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.