The Ecological Human


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