TEDSalon London Spring 2011

Martin Hanczyc: The line between life and not-life

Filmed:

In his lab, Martin Hanczyc makes "protocells," experimental blobs of chemicals that behave like living cells. His work demonstrates how life might have first occurred on Earth ... and perhaps elsewhere too.

- Chemist
Martin Hanczyc explores the path between living and nonliving systems, using chemical droplets to study behavior of the earliest cells. Full bio

So historically there has
00:15
been a huge divide between what people
00:17
consider to be non-living systems on one
00:20
side, and living systems on the other side.
00:23
So we go from, say, this beautiful and
00:25
complex crystal as non-life, and this rather
00:27
beautiful and complex cat on the other side.
00:30
Over the last hundred and fifty years or so,
00:33
science has kind of blurred this distinction
00:36
between non-living and living systems, and
00:38
now we consider that there may be a kind
00:40
of continuum that exists between the two.
00:42
We'll just take one example here:
00:45
a virus is a natural system, right?
00:47
But it's very simple. It's very simplistic.
00:49
It doesn't really satisfy all the requirements,
00:51
it doesn't have all the characteristics
00:53
of living systems and is in fact a parasite
00:55
on other living systems in order to, say,
00:57
reproduce and evolve.
01:00
But what we're going to be talking about here
01:02
tonight are experiments done on this sort of
01:04
non-living end of this spectrum -- so actually
01:06
doing chemical experiments in the laboratory,
01:08
mixing together nonliving ingredients
01:11
to make new structures, and that these
01:13
new structures might have some of the
01:15
characteristics of living systems.
01:17
Really what I'm talking about here is
01:19
trying to create a kind of artificial life.
01:21
So what are these characteristics that I'm
01:23
talking about? These are them.
01:25
We consider first that life has a body.
01:27
Now this is necessary to distinguish the self
01:29
from the environment.
01:31
Life also has a metabolism. Now this is a
01:33
process by which life can convert resources
01:35
from the environment into building blocks
01:38
so it can maintain and build itself.
01:40
Life also has a kind of inheritable information.
01:43
Now we, as humans, we store our information
01:45
as DNA in our genomes and we pass this
01:47
information on to our offspring.
01:50
If we couple the first two -- the body and the metabolism --
01:52
we can come up with a system that could
01:54
perhaps move and replicate, and if we
01:56
coupled these now to inheritable information,
01:58
we can come up with a system that would be
02:01
more lifelike, and would perhaps evolve.
02:03
And so these are the things we will try to do
02:05
in the lab, make some experiments that have
02:07
one or more of these characteristics of life.
02:09
So how do we do this? Well, we use
02:12
a model system that we term a protocell.
02:14
You might think of this as kind of like a
02:16
primitive cell. It is a simple chemical
02:18
model of a living cell, and if you consider
02:20
for example a cell in your body may have
02:23
on the order of millions of different types
02:25
of molecules that need to come together,
02:27
play together in a complex network
02:29
to produce something that we call alive.
02:31
In the laboratory what we want to do
02:34
is much the same, but with on the order of
02:36
tens of different types of molecules --
02:38
so a drastic reduction in complexity, but still
02:40
trying to produce something that looks lifelike.
02:42
And so what we do is, we start simple
02:45
and we work our way up to living systems.
02:47
Consider for a moment this quote by
02:50
Leduc, a hundred years ago, considering a
02:52
kind of synthetic biology:
02:54
"The synthesis of life, should it ever occur,
02:56
will not be the sensational discovery which we
02:58
usually associate with the idea."
03:00
That's his first statement. So if we actually
03:02
create life in the laboratories, it's
03:04
probably not going to impact our lives at all.
03:06
"If we accept the theory of evolution, then
03:08
the first dawn of synthesis of life must consist
03:10
in the production of forms intermediate
03:12
between the inorganic and the organic
03:14
world, or between the non-living
03:16
and living world, forms which possess
03:18
only some of the rudimentary attributes of life"
03:20
-- so, the ones I just discussed --
03:22
"to which other attributes will be slowly added
03:24
in the course of development by the
03:26
evolutionary actions of the environment."
03:28
So we start simple, we make some structures
03:30
that may have some of these characteristics
03:32
of life, and then we try to develop that
03:34
to become more lifelike.
03:36
This is how we can start to make a protocell.
03:38
We use this idea called self-assembly.
03:40
What that means is, I can mix some
03:42
chemicals together in a test tube in my lab,
03:44
and these chemicals will start to self-associate
03:46
to form larger and larger structures.
03:48
So say on the order of tens of thousands,
03:50
hundreds of thousands of molecules will
03:52
come together to form a large structure
03:54
that didn't exist before.
03:56
And in this particular example,
03:58
what I took is some membrane molecules,
04:00
mixed those together in the right environment,
04:02
and within seconds it forms these rather
04:04
complex and beautiful structures here.
04:06
These membranes are also quite similar,
04:08
morphologically and functionally,
04:10
to the membranes in your body,
04:12
and we can use these, as they say,
04:14
to form the body of our protocell.
04:16
Likewise,
04:18
we can work with oil and water systems.
04:19
As you know, when you put oil and water together,
04:21
they don't mix, but through self-assembly
04:23
we can get a nice oil droplet to form,
04:25
and we can actually use this as a body for
04:27
our artificial organism or for our protocell,
04:29
as you will see later.
04:31
So that's just forming some body stuff, right?
04:33
Some architectures.
04:35
What about the other aspects of living systems?
04:37
So we came up with this protocell model here
04:39
that I'm showing.
04:41
We started with a natural occurring clay
04:43
called montmorillonite.
04:45
This is natural from the environment, this clay.
04:47
It forms a surface that is, say, chemically active.
04:49
It could run a metabolism on it.
04:51
Certain kind of molecules like to associate
04:53
with the clay. For example, in this case, RNA, shown in red
04:55
-- this is a relative of DNA,
04:57
it's an informational molecule --
04:59
it can come along and it starts to associate
05:01
with the surface of this clay.
05:03
This structure, then, can organize the
05:05
formation of a membrane boundary around
05:07
itself, so it can make a body of
05:09
liquid molecules around itself, and that's
05:11
shown in green here on this micrograph.
05:13
So just through self-assembly, mixing things
05:15
together in the lab, we can come up with, say,
05:17
a metabolic surface with some
05:20
informational molecules attached
05:22
inside of this membrane body, right?
05:24
So we're on a road towards living systems.
05:26
But if you saw this protocell, you would not
05:30
confuse this with something that was actually alive.
05:32
It's actually quite lifeless. Once it forms,
05:34
it doesn't really do anything.
05:36
So, something is missing.
05:38
Some things are missing.
05:40
So some things that are missing is,
05:42
for example, if you had a flow of energy
05:44
through a system, what we'd want
05:46
is a protocell that can harvest
05:48
some of that energy in order to maintain itself,
05:50
much like living systems do.
05:52
So we came up with a different protocell
05:54
model, and this is actually simpler than the previous one.
05:56
In this protocell model, it's just an oil droplet,
05:58
but a chemical metabolism inside
06:00
that allows this protocell to use energy
06:02
to do something, to actually become dynamic,
06:04
as we'll see here.
06:07
You add the droplet to the system.
06:09
It's a pool of water, and the protocell
06:11
starts moving itself around in the system.
06:13
Okay? Oil droplet forms
06:15
through self-assembly, has a chemical
06:17
metabolism inside so it can use energy,
06:19
and it uses that energy to move itself
06:21
around in its environment.
06:23
As we heard earlier, movement is very
06:25
important in these kinds of living systems.
06:27
It is moving around, exploring its environment,
06:29
and remodeling its environment, as you see,
06:31
by these chemical waves that are forming by the protocell.
06:33
So it's acting, in a sense, like a living system
06:35
trying to preserve itself.
06:37
We take this same moving protocell here,
06:40
and we put it in another experiment,
06:43
get it moving. Then I'm going
06:45
to add some food to the system,
06:47
and you'll see that in blue here, right?
06:49
So I add some food source to the system.
06:52
The protocell moves. It encounters the food.
06:54
It reconfigures itself and actually then
06:56
is able to climb to the highest concentration
06:58
of food in that system and stop there.
07:00
Alright? So not only do we have this system
07:02
that has a body, it has a metabolism,
07:04
it can use energy, it moves around.
07:06
It can sense its local environment
07:09
and actually find resources
07:11
in the environment to sustain itself.
07:13
Now, this doesn't have a brain, it doesn't have
07:15
a neural system. This is just a sack of
07:17
chemicals that is able to have this interesting
07:19
and complex lifelike behavior.
07:21
If we count the number of chemicals
07:23
in that system, actually, including the water
07:25
that's in the dish, we have five chemicals
07:27
that can do this.
07:29
So then we put these protocells together in a
07:31
single experiment to see what they would do,
07:33
and depending on the conditions, we have
07:35
some protocells on the left that are
07:37
moving around and it likes to touch the other
07:39
structures in its environment.
07:41
On the other hand we have two moving
07:43
protocells that like to circle each other,
07:45
and they form a kind of a dance, a complex dance with each other.
07:47
Right? So not only do individual protocells
07:49
have behavior, what we've interpreted as
07:51
behavior in this system, but we also have
07:53
basically population-level behavior
07:55
similar to what organisms have.
07:58
So now that you're all experts on protocells,
08:01
we're going to play a game with these protocells.
08:04
We're going to make two different kinds.
08:06
Protocell A has a certain kind of chemistry
08:08
inside that, when activated, the protocell
08:11
starts to vibrate around, just dancing.
08:13
So remember, these are primitive things,
08:15
so dancing protocells, that's very
08:17
interesting to us. (Laughter)
08:19
The second protocell has a different
08:21
chemistry inside, and when activated,
08:23
the protocells all come together and they fuse
08:25
into one big one. Right?
08:27
And we just put these two together
08:29
in the same system.
08:31
So there's population A,
08:33
there's population B, and then
08:35
we activate the system,
08:37
and protocell Bs, they're the blue ones,
08:39
they all come together. They fuse together
08:41
to form one big blob, and the other protocell
08:43
just dances around. And this just happens
08:45
until all of the energy in the system is
08:47
basically used up, and then, game over.
08:49
So then I repeated this experiment
08:52
a bunch of times, and one time
08:54
something very interesting happened.
08:56
So, I added these protocells together
08:58
to the system, and protocell A and protocell B
09:00
fused together to form a hybrid protocell AB.
09:02
That didn't happen before. There it goes.
09:04
There's a protocell AB now in this system.
09:06
Protocell AB likes to dance around for a bit,
09:09
while protocell B does the fusing, okay?
09:12
But then something even more interesting happens.
09:15
Watch when these two large protocells,
09:18
the hybrid ones, fuse together.
09:20
Now we have a dancing protocell
09:22
and a self-replication event. Right. (Laughter)
09:25
Just with blobs of chemicals, again.
09:29
So the way this works is, you have
09:31
a simple system of five chemicals here,
09:33
a simple system here. When they hybridize,
09:35
you then form something that's different than
09:37
before, it's more complex than before,
09:39
and you get the emergence of another kind of
09:41
lifelike behavior which
09:43
in this case is replication.
09:45
So since we can make some interesting
09:47
protocells that we like, interesting colors and
09:49
interesting behaviors, and they're very easy
09:51
to make, and they have interesting lifelike
09:53
properties, perhaps these protocells have
09:55
something to tell us about the origin of life
09:58
on the Earth. Perhaps these represent an
10:00
easily accessible step, one of the first steps
10:02
by which life got started on the early Earth.
10:04
Certainly, there were molecules present on
10:07
the early Earth, but they wouldn't have been
10:09
these pure compounds that we worked with
10:11
in the lab and I showed in these experiments.
10:13
Rather, they'd be a real complex mixture of
10:15
all kinds of stuff, because
10:17
uncontrolled chemical reactions produce
10:19
a diverse mixture of organic compounds.
10:21
Think of it like a primordial ooze, okay?
10:23
And it's a pool that's too difficult to fully
10:26
characterize, even by modern methods, and
10:28
the product looks brown, like this tar here
10:30
on the left. A pure compound
10:32
is shown on the right, for contrast.
10:34
So this is similar to what happens when you
10:36
take pure sugar crystals in your kitchen,
10:38
you put them in a pan, and you apply energy.
10:40
You turn up the heat, you start making
10:42
or breaking chemical bonds in the sugar,
10:44
forming a brownish caramel, right?
10:46
If you let that go unregulated, you'll
10:48
continue to make and break chemical bonds,
10:50
forming an even more diverse mixture of
10:52
molecules that then forms this kind of black
10:54
tarry stuff in your pan, right, that's
10:56
difficult to wash out. So that's what
10:58
the origin of life would have looked like.
11:00
You needed to get life out of this junk that
11:02
is present on the early Earth,
11:04
four, 4.5 billion years ago.
11:06
So the challenge then is,
11:08
throw away all your pure chemicals in the lab,
11:10
and try to make some protocells with lifelike
11:12
properties from this kind of primordial ooze.
11:14
So we're able to then see the self-assembly
11:17
of these oil droplet bodies again
11:19
that we've seen previously,
11:21
and the black spots inside of there
11:23
represent this kind of black tar -- this diverse,
11:25
very complex, organic black tar.
11:27
And we put them into one of these
11:29
experiments, as you've seen earlier, and then
11:31
we watch lively movement that comes out.
11:33
They look really good, very nice movement,
11:35
and also they appear to have some kind of
11:37
behavior where they kind of circle
11:39
around each other and follow each other,
11:41
similar to what we've seen before -- but again,
11:44
working with just primordial conditions,
11:46
no pure chemicals.
11:48
These are also, these tar-fueled protocells,
11:50
are also able to locate resources
11:52
in their environment.
11:54
I'm going to add some resource from the left,
11:55
here, that defuses into the system,
11:57
and you can see, they really like that.
11:59
They become very energetic, and able
12:01
to find the resource in the environment,
12:03
similar to what we saw before.
12:05
But again, these are done in these primordial
12:07
conditions, really messy conditions,
12:09
not sort of sterile laboratory conditions.
12:11
These are very dirty little protocells,
12:13
as a matter of fact. (Laughter)
12:15
But they have lifelike properties, is the point.
12:17
So, doing these artificial life experiments
12:20
helps us define a potential path between
12:23
non-living and living systems.
12:26
And not only that, but it helps us
12:29
broaden our view of what life is
12:31
and what possible life there could be
12:33
out there -- life that could be very different
12:35
from life that we find here on Earth.
12:37
And that leads me to the next
12:40
term, which is "weird life."
12:42
This is a term by Steve Benner.
12:44
This is used in reference to a report
12:47
in 2007 by the National Research Council
12:49
in the United States, wherein
12:51
they tried to understand how we can
12:53
look for life elsewhere in the universe, okay,
12:55
especially if that life is very different from life
12:57
on Earth. If we went to another planet and
12:59
we thought there might be life there,
13:02
how could we even recognize it as life?
13:04
Well, they came up with three very general
13:06
criteria. First is -- and they're listed here.
13:08
The first is, the system has to be in
13:10
non-equilibrium. That means the system
13:12
cannot be dead, in a matter of fact.
13:14
Basically what that means is, you have
13:15
an input of energy into the system that life
13:17
can use and exploit to maintain itself.
13:19
This is similar to having the Sun shining
13:22
on the Earth, driving photosynthesis,
13:24
driving the ecosystem.
13:26
Without the Sun, there's likely to be
13:28
no life on this planet.
13:30
Secondly, life needs to be in liquid form,
13:32
so that means even if we had some
13:34
interesting structures, interesting molecules
13:36
together but they were frozen solid,
13:38
then this is not a good place for life.
13:40
And thirdly, we need to be able to make
13:42
and break chemical bonds. And again
13:44
this is important because life transforms
13:46
resources from the environment into
13:48
building blocks so it can maintain itself.
13:50
Now today, I told you about very strange
13:52
and weird protocells -- some that contain clay,
13:54
some that have primordial ooze in them,
13:56
some that have basically oil
13:59
instead of water inside of them.
14:01
Most of these don't contain DNA,
14:03
but yet they have lifelike properties.
14:05
But these protocells satisfy
14:07
these general requirements of living systems.
14:10
So by making these chemical, artificial
14:13
life experiments, we hope not only
14:15
to understand something fundamental
14:17
about the origin of life and the existence
14:19
of life on this planet, but also
14:21
what possible life there could be
14:23
out there in the universe. Thank you.
14:25
(Applause)
14:28

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About the Speaker:

Martin Hanczyc - Chemist
Martin Hanczyc explores the path between living and nonliving systems, using chemical droplets to study behavior of the earliest cells.

Why you should listen

Martin Hanczyc is developing novel synthetic chemical systems based on the properties of living systems, in a quest to understand how life forms. These synthetic systems, or "protocells," are model systems of primitive living cells and chemical examples of artificial life. As Rachel Armstrong puts it: "Although the protocell model system is just a chemically modified oil droplet, its dynamics are astonishingly varied and complex."

He's based at the Institute of Physics and Chemistry and the Center for Fundamental Living Technology (FLinT) in Denmark. He is also an Honorary Senior Lecturer at the Bartlett School of Architecture, University College London.

More profile about the speaker
Martin Hanczyc | Speaker | TED.com