I study collective behavior in a bunch
of different areas so normally at
beginning up here to tell you about
robots were about social insects or
designing molecules but this is the
thing I think is really important to
talk to you about 10 years ago my sister
decided she wasn’t sure anymore that she
still wanted to have kids because she’d
become worried that the world they’d
grow up in was going to be a
post-apocalyptic disaster movie and
that’s my fault
I’ve been doing some research in
evolutionary theory which sounds like a
very academic topic right you know I’m
very much focused on the past really not
relevant to our actual lives today but
some of the implications of what I was
studying together with things going on
in the world got me really worried about
conclusions that I couldn’t avoid
drawing it started with looking at the
evolution of cooperation which is kind
of a surprising thing if you think about
it if evolution is driven by competition
right and in organisms main competitors
or others of its own species then why
should cooperation be as successful is
it apparently is the accepted
explanation is about shared genes so I
may do something that looks like I’m
being helpful but actually I’m helping
you only because and only as much as we
have genes in common
so I’m actually acting in my own
self-interest even if it doesn’t look
like it because I’m acting in my genes
interest and the standard theory says
that organisms doing things not in their
own interest is impossible if you’ve got
two versions of an organism one that’s
self-sacrificing and one that’s selfish
the standard theory says the selfish
kind should win right it should out of
all the other and it should survive
while the self-sacrificing type dies
the thing is that established theory is
based on a hidden assumption which is
that everything is mixed together
essentially everything is happening in
the same place anything that happens
anywhere affects everyone equally but if
instead things are spread out in space
as we call that a spatial system so that
things can be different in different
different locations then everything
changes so let’s look at a very simple
model suppose you’ve got some organism
of interest and it consumes some
resource and this is a general model
it’s very abstract this could apply to
predators and prey could describe
herbivores and plants could be bacteria
the only important thing here is that
you’ve got these two interacting types
one of which lives at the expense of the
other so both these organisms and these
resources can reproduce themselves and
the organisms consume the resources and
the evolution comes into this model by
letting the organisms change how fast
they’re reproducing so any particular
organism has a fixed reproduction rate
so that’s set by its genes but when it
reproduces there can be some mutation
and the offspring can have a value
that’s a little bit higher or a little
bit lower than the parent and then you
can ask how does this reproduction rate
evolve in the population over time well
if everything is mixed together
if all of the resources are in one pool
supply and everyone has access to it
then what you see is this rate increases
over time it just keeps on increasing
which makes sense if you’re reproducing
faster you’ll tend to have more
offspring they will tend to inherit your
higher reproduction rate and so there’s
always this advantage to reproducing
more and using more resources but if
instead things are spatial if
reproduction and consumption are
happening only locally and what happens
in one place affects only the nearby
area at first it doesn’t immediately
affect everyone everywhere then what you
see is very different the reproduction
rate increase
at first but then it stops it reaches an
equilibrium and it doesn’t keep going
higher in fact if you start off the
population reproducing faster it’ll
actually evolve to fall to that
equilibrium level so this is a
completely different result in the mixed
case more consumption always wins in the
spatial case restraint always wins okay
so what’s going on here why is there
this difference if you look at the
spatial model running in a simulation
you can see that the population
organizes itself to have this sort of
patchy structure and in particular
there’s a limit to how far and how fast
the organisms can spread before they run
out of resources so suppose you’ve got
two types of these organisms one that’s
reproducing fast and one that’s
reproducing slow well in a head-to-head
competition for a single patch of
resources the fast type is going to have
an advantage right it’s going to be able
to grab more of those resources for
itself but if more resources aren’t
becoming available as fast as they’re
getting used up then at some point that
fast type is going to run out of
resources and it’s going to die out and
then surviving slower ones from
somewhere else can come in and
repopulate that area and you can see
that happening in this graph over time
if you look not just at the average
reproduction in the population but if
you look at the maximum you can see
places where a faster reproducing type
shows up and it does well for a while
this fastest rate in the population
keeps increasing and it keeps increasing
and then it suddenly Falls and that’s
where that type ran out of resources and
died out and that happens over and over
again and it’s those local separated
extinctions that make it possible for
the population overall to have this
limitation as equilibrium and if you go
back to the mixed case you can’t have a
local extinction here there’s no such
thing as local and if you watch what
happens as this runs for longer what you
see actually at some point is global
extinction everyone dies everywhere it’s
the same thing that was happening little
subpopulations in the spacial case but
here it has to happen to the whole
population
if everybody’s eating out of the same
pot everyone has to pay the penalty of
using too much so what this model is
telling us then is why is their
cooperation and restraint in nature
because nature is spatial things are
spread out and there is always an
advantage in the short-term to consuming
more and you keep getting types showing
up that do consume more and then they
push things too far and they kill
themselves off now it turns out that
that’s true also of human beings
repeatedly throughout human history
local societies have arisen and then
vanished we’re a major contributing
factor has been over exploiting their
resources it’s happened multiple times
in Polynesia it happened to the Maya and
Central America to the North’s in
Greenland to the ancestral Puebloans in
the southwestern US the list goes on and
there are a number of recurring elements
in what happened in each of these
historical examples wide scale
deforestation soil erosion extinctions
of species this list goes on – and of
course these are all things that are
happening right now in a major way along
with plenty of other examples of
resources that were in the process of
depleting and the timescale and
depleting them is not centuries it’s not
millennia it’s decades and the
difference now is all of these are
global resource issues we’re now
operating at the scale of the entire
world and the world is now connected
things that happen in one place do
affect people everywhere for the first
time in history we’ve essentially made
our world a mixed system and again the
thing you can expect to happen in a
mixed system is for consumption to keep
on increasing to keep using up more and
more resources until eventually there’s
resource exhaustion and death everywhere
you remember that post apocalyptic
disaster movie I promised you okay but
wait wait hang on because look wait this
doesn’t apply to us right I mean the the
creatures in this model are
mindless automata they’re just blindly
doing whatever it is that they’re
programmed to do but we’re more capable
than that right I mean we have brains we
can see trouble coming and take steps to
avoid it but that’s true only if we use
that ability because another thing that
people are really good at is doing
things backwards first deciding on
something we want to do and then finding
ways to justify it only paying attention
to evidence that supports the thing we
want and ignoring or denying facts we
don’t like that’s a very human thing to
do it’s very easy but it’s dangerous if
we act like the mindless automata if we
keep doing the thing that seems like a
good idea in the short term and ignore
what we can anticipate or the long term
consequences we know where that ends up
so how do we avoid the extinction that
we see in the model is the answer to
disconnect the world to split everything
back up into its own little enclaves no
now that just makes it a local problem
each separate area still has to deal
with the same basic issue remember even
in the spatial system there’s still
local catastrophes if your little region
gives in to the short-term incentives
for over exploiting it still dies and
yes it may be some cold intellectual
comfort to know that other societies
survive somewhere else but if your
society dies you know that’s a problem
for you so okay so maybe the answer then
is technology right this is something
something you sometimes hear people say
in this context it’s okay
technology will save us there’s always
going to be some new advance so that as
we run out of one resource another one
will become available and there has been
some truth to that in our current
society and its recent history but there
are a few things we’re thinking about
there first that has sometimes been true
it hasn’t always been true there are
plenty of historical examples of
societies that did not find another
resource and they disappeared do we
really want to bet ever
thing that we’re always going to find a
solution just when we need it to step
off that cliff and say oh it’s okay
we’ll invent a parachute on the way down
the second point is there’s a difference
between more resources and unlimited
resources so let’s go back to the
spatial model and suppose that at some
point technological advance occurs and
makes more resources available okay
great then the equilibrium level
increases but there’s still an
equilibrium it’s still limited if you
consume without limit
you still die a third point is this is a
long-term effect let’s suppose that
you’ve got a population at equilibrium
so it’s consuming resources of the same
rate they become available and the
population size is staying about the
same and now you add to this population
one more organism that’s consuming
faster so that introduced one and its
offspring can have an advantage of the
original kind and that can be a very
major advantage that can persist for a
long time but eventually the
consequences of its over exploitation
come back to bite it and it dies out
meanwhile the equilibrium type survives
indefinitely and it’s not obvious to one
of these organisms just looking around
which of these paths it’s on at this
point right things look like they’re
going great but it’s important to know
whether that’s the real situation or a
temporary state of affairs so what is
the solution how can we avoid the
extinction that we see in the model well
we are more capable than the brainless
creatures in the model we can anticipate
the future and we can choose to change
it science is our ability to understand
the world and what’s going to happen in
it we have to use that ability paying
attention to reality matters it has to
be important to us and it has to be
important to our decision-makers and
sustainability matters sustainability is
just another word for that equilibrium
between the resources that are becoming
available and the resources you’re
consuming if you keep spending more than
you’re in
and eating into your savings at some
point you’re gonna be in trouble in the
same way if you really want a society
and what is achieved to last really into
the long term then being aware of that
balance is important and it’s important
to make it a priority to maintain it I
mentioned that ten years ago my sister
decided she wasn’t sure anymore or she
still wanted to have kids
well people do things that are important
to him seven months ago she welcome to
mica people do care about the future
what we’ve achieved is important to us
we want this world to last through our
lives and to the next generation and
beyond and so that balance between
resources and consumption is critical
and we have to be aware of that balance
and it has to be important to us to be
aware when something is important enough
to enough people we find ways of making
it happen we have to choose to be the
capable planners instead of the mindless
automaton because if we don’t mindfully
maintain that equilibrium the world is
not going to maintain it for us the
incentives favor short term over long
term and the theory and the history both
tell us if we let things take their
course we can absolutely expect
overconsumption and collapse to be the
end of the story and one way or the
other
we’re going to make a choice
[Applause]
you
of different areas so normally at
beginning up here to tell you about
robots were about social insects or
designing molecules but this is the
thing I think is really important to
talk to you about 10 years ago my sister
decided she wasn’t sure anymore that she
still wanted to have kids because she’d
become worried that the world they’d
grow up in was going to be a
post-apocalyptic disaster movie and
that’s my fault
I’ve been doing some research in
evolutionary theory which sounds like a
very academic topic right you know I’m
very much focused on the past really not
relevant to our actual lives today but
some of the implications of what I was
studying together with things going on
in the world got me really worried about
conclusions that I couldn’t avoid
drawing it started with looking at the
evolution of cooperation which is kind
of a surprising thing if you think about
it if evolution is driven by competition
right and in organisms main competitors
or others of its own species then why
should cooperation be as successful is
it apparently is the accepted
explanation is about shared genes so I
may do something that looks like I’m
being helpful but actually I’m helping
you only because and only as much as we
have genes in common
so I’m actually acting in my own
self-interest even if it doesn’t look
like it because I’m acting in my genes
interest and the standard theory says
that organisms doing things not in their
own interest is impossible if you’ve got
two versions of an organism one that’s
self-sacrificing and one that’s selfish
the standard theory says the selfish
kind should win right it should out of
all the other and it should survive
while the self-sacrificing type dies
the thing is that established theory is
based on a hidden assumption which is
that everything is mixed together
essentially everything is happening in
the same place anything that happens
anywhere affects everyone equally but if
instead things are spread out in space
as we call that a spatial system so that
things can be different in different
different locations then everything
changes so let’s look at a very simple
model suppose you’ve got some organism
of interest and it consumes some
resource and this is a general model
it’s very abstract this could apply to
predators and prey could describe
herbivores and plants could be bacteria
the only important thing here is that
you’ve got these two interacting types
one of which lives at the expense of the
other so both these organisms and these
resources can reproduce themselves and
the organisms consume the resources and
the evolution comes into this model by
letting the organisms change how fast
they’re reproducing so any particular
organism has a fixed reproduction rate
so that’s set by its genes but when it
reproduces there can be some mutation
and the offspring can have a value
that’s a little bit higher or a little
bit lower than the parent and then you
can ask how does this reproduction rate
evolve in the population over time well
if everything is mixed together
if all of the resources are in one pool
supply and everyone has access to it
then what you see is this rate increases
over time it just keeps on increasing
which makes sense if you’re reproducing
faster you’ll tend to have more
offspring they will tend to inherit your
higher reproduction rate and so there’s
always this advantage to reproducing
more and using more resources but if
instead things are spatial if
reproduction and consumption are
happening only locally and what happens
in one place affects only the nearby
area at first it doesn’t immediately
affect everyone everywhere then what you
see is very different the reproduction
rate increase
at first but then it stops it reaches an
equilibrium and it doesn’t keep going
higher in fact if you start off the
population reproducing faster it’ll
actually evolve to fall to that
equilibrium level so this is a
completely different result in the mixed
case more consumption always wins in the
spatial case restraint always wins okay
so what’s going on here why is there
this difference if you look at the
spatial model running in a simulation
you can see that the population
organizes itself to have this sort of
patchy structure and in particular
there’s a limit to how far and how fast
the organisms can spread before they run
out of resources so suppose you’ve got
two types of these organisms one that’s
reproducing fast and one that’s
reproducing slow well in a head-to-head
competition for a single patch of
resources the fast type is going to have
an advantage right it’s going to be able
to grab more of those resources for
itself but if more resources aren’t
becoming available as fast as they’re
getting used up then at some point that
fast type is going to run out of
resources and it’s going to die out and
then surviving slower ones from
somewhere else can come in and
repopulate that area and you can see
that happening in this graph over time
if you look not just at the average
reproduction in the population but if
you look at the maximum you can see
places where a faster reproducing type
shows up and it does well for a while
this fastest rate in the population
keeps increasing and it keeps increasing
and then it suddenly Falls and that’s
where that type ran out of resources and
died out and that happens over and over
again and it’s those local separated
extinctions that make it possible for
the population overall to have this
limitation as equilibrium and if you go
back to the mixed case you can’t have a
local extinction here there’s no such
thing as local and if you watch what
happens as this runs for longer what you
see actually at some point is global
extinction everyone dies everywhere it’s
the same thing that was happening little
subpopulations in the spacial case but
here it has to happen to the whole
population
if everybody’s eating out of the same
pot everyone has to pay the penalty of
using too much so what this model is
telling us then is why is their
cooperation and restraint in nature
because nature is spatial things are
spread out and there is always an
advantage in the short-term to consuming
more and you keep getting types showing
up that do consume more and then they
push things too far and they kill
themselves off now it turns out that
that’s true also of human beings
repeatedly throughout human history
local societies have arisen and then
vanished we’re a major contributing
factor has been over exploiting their
resources it’s happened multiple times
in Polynesia it happened to the Maya and
Central America to the North’s in
Greenland to the ancestral Puebloans in
the southwestern US the list goes on and
there are a number of recurring elements
in what happened in each of these
historical examples wide scale
deforestation soil erosion extinctions
of species this list goes on – and of
course these are all things that are
happening right now in a major way along
with plenty of other examples of
resources that were in the process of
depleting and the timescale and
depleting them is not centuries it’s not
millennia it’s decades and the
difference now is all of these are
global resource issues we’re now
operating at the scale of the entire
world and the world is now connected
things that happen in one place do
affect people everywhere for the first
time in history we’ve essentially made
our world a mixed system and again the
thing you can expect to happen in a
mixed system is for consumption to keep
on increasing to keep using up more and
more resources until eventually there’s
resource exhaustion and death everywhere
you remember that post apocalyptic
disaster movie I promised you okay but
wait wait hang on because look wait this
doesn’t apply to us right I mean the the
creatures in this model are
mindless automata they’re just blindly
doing whatever it is that they’re
programmed to do but we’re more capable
than that right I mean we have brains we
can see trouble coming and take steps to
avoid it but that’s true only if we use
that ability because another thing that
people are really good at is doing
things backwards first deciding on
something we want to do and then finding
ways to justify it only paying attention
to evidence that supports the thing we
want and ignoring or denying facts we
don’t like that’s a very human thing to
do it’s very easy but it’s dangerous if
we act like the mindless automata if we
keep doing the thing that seems like a
good idea in the short term and ignore
what we can anticipate or the long term
consequences we know where that ends up
so how do we avoid the extinction that
we see in the model is the answer to
disconnect the world to split everything
back up into its own little enclaves no
now that just makes it a local problem
each separate area still has to deal
with the same basic issue remember even
in the spatial system there’s still
local catastrophes if your little region
gives in to the short-term incentives
for over exploiting it still dies and
yes it may be some cold intellectual
comfort to know that other societies
survive somewhere else but if your
society dies you know that’s a problem
for you so okay so maybe the answer then
is technology right this is something
something you sometimes hear people say
in this context it’s okay
technology will save us there’s always
going to be some new advance so that as
we run out of one resource another one
will become available and there has been
some truth to that in our current
society and its recent history but there
are a few things we’re thinking about
there first that has sometimes been true
it hasn’t always been true there are
plenty of historical examples of
societies that did not find another
resource and they disappeared do we
really want to bet ever
thing that we’re always going to find a
solution just when we need it to step
off that cliff and say oh it’s okay
we’ll invent a parachute on the way down
the second point is there’s a difference
between more resources and unlimited
resources so let’s go back to the
spatial model and suppose that at some
point technological advance occurs and
makes more resources available okay
great then the equilibrium level
increases but there’s still an
equilibrium it’s still limited if you
consume without limit
you still die a third point is this is a
long-term effect let’s suppose that
you’ve got a population at equilibrium
so it’s consuming resources of the same
rate they become available and the
population size is staying about the
same and now you add to this population
one more organism that’s consuming
faster so that introduced one and its
offspring can have an advantage of the
original kind and that can be a very
major advantage that can persist for a
long time but eventually the
consequences of its over exploitation
come back to bite it and it dies out
meanwhile the equilibrium type survives
indefinitely and it’s not obvious to one
of these organisms just looking around
which of these paths it’s on at this
point right things look like they’re
going great but it’s important to know
whether that’s the real situation or a
temporary state of affairs so what is
the solution how can we avoid the
extinction that we see in the model well
we are more capable than the brainless
creatures in the model we can anticipate
the future and we can choose to change
it science is our ability to understand
the world and what’s going to happen in
it we have to use that ability paying
attention to reality matters it has to
be important to us and it has to be
important to our decision-makers and
sustainability matters sustainability is
just another word for that equilibrium
between the resources that are becoming
available and the resources you’re
consuming if you keep spending more than
you’re in
and eating into your savings at some
point you’re gonna be in trouble in the
same way if you really want a society
and what is achieved to last really into
the long term then being aware of that
balance is important and it’s important
to make it a priority to maintain it I
mentioned that ten years ago my sister
decided she wasn’t sure anymore or she
still wanted to have kids
well people do things that are important
to him seven months ago she welcome to
mica people do care about the future
what we’ve achieved is important to us
we want this world to last through our
lives and to the next generation and
beyond and so that balance between
resources and consumption is critical
and we have to be aware of that balance
and it has to be important to us to be
aware when something is important enough
to enough people we find ways of making
it happen we have to choose to be the
capable planners instead of the mindless
automaton because if we don’t mindfully
maintain that equilibrium the world is
not going to maintain it for us the
incentives favor short term over long
term and the theory and the history both
tell us if we let things take their
course we can absolutely expect
overconsumption and collapse to be the
end of the story and one way or the
other
we’re going to make a choice
[Applause]
you
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