Finding life we cant imagine Christoph Adami

so I have a strange career I know it

because people come up to me like

colleagues and say Chris give a strange

career and I can see that point because

you know I started my career as a

theoretical nuclear physicist and I was

thinking about quarks and gluons and

heavy ion collisions and I was only 14

years old no no no no I wasn’t 14 years

old but after that I actually had my own

lab in a computational neuroscience

department and I wasn’t doing any

neuroscience later I would work on

evolutionary genetics and work on

systems biology but I’m gonna tell you

about something else today I’m gonna

tell you about how I learned something

about life and I was actually a rocket

scientist I was a rocket something I

wasn’t really a rocket scientist but I

was working at the Jet Propulsion

Laboratory in sunny California where

it’s warm whereas now I’m in the Midwest

and it’s cold but it was an exciting

experience one day a NASA manager comes

into my office sits down and says can

you please tell us how do we look for

life outside earth and that came as a

surprise to me because I was actually

hired to work on quantum computation yet

I had a very good answer I said I have

no idea and he told me bio signatures we

need to look for a bio signature and I

said what is that and he said it’s any

measurable phenomenon that allows us to

indicate the presence of life and I said

really because it’s not easy I mean way

of life can’t you apply like a

definition like for example a Supreme

Court like a definition of life and then

thought about it a little bit and I said

well is it really that easy because yes

if you see something like this then all

right fine

I’m gonna call it a life no doubt about

it but here’s something it goes like

right that’s life - I know that extent

if you think that life is also defined

by things that die you’re not in luck

with this thing because that’s actually

very strange organism it grows up into

its adult stage like that and then goes

through like a Benjamin Button phase

initially goes backwards and backwards

until it’s like a little embryo again

and then actually grows back up and back

down and back up sort of yo-yo and it

never dies so it’s actually life but

it’s actually not as we thought life

would be and then you see something like

that and it was like my god what kind of

a life-form is that anyone know it’s

actually not life it’s a crystal so once

you start looking and looking at smaller

and smaller things so this particular

person wrote a whole article and said

hey these are bacteria except if you

look a little bit closer you see in fact

that this thing is way too small to be

anything like that so he was convinced

but in fact most people aren’t and then

of course NASA also had a big

announcement in fact President Clinton

gave a press conference about this

amazing discovery of life in a Martian

meteorite except that nowadays it’s

heavily disputed if you take the lessons

of all these pictures then you realize

well actually maybe it’s not that easy

maybe I do need a definition of life in

order to make that kind of distinction

so can life be defined well how would

you do about it well of course you go to

breathe you know Encyclopedia Britannica

and open that L know of course you don’t

do that you put it somewhere in Google

and then you might get something and

what you might get and you go there

anything that actually refers to you

know things that we are used to you

throw away and then you can might come

up with something like this and it says

something complicated with lots and lots

of concepts who on earth would write

something as convoluted and complex and

inane it’s actually you know a really

really important set of concepts so I’m

highlighting just a few words and saying

definitions like that rely on things

that are not based on amino acids or

leaves

or anything that we are used to but in

fact on processes only and if you take a

look at that this was actually in a book

that I wrote that this was artificial

life and that explains why that NASA

manager was actually in my office to

begin with because the idea was that

with concepts like that maybe we can

actually manufacture a form of life and

so if you go and ask yourself what on

earth is artificial life let me give you

like a whirlwind to of how all this

stuff came about and it started out

quite a while ago when someone wrote one

of the first successful computer viruses

and for those of you who aren’t old

enough you have no idea how this

infection was working namely through

these floppy disks but the interesting

thing about these computer virus

infections was that if you look at the

rate at which these infection work they

show like the spiky behavior that you’re

used to like from flu virus and it is in

fact due to this arms race between

hackers and operating system designers

that things go back and forth and the

results is kind of a tree of life of

these viruses a phylogeny that looks

very much like the type of life that

we’re used to at least on the viral

level so is that life not as far as I’m

concerned why because these things don’t

evolve by themselves in fact they have

hackers writing them but the idea was

taken very quickly a little bit further

when a scientist working at the Santa Fe

Institute decided why don’t we try to

package these little viruses in

artificial worlds inside of the computer

and let them evolve and this was stay in

rasmussen and he designed the system but

it didn’t really work because these

viruses were constantly destroying each

other but there was another scientist

they had been watching this an ecologist

and he went home and said I know how to

fix this and he wrote the chera system

and in my book is in fact one of the

first truly artificial living systems

except for the fact that these programs

didn’t really grow in complexity so

having seen this work worked a little

bit on us this is where I came in and I

decided to create a system that has all

the properties that are necessary to see

in fact the evolution of complexity more

and more complex programs constantly

evolving and of course since I really

don’t know how to write code I’ll help

him decide two undergraduate students at

California Institute of Technology that

worked with me that’s Charles or free on

the left titus brown on the right they

are now actually respectable professors

at Michigan State University but I can

assure you back in the days you know we

were not a respectable team and I’m

really happy that no photo survives of

the three of us anywhere close together

but what is the system like well I can’t

really go into the details but what you

see here is some of the entrails but

what I want you to focus on is this type

of population structures about ten

thousand programs sitting here and all

different strains are colored in

different colors and as you see here

there are groups that are growing on top

of each other because they’re spreading

anytime there’s a program that’s better

that’s surviving in this world due to

whatever mutation that is acquired it’s

going to spread over the others and

drive the others to extinction so I’m

going to show you a movie where you’re

gonna see that kind of dynamics and this

movie star I mean these kind of

experiments are started with programs

that we you wrote ourselves we write our

own self replicator are now very proud

of ourselves and we put them in and what

you see immediately is that there are

waves and waves of innovation by the way

this is highly accelerated so it’s like

a thousand generations a second but the

system goes like what kind of a dumb

piece of code was this this can be

approved upon in so many ways so quickly

so you see waves of new types taking

over the other types and this type of

activity goes on for quite a while until

the main easy things have been acquired

by these programs and then you see sort

of like a stasis coming on where the

system essentially ways for a new type

of innovation like this one which is

going to spread over all the innovations

that were before and is erasing the

genes that it had before until a new

type of higher level of complexity has

been achieved and this process goes on

and on and on so what we see here is a

system that lives in very much the way

that we’re used to life goes but what

the NASA people had asked me really was

do these guys

have a bio signature can we measure this

type of life because if we can may we

have a chance of actually discovering

life somewhere else without being biased

by things like amino acids so I said

well perhaps we should construct a bio

signature based on life as a universal

process in fact it should perhaps make

use of the concepts that I developed

just in order to sort of capture what

this simple living system might be and

the thing I came up with I have to first

give you sort of a introduction about

the idea and maybe that would be a

meaning detector rather than a life

detector

and the way we would do that it’s like

okay I would like to find out how I can

distinguish text that was written by a

million monkeys as opposed to texts that

are in our books I don’t like to do it

in such a way that I don’t actually have

to be able to read the language because

you know I’m sure I won’t be able to as

long as I know that there’s some sort of

alphabet so here would be a frequency

plot of how often you find each of the

26 letters of the alphabet in a text

written by random monkeys and obviously

each of these letters comes off about

roughly equally frequent but if you now

look at the same distribution in English

text it looks like that and I’m telling

you this is very robust across English

text and if I look at French text it

looks a little bit different or Italian

or German they all have their own type

of frequency distribution but it’s

robust it doesn’t matter what it writes

about politics or about science it

doesn’t matter whether it’s a a poem or

whether it is in a mathematical text

it’s a robust signature and it’s very

stable as long as our books are written

in English because people are rewriting

them and recopying them it’s going to be

there so that inspired me to think about

well what if I try to use this idea in

order not to detect random text from

text with meaning but rather detect the

fact that there is meaning in the

biomolecules that make up life but first

I have to ask what are these building

blocks like the alphabet elements that I

showed you well

that we have many different alternatives

for such a set of building blocks we

could use amino acids we could use

nucleic acid covered silica acid fatty

acids and for chemistry is extremely

rich and our body uses a lot of them so

that we actually to test this idea first

take took a look at amino acids and some

other carboxylic acids and here’s the

result here is in fact what you get if

you for example look at the distribution

of amino acids on a comet or in

interstellar space or in fact in a

laboratory where you made very sure that

in your primordial soup that there is no

living stuff in there what you find is

the mostly lysine and then alanine and

that’s a trace element of the other ones

okay that is also very robust what you

find in systems like Earth where there

are amino acids but there is no life but

suppose you take a you know some dirt

and dig through it and then put it into

these spectrometers because there’s

bacteria all over the place or you take

water anywhere on earth because it’s

teeming with life and you make the same

analysis this spectrum looks completely

different of course there’s still

glycine and alanine but in fact there

are these heavy elements this heavy

amino acids that are being produced

because they are valuable to the

organism and some other ones that are

not used in the set of twenty there will

not appear at all at any type of

concentrations so this also turns out to

be extremely robust it doesn’t matter

what kind of sediment you’re using to

grind up with its bacteria or any other

you know plants or animals anywhere

there’s a life you’re going to have this

distribution as opposed to that

distribution and it is detectable not

just in the amino acids now you could

ask well what about these variants

they’re variants being the denizens of

this computer world where they are

perfectly happy replicating and growing

in complexity so this is the

distribution that you get if in fact

there is no life

they have about twenty eight of these

instructions and if you have a system

where they’re being replaced one by the

other it’s like the monkeys riding on a

typewriter each of these instructions

appears was roughly the equal frequency

but if you now take us take a set of

replicating guys like in the video that

you saw it looks like this so are there

some instructions that are extremely

valuable to these organisms and their

frequency is going to be high and

there’s actually some instructions that

Yuri only want to use once if ever so

they write either poisonous or really

you know should be used at less of a

level than random and in this case the

frequency is lower and so now we can see

is that really a robust signature I can

tell you indeed it is because this type

of spectrum just like what you’ve seen

in box and just like what you’ve seen in

many ways it’s it doesn’t really matter

how you change the environment it’s very

robust it’s going to reflect the

environment so I’m going to show you now

a little experiment that we did and I

have to explain to you the top of this

graph shows you that frequency

distribution that I talked about okay

here in fact that’s the lifeless

environment where each instruction

occurs at an equal frequency and below

there I show in fact the mutation rate

in the environment and I’m starting this

Anna mutation rate that is so high that

even if you would drop a replicating

program that would otherwise happily

grow up to fill the entire world if you

drop it in it gets mutated less

immediately okay so there is no life

possible at that type of mutation rate

but then I slowly turn down the heat so

to speak and then there is this

viability threshold where now it would

be possible for a replicator to actually

live and indeed we’re going to be

dropping these guys into that soup all

the time

so let’s see how what that looks like so

first nothing nothing nothing too hot

too hot now the viability threshold is

reached and the frequency distribution

has dramatically changed and in fact

stabilized so now I what I did there is

I just I was being nasty I just turned

up the heat again again and of course it

reaches the viability threshold and I’m

just showing this to again because it’s

so nice you hit the viability threshold

the distribution changes to alive

then once you hit the threshold where

the mutation rate is so high that you

cannot sell for produce you cannot copy

the information forward to your

offspring without making so many

mistakes that your ability to replicate

vanishes and then that signature is lost

what do we learn from that well I think

we learn a number of things from that

one of them is if we are able to think

about life in abstract terms and we’re

not talking about things like plants and

we are talking about amino acids and

we’re not talking about bacteria but we

think in terms of processes then we can

start to think about life not as

something that is so special to earth

but that in fact could exist anywhere

because it really only has to do with

these concepts of information of storing

information within physical substrates

anything bits nucleic acids anything

that’s an alphabet and make sure that

there’s some process so that this

information can be stored for much

longer than you would expect the time

scales for the deterioration you know of

information and if you couldn’t do that

then you have life so the first thing

that we learn is that it is possible to

define life in terms of processes alone

without referring at all to the type of

things that you know we hold dear as far

as the type of life on Earth is and that

in a sense removes us again like all of

our scientific discoveries or many of

them it leads to a continuous death

rolling of man of like how I think we’re

special because we are live well we can

make life we can make life in the

computer granted it’s limited but we

have learned what it takes in order to

actually construct it and once we have

that then it is not such a difficult

task anymore to say if we understand the

fundamental processes that do not refer

to any particular substrate then we can

go out and try other worlds figure out

what kind of chemical alphabets might

there be figure enough about

the normal chemistry the geochemistry of

the planet so that we know what this

distribution would look like in the

absence of life and then look like two

large deviations from this this thing

sticking out which says this chemical

really shouldn’t be there now we don’t

know that there is life then but we

could say well at least I’m gonna have

to take a look very precisely at this

chemical and see well you know where it

comes from

and that might be our chance of actually

discovering life when we cannot visibly

see it and so that’s really the only

take-home message that I have for you

life can be less mysterious that we make

it out to be when we try to think about

how it would be on other planets and if

we remove the mystery of life then I

think it is a little bit easier for us

to think about how we live and how

perhaps we’re not as special as we

always think we are and I’m gonna leave

you with that and thank you very much