Cambrian
all the way up to the present almost
present. So
>> So let's define the Cambrian for those
who who might not know.
>> So the Cambrian period starts at 542
million years ago
>> and that sort of starts the you know
it's not the very beginning of of big
life forms but it's sort of much the
starting gun for the the evolution
event. It's the first time you see
actual animal fossils for instance is
the the very bottom of the camber. So
542 million.
>> And so at this time is it 100% in the
oceans?
>> Um well there's land. It's just there's
not I mean life.
>> Yeah. Yeah. There's it's not clear
what's on land. There's land but it's
not clear if there's anything living on
land at all. That's one of the
unanswered questions.
>> I see.
>> Um there's probably some
>> kind of microscopic microbes on land,
but hard to know. Yeah.
>> Um but it predates certainly any plants
or anything on land. So then then you go
through this sequence where you
eventually evolve a diverse ecosystem in
the oceans and then then you see land uh
start to be populated by some very early
land plants and some very early land
animals but again probably little insect
like or spider-like things and little
tiny plants that might be only three
inches tall or two inches tall,
>> right?
>> And then eventually you start to get uh
bigger plants in the first forests. So,
wait, wait. You know, one of the things
I saw on YouTube,
>> of course, that I discovered were these
big giant fungus things.
>> Yeah.
>> Yeah. So, that's a it's a fossil known
as prototaxes.
>> Okay. That's a mouthful. Um, it is a
like most fossil names are mouthfuls.
I'm going easy.
>> It's not like in my field of
astrophysics. Black hole.
>> No, no, no. We We got some good names
for you. So this prototaxes
uh very weird enigmatic because it's a
it's a
>> looks like it's a fungus of some sort.
>> And they are these big trunklike chunks.
>> Yeah.
>> And that's all you get.
>> Yeah.
>> And then you can look at this in
cross-section and you slice them up and
look in cross-section and you can see
things that kind of look like fungal
threads and fungal hygiene.
>> Um but they're way bigger than anything
else around there. And
>> when they first appeared, how big they
got, and what they actually related to
is pretty much at the hairy edge of what
we know.
>> Yeah.
>> Because they're only known from a few
places in the world.
>> And how big they got, well, there's a
couple that look like they might have
been pretty big. So you see
reconstructions of them, but that's just
somebody saying, "Well, I'm going to
paint some big thing that looks like a
big thing." So, a lot of debates on this
stuff. And so much of early life is like
that. We have fragments of these things,
>> right?
>> And you have preservation that doesn't
show all the details. Yeah.
>> And it's like it's likely that they're
fungi.
>> Yeah. Yeah.
>> They might be something else, but who
knows what else it would be.
>> They could be neither plant nor fungi.
Could be something different
potentially,
>> but they're organic. You know, they're
not an animal. So, you're kind of like
in a realm of the things that we know
about, fungi seem to be a reasonable
interpretation. And I think the further
back you go in time,
>> the blurrier the view is. And there's
plenty of things in the fossil record
where we know we've seen this thing
before. We've given it a name. We don't
know where it fits on the tree of life.
>> So, so here's the question then. If
you're a paleobotonist, is there are
there paleo fungicists?
>> There are. There are.
>> Wow.
>> So, I mean there's paleo anything you
want because any living thing has it has
its fossil story and you know science
like we all specialize and specialize
and I'm I I
>> became a paleobotonist because you got
to get a PhD in something.
>> Yeah.
>> But I love the whole story. the whole
story of ancient life, ancient earth.
Yeah.
>> And everything's in context. So,
paleobotney is in the context of where
were the first plants,
>> right? Yeah.
>> Right. And uh and so and then when were
the first forests and then when the
first leaves and the first seeds and the
first walnuts.
>> So, is there a case of
plants becoming, you know, is it a
something that happened a single time
and spread out or is it something that
just kept popping up and then was able
to survive? It's a hard question to
answer because um but one thing is very
clear and important thing to realize is
that it looks like because of the
presence of DNA that all life forms are
related to each other. They all have
DNA.
>> Yeah.
>> And so when you start to evolve a
complex life form, no matter what it is,
Yeah. it it's got its own DNA.
>> It still implies it's related to the
other things that formed,
>> right? And the further you go down the
evolutionary tree, um, the less likely
it is you're going to reproduce the same
thing because it's had its pathway that
you've already gone down.
>> So the the new stuff
>> Yeah.
>> takes the blueprint from the older stuff
and builds on that,
>> right?
>> Yeah. Yeah. But a lot of the old stuff
is still here, right?
>> It's true. But then this is this is why
we're so worried about extinction
because let's take for instance a um
bison.
>> Yeah. If a bison goes extinct,
we're kind of done because you can't
re-evolve a bison.
>> You can't go back to the start. The
extinction is when you lose that whole
lineage.
>> Yeah. It's a whole process that you've
lost,
>> right? You and it's like, you know, it's
it's it's, you know, it's genealogy goes
back all the way back to those first DNA
molecules back in the ocean. So, um, and
the fossil record is full of things
where you lose things like the big
dinosaurs, like the long neck dinosaurs.
>> Yeah.
>> They're not just going to pop up one day
again. They're we had them, they're
gone.
>> They're gone. They're gone.
>> Right. And that's that's the cruel thing
of evolution and extinction is things
are the ends of lineages. So, when you
lose them for whatever reason,
>> Yeah.
>> Um, they're not coming back.
>> So, what do we represent then? All life
forms today. So I read somewhere that
something like 99% or higher of all life
species have are no longer here. Yeah.
But then I think what does that really
mean? That doesn't mean they necessarily
like there's extinction that comes from
uh you know birds are still here but yet
they are dinosaurs and we say dinosaurs
are extinct. So you evolve to something
new. You didn't die off. So it's not the
end of the lineage. So when you say that
sort of phrase that 99% of all species
are gone, does that mean that uh you
know what what percentage of them
evolved into something else and what
percentage of them just died off?
>> Again, hard to say because we have no
idea how many things were alive at any
point in the past because the fossil
record is so incomplete.
>> Right.
>> Right. So you don't really know. And
your point's well taken. Certain things
do have descendants, but you can destroy
entire lineages. So for instance, if the
birds go extinct Yeah. Yeah.
>> Then dinosaurs will be truly extinct.
>> Mhm.
>> Right. And birds were just one branch of
dinosaurs. So all the other branches of
dinosaurs went extinct
>> except for the bird branch.
>> Yeah. Yeah.
>> So you know and there were some really
cool dinosaurs. I mean there's this
thing called Patagot Titan that is 100
ft long and its head's 60 feet above the
ground and its one leg bone is taller
than I am. Man, it is so hard for me to
imag I I I step into the museums like
yours and I see these giant animals and
I just cannot
envision that thing walking around,
right? It's it's hard enough when you
see an elephant lumbering along, right?
Something many times the size of an
elephant like the mechanics of that, you
know, are they fast moving cuz they were
warmblooded, right?
>> Do the big ones? Who knows? Maybe, maybe
not. I mean, this is like a good theory.
Some of the some of the more birdlike
dinosaurs almost surely were
warm-blooded, but the big ones, you
know, they're big animals and there all
sorts of mysteries about those animals.
And I I will say that
>> were it not for fossils,
>> we'd never have an idea that those
animals existed, first of all,
>> and when you see them in museums, like,
I can't believe that thing existed. But
I'll tell you what, when you are digging
and you find one of those things,
>> that's where your brain gets rung hard
because
>> you dig out a 7 foot long femur.
>> Yeah.
>> And you know that you dug it out.
>> There's zero doubt in your mind that
that was a living animal.
>> Yeah.
>> And those long neck, longtailed
dinosaurs, the sorapods,
>> they were around on planet Earth for
like 150 million years. Humans are
300,000 years.
>> Geez. Yeah. So, here's a kind of animal
that and they're found on all continents
that was a very successful kind of
animal. So, even if we can't imagine how
they walked,
>> they walked.
>> Yeah. They walked 150 million years of
lineage.
>> Yeah. And Okay. So I I' I've studied
human history a bit and one of the
things that is mindblowing to me is
during Homo erectus's time of two
million years brain volume went from
like 600 cc's to 1200 it doubled right
in 2 million years. So now you're
talking about something a lineage that's
150 million years.
>> The difference be before the the before
state and the just before the meteorite
hit like what were the major changes
that happened? Was it just the evolution
into small mammals and different
reptiles or
>> did some of them become smart? Like
what? So here's here's the thing that's
so incredible is that the the state of
the planet does change from time to
time. like there the planet is in orbit
around the sun. It's got the moon. The
moon gives us its months. The earth you
know it's rotation around the sun gives
us our seasons. We have these things
that are there but but certain things
have changed like the earth is slowing
down in its rate of rotation for
example. So there used to be 480 days
per year.
>> Wow.
>> Now there's only 365 days per year
because
>> so as the earth is orbiting the sun it's
spinning. So it would go get 480 spins
in by the time it made one complete
orbit.
>> Right. Yeah. So the days are a little
bit shorter
>> and so things like that happen or
>> we get a little bit closer to the sun so
the climate's a little bit warmer or a
little bit further away.
>> What is that? The Melankovich cycles or
something like that.
>> Yeah. And those are pretty like those
happen on these sort of 20,000 40,000
100,000 year cycles.
>> And if if nothing else was changing at
all on the planet, if just the
Mankovich, you'd have this cool warm
cool warm tick- tock thing going back
and forth on these cycles. And that's
what's driving things like the most
recent glacial periods, the advances and
retreats of the the big ice sheet that
covered North America, for instance.
Yeah. And today, um, we sit here and
enjoying our weather in Boston and
Seattle and New York. But if we were
here 20,000 years ago, there was 3,000
ft of ice on top of Seattle, New York,
and Boston. 3,000 ft.
>> Wow.
>> That's six Space Needles, you know. It's
like it's And that was only 20,000 years
ago. or it's like more than half a mile
ice on top of what we call cities today.
So there's there are processes that are
happening over time and and when you
shift a major process for whatever
reason that then challenges the life
forms to respond,
>> right?
>> But those long neck dinosaurs which
first appear, you know, sometime in the
Jurassic period, maybe 180 million
years, they kind of disappear at the
asteroid impact at 66 million years.
They've got well over a hundred 100 plus
uh million years of time. They were
living in a time when there were no
polar ice caps.
>> The entire 100 million years or so.
>> Yeah. There was some times where it
cooled down a little bit, but the
evidence for polar ice caps there is
very sparse. Which means that um and I
see the world of the last 400 years, I
see the world as a view between the
battle between trees and ice. Ooh.
>> Cuz when there's lots of ice, there's
not so many trees.
>> When the ice retreats, there's more
trees.
>> I see.
>> So, and uh today, for instance,
Antarctica is covered by 10,000 ft of
ice.
>> And Greenland, the same.
>> Yeah.
>> Dial the clock back 50 million years.
Antarctica was completely forested.
Greenland was completely forested. There
were no ice caps on the planet. So, you
have a tree world
>> versus an ice world. So,
>> how many years ago was that? Well, 56
million years ago was a high peak. 100
million years was even a higher peak of
temperature. But remember, dinosaurs um
first appear in the geological record
around 230 million years ago and they
disappear at 66 million years except for
the birds, right? That one lineage that
survived. So, you have this nice long
chunk of time where
>> dinosaurs um
>> these long neck dinosaurs, they
survived. That lineage had a long time,
but it lived in a world that wasn't all
that different. It was a forested world.
>> Yeah.
>> And to become a big herbivore, what do
you need?
>> You need like endless salad.
>> So, Mr. Paleo botnist.
>> Now, we come back to it.
>> Were trees hella big to feed all these
big dinosaurs? Is it a different forest
world than in the forest worlds we have
today than like the Amazon or the Congo?
>> So, the now you're talking about
language here.
>> All right,
>> we've gotten rid of all this earlier
stuff. Now, we're on to the plants. But
the the thing is that um think about
trees. People don't think about trees
very much at all. I mean, I find that
people are they love animals and they
just ignore plants. Yeah. Now, there's
gardeners, of course, that like growing
plants.
>> Wait a minute, man. Let's get back to my
Mississippi upbringing. So, one of the
things I used to be proud of that I
can't do anymore was, you know, the
ability to identify trees by their bark
and leaves like because, you know, we
haul pulp wood and, you know, you had to
get this for firewood and you, you know,
you ate this or that. So, you knew your
forest. Today I just I lost it all.
Yeah. Yeah.
>> And if you go to Mississippi, there's a
nice diversity of trees. You know, if
you went out and walked in the forest
and down if you walk in the swampy
areas, a lot of bald cypress every and
sweet gum and sour gum and that kind of
stuff.
>> Uh but if you go to the Amazon today,
>> you walk in one acre of forest, you
might have two or 300 species of trees.
>> Wow.
>> Like Mississippi might have 20 or 30.
Wow.
>> Amazon might have two or 300. It's just
an interesting thing. It's like we ask
now the question when did the first
tropical rainforests form?
>> Okay.
>> When did the first uh pine forests form?
When did the first redwood forests form?
Because there's different kinds of
plants. There's about on planet Earth
today. There's about 400,000 different
species of plants.
>> Okay.
>> Now, about that maybe 100,000 different
species of trees.
>> Okay.
>> All right. So, there's a lot of
different kinds of trees. And trees are
very interesting because um the
different kinds of trees have long
lineages. So there is a thing known as
the GKO tree
>> behind GKO fossils that go back 180
million years.
>> Wow.
>> So the Genko trees are alive with the
dinosaurs. So there actually are some
kinds of trees that are alive today
>> that were alive with those dinosaurs.
>> And this is the kind of cool thing is
that the the planets always changing,
but some of the some of the cast members
in the play
>> Yeah.
>> have long roles. How long can a seed
last? Like I can imagine that if there's
some big disaster, you know, seeds can
even though if even if all the trees get
burned up, you know, the seeds may
survive for some like what's the
longest?
>> There's some examples of very old seeds
like archaeological sites that have
germinated. So thousands of years maybe
in some rare cases,
>> but that gives you enough time.
>> Yeah. you preserve the seed and we have
these seeds that were frozen in a seed
bank in in the Swallbard and the Arctic
Islands.