The key to understanding a functionlalsit perspective on the origin of life
is understanding the adaptive arrow of time.
If I were to show you this slide and ask you which
way does time flow, from left to right
or right to left; from the fresh to rotten or
rotten to fresh, everyone would know the
answer to that. That's because you have
a basic intuition about the second law of thermodynamics.
Systems tend to become disordered in time.
Arthur Eddington famously described this phenomenon
the arrow of time, by asking us to consider
an arrow and if we follow that arrow and
find more and more of the random element
in the state of the world, then that
points towards the future. But if the
random element decreases, the arrow points
towards the past. And "time's arrow"
expresses the one-way property of time.
Now, most of you are thinking, "wait a second,
there is a forward arrow that leads
to greater order", and that's what Darwin
worked on. And so, if I showed you this picture
and said, "which is the initial state and
which is the final state?" Those of you
familiar with the phenomena of industrial melanism
in Northern England, would say, 'well, the final
state here is the adaptive state" Its the dark
moth with the dark background which makes
the moth less susceptible to predators.
And Ronald Fisher expressed this alternative
to Eddington's arrow of time as Darwinian arrow
of time. Where he said it was Darwin's
chief contribution not only biology
but of the whole natural science to have brought
to light a process by which randomness
that you start with, in the process of time
decreases, such that very improbable things
their non-occurrence becomes highly probable.
So, the Darwinian arrow of time rather than
increasing probable things, disorder, increases
improbable things.
And the standard framework for understanding this
increase in improbable things is evolution by
natural selection on fitness landscapes. So there are
many probable states of the world, and they
are all low-fitness. But there is one
high-fitness state of the world, which in terms of
of the space of possibilities, is highly improbable.
And, that's what natural selection does.
It selects more of these possible states
a very improbable one. And, so the
physical arrow of time says you are going to roll down-hill
and end up in one of these more probable states
and the adaptive arrow of time says you are
gonna move uphill and end up in a very improbable ordered state.