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.