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[Music]

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I'm throwing my pleasure to be here

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today to tell you about some of the work

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we do at LC I'm going to cover the the

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topic of how we go from the origin of

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life to something a little more

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complicated that we think could have

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been the ancestor of all the living

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things we see on the planet today I am a

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chemist so I tend to think of this in

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chemical terms as a chemical problem so

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bear that in mind so the central

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question we're trying to understand we

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heard a lot of talks this morning about

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how planets form and how the atmosphere

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and oceans originated but how we went

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from a primitive earth that had no life

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on it was just Rock and water and gas to

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the kind of planet we live on today

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right which is just covered in living

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things doing incredibly complex

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ecosystems all kinds of amazing

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organisms that are doing interesting

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things to stay alive and make copies of

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themselves in the oceans on dry land

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tropical jungles and even if we get down

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to the microscopic level there's an

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incredible diversity and richness of

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life at the microscopic scale right this

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is very complex so the question is how

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did we get to that from this lifeless

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state and it's really quite a vexing

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problem so Charles Darwin when he was

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formulating his theory of evolution by

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natural selection came up with the idea

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that organisms changed through time and

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a an ancestor organism can give rise to

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say two different types of organism

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right but if you reverse that and go

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backwards in time the implication is

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that all these organisms at the tip that

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are alive today have a common ancestor

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all right and in fact they shouldn't

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have a single origin if they're all

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related and he wrote that in the first

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edition of his book very eloquently

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there is grandeur in this view of life

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with its several powers having been

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originally breathed into a few

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worms were into one and then once you

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have that first thing it is free to

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become many new things but this question

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of how you make that first thing it's

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very complicated all right we have a

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general scheme for how we think this

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process occurs and what we think happens

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is we have some sort of chemistry that

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takes place before you have living

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things this is chemistry that the

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environment does I'll show you some

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examples of that there's some process

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here that we don't understand very well

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at all that gives rise to a first living

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thing that first living thing may be

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very different from living things as we

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recognize them today but it goes through

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some period of work of evolution until

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it gave rise to what we call Luca or the

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last Universal common ancestor and

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that's that putative organism is the

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thing that gave rise to all the species

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we see today okay and which is

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contemporary biochemistry so things we

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don't know what kinds of chemicals are

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necessary for this process and how those

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chemicals come together to make living

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systems without the assistance of other

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living systems there's two ways you can

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think about this um one is this sort of

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bottom-up approach so you're if you're a

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chemist you say okay what chemicals do I

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have how can I put them together to do

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interesting reactions if you're a

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biologist we you can do what's called a

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top-down approach you can say what sorts

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of things do all modern organisms have

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in common and if you say ok with only

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the ones that they have in common or the

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the crucial ones which ones of those can

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we cut away can we design a simpler

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first organism so you're comparing

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modern biology ok so we know a little

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bit about when we think this happened we

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can date the earth pretty well at this

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point we know the earth is about four

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and a half billion years old so we're

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going back in time along this axis we

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are here alright this is the present day

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0 years in the past if we look at the

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geological record we have evidence for

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biology

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going back about three and a half

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billion years ago that's it's quite

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remarkable what we do see things that we

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can agree are evidence of living

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organisms we also have some indication

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of one there was liquid surface water on

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the earth so we think all living things

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need water so that the planet had to

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cool enough for that to exist and what

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that leaves us with is about a billion

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year window for this process of life to

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originate right now it doesn't mean life

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didn't start earlier we just don't have

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evidence for it okay and really the big

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question is we don't know if this

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process takes a week or a billion years

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all right it could it could be that it's

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just something that takes an incredibly

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long amount of time it will be very

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difficult to observe in a laboratory so

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this is a this is a fundamental unknown

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okay so just to give you some context

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for why it is so difficult for us to

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know when life started because the earth

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is such a dynamic planet which we heard

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today about the process of tectonics

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that rocks are constantly being made in

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these are called mid-ocean ridges in the

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middle of the ocean we have new rock

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coming up from the interior of the earth

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cycling out like a conveyor belt and

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eventually being pushed back down into

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the earth in fact all of this rock is

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fairly young maybe the oldest oceanic

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crust is four hundred million years old

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right so it's not very old at all the

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rocks that make up the continents can be

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quite a bit older but these little

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regions in purple here are the oldest

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you know large domains of rocks we know

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of there are only about three and three

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and a half billion years old okay so the

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point is because the earth is constantly

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doing this recycling the oldest rocks

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really aren't available to us which are

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the rocks we would be the most

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interested in there are a couple of

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regions where we have rocks that are

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almost four billion years old but

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they're heavily they've been heated if

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they've been put under pressure and we

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don't think that we're

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to be able to find evidence of life very

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easily in these kinds of rocks okay so

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so again switching to this sort of

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top-down approach we can look at what we

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think is a simplest form of life that we

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see today there's something like a

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bacterial cell actually it's a pretty

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sophisticated little machine that's

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function is making more bacteria right

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and if you're not familiar with the

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shape the structure of a cell the cell

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has a cell membrane it is a wall that

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encloses the contents of the organism it

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has a genetic molecule called DNA which

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stores the information for making copies

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of the cell and it has various small

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molecules that help integrate the

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functions of these different components

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all right and here's an electron

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micrograph of a bacterial cell just so

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you get a sense unlike a machine that

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you're more familiar with all of the

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parts are mixed together

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right they work in it by even though

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they're always diffusing around and

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moving in space and time okay so just to

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give you some appreciation if you can

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play this video this is a approximately

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real-time animation of the process by

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which DNA in our bodies and bacterial

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bodies and all living things bodies gets

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converted to another molecule called RNA

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so this is copying of information by a

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protein a series of protein enzymes all

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right so you're gonna see this protein

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enzyme coming here it's moving along the

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DNA which is the red strand and it is

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copying an RNA molecule which is the

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yellow stand this is approximately how

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fast this occurs in in real time and

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yourselves so this is all going on right

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now and inside of us very quickly that

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RNA strands then gets picked up by a

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rather complicated other machine within

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the cell called the ribosome which takes

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that information using adapter molecules

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and turns it into a third kind of

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polymer called a protein all right so

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you see in a second here there's the

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protein starting to emerge from this

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large machine

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so it's a very complicated process right

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there's there's a way of translating

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from one language to another language to

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a third language very precisely and very

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quickly all right is very difficult to

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understand how a process that complex

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could have arisen by itself so we think

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we're looking for simpler types of

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chemistry that eventually became more

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complex over time so there was a

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hungarian theoretician named tea borg

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aunty who came up with this notion of

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you can think of a cell in a very

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idealized way as just being three

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systems okay one of those systems is a

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container that keeps everything together

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all right one of those systems is again

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some sort of metabolism or machinery for

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making the parts and the third system is

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something like a blueprint it contains

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the information for making the other

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parts and those things all have to be

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connected together in order for the

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whole system to propagate itself

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together but the important you know

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message here is maybe you could make

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these kind of machines these kinds of

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systems out of completely different

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types of chemicals than modern

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and indeed you know we might expect if

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we went to look for life on other

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planets it might have evolved into a

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pretty different configuration than the

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way our life is so let's take a little

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bit about where we get the chemicals

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from to start this process so space is

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one source we have things like comets

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and meteorites they're always coming in

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so it's actually a image captured from a

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dashboard camera on a car of a meteorite

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that exploded over Russia a few years

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ago these kind of processes are

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happening today we know something about

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the contents of these materials in terms

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of chemicals we believe these things

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were happening more frequently on the

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early Earth another possibility is that

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storms and sorts of processing of the

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Earth's atmosphere generated different

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kinds of chemicals it's a view of

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lightning storms from space these little

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purple flashes again there's there's

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lightning on earth all the time we

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believe that's been happening for

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billions of years and you can get some

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very interesting chemistry taking place

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in the region right next to a lightning

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bolt it's very hot it's able to do

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interesting chemistry and there's a

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third possibility these are not mutually

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exclusive in fact because the earth is

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releasing heat from its interior that

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heat comes into contact with ocean water

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and rock deep in the Earth's surface so

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sucking ocean water down here comes into

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contact with hot rock and it gets

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ejected as extremely hot water that is

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also able to do very interesting

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chemistry right so there's a lot of ways

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we think we can make chemicals on a

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primitive lifeless planet just to give

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you an example I actually do work on

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meteorites as part of my job this is

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this is not my my personal work but we

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do this kind of thing you can take

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meteorites and you can extract the

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organic chemicals from them and analyze

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them and there's a device called a mass

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spectrometer which essentially allows

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you to weigh the types of chemicals that

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are in it and what you end up with this

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is an example of a meteorite that fell

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in Australia there are thousands and

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thousands and thousands of calm

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pounds with distinct weights okay so

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they're all different types of organic

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compounds and just as there might be

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more than one person in this room always

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say 75 kilograms there may be multiple

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chemicals that have the same weight so

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in fact this is probably tens of

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millions of distinct types of organic

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compounds right very very complex

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another example this is something you

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can do in the lab if you put some simple

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gases like methane ammonia and water and

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a flask and we pass a little electric

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discharge here says electric discharge

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generator the spark simulating lightning

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after a couple of days that gas gets

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turned in again to a very very very

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complex mixture of organic compounds

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right this is something you can witness

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over you know days in the laboratory and

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it's simply because in that electric

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discharge these molecules get ripped

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apart and recombined and then undergo

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more complex chemistry that eventually

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gives rise to again millions of

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different types organic compounds so how

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do we put those things together to

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actually make a living thing that is a

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much more complex question yeah

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one of the things we think might be

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really important in this process is in a

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very general sense it's something in

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chemistry that we call Auto catalysis

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all right

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and auto catalysis is simply this when a

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chemical reaction you can think you have

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you have things that you mix together

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and you get a product right in an auto

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catalytic process the product of the

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reaction actually goes back and speeds

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up the reaction right so it's a catalyst

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for its own production and if you look

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at the amount of product over time it

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actually increases and increases over

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time right that's it the more C you have

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the more of it you can make the which

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gives you more C which means you can

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make more C and so on and so forth there

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are different ways you can think about

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doing this but that basic process of

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amplification

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through Auto catalysis maybe a very

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important thing in biology and if you

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want to think about that in a biological

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terms you know you take carrots and you

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give it to rabbits you give them rabbits

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and you get more rabbits which can eat

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more carrots to make more rabbits Steve

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more carrots make more rabbits and so on

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and so on so that is a it feels like a

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very biological process to us yeah we

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have different ways we can we can

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simulate these sort of processes in

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computers so sort of reaction diffusion

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processes where you can actually have

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two of these systems coupled where the

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product of one reaction becomes the food

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for the next and you can see that you

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can get very complex sort of lifelike

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behavior and a computer from these very

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simple reaction models yeah so things

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that seem to make copies of themselves

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by converting food into their own

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substance so I'll give you one more kind

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of real-world example this is so we take

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two two simple molecules

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HCN hydrogen cyanide and formaldehyde

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it's a HCHO it's one has three atoms

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when I was four atoms put it in water

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we're gonna look at this reaction under

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a microscope all right this is about two

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millimeters across and then we're

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speeding this up to about five hours the

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molecules are smaller than you can see

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with a microscope but over time you'll

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notice you start seeing some little

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and it gets faster over time and it gets

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faster and faster over time you start

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seeing more and more and more and more

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of these so it turns into a complete

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00:16:34,370 --> 00:16:29,790
snowstorm of something being formed

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essentially it seems to be an

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autocatalytic process and it's a very

382
00:16:43,530 --> 00:16:39,840
interesting one I'll show you a little

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more more more MORE until you at some

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point you start running out of the

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starting chemical when it's closed out

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so you have these very large and complex

387
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sort of structures that form you could

388
00:17:01,530 --> 00:16:58,089
pick those things and look at them under

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00:17:04,919 --> 00:17:01,540
a higher power microscope and you see in

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00:17:07,699 --> 00:17:04,929
fact that what they are is small kind of

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00:17:12,120 --> 00:17:07,709
cell sized little capsules of chemicals

392
00:17:13,559 --> 00:17:12,130
all right they're hollow you can put

393
00:17:15,150 --> 00:17:13,569
stuff inside them when you put them

394
00:17:17,460 --> 00:17:15,160
under the high pressure or the low

395
00:17:20,250 --> 00:17:17,470
pressure of the electron microscope they

396
00:17:23,549 --> 00:17:20,260
explode sort of like the eggs in the

397
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alien or so you know they rupture you

398
00:17:28,710 --> 00:17:25,870
can drill holes in them we know they're

399
00:17:30,600 --> 00:17:28,720
hollow so there's this very interesting

400
00:17:32,970 --> 00:17:30,610
chemical phenomena that we don't

401
00:17:34,980 --> 00:17:32,980
understand very well that might be

402
00:17:37,380 --> 00:17:34,990
relevant to this sort of process there's

403
00:17:39,530 --> 00:17:37,390
auto catalytic they use very simple

404
00:17:41,730 --> 00:17:39,540
chemicals to become more complex things

405
00:17:44,460 --> 00:17:41,740
so on

406
00:17:46,140 --> 00:17:44,470
we know we're trying to understand the

407
00:17:50,100 --> 00:17:46,150
chemistry of these kind of systems which

408
00:17:53,340 --> 00:17:50,110
can be quite complex in this case this

409
00:17:55,560 --> 00:17:53,350
does seem to be a auto catalytic process

410
00:17:58,350 --> 00:17:55,570
it goes around it's cyclic it puts out a

411
00:18:00,390 --> 00:17:58,360
large molecule as a product so you can

412
00:18:02,310 --> 00:18:00,400
think of these the HCN as being the food

413
00:18:06,030 --> 00:18:02,320
in this case it feeds in at four places

414
00:18:08,130 --> 00:18:06,040
and the cycle the aldehyde is a catalyst

415
00:18:10,890 --> 00:18:08,140
it gets regenerated in a return of the

416
00:18:14,010 --> 00:18:10,900
cycle that thing outputs these little

417
00:18:16,140 --> 00:18:14,020
ball shaped things and the ball shaped

418
00:18:19,080 --> 00:18:16,150
things themselves seem to be a catalyst

419
00:18:21,810 --> 00:18:19,090
for the overall process so this is a

420
00:18:24,780 --> 00:18:21,820
form of to two types of nested auto

421
00:18:28,680 --> 00:18:24,790
catalysis yeah so oh where does that

422
00:18:31,110 --> 00:18:28,690
leave us I think we really don't know

423
00:18:33,900 --> 00:18:31,120
how life started or evolved to give the

424
00:18:36,090 --> 00:18:33,910
protein oh we have a lot of models we

425
00:18:37,470 --> 00:18:36,100
can test things in the laboratory see

426
00:18:40,940 --> 00:18:37,480
which ones are better and which ones are

427
00:18:47,250 --> 00:18:40,950
worse we know something about the timing

428
00:18:48,419 --> 00:18:47,260
plus or minus a billion years yeah we

429
00:18:50,190 --> 00:18:48,429
know something about the types of

430
00:18:51,870 --> 00:18:50,200
chemicals were involved not not

431
00:18:54,149 --> 00:18:51,880
everything not as much as we need to

432
00:18:56,760 --> 00:18:54,159
certainly we know something about

433
00:18:57,180 --> 00:18:56,770
self-assembly chemistry not everything

434
00:19:00,180 --> 00:18:57,190
we need

435
00:19:03,060 --> 00:19:00,190
no but something there are many many

436
00:19:05,760 --> 00:19:03,070
many very mysterious problems left to be

437
00:19:08,610 --> 00:19:05,770
solved in this field so hopefully we'll

438
00:19:16,000 --> 00:19:08,620
make some progress here and I lastly

439
00:19:32,270 --> 00:19:16,370
[Applause]

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[Music]