good evening everyone welcome i'm jerry
Sabol off I'm the the past president of
Santa Fe Institute and now an external
professor at SFI thank you I can promise
you tonight it'll be much more fun and
definitely more intellectually
stimulating than any Republican debate
so certainly if the last one was any
guide so thank you for being here we all
appreciate it I'm delighted to welcome
you to the second night of our 2015 rule
on lecture series and very pleased to
introduce Jennifer Dunn SFI is vice
president for science
last night David Krakauer gave you a
nice overview of Jenn's distinguished
career which I won't repeat but I do
want to say as an archaeologist how
really tickled I am that Jennifer has
been collaborating with archaeological
colleagues of mine in bringing important
new food the food web approach of which
we heard in her terrific talk last night
to the world of archaeology and in the
whole realm of human ecology this
introduction of the study of food webs
of which jennifer has been in the
vanguard has the potential to
significantly strengthen archaeological
understanding of the past especially
given the long history of archaeological
as well as historical and geographical
research that has not taken a true
systemic approach to humans in in their
environment until very very recently so
if one looks back and I was just having
fun going going back in time to the mid
19th century let me give you a quote of
the kind of environmental human thinking
that was going on that time which is
very very deterministic here's the quote
give me the physical map of a country
and I pledge myself to tell you a priori
what part that country will play in
history not by accident but by necessity
not at one epoch but all epochs end
quote you won't be surprised to know
that when that kind of maximum of
determinism was taken to geographical
mass
somehow northern Western Europe always
seemed to be the best place for high
civilization to evolve coincidence I'm
sure by the beginning of the 20th
century in reaction to this kind of
determinism one emerged one saw kind of
an approach sometimes labeled possible
ISM so here's another quote there are no
where necessities but everywhere
possibilities and man is a master the
possibilities is the judge of their use
in other words there literally was no
relationship argued at that time between
the environment and human ecology and
evolution it was the classic argument
against the terminus at that time was
that similar cultures exist in different
environments and different cultures
exists in the same environments
therefore environment can have no real
impact on human development but in
effect this possible is view which held
sway in much of the 20th century
essentially says that the explanation of
human environmental relationship is
impossible this is not very satisfying
for a whole bunch of of reasons and
fortunately beginning at least in in the
mid 20th century saw another develop
which we might call probable ism which
looked at the causal influence of the
environment on certain aspects of human
cultural groups especially technology
but essentially ignored the other
aspects of culture it was not a holistic
perspective and I think this is really
the the key all of these approaches in
the nineteenth twentieth century of
going on till very recently saw in the
environment and humans as separate the
environment influencing or not humans in
their cultures but the last few decades
a full systemic ecological view with
both humans and the environment as part
of the same system is emerged and as we
will see this evening this is a more
scientifically powerful approach with
great potential not just for archaeology
but for the broader understanding of
life on the planet and to really give
you a good understanding
of this new human ecology please join me
in welcoming Jennifer Dunn will be
talking to us about the ecological human
thanks Jerry and thank all of you for
coming here tonight last night
I discussed the hidden order of complex
ecosystems which I'll recap briefly
there's an extraordinary diversity of
life on Earth of species on earth our
best current estimate of non bacterial
species is about 10 million species
previous estimates have been 3 to 100
million only 1.2 million are actually
described and named however for me where
all of this enormous diversity gets
really interesting is how they process
and use one of the fundamental
currencies of life energy so all life
needs energy to fuel its metabolism to
survive and reproduce and there are two
primary ways to get energy first to be
an autotroph like a plant that gets
energy generates energy directly from
solar radiation or second to be a
heterotroph like this owl and get your
energy from eating other organisms in
this case by hunting killing and feeding
on this very poor unsuspecting little
mouse however as we know from elementary
school these types of predator prey and
more generally what we call consumer
resource interactions are embedded in
more complex food chains so this is a
food chain from this area at the base we
have plants in this case it's taraxacum
officinalis in the mouth of the rabbit
that's otherwise known as dandelions and
so that's eaten by the rabbit and we
represent the plant with the green
sphere on the right and the arrow shows
the biomass going up into the rabbit
shown in red and then the rabbit can be
eaten by western diamondback
rattlesnakes shown above that and that
we represent by adding a blue node to
represent the snake and an arrow flowing
up to that and then on top is one of my
favorite birds and it's also the New
Mexico State bird the greater Roadrunner
and the cuckoo family which eats
western diamondback rattling and we
represent that with an orange sphere of
course this is still a very simplistic
view of species interactions in any
habitat there are hundreds to thousands
of co-occurring species that can and do
interact with each other through feeding
interactions and a variety of other ways
of interacting any ecological community
contains myriad food chains that are all
interwove and together forming a complex
food web like this one so this
represents a comprehensive and highly
resolved food web for Little Rock Lake
in Wisconsin there are close to a
hundred species and a thousand of
feeding links in this food web the
vertical axis represents trophic level
which is how many feeding links on
average animals are from the primary
producers at the base of the web in this
case algae so trophic level is a measure
of how many times biomass is transformed
into energy as it passes up and
throughout the food web dozens of
detailed food webs have been compiled
and analyzed over the last two decades
each food web appears intractably
complex in and of itself and various
food webs appear to be quite different
from each other in a multitude of ways
the number and types of species the
number and types of feeding interactions
the environmental context and the way
all of these species and interactions
are glued together in networks of
interdependence I call this the apparent
complexity of ecosystems however and
this is the big summary slide from last
night it turns out that we can use tools
from Network theory to analyze and
compare the organization and properties
of these food webs when we do we find
quantifiable hidden order in the way
that feeding interactions organized at
the ecosystem level I focused in
particular on the pattern of how diet
specialists and diet generalists are
distributed in a food web it turns out
that the distribution of the number of
links per consumer in a food web shown
in the top graph follows a remarkably
universal pattern most organisms in a
given food web are relatively
specialized in their feeding habits
while very few are strong generalists
and we'll be revisiting this issue of
diet generality later in this talk this
universal pattern is the same across
food webs from diverse habitats
including marine systems estuaries lakes
rain forests and deserts and it also
applies to food webs like the one in the
upper right corner that include the
enormous diversity of parasites which
are the blue nodes usually ignored in
ecological analyses it even applies to
very ancient ecosystems shown at the
bottom right stretching back more than
half a billion years to the burgess
shale during the time of the Cambrian
radiation of multicellular life on earth
this is despite the fact that many of
the marine creatures that live then had
bizarre body plans that no longer exist
they were evolutionary dead ends back to
energy so the basic metabolic rate of a
human is about the same as a hundred
watt incandescent light bulb this is
predictable from our body size as it is
for everything from mice to blue whales
as is the case for other animals we meet
our energy requirements by feeding on
other organisms and thus like all other
organisms humans are a part of complex
food webs both as predators and prey as
a sidenote some of you may recognize
this particular human and if you don't
you will after this ADA King Countess of
Lovelace was born 200 years ago this
December and she was the only legitimate
child of Lord Byron ADA was an English
mathematician and writer and more
importantly as considered the first
computer programmer she worked with
Charles Babbage on his analytical engine
a proposed mechanical general-purpose
computer and wrote the first algorithm
intended to be carried out by a machine
so she is a foundational part of the
intellectual history that led up to the
overwhelming centrality of computers to
today's science technology and culture
in a sense or intellectual lightbulb
show much brighter than most and Ada
Lovelace Day is on October 13th this
year the day celebrates the achievements
of women in science technology
engineering
mathematics okay so it's appropriate
that ADA is a figure from history who
enlightens our current notions of
computing and science this talk will
focus on how humans in the past
interacted with species as a way to
understand different kinds of roles and
impacts humans can have in the context
of complex ecological networks these
lessons from the past can provide new
ways to understand and promote
ecological sustainability in a world
dominated in many ways by humans
this image shows nineteenth-century
Aleut a Native American tribe of the
Aleutian island chain of Alaska fishing
for COD from kayaks the small amounts of
fish they caught went directly directly
to their subsistence the lower image
shows a very different relationship
between humans and fish it shows a super
trawler strip-mining fish off of the
west african coast to meet the demands
of the global seafood trade they are
indiscriminately catching many different
species of fish in marine invertebrates
and discarding 90% or more of what they
catch and in fact a study was just
released by the World Wildlife Fund
which tracked a hunt several populations
across 1,200 species of marine fishes
mammals birds and reptiles and looking
at changes between 1970 and 2012 and
there's been an overall 49 percent
reduction in those populations a 50
percent reduction not just of the fishes
with of course certain fishes like tunas
seeing 75 percent or greater reductions
over a 40-year period so the rest of the
talk tonight will focus on how we can
use an ecological network framework to
think about human roles in and impacts
on ecosystems although I'll mostly focus
on humans as predators in food webs I
wanted to share an amusing little
factoid I ran across in Harper's
recently about humans getting killed by
other species
so we've been hearing a lot lately about
humans getting attacked by sharks
particularly on the east coast of the
United States and in Australia however
for every one person killed by a shark
27 people are killed by cows although
presumably not because the cows want to
eat the people just because they're
probably pissed off at them so just keep
that in mind the next time you're hiking
or biking past a cow okay
on with the talk while it is clear that
humans have are having major impacts in
biodiversity not much is known in a
quantitative way what those impacts mean
for complex food webs
because species are embedded within
complex networks of interdependence
through feeding and other relationships
disturbances that affect one species
have the potential to spill over into
many other species through direct and
indirect pathways so let's look at food
webs through time for two systems
heavily impacted by humans over the past
10,000 years first we'll look at the
adriatic sea and then we'll take a look
at Egypt
this is rovinj a really wonderful
coastal town on the Istrian peninsula of
croatia that i had the pleasure of
visiting a few years ago ravine was
ruled by the Republic of Venice from the
late 1200 s to the late 1700s and it has
a very venetian feel and off to the
right you can see a shrimp boat coming
back in rovinj is located on the
northeastern edge of the Adriatic up
towards the top in between Trieste and
Pola and across from Venice six
countries and many towns and cities are
located along the coast of the Adriatic
Sea the taking of marine resources by
humans has been an integral part of the
adriatic seas history for over 10,000
years
Hika lots and Martic all colleagues of
mine at Dalhousie University in Canada
compiled a variety of biodiversity
ecosystem function and food web data
over tens of thousands of years of human
presence in this region they considered
10 different cultural periods from
earlier pre human hunter-gatherer and
Agricultural periods to local market
classical
medieval periods too modern and global
periods throughout time there has been
development growth and expansion of
trade markets and economies from highly
localized lies subsistence and
agricultural activities to regional
activities to global activities these
changes were driven by increasing
commercialism industrialization and
urbanization over the last two thousand
years which includes the classical
medieval modern and global cultural
periods the human population of towns
along the adriatic remained relatively
steady at under twenty million people it
began to expand rapidly in the 1700s
reaching over a hundred million people
today this of course is the pattern of
human population growth around the world
this graph shows trends and relative
species abundances over the last several
tens of thousands of years in the
adriatic the colored lines are for
non-human taxa and when I use the term
taxa I just mean groups of species that
are similar which show only slight
declines until the last one or two
hundred years at which point they begin
to drop sharply the exception is birds
which first decline sharply around 500
BC humans shown what the grey line show
the opposite trend of course this graph
presents species declines in a different
way
it shows the percent of species that are
classified as depleted which means that
they are at fifty percent or less of
their traditional abundance those that
are rare which means they're at ten
percent or less and those that were
completely extirpated that top line
which means they became extinct from the
Adriatic so the trends for all of these
are increasingly negative and meanwhile
the grey line shows the number of
invading non-native mollusks which is
increased sharply over the last 200
years going from zero to 80 and this
graph shows yet another way of
classifying species declines in terms of
water water quality as habitat builders
and filter feeders have sharply declined
shown in the colored lines water quality
has become increasingly degraded shown
by the grey line
the adriatic sea food web follows
similar trends with the greatest impacts
seen in the last 200 years of human
presence in this region these two
versions of the adriatic sea food web
are not necessarily not as detailed as
other food webs i have shown and will
show as it is very hard to get detailed
species interaction data over multiple
time slices so the taxa and these webs
are pretty highly aggregated and as i
said their groups of similar kinds of
species from the early modern period
1500 to 1800 until the late global
period now 25% of taxa groups have
either been reduced to such low
populations they're effectively not
viable or they've been extirpated
vertebrates such as seals turtles and
birds have been particularly hard-hit a
version of these images was published in
an article in Scientific American on
this research in 2012 called the
dwindling web how human exploitation has
reshaped a marine ecosystem one
consequence of the contraction of the
adriatic sea food web is that our
analyses show that the reduced current
webs are much less robust to further
perturbation any text is subsequently
lost from this food web will result in
an ever greater chance that the food web
will unravel through cascading
extinctions due to species dependencies
on each other basically the the
redundancy of feeding roles that used to
exist in this food web have been
stripped away leaving it very vulnerable
to further disturbance ok let's move a
bit south and east from the Adriatic Sea
to Egypt here is a very simplified
environmental timeline of Egypt over the
last several thousand years it shows a
long humid period that stretched from
11,000 years ago to 5,000 years ago and
between 5,000 and 3,000 years ago there
were three major a ridah fication and
desertification events the great
pyramids were built a bit more than
4,500 years ago in between the first two
major a major of ratification events my
Asif I colleague Justin Yankel and his
collaborators were able to reconstruct a
detailed Egyptian mammal predator
herbivore network over the last six
thousand years of Egyptian history
they integrated paleontological and
archaeological evidence with depictions
of mammals from Egyptian antiquities
artifacts to infer which species were
present when for example this is the
here accomplice palette also known as
the two dogs palette which is in the
Ashmolean Museum of Oxford it is about
five thousand one hundred and fifty
years old and shows mammals present in
Egypt at that time frame by two wild
dogs clasping paws ostrich hartebeest
wildebeest ibex Oryx and giraffe are
depicted as are several fictitious
animals such as serpent necked Panthers
that encircle the central depression on
the reverse side Bulls and gazelles
confront lions leopards and a winged
Griffon this hunting scene is from one
side of King Tutankhamun's painted box
built more than 3000 years ago and it
displays a variety of different mammals
that humans hunted at that time
artifacts like these from different time
periods of Egyptian deep history
combined with other information allowed
the remarkable data reconstruction at
the heart of the study in the Late
Pleistocene about 12,000 years ago there
were 38 species of mid and large bodied
mammals 8 carnivores and 30 ungulate
herbivores the carnivore ungulate piece
of the broader food web of Egypt
contracted as the climate became more
arid and human population densities
increased most notably mid sized
herbivores such as gazelles which linked
to the most predators declined and
disappeared at the time of the pyramids
about 4600 years ago we already see
significant declines in the herbivores
by 3300 years ago about half of the
original species including some of the
Predators were gone the food web of
today retains only 20% of the species
present in the Late Pleistocene thus the
Egyptian mammal network effectively
collapsed from 38 species in the Late
Pleistocene to only eight species three
carnivores and five herbivores today
analysis of the network through time
shows that the predator-prey ratio
increasing
Gatling this indicates the preferential
loss of the prey in the system the
ungulate herbivores their extinctions
were non-random and were associated with
the desertification events the
extinctions in this ecosystem sustained
over 6000 years were likely attributable
to synergies among multiple stressors
direct impacts from human hunting the
loss of forage for herbivores as land
was transformed into agricultural
production and the impacts of climate
change on forage and water availability
this study did not pin down the
particular causes or their relative
contributions to the observed
extinctions that's something for future
research as was the case for the
adriatic sea food web analyses showed
that the increasingly de popper at
egyptian mammal network was also
becoming less and less stable as the
network lost species and links that lost
redundance which leaves it with
decreased ability to withstand further
further perturbations so these are just
two examples of the massive unraveling
of some food webs that has occurred over
the last several thousand years in the
adriatic sea the 25% reduction of the
marine food web particularly in the last
200 years is likely mostly attributed
ball to the industrialization of fishing
and the expansion of global markets for
seafood and as just mentioned in the
egyptian mammal net carnivore herbivore
network even more dramatic declines over
the last six thousand years are probably
due to synergies between climate or
ridah fication and human hunting and
agriculture in both cases the food web
has lost four Dundas II and has low
robot robustness to future impacts a
snowball effect which will only be
magnified by other impacts such as
anthropogenic climate change so far we
don't really have much evidence for the
title of this talk the ecological human
it should it be the non ecological human
however for the rest of the talk I'm
going to shift to assessing what roles
humans play in food webs particularly in
pre-industrial non urban contexts in
other words what can we understand about
the ecological roles that humans play as
predators and consumers and food webs
this hopefully can provide us with new
kinds of insight into sustainability of
the complex socio ecological system
that we are all a part of this is a
photograph of Cenac Island taken by one
of my collaborators Spencer wood Cenac
is at the far eastern end of the
Aleutian archipelago in Alaska it is a
bit south and west of the tip of the
Alaskan Peninsula it has been ice-free
for sixteen thousand years there is a
six thousand year record of human
presence on Cenac with a hundred and
twenty eight known sites shown here in
yellow mostly around the perimeter of
the main island and the archeological
work was done by my colleague herb Manor
the people who became the alley across
Beringia eight thousand to ten thousand
years ago they had a peak population
across the Aleutian island chain of
fifteen to twenty five thousand they
were foragers and they foraged in every
habitat available to them the marine
system the freshwater system and the
terrestrial system the population of
Cenac was probably in the dozens to
hundreds increasing over time with lower
populations during warm periods due to
less marine productivity the last of the
Cenac Aleut left Cenac island in the
1960s to move to King's Cove on the tip
of the Alaskan Peninsula for fish
cannery jobs the research I'll describe
is part of a broader project meant to
integrate archaeological ecological and
climatic data in order to understand
various aspects of the bio complexity of
the Cenac archipelago over the last
several thousand years and one thing to
note is the Cenac Ally at the they have
a corporation the snack Corporation
which still owns and controls the Cenac
archipelago and they were very
supportive we could not have been there
doing this work without their support
one of the main reasons they're
supportive of this work is because they
it's actually very much in their
interest to have scientific studies
documenting their feeding habits and
their hunting habits through time
because this is important in terms of
what rights they have now in terms of
fishing and hunting in today's world so
that this kind of scientific information
actually makes its way into legal cases
in some cases so they're very supportive
of this work
the questions I'm particularly
interested in are what roles did
pre-industrial humans play in North
Pacific food webs how did human foragers
compare to other species and what can we
learn about sustainability if anything
from how humans interacted with an
impact at other species previous food
web datasets like the ones I discussed
yesterday did not explicitly include
humans as a node within the food web
ecology traditionally studies human-free
nature or its studies what kinds of
human impacts might be on human free
ecosystems it treats humans as an
external forcing factor for example for
my PhD I studied the impacts of
simulated climate warming on subalpine
meadow ecosystems in the Colorado
Rockies of course ecosystems are not
human free at all there is no ecosystem
on earth that is free of human impacts
and they have not been so for a very
long time we feel that ecological
networks are a good way to bring humans
back into ecology analysis and Cenac
Island provided an excellent place to
see what we could do along those lines
as was the case in the Egyptian study we
integrated several different kinds of
data to come up with our food webs the
top photo shows my colleague Spencer
Wood and Roley Russell systematically
sampling of the diversity of species in
the intertidal system of Cenac the
bottom left photo shows a sample
archaeological pit dug into a midden
these are old trash heaps often
associated with human home and cooking
sites the bottom right photo shows some
of what comes out of those midden cores
lots and lots of bones and shells the
archaeologists can identify these two
the species these types of field based
data were augmented with information
from the literature with ethnographic
information and interviews with valued
elders about their traditional eating
habits because a lot of times of things
that they ate were all soft body parts
and were preserved in the mid uns so
here are a few of the species that we
know that the snack alio date it
includes everything from algae to sea
cucumbers and which of course are
actually not cucumbers they are animals
and it's a little hard for me to believe
that any
get a sea cucumber but they did - shrimp
octopus malice and sea otters and here
even more species the Cenac alley at
eight including sea urchins and nominees
fishes clams and seals and sea lions
here is one food chain of many that the
Cenac Alley were a part of the alley at
a sea lions which eight great sculpins
which ate shrimp which ate phytoplankton
an idealized food chain is shown on the
right where primary producers are shown
in green invertebrates and yellow fishes
and orange and mammals including the
humans in red when all of the feeding
interaction data among the nearshore
marine species as well as species like
humans which forage extensively
extensively in the marine habitats are
compiled this extremely complex food web
pops out the colors mean the same things
I just mentioned with the addition of
birds and purple and miscellaneous taxa
like protozoa bacteria and lichen and
blue with 513 species and almost 6,800
feeding links this is the most diverse
and highly resolved marine food web out
there and it is the only detailed
complex food web to explicitly include
humans humans are they're pointed to
near the top of the web the Cenac Aleut
fed on a hundred and twenty-two species
in this food web which is almost a
quarter of the species available to them
the things that they fed on are shown
here in colored a couple of things are
noticeable humans fed at all trophic
levels from primary producers to top
carnivores and they fed on a wide
diversity of organisms as shown by the
colors of the prey species so when I was
first looking at this data you know I
was like well 122 species seems like a
lot but really how does it actually
compared to other prey species this
histogram shows the number of predators
that have a particular number of prey
species in other words this shows the
distribution of number of Link's from
consumer species to resource species as
we saw yesterday most consumers are
relatively specialized with five or
fewer resources and those are the ones
labeled specialist to the left
however there is what we call a very
long tail to the right a consisting of a
few highly generalized feeders which
feed on 50 or more resource species
humans are way out at the end of the
tail along with Pacific cod they can be
considered super generalists in this
food web and this does follow a similar
kind of exponential distribution like we
have seen for other food webs which I
discussed yesterday in this version of
the web I have darkened only those
species and their links that are more
than two links away from humans it turns
out that 96% of the species in this
marine food web are within two links of
humans that includes the species that
humans feed on directly and all the
species connected to those either as
predators or as prey in other words
humans were very closely connected to
almost all the other species within this
ecosystem
thus humans played very particular and
potentially important roles in this food
web they were super generalists they
were highly omnivorous feeding on many
different kinds of species at multiple
trophic levels and they had short path
lengths connecting them to most other
species something also important to take
into account is that they sometimes use
hunting and fishing technology like
kayak Spears and fish hooks allowing
them to feed more strongly than they
should be able to given their body size
so although humans were positioned to
greatly negatively affect the marine
food web in this system there were no
apparent long-term extinctions over
6,000 years whether due to humans or to
climate we decided to do some modeling -
to investigate how a species like humans
could invade a system like this 6,000
years ago bringing with them hunting
technology and special roles and not
induce lots of extinctions we used a
relatively simple model of dynamics of
species feeding interactions which can
be boiled down in this way what we're
trying to do is to track changes in
species biomasses over time so if you
think about a food web there's a bunch
of different populations a species
represented within the food web and
you've just been showing snapshots of
the structure of the food web but what's
really going on of course is that
through time due to the interactions
between species some species are
increasing in terms of their number
and their total species biomass across
all the individuals and then they're
contracting and they're getting bigger
again and that's happening for all the
species concurrently and so you get
these very interesting complex dynamics
through time so what does that do to
what we've done is we've boiled that
down to three factors you know and again
this is a very simplified view but
feeding is very central in to ecological
dynamics so you can lose biomass or
individuals due to just metabolic
activity just basically burning energy
to live you can gain biomass by eating
resources by eating prey and you lose
biomass to consumers by the things that
eat you so all of that you're not
supposed to understand this that's all
of that and a little bit more is encoded
into mathematical formulas and which we
use to simulate the changes in species
biomasses and populations over time in
idealized food webs we took a bunch of
idealized food webs and we basically let
them run until their we just had a bunch
of species that were dynamically
changing but none of the species were
going extinct so they were dynamically
persistent through time and we invaded
them with a species that had the
characteristics of the Cenac Aleut with
a super generalist species that was
highly omnivorous we also added a
parameter to our models which we could
change to reflect the ability of the
invader to sometimes feed more strongly
than expected for its body size this was
how we simulated the use of hunting
technology this graph shows the
proportion of species that go extinct
when the food web is invaded by this
human-like species from left to right
the invader feeds strongly on increasing
fractions of its prey species what we
see is that as long as the invading
species limits how many species it feeds
on strongly there are relatively few
extinctions and indeed the Cenac Aleut
only used hunting technology
occasionally often they were just in the
intertidal gathering shellfish for
dinner another thing that's going on in
this
model which reflects what goes on in
nature is that all generalists and food
webs price which when it gets harder to
find or capture some preferreds prey
species for food for whatever reason the
predator switches to something else even
if it is less preferred so basically
what happens a generalist has many
potential prey species but it has
preferences and it's if a preferred
species is there and available it'll go
after it and kill it and eat it
but sometimes part you know and often
just in response to the predation
pressure you know that individuals go
away they're eaten it gets harder and
harder to find individuals of that
preferred species and then all of a
sudden some slightly less preferred
species that it has is now more abundant
and more right there so the generalist
predator starts going after this
different species so this kind of prey
switching has been shown repeatedly for
all kinds of generalists and all
different kinds of food webs and it
turns out that within a food web context
it's very very stabilizing for the food
web it allows the focal prey species to
recover from heavy predation and and
that basically minimizes how many
extinctions you see as compared to if a
generalist just kept focusing focusing
focusing on the same species without
ever changing and like other generalists
humans in this system prey switched when
the weather was really nice the snack
alley it would hop into their kayaks and
they would go in hunt marine mammals
particularly sea lions which they both
ate and used their hides for their
kayaks when the weather was terrible
which was much of the time they would
just focus their efforts on foraging for
shellfish in the intertidal so in
summary although humans played special
potentially disruptive roles in this
food web and had the potential for even
more disruptive impact through their use
of hunting technology the Cenac Aleut
engaged in ecologically normal behavior
in terms of preys switching and minimal
strong feeding these were factors that
likely helped to minimize negative
effects such as extinctions over
thousands of years combined with other
things like the fact that the human
population wasn't massive
on the island and that you have the
ability for species to recolonize from
outside the system we can contrast this
with other cases such as bluefin tuna in
today's world
bluefin populations have been decimated
compared to historical levels most
recently as a result of high demand in
the luxury sushi market in this case as
the bluefin tuna gets rarer their value
to humans in this case their economic
value goes up so instead of switching to
some other more abundant fish which is
what an ecological generalist would do
humans instead increase fishing pressure
on the bluefin driving them ever closer
to extinction this is a very non
ecological behavior that's obviously
really bad news for the bluefin tuna but
it's also bad news for the food webs
it's a part of it introduces a
destabilizing dynamic that can result in
further extinctions in the rapid
unraveling of the food web this type of
divergence of modern industrialized
human predators from other predators in
terms of their behavior and impact was
highlighted in a very recent paper
published in the journal science on the
unique ecology of human predators it
suggests that modern humans function as
an unsustainable super predator and
that's actually the term they used just
like I use the term super generalist the
study showed that humans are extreme in
preferentially killing adult prey an
adult prey or where the reproductive
capital of populations resides they kill
them at a far higher rate than non-human
predators this is particularly true for
terrestrial carnivores and fishes okay
let's move on to the final case study
which is centered on the island of
Moorea in French Polynesia we're moving
almost due south from the Aleutian
Islands which form a border between the
Bering Sea and the North Pacific Ocean
down to the South Pacific Ocean the
Polynesian expansion was the most
dramatic burst of overwater exploration
in human history around 3500 years ago a
seafaring and farming people originating
in the Bismarck Archipelago northeast of
New Guinea swept nearly 2,000 miles
across open oceans east of the
Solomons to reach Fiji Samoa and Tonga
they became the ancestors of Polynesians
by a thousand years ago the Polynesians
had reached and invaded every habitable
bit of land in the vast Triangle of
ocean marked by Hawaii New Zealand and
Easter Island a variety of archipelagos
make up French Polynesia whose most well
known islands are Tahiti and Bora Bora
in the society islands our project which
seeks to explore the socio ecosystem
dynamics of natural human networks on
Polynesian islands is focused on three
of the society islands mal PD riot and
Marana and on one of the Gombe islands
further to the east Mangareva we're in
the very early stages of this research
I'll focus for now on Mariah next to the
Headey which is a relatively young large
and nutrient-rich island in Monga Ava of
the far-off Gombe Islands to the east
which is relatively old small and
nutrient poor both currently support
smaller human populations than they did
hundreds of years ago these islands are
useful to study and compare because they
were invaded by humans at the same time
a thousand years ago and they had
similar but slightly different pre human
ecologies and environment environmental
context so we're using an ecological
Network framework to understand
different ecological and cultural
development outcomes on the islands some
islands like Mariah have sustained more
humans fewer extinctions and lower
environmental degradation compared to
islands like Monger Ava and I'm
personally interested in quantifying how
humans interacted with other species
over time on these different islands in
addition we are developing dynamic
models of feedbacks between the
ecosystems and environment and human
behaviors related to different modes of
resource extraction subsistence
agricultural and economic we intend for
this research in our models to inform
forecasting and decision-making related
to the sustainability of these islands
as socio ecological systems to that end
we are interacting quite actively with
local pollinate a Polynesian politicians
management managers educators and elders
who are active supporters of this
research
when Polynesians arrived a thousand
years ago they brought dozens of species
with them effectively they brought their
own little food webs and their canoes
with them
these included to the three dozen mostly
agricultural plant species including
breadfruit taro banana yams coconut
sweet potatoes sugar cane and turmeric
they also brought at least a dozen
animal species some were intentional
livestock such as pigs chickens and dogs
others were unintentional hitchhikers
the Pacific rat lizards snails and
various insects humans directly
interacted with hundreds of species on
these islands the archeologists involved
with this project pack hurch working on
Munger Ava and Jenny Kahn working on the
society islands are compiling data on
all of the myriad species that humans
interacted with including the species
relative abundance during time 200 year
time slices over the thousand years of
human occupation we're using these data
to construct human centered interaction
networks in order to see how they change
across time and across the islands and
to see whether in how they are
associated with other factors such as
extinctions agricultural production and
size and age of the islands in addition
to using species for food drink its
vices humans also use species in other
major ways for medicine for clothing
ritually for fuel for housing as
ornamental garden plants and for
artifacts and artifacts include anything
from canoes to Spears to bowls to fish
hooks anything portable basically a
number of species were used for multiple
purposes the sea snail turbot for
example was eaten as well as carved into
fish hooks and vegetable peelers our
first set of data are emerging from the
work done by Pat Kerch over the last 15
years on monger Ava monger Ava lies
about a thousand miles east of Tahiti
and Moorea it has a rich large Lagoon
but very limited land the story of
monger Ava is really amazing for the
first 300 or 400 years of human presence
monger Ava had a population of seventh
several thousand people and an engaged
in trade with the Marquesas in the
society islands to the west they also
expanded their population to too small
Marge
habitable Islands a few hundred miles to
the east Pitcairn and henderson Pitcairn
was particularly important because it
was a source of hard basalt rock that
was not present a monger Ava that was
really important for making tools
however the monger Ravens the
Polynesians of Munger Ava engaged in
excessive logging to clear for
agriculture leading to almost complete
deforestation and severe environmental
degradation this was really aggravated
by rats and humans decimating the bird
populations whose guano was the only
source of renewable nutrients as a
result of the deforestation the
Polynesians of Munger Ava no longer had
logs necessary for making canoes which
were needed for inner island trade
either with the major islands to the
west or Pitcairn and Henderson who
completely dependent on monger Ava now
this does seem like a really serious
oversight let's see if we cut all the
trees down how are we gonna actually do
any of this trade that we need to do so
the two small islands were quickly
abandoned in Monga raven AO isolated
underwent cultural breakdown its
population severely contracting Jared
Diamond counts monger Ava as one of the
classic collapse stories along with
Easter Island or robbing away further to
the east and the name Pitcairn may be
familiar to some of you it was reinvade
abides in 1790 in particular by the
mutineers of HMS Bounty led by Fletcher
Christian although Pitcairn was
uninhabited when they landed the
mutineers found evidence that it wasn't
always so
temple platforms petroglyphs and stone
tools gave testimony to pick herons
former Polynesian settlers and the HMS
Bounty mutineers had a hard time making
their own living on Pitcairn something
the Polynesians had already figured out
a few hundred years prior previous to
that so much of the data that Pat is
compiling comes from digs at sites such
as this than a Nanga itty rock shelter
on manga rave and nearby atolls an
enormous amount of archaeological
material comes out of these digs
including bones and shells as well as
many type
of artifacts like fish hooks and sinkers
analysis of just the fish bones at this
one site revealed that humans were
hunting and eating a diverse assemblage
of reef and benthic benthic fishes in
this case dominated by parrotfish
groupers and convict tangs an initial
look at the human use of species of
monger Ava reveals that they interacted
directly with a minimum of three hundred
and thirty taxa while the majority of
links from humans to other species were
for food they also use many other
species for artifacts and as garden
ornamentals as well as fuel all eight
categories of use are represented
including the use of kava as a ritual
soporific several dozen of the species
had multiple types of uses of the
species that were eaten the great
majority were marine fishes but a
variety of marine invertebrates plants
birds and mammals and algae were also
eaten one of the mammal feeding links is
a cannibalistic link of human eating
human and not in the sense that I talked
about yesterday
so yesterday I talked about how mammals
are actually obligate cannibals because
the young feed on Mother's Milk
so cannibalism isn't always the killing
and complete eating of something it's
any biomass transfer between two
individuals of the same species so
humans are obligate cannibals in that
way but this was the more kind of
traditional cannibalistic link so and
that there is a lot of there's
archaeological evidence of the
cannibalism that occurred during the
period of cultural breakdown so I had a
quote from the famous famous Anglo Irish
satirist Jonathan Swift who wrote
Gulliver's Travels last night and
tonight I bring you another in 1729
Swift published a modest proposal for
preventing the children of poor people
in Ireland being a burden on their
parents or country and for making them
beneficial to the public we just don't
have titles like that anymore so as a
part of that he wrote I have been
assured by a very knowing American of my
acquaintances in London that a young
healthy child
well nursed is that a year old
most delicious nourishing and wholesome
food indeed the monger Ravens may they
probably resorted to cannibalism in the
face of food shortages he was joking
about it they were not ultimately we
intend not only to compare human
centered use networks among french
polynesian islands through time
we're also compiling comparable data
sets for the Aleutian Islands system I
already talked about and for nearby
Southwest ancient Pueblo in sites near
Mesa Verde and southern Colorado via
work done by Stephanie Crabtree I'd like
to do this type of comparison for as
many places through time as I am able
also as we did for Cenac Island we are
also compiling detailed full food web
data including humans for Moran
building on a previous project called
Marais abaya code this project led by
Neil Davies who's at UC Berkeley and is
the director of the Gunn field station
on Moriah and also led by Chris Mayer of
the Smithsonian and Neil is involved in
in the current Mireya work that I was
just talking about basically this
involved DNA barcoding of all non
microbial species on the island and in
the surrounding waters this was a
massive undertaking having the more
complete food web data which will take
quite a while to compile we have the
species list but the filling and the
feeding links takes a long time will
allow us to see how humans compared to
other species and the Marana food webs
and their roles and impacts as predators
and also to compare to other systems
like Cenac and also the ancient Pueblo
insights because Stephanie has compiled
this kind of data for those sites all of
this research and much much more is
feeding into an ambitious unique project
to turn all kinds of research based on
Moriah which is very well studied
including ecological marine
archaeological economic physical
oceanography cultural and social
Geographic climatic so on and so on into
an integrated virtually ecology lab as
this news piece from earlier this year
in the journal Nature States a digital
version a digital version of Marea will
provide a way to experiment with an
entire ecosystem
this is being done explicitly with
future sustainability and planning in
mind it is a way of making the rubber
meet the road in terms of integrating
and transforming tons of piecemeal
scientific research into something
rigorous and quantitative that can be
used to forecast possible futures for
the island under different kinds of
scenarios Mireya in this case in a sense
is serving as a microcosm for the whole
world this is called the Maria idea
project to the island digital ecosystem
avatar and it consists of an
international consortium of universities
including Berkeley CNRS and France
ETH Zurich Oxford and Santa Barbara as
well as the Santa Fe Institute through
my own involvement ultimately all of
this research is meant to provide new
ways of understanding our roles within
ecosystems and our impacts on ecosystems
there are myriad interactions with other
species whether as hunter-gatherers as
backyard gardeners or as consumers and a
giant food industrial complex
one thing is clear if we want a
sustainable future it will require
understanding these types of things in a
much deeper more quantitative and more
nuanced way and it will require
consciously placing limits on extreme
nani nani ecological behavior it's time
for us to embrace our ecological human
potential and as was the case last night
I owe big thanks to dozens of people who
were involved in the research described
tonight as well as much more that I
didn't have time to discuss but there
are a few key collaborators I want to
acknowledge who were centrally important
to the work described here many of whom
I mentioned throughout the talk this
research was supported financially in
large part by various grants over the
last 10 years from the National Science
Foundation and as always I'm extremely
grateful to the Santa Fe Institute and
to my excellent friends and colleagues
there for providing an intellectually
stimulating and supportive environment
for conducting this kind of
transdisciplinary fundamental research
on complex systems and finally thank you
very much for joining me tonight
so there's time for a few questions
hi yeah I mean I actually didn't talk
about information tonight I mentioned it
last night I mean the two basic
currencies of life on Earth are that of
information so think of for example
genetic material is passing on
information from one generation to the
next and energy which is the thing that
we need in order to fuel our metabolic
processes in order to have life on Earth
and so really what the the ecological
network research that I'm talking about
really focuses on the energy part of
that equation and basically what how how
does life organize itself at different
scales and through time in order to
supply and provide and process the
energy needed to support this huge
diversity of life so that's you know
very simple kind of general big-picture
overview on that in the back a very wide
ecosystem right
right so the question was the Aleutian
Islands are are part of a very
productive ecosystem and are we studying
differences in productivity across
islands and the Aleutians to understand
kind of the impacts on food webs and
other things so that would be a great
thing to be able to study because I mean
I think I mean one of the things I
didn't necessarily make it super
explicit is that doing these kinds of
comparisons is really powerful and we
always look for opportunities to do
comparative research I don't have that
we don't have that kind of information
for the Aleutians so we really focused
that was really a test case to see what
we could get out of doing a food web
type of analysis including humans
explicitly for one particular part of
the Aleutian Islands but in the process
of putting together the data that
resulted in the food web that I showed
for Cenac my colleague Spencer would
actually created a massive database that
includes many many thousands of species
and tens of thousands of feeding action
interactions for the entire North
Pacific and and so what's what we're
doing now with that kind of increasingly
people are putting together these kinds
of very broad datasets and we make
queries of those datasets based on
particular sets of species in different
places so we have the potential if we
know what relative levels of
productivity are in different spots
along the Aleutians or in the North
Pacific of actually doing the kind of
comparison that you're talking about and
it's certainly something I mean the
productivity and I mentioned this very
briefly is very much linked to how warm
it is so in marine systems warmth is
actually bad for productivity so you see
very clearly in populations of the Cenac
Aleut and also of marine mammals and
other things their populations go down
during periods of low productivity
associated with warmer climate so there
are some very interesting sorts of
patterns that we have started to see
with some of that in the back
right well let me let me address the
second one because I thought about it a
little bit after we talked so the second
question was to comment on the idea that
the planet doesn't need humans but
humans need the planet and I mean this I
was talking about this with a colleague
at work today or I was talking about the
age of species through evolutionary time
and no species is forever in the
geologic time cycle all species go away
and that's going to be true for humans
too so and you know and this is actually
I mean this is also something that feeds
into eco and so that's evolutionary
dynamics species on average exist for
about 2 million years humans have been
around as a species for about 200,000
years you know at what point we wink out
of the geologic time who knows but it's
going to happen at some point so no the
planet doesn't need us just like it
doesn't need any species but yes every
species depends on the other species
that it interacts with in some way when
it's when they're existing another thing
about ecological dynamics humans have
had this you know increasing population
trajectory over time but ecological
dynamics tells us that species they
don't go up forever they cycle their
population cycle we see this repeatedly
and we see it both in empirically and in
a model systems and humans are not going
to escape that dynam dynamic either
again what timescales we're talking
about I have no idea but there's a lot
of interesting issues around that
so yes
the question is basically what about
Hawaii it's a volcanic island and I mean
there's many ways of thinking I mean
there's a lot of very interesting
research that has happened in Hawaii and
I'd actually there's a there's very good
opportunities to replicate to do this
kind of work on Hawaii and in fact Pat
Kerch has done a lot of work on Hawaii
along with a lot of ecologists and I
just want to say something more
generally about Islands I mean I've been
talking a lot about Islands in the
second half of the talk islands are just
these really nice microcosms they're
these kind of contained little systems
that that provide a sort of manageable
place to study you know a wide array of
much broader issues but in an integrated
sort of contained way and so they've
proven very useful to a lot of different
natural and social scientists in terms
of studying things that would might be a
little harder to sort of container put
boundaries on on a big continent and the
idea is that we can take lessons that we
learn from islands and especially where
we can do comparative work and sort of
apply those to much broader places that
aren't is obviously contained as an
island ecosystem so I've been become
very convinced of sort of the utility of
studying islands over the last few years
because of this yes
I know it's always a little hard you
don't want to be totally doom and gloom
yeah I mean there's a couple of
different things I said the question was
you know what can we take away from this
that's not completely doom and gloom
especially in light of things like
climate change and you know this was I
mean in terms of and I mentioned some of
this in terms of the specific work
especially on my on uh on Mariah and in
french polynesia where we're working
really closely with the Polynesians in
order to come up to use the science to
talk about planning in the context of
things like coming plant and climate
change and how it's likely to affect
mariah and other islands in terms of
things like even like mosquito control
or what kinds of choices to make about
tourism how much development to allow or
not to allow given you know what we
understand about the climate about the
food webs about you know the relative
sort of taking of fish from the lagoons
versus agriculture and other things and
so there's so we're working very
actively in a positive way in that sense
and a more local in a more local context
in Marana in terms of the bigger picture
I mean one of the things that we're
trying to do and also with the paper
that I mentioned that just came out in
science is to it's really helpful to put
our fingers on you know what really
uniike illogical behavior is and what it
means things like the super predator
kind of finding and the way that we're
fishing overfishing the Seas you know
that requires us taking that information
and doing something with it and that's
not just you and me but that's actually
policies and setting limits in very
serious ways so you know I think
knowledge is important if we don't know
what we're doing and we don't know what
are what different kinds aspects of
behavior are having negative impacts
versus neutral impacts or perhaps even
positive impacts we can't even begin to
do the right things in terms of policy
and making intelligent limits and
decisions but it's a hard question
