Journey of the Universe weaves together the discoveries of the evolutionary sciences together with humanities such as history, philosophy, art, and religion. This course draws on the Journey of the Universe Conversations, a series of 20 interviews with scientists and environmentalists. The first 10 interviews are with scientists and historians who deepen our understanding of the evolutionary process of universe, Earth, and humans. The second 10 interviews are with environmentalists, teachers, and artists who explore the connections between the universe story and the practices for a flourishing Earth community.
Life's Emergence (Terry Deacon and Ursula Goodenough)
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From the course by Yale University
Journey Conversations: Weaving Knowledge and Action
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Yale University
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Course 2 of 3 in the Specialization Journey of the Universe: A Story for Our Times
From the lesson
Emergence of Life, Learning, and Humans
We discuss the oxygen crisis two billion years ago and the endosymbiosis that dealt with it creatively. We too will deal with the enveloping crises of our time, first of all by tending to them, by taking responsibility for them.
Meet the Instructors
Mary Evelyn TuckerSenior Lecturer and Senior Research Scholar
Yale School of Forestry and Environmental Studies
John GrimSenior Lecturer and Senior Research Scholar
Yale School of Forestry and Environmental Studies
[MUSIC]
How are we going to tell the story of life?
How did it all begin?
What theory shall we offer to explain this?
The simple truth is that no one knows with full certainty.
But even though the detailed explanations still elude us,
scientists have begun to pose the whole question of life
from a radical new perspective, that of self-organization.
You see during the modern period we thought of the world is machine like, and
then, life was an accident.
But now with the work of a number of chemists,
notably Ilya Prigogine who won the Nobel Prize for this work,
we are beginning to discover the act of patterning in matter itself.
It's intrinsic to matter.
[MUSIC]
From this new perspective, life is not an accident.
Life is inevitable.
A planet reaches a certain complexity in its matter, and
then life blossoms forth quite naturally.
[MUSIC]
Consider whirlpools, this spiral swirling action can appear anywhere so
long as there is a body of liquid moving water.
It is not the water itself that endures as a spiral,
because the water molecules are constantly flowing in and out of the whirlpool.
It is rather the emergent dynamic structure that endures.
[MUSIC]
[SOUND] Such is the nature of life.
The universe began as a great outpouring of cosmic breath, cosmic energy.
But then swirled and twisted and complexified until it could burst forth
into flowers, animals and fish, all of these elegant explosions of energy.
But it's not just energy and it's not just living energy.
This is energy that is aware.
[MUSIC]
By awareness or sentience, we mean something that is more than what takes
place in the realm of elementary particles and yet
less than full human consciousness.
So where does such awareness arise?
Some biologists are beginning to speculate that awareness has its
foundation in the very self-organizing dynamics of the universe.
For cell biologist Ursula Goodenough,
this awareness is a kind of primitive discernment.
And it reveals itself especially in the membrane of each cell,
that thin, skin-like layer that covers every cell.
[MUSIC]
[NOISE] If we had microscope for
eyes we could see it all happening right here in these tide pools.
There are millions of cells are swarming about and
they're encountering molecules over and over again.
And with every encounter, discernment emerges, why?
Because a decision has to be made, an intelligent decision.
Up on the cliff over here, there's an ancient castle.
It'll help me explain.
[MUSIC]
This church, which is called Metamorphosis,
is nearly a thousand years old.
Above it is a castle that once guarded entrants into the magical Potomi Valley.
The castle was built to do what membranes do, let your friends in,
keep your enemies out.
[MUSIC]
The ongoing creativity of the universe is seen in the complex development of
life itself.
[MUSIC]
After it had circled the sun for hundreds of millions of years, earth's most
primitive organisms developed molecules that would resonate with the sun.
How are we to picture this process involving earth and sun,
bringing forth photosynthesis?
As an engineering project?
I guess, but try a new metaphor.
Imagine two lovers longing for each other.
What is it they truly desire?
[MUSIC]
Their relationship is charged with energy and promise.
There's the sun, exploding with brilliance.
There's the earth, basking in the sun's rays.
[MUSIC]
But earth is not passive, earth's systems attune to the sun,
changing their molecular structures in order to draw in light and
convert it to food.
[MUSIC]
As the complexity of life deepens, entwinement itself also deepens.
[MUSIC]
Ursula Goodenough, welcome.
>> It's a pleasure to be here, Mary Evelyn.
>> It's so good to see you.
You're a professor of biology at Washington University in St.Louis.
You've been a past president of the American Association of Cell Biology.
You've written a book on the sacred depths of nature.
And recently you were elected to the American Academy of Arts and Sciences,
congratulations.
>> Thank you so much, it was an honor.
Your whole life has been dedicated to the study of the cell,
one of the most amazing creations of evolution.
Can you tell us, when did this first cell emerge in this huge evolutionary story?
Well pretty quickly, apparently, after the earth was formed.
So the earth was formed 4.567 billion years ago.
And there's evidence for life at about 3.8 billion years ago.
And then the planet cooled down enough and life, probably the first kinds of life,
showed up soon after that, which is very interesting.
>> And the first kinds of life, these very small bacteria?
>> Well, we call their modern counterparts bacteria.
We don't really know what they were like, except for the sort of fossil remnants.
But the fossil remnants say that if we look around for
life that's on the planet today, for something that looks like
these pyrite fossils, then bacteria are the closest ones.
>> The very first ones came in the early emergence of the planet.
>> Yes.
>> But what about the nucleated cell, the eukaryote?
>> At least 1.5 billion years ago, probably deeper than that.
But that's the number that's around now.
So these prokaryotic-like cells, so they're the bacteria but
there's another group that are also called prokaryotes and they're the archaea.
Now in modern times they live in very extreme environments, in hot springs and
they can live in sulphuric acid, they're very cool critters.
And the current understanding is that what happened was That there were
these bacteria, there were these archaea and that they actually fused
together to form the first eukaryotes because some of the genes in
eukaryotes are more like the bacteria and some are more like the archaea.
So the idea was that they came together.
And formed this new kind of like called the Euchariad
>> How do we get from there to
multicellular organisms?
>> Well multicellularity has actually evolved many times.
>> Most people think of animals but
of course people would quickly think of plants that are also multi-cellular.
But then there are a number of algae that are multi-cellular, so
it's an idea that has happened apparently independently a number of different times.
>> And in your studies of cells, you have a sense of the multiple
dimensions of them and even perhaps a sense of awareness that these cells have.
Can you tell us about that sense of awareness?
>> If you're going to be an organism you have to be aware of your circumstances.
And so probably very early on there were proteins put into the surrounding
membrane of cells that are particularly set up to detect light,
to detect various odors of putative foods, to detect touch,
to be aware if things are too hot or too cold.
In order to be a successful organism, there will be selection for
having all of these different kinds of awareness.
Now we as humans, think of awareness as a very complex, brain based, kind of thing.
But we're trying to make a living in a very complicated environment.
If you're just a single cell,
you don't need to be aware of everything that's going on.
You just need to be aware of the things that are going to allow you to
flourish and go forth.
And you've even spoken about this as a sense of self,
what kind of characteristics does a sense of self imply?
>> Yeah I love the concept of self.
What we often talk about is unicellular organisms or multi-cellular organisms.
But I find it more interesting and juicy to think of any organism as a self.
And sometimes when I say this to someone they say a bacterium is a self?
And that's because we humans are used to thinking of ourselves our egos,
all of that kind of stuff.
But then If you ask well, would you say that a bacterium maintains itself?
And I'd say, well yeah.
And would you say that it protects itself with its wall?
Well, yeah. And would
you say that it reproduces itself?
And yes.
And then we start to understand that what an organism really is,
is a self that is self-maintaining, self-protecting, self-reproducing.
And that all of the single cells on the planet who ourselves are doing just that.
In a very modest way, but
that's all they need to do to carry out their basic legacy.
And it's only been quite recently in time,
recent 1.5 billion years that some of these eukaryotes have decided
to actually have a self that's made up of cells.
And all of the cells in a multi-cellular being,
like this plant, each of them is specialized to do different things.
Some are specialized to make roots.
Some are specialized to make leaves.
Some are specialized to make flowers.
And so the self is the whole multi-cellular organism.
And the individual cells in the multi-cellular organism, I would claim
aren't really selves anymore, they are all cooperating to get this self to happen.
>> This notion then of awareness and self qualities even
at the cellular level of life, it's quite an extraordinary concept really.
>> I love it.
>> So how does the membrane hold this cell together and
invite something in, perhaps, for food and energy exchange.
>> Uh-huh.
>> How does the membrane work?
>> Well, the very first life may not have even been surrounded by a membrane,
it may have been something else.
But what evolved so that the first common ancestry to all of life clearly
was unicellular self and had a membrane around it.
And the membrane is something that we're kind of familiar with in terms of
just a soap bubble.
I mean it's really made out of fat and it's very, very thin.
It distinguishes the self from the non self, from the rest of the environment.
But if you made an organism that was completely separated from its environment.
Then of course, it wouldn't work, because it has to get nourishment and so
on from the outside.
And so it does this through its membrane,
it has some proteins usually in it that are called receptors.
And they have a particular shape until, let's say, light hits it or
a chemical hits it, in which case, it changes its shape.
And when it changes its shape, the inside of the cell notices and
starts to pay attention and say I've got to do something different.
Like I've got to move towards this light or move towards this food.
And many of the responses involve actually
opening up little things called channels in this membrane.
The channel will open up very rapidly and close again but
some materials from the outside are let in during that movement.
And so, all of these responses to the receptor being
stimulated are, what I call, awareness.
And then response to awareness, which is exactly what we do.
We're aware of something, and then we respond to it.
>> How would photosynthesis be a part of that receptor?
>> Photosynthesis would really come, in my mind,
more in the self-maintenance category, for organisms that can do it.
They do have receptors that tell them where light is.
And if you're a little photosynthetic bacterium, there's a very elaborate
way of figuring out where the light is and swimming toward it.
Plants are stuck in the ground.
But I don't know whether you've ever had a house plant that kind of reached around
and turned all its leaves so that it would face the light.
So it does have awareness of where the light is and
tries to avail itself of the light as much as possible.
If the light is too bright, also it has lots of protective mechanisms.
Plants are aware.
But the actual photosynthesis,
the actual just taking the photons and turning them into sugar.
That's just regular old biochemistry.
[LAUGH] I wouldn't call that awareness.
I would say that in order to make a living as a photosynthetic organism,
you have to know where the light is.
And if you can't figure that out, then you don't make it.
>> So what you're saying is fascinating in terms of this sense of an interiority,
if you will, this kind of awareness, selfhood as you're defining it.
How does mobility come into that for organisms?
>> Well, all organisms are inside that membrane.
There's lots of little things called organelles and
stuff like that inside the cell.
And they're trucking around all the time, they have little motors that attach to
them and they move to the Edge of the cell and they move back.
So, there's motility within all cells.
And then some cells, like plants,
if they move at all it's very limited.
Yeast cells, most of the fungi don't move.
But it's interesting when I ask my class, give me a list of properties
that would describe an organism, describe something that's alive.
Almost the first hand that always goes up says it moves,
because we're so used to thinking of something that's dead as no longer moving,
and something that's alive that is moving.
So motility is useful, but there are many organisms that have dispensed with that.
>> And how about this extraordinary creation of the nuclei?
How is that functioning for the cell?
>> It's extraordinary in the sense that it defines this eukaryote group.
But it's not that big an adventure, [LAUGH] actually.
Everybody's got DNA, and the prokaryotes,
these bacteria and these archaea, have their DNA in little
islands inside of the cell that doesn't have a membrane around it.
And the eukaryote has its DNA in a little island, but it puts a membrane around it.
And once it has that membrane, it can regulate what's going in and
out of a nucleus.
So there's very classy ways that it's doing that.
>> One other question, I think, about the cell and
this emergence of DNA surrounded by a membrane.
Since that's something that we only began to understand in the 20th century,
so many of these processes were not visible to us and so on.
But again, give us just a very brief sense of how the DNA is working within a cell.
>> DNA encodes instructions for being that kind of organism.
So when we think of instructions for making something,
we usually have in mind a blueprint, that's what comes to our mind.
And you say so DNA must be a blueprint, and that's not what it is at all.
It's instead a whole lot of different sequences that have the instructions for
making a particular kind of protein.
And these instructions for
making a particular kind of protein are under regulation.
So if there's lots of light, you might up the expression of that gene,
up the expression of that protein, be doing more photosynthesis.
So it's a very flexible set of instructions where you can call upon this
gene here and this gene there.
But the DNA is in a way, I think of it as almost passive.
It's just sort of sitting there with the instructions, and
these proteins are the ones that are actually flipping these genes on.
And then proteins are made from the genes, they come back out,
the proteins go back in.
And so proteins rule.
I mean, they're the ones, if there's no DNA, there's no proteins.
The proteins are encoded by the DNA.
But it's the proteins that are actually generating cool stuff like awareness or
photosynthesis or cell division or whatever.
And the DNA just is a repository of how you can do that.
If you look in the genome of Mary Ellen Tucker, or in the genome of this plant, or
in the genome of modern bacteria,
they all have a lot of genes that they share in common.
Which means that we all came from an original kind of cell,
it's not the first cell.
The first cell was probably something much simpler.
The first cell figured stuff out over maybe a billion years,
but then finally, something went [SOUND] this works.
And that basic, this works, that basic plan of this common
ancestor living maybe 3 billion years ago, has never been given up.
Everybody uses the same code,
because it's all set up to operate as a whole and not by chance.
>> Ursula, we would love to have you talk a little bit
about the emergence in cells of sexuality.
How did that come about?
>> Well, the early cells were exchanging this DNA that we've been talking about,
and just trading genes back and forth, sort of indiscriminately.
And when the eukaryotes came along, we've now learned,
they also had a very different idea, which was to exchange DNA.
That still goes on, but now, one only exchanges DNA between two types.
In our cells between male and female, and the males and
females have to be the same species.
And so the whole process of speciation that we see in
eukaryotic lineages is based on sex and was invented at the very beginning.
Or at least the common ancestor to all of the eukaryotes
was clearly a sexual creature that already had this ability to have two types,
male and female, and to only exchange DNA within its species,
which allows you then to undergo this critical process of speciation.
The process of speciation is such that one group that is interbreeding and
only exchanging DNA with each other, one group splits off and
becomes a new group that is only exchanging DNA with each other.
And that's the major pattern that we see
in the evolution of eukaryotes is this process of speciation.
And that all has to do with this invention of sex.
[MUSIC]
>> Terry, welcome.
Would you introduce yourself to the audience here?
>> Well, I'm a professor of biological anthropology.
Spent my career studying the evolution of human brains and all the things that
are related to that, including human intelligence and particularly language.
>> How did you get interested in human intelligence and cognition?
>> Well, I've always had an interest to some extent in that, and
in the sciences in general.
But of course, human cognition, human brains, are some of the more
complicated questions, and some of the more interesting questions.
I think that probably the one event that stands out in my mind was
learning that brains are made up of cells that are basically talking to each other.
And the idea that little cells, communicating like a society,
could produce me as an emergent experience, as something that
wasn't a cell but was all of that talking, just was too exciting.
And I had to understand how it worked.
>> That is awesome.
So we're going to hear something about this community of cells.
Before we get to how even multicellular animals emerged,
can you give us a feel for this amazing story of here we have
the universe 13.7 billion years, earth 4.5 billion years.
When did the first cell emerge?
>> Interestingly enough, you might think that it took a lot of time for
this to happen.
But actually, the Earth was too hot for any life for
quite a bit of time until about three and a half billion years ago.
And almost as soon as the Earth is cool enough to have life begin it begins.
We don't know that it began it selves that we understand now but
something like it very simple.
And didn't take long for those to complexify to become things like we would
imagine to be viruses and bacteria today.
And they began to change the world.
The world changed radically in only about a billion years.
That's a long time in our framework, but for life not much.
And those little cells actually poisoned the atmosphere,
filled it full of oxygen as they learned to turn sunlight into energy.
And that changed things radically.
Oxygen was actually a poison at the time.
But as organisms adapted to it oxygen became useful, and
oxygen is a very powerful molecule and it made possible big organisms.
Because you need big energy for big organisms and so
with oxygen there we get the evolution of larger and more complicated organisms and
of course we're the end of that process three and a half billion years later.
>> So the first multicellular animals emerged approximately when would we say?
>> Well, there's a period of time where they're coming and going.
But what we really see things that we would today recognize as plants and
animals, somewhere in the range of half a billion years ago.
And there's a big explosion of diverse body plans both for animals and plants.
And the thing that's so interesting about them that we recognize in animals and
plants today is they have repeated parts.
Their bodies are made of similar kinds of themes and variations.
So leaves look at each other, petals and
flowers look like leaves, stamens look like branches.
And our bodies are repeated parts.
And you think about the segments of worms, the segments of insects and you and
I have vertebrae and ribs that are repeated parts.
Our hands and our feet are theme and variations on each other.
That's what really made multicellular animals and plants possible.
And somehow, life figured out how to turn basically duplicated genes copying genes.
They're genes that are copies of each other, began to code for
different whole body regions.
And they became duplicates of each other and
then you have this elaborate explosion.
It happened very fast after a half billion years ago.
>> Is there any name for that?
This repeated patterning over.
>> It's an interesting story because it actually begins well before Darwin.
This idea was really first picked up by Wolfgang von Goethe, the poet,
scientist, philosopher.
Who's studying plants came to the realization
there's this underlying form logic and he was so excited about it.
It actually drove biological science for the first half of the nineteenth century
until Darwin as the major reason to think about life and how it works and so on.
Today we now recognize that it has to do with the way evolution and
development work together.
Darwin effectively could ignore that part of life and could talk about
adaptation but didn't really talk about how the forms came about.
And today, really at the end of the 20th century a field that's now called EvoDevo
for bringing evolution and devo for development together.
Recognizes that there are processes in how organisms develop that have this theme and
variation logic so that parts are repeated and used over again in different ways.
>> A fascinating notion, isn't it, that form actually inspired Goethe,
and then later, we're understanding this patterning throughout.
>> We actually didn't understand where this regularity came from until
the beginning of the 1980s.
And what was discovered were that there were genes
that controlled whole suites of other genes.
Sort of like an orchestra conductor.
One gene that causes other genes to be turned on and off.
And in so doing, one gene can play a role in producing lots of body parts.
But if that gene gets copied, gets duplicated and
those duplicates start to change to become a little bit different.
Sort of like the conductors twin beginning to have different experiences and
conducts the same piece of music just a little bit differently.
And so that limb looks a little bit different than the other limb.
That mouth part looks a little bit different from that antenna and so on.
That theme and variation develops out of that kind of logic.
That's what really happened to cause this explosion of animals and plants and
fungi that we know today as these complicated organisms.
>> Fascinating, so does that affect as well this amazing
emergence of reflexive consciousness, so to have anything to do with that?
>> Well, clearly does because what this tells us is that using
the same principles, the same form making principles and
generating them and testing them against the world.
What you do is you produce new capacities,
new capabilities that weren't there before.
Using the old patterns in new ways.
Darwin described this as descent with modification.
He didn't think of evolution as adding things.
He thought of it as taking what was there and modifying it a little bit for
new functions.
Well that's what development allows this process to do.
It allows duplications of functions to take on new functions.
And that turns out to be one of the major ways
that new features come into the world.
Not by being just added on top like a new invention but
actually a twist on an old story.
[MUSIC]
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