the
Climate
and
of
Civilization
Maya
Collapse
A seriesofmulti-yeardroughtshelped todoom an ancient culture
Larry C. Peterson and Gerald H. Haug
theirmagnificent architecture
and
With
sophisticated knowledge of
astronomy and mathematics, theMaya
boasted one of the great cultures of the
ancient world. Although they had not
discovered thewheel and were with
out metal tools, theMaya constructed
massive pyramids, temples and monu
ments of hewn stone both in large cit
ies and in smaller ceremonial centers
throughout the lowlands of the Yuca
tan Peninsula, which covers parts of
and
what are now southern Mexico
Guatemala and essentially all of Belize.
From celestial observatories, such as
the one at Chich?n Itz?, they tracked
the progress of Venus and developed
a calendar based on a solar year of 365
days. They created their own system
of mathematics, using a base number
of 20 with a concept of zero. And they
developed a hieroglyphic scheme for
writing, one that used hundreds of
elaborate
signs.
During its Classic period (250-950
a.D.), Maya civilization reached a zenith.
At itspeak, around 750 a.D., thepopula
tionmay have topped 13million. Then,
between about 750 and 950 a.D., their
society imploded. The Maya abandoned
what had been densely populated urban
centers, leaving their impressive stone
edifices to fall into ruin. The demise of
a
Larry C. Peterson is professor ofmarine geology
Marine
and geophysics at theRosenstiel School of
and Atmospheric Science of theUniversity ofMiami
He received his Ph.D. ingeological sciences at Brown
University in 1984. Gerald H. Haug earned his
Ph.D. at theUniversity ofKiel, Germany, in 1995.
He is currently head of theClimate Dynamics and
Sediments Section at theGeoForschungsZentrum
inPotsdam and holds an appointment as professor
at theUniversity ofPotsdam. Address for Peterson:
Miami, 4600
RSMAS-MGG,
University of
Richenbacher Causeway, Miami, FL 33149.
Internet: [email protected]
322
American
Scientist, Volume
ern tropics converge, forcing air to rise
Maya civilization (which archaeologists
and bringing on cloudiness and abun
call "the terminalClassic collapse") has
dant rainfall.During thewinter months,
been one of the great anthropological
zone
the intertropical convergence
mysteries ofmodern times.What could
have happened?
shifts far to the south, and dry con
ditions prevail over both the Yucatan
Scholars have advanced a variety
of theories over the years, pinning the Peninsula and northern South Ameri
ca. Then, with the coming of summer,
fault on everything from internalwar
this zone migrates north again, bring
fare to foreign intrusion, fromwide
a dan
to
disease
of
outbreaks
ing life-giving rain to theYucatan and
spread
southern Caribbean region.
gerous dependence on monocropping,
to
The Maya had to deal with this sea
from environmental degradation
sonal contrast and, inparticular, had to
climate change. Some combination of
these and other factors may well be
cope with a long dry season each year.
in re
This feature of their environment had
where the truth lies. However,
cent years, evidence has mounted that special significance, because surface
unusual shifts in atmospheric patterns waters tend to dissolve the limestone
took place near the end of the Classic
bedrock of theYucatan, forming caves
to
credence
the
and underground rivers but leaving
Maya period, lending
notion that climate, and specifically
little opportunity forwater to flow
drought, indeed played a hand in the over land. So theMaya could not sim
decline of this ancient civilization.
ply locate their settlements along ma
Rainforest Crunch
Given the common image of lostMaya
cities buried beneath tangles of jungle
vegetation,
itmay
come
as
a
surprise
to discover that theYucatan is, in fact,
a seasonal desert. The lush landscape
summer rains for
depends heavily on
nourishment, rains that vary consider
ably across the peninsula. Annual pre
cipitation ranges from as little as 500
millimeters along the northern coast
to as high as 4,000 millimeters in parts
of the south. As much as 90 percent of
thismoisture falls between June and
September, and a pronounced winter
dry season runs from January toMay.
This wet-dry contrast results from the
seasonal migration ofmoisture associ
ated with the intertropical convergence
zone, an atmospheric feature that is
sometimes known as the "meteorologi
cal equator." In this zone, the easterly
tradewinds of the northern and south
jor
watercourses.
Even
important
re
gional centers?such as Tikal, Caracol
and Calakmul?developed
in places
that were without permanent rivers
or lakes. The lack of surface water for
four or fivemonths of the year in such
areas spurred the construction of large
scale water-collection
systems.
Many cities were designed to catch
rainfall and channel it into quarries, ex
1. As
Figure
oped by
lead one
engraving de
of the Yuca
this 19th-century
picts, Victorian-era
tan revealed many
explorations
ancient Maya
jungle?an
to believe
ruins envel
observation
that the onset
that might
of steamy
conditions
to the col
contributed
tropical
In fact, drought
civilization.
lapse of Maya
to have been the culprit. The authors
appears
how they were able to gauge the cli
for Classic Maya
times during the first
A.D. Their record shows a series
millennium
describe
mate
of severe droughts
that coincide
remarkably
with the abandonment
of Classic Maya
well
sites.
(Engraving
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by Frederick
Catherwood.)
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its indicate that the driest interval of
the last 7,000 years fell between 800
and 1000 a.D.?coincident
with the
of
Classic
civilization.
Maya
collapse
Later work by these same investigators
found evidence for a recurrent pat
tern of drought, which seems also to
explain other, less dramatic breaks in
Maya cultural evolution.
on artificial reservoirs
cities commonly depended
Figure 2.Maya
of water. The residents of Tikal, for example, constructed several
the 10,000 or so people
center, enough to provide
living there with
ed from map of Carr and Hazard
1961, courtesy of the University
to provide
reservoirs
water
a year-round source
(blue) near the city
for 18 months.
of Pennsylvania
(Adapt
Museum.)
cavations and natural depressions that mous amount of information on mod
had been specially prepared to retain the ern weather and climate, draws on
the record of historical droughts and
captured water without letting it seep
into the ground. Tikal, forexample, had
farnines, and heaps on evidence from
numerous reservoirs, which together
archaeology and from geological stud
were capable of holding enough water
ies of ancient climates. To demonstrate
tomeet the drinking needs of roughly
the importance of the porous limestone
10,000 people forabout 18months. The
bedrock, for example, he quotes Diego
Maya also built reservoirs on the tops de Landa, Bishop of Yucatan, who in
of hills, using gravity to distribute the
1566 wrote: "Nature worked so differ
water through canals into complex ir
ently in this country in thematter of
the
rivers and springs, which in all the rest
rigation systems.Despite
sophistica
tion of their hydrological engineering,
of theworld run on top of the land, that
theMaya ultimately depended on the here in this country all run and flow
seasonal rains to replenish theirwater
through secret passages under it."
natural
in
Gill builds an impressive case. When
supplies,
groundwater being
accessible over a considerable portion of his work was firstpublished (fiveyears
their realm.
ago), the most compelling evidence
In his fascinating book, The Great
fordrought came from sediment cores
archae
thatDavid A. Hodell, JasonH. Curtis,
Maya Droughts, independent
Mark Brenner and other geologists at
ologist Richardson B. Gill persuasive
theUniversity of Florida had collected
ly argues that a lack of water was a
a number of Yucatan lakes. Their
in
factor
the
terminal
Classic
from
major
an
enor
measurements
Gill
of these ancient depos
collapse.
pulls together
324
American
Scientist, Volume
The Venezuelan Connection
Our own contribution to the under
standing of climatic conditions during
the time of the tenriinalClassic collapse
comes from a distant location, one not
inhabited by theMaya at all. Offshore
of thenorthern coast of Venezuela sits a
remarkable depression in the continen
tal shelf known as the Cariaco Basin.
Reaching depths of about a kilometer
but surrounded by the shallow shelf
and banks, the Cariaco Basin acts as a
natural sediment trap.What ismore,
the shallow lip of the basin prevents
its deeper waters frommixing readily
with the open ocean to the north. As a
result, deep Cariaco waters are devoid
of dissolved oxygen (and have been
since near the end of the last glacial pe
riod, some 14,500 years ago). The lack
of oxygen means that themuddy floor
of the basin cannot support bottom
dwelling marine organisms, which in
other places churn up the sediment
in their search for food. This lack of a
deep-sea fauna preserves the integrity
of the sediments, which here are made
up of paired light and dark layers, each
less than a millimeter thick.
The origin of these layers is easy
enough to understand: During North
ernHemisphere winter and spring, the
intertropical convergence zone sits at its
southernmost position near the equa
tor,which means that little rain falls
over the Cariaco Basin. At this time of
year, strong tradewinds blow along the
northern coast of Venezuela, causing
cool, nutrient-richwaters to rise,which
in turn allows plankton living near the
surface to proliferate. When these or
ganisms die, their shelly remains fall
to the bottom, where they form a light
colored layer. During the summer, as
the northern hemisphere warms, the
intertropical convergence zone moves
steadily northward until it takes up a
position near thenorthern coast of South
America. The trade winds diminish,
and the rainy season begins, increasing
the flow of local rivers,which then de
liver a considerable load of suspended
sediment to the sea. These land-derived
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March
January
May
July
September
November
to investigate climate conditions
from the Cariaco Basin off Venezuela
Figure 3. The authors turned to sediments
affecting the Classic Maya,
the same general climate, with distinct rainy
who lived in the Yucatan Peninsula, more than 2,000 kilometers
away (top). Both places experience
the equatorial
band of high precipitation
falls to the south of both the Yucatan and Cariaco
and dry seasons.
This yearly pattern arises because
north to encompass
both areas (dark green in lower panels). Why did the
Basin during Northern Hemisphere
winter but by summer moves
of the Cariaco
Basin in particular? Unlike
other deep-sea
authors choose to examine
the sediments
sites, this basin is surrounded
by shallow
that prevents deep Cariaco waters from mixing with the open ocean. As a result, these waters
continental shelf on all sides, a configuration
churn up the fine layers of sediment laid down during
otherwise
oxygen and do not support burrowing
deep-sea
organisms, which would
wet and dry season. The undisturbed
record of ancient climate.
sediments of the Cariaco Basin thus preserve a detailed
eventually settle out of the
water, leaving on the ocean floor a dark
colored layer of rnineral grains on top
of the earlier accumulation
of light
colored microfossil shells.
materials
organisms
Although
burrowing
mix up such seasonal deposits else
where, the anoxic Cariaco Basin pre
serves these distinct light-and-dark
couplets. This dramatic alternation in
composition provides a built-in clock
that geologists can use to determine
with yearly resolution just when the
sediments were laid down. And for
tunately, at least for people interested
in the history of Maya
civilization,
lack
each
both the Yucatan and northern Ven
sequence of sediment cores expressly for
the purpose of probing tropical climate
ezuela experience the same general
with
both
of
seasonal
rainfall,
pattern
change. The study of those sediments,
areas today near the northern limit of which had accumulated at an enormous
rate and had remained completely un
the intertropical convergence zone.
Hence marine sediments from theCa
disturbed since the time of deposition,
riaco Basin hold considerable
infor
offered us and other geologists a rare,
mation about the shifts in climate that high-resolution glimpse into the distant
theMaya experienced.
past. An important aspect of our work
on these sediments has been to use the
Our efforts to read that archive be
in
concentration of mineral grains eroded
when
the
scientific
1996,
gan
drillship
from land to gauge the amount of rain
JOIDES Resolution, operated by an in
that fell on adjacent parts of the South
ternational research collaboration called
continent.
theOcean Drilling Program, sailed to the American
center of theCariaco Basin. Once there,
One could, of course, gain such an
these
technicians obtained a 170-meter-long
understanding
by examining
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themiddle, producing records that are
farmore detailed than what could be
expected from extracting and measur
ing individual samples.
We initiallymade measurements of
x-ray
fluorescence
using
a core
scanner
Swiss Federal Institute of Technology
in Zurich, we did much better using a
special
"micro"
x-ray
fluorescence
sys
tem they had set up in their lab. This
instrument was designed
for small
not
of deep
stretches
samples,
long
sea sediment, but it could accommo
date short slabs of material cut from
our cores. This device allowed us to
make elemental analyses with a 50
housed at Bremen University inGerma
ny,where theOcean Drilling Program
maintains a repository of cores.We de
termined the titanium and iron concen
tration at 2-millimeter spacings over a micrometer
measurement
spacing,
4. Sediments
from the Cariaco
Ba
Figure
sediment section of interest, one that which in theCariaco cores corresponds
sin contain finely laminated
sediments. The
had already been dated using radiocar
to about two months of time?an in
lighter layers are composed mostly of micro
but after finding nearly identical
bon,
credibly fine resolution formarine sed
shells formed in the surface waters
scopic
in these two elements, we
variations
iments, which more typically encom
the dry season, whereas
the darker
during
chose to track only titanium.
hundreds to thousands of years of
an
pass
contain
abundance
of
mineral
layers
frag
Within this interval, and at thismea
ments swept into the basin from nearby por
geologic history in a single sample.
surement resolution, themost obvious
tions of the South American
continent dur
Using G?nther and Aeschlimann's
This
section
feature is the generally low titanium wonderful
of core
instrument, we measured
ing the rainy season.
measures
across. (Pho
about 10 centimeters
two slabs of sediment that together
level in layers deposited
between
cover the time interval from about 200
about 500 and 200 years ago, a period
tograph courtesy of the authors.)
that corresponds towhat some clima
to 1000 a.D., focusing on those layers
sediments directly under amicroscope,
the
Ice
call
Little
These
tologists
Age.
deposited during the terminal Classic
but characterizing vast numbers of
results presumably reflect dry condi
collapse. This interval revealed a se
sediment couplets in thisway would
tions and indicate that the intertropical
ries of four distinct titaniumminima?
zone
have been extraordinarily
tedious.
its
and
associated
convergence
likelymulti-year droughts, which took
So we sought out a more efficient ap
rainfall must not have reached as far place during a period thatwas already
north as they do now. We also found
drier than normal. When exactly did
proach. Of the several methods we ex
to
the
most
useful
be
several other broad intervals of low
these intense dry spells settle over the
plored,
proved
themeasurement of titanium and iron, titanium, including one in sediments
Maya heartland? Although the count
elements that are abundant in most
800
1000
between
about
and
deposited
ing of sediment couplets gives precise
continental rocks but not in the shelly
information on the duration of these
a.D., which corresponds to the period
remains of marine organisms. High
of severe drought thatHodell and his
droughts (which range from three to
levels of titanium and iron thus indi
had
Yu
inferred
from
nine
their
colleagues
years) and the spacing between
cate that large amounts of silt and clay
catan
lake cores.
them (around 40 to 50 years), the ab
were washed off the adjacent land and
Hodell's work had led to the impres
solute dating of these events remains
a little vague. Radiocarbon measure
sion that an extended "megadrought"
swept into the basin. That is, finding
lots of titanium and iron at a particular
ments for the core we used in combi
plagued theMaya homeland fora cen
or
conse
level in these sediments means
that
with
nation with counting couplets would
two,
tury
devastating
rainfall in this region?and
for the indigenous popula
quences
by infer
iron concentration
ence
over
the Yucatan?must
tion. But this interpretation troubled
have
some Mayanists. They pointed out ar
been high at the time of deposition.
Low titanium and iron, by contrast,
chaeological evidence for considerable
means
that rain was
sparse.
variability in the timing and regional
pattern of collapse. A "one drought fits
A First-millennium Rain Gauge
all" model seems too simplistic, given
The measurement
of elemental con
that the collapse apparently happened
centrations in sediments by traditional
at different places at different times,
is time consuming and has
methods
while affecting some population cen
tershardly at all.
the further drawback that it destroys
thematerial under study. But recently
Although the Cariaco Basin is quite
distant from the Yucatan, its unique
geologists have overcome these prob
lems with a technique called x-ray flu
sediments offered the possibility of ob
orescence, which involves illummating
taining an immensely detailed chro
5. To register changes
in sediment
a sample with x rays and
Figure
measuring
nology of ancient climate swings, and
and at high res
composition
quantitatively
as
a
we
amount
as
the
of light given off
func
wanted to push the record
far
the authors measured
the concen
olution,
as itwould go so as to provide fur
tion ofwavelength. Suitable analysis of
tration of iron and titanium, elements
that
this light spectrum (which can be fully ther insight into the climate during
reflect the amount of material
eroded
from
the Maya
automated) reveals the concentration
sec
collapse. Unfortunately,
continental
rocks. A 2-millimeter-long
we had reached the maximum
ana
of various elements in the sample. This
tion of sediment
(left) shows three light-dark
sediment couplets
(three years of deposition)
approach allows for the rapid assess
lytical resolution of the Bremen core
scanner. But with the help of Detlef
ment of elemental abundances in sedi
and three corresponding
cycles in elemental
ment cores that have been split down
G?nther and Beat Aeschlimann at the concentration (right).
326
American
Scientist, Volume
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500
Figure
6. Measurements
carried
0
1,000
age of sediments (years)
out on Cariaco
Basin
2,000
1,500
cores obtained
reflect broad variations
in Earth's climate through
Program
as "the Medieval
Warm Period"
of what have become known
Drilling
by the Ocean
time, including manifestations
and "the Little Ice Age"
(lower
were able to
panel). Using slabs of sediment taken from one of the recovered cores, the authors
in time of about two months,
track swings between wet and dry conditions with a resolution
their
the record shown here has been smoothed
for clarity (middle panel). Focusing
although
laid down during the terminal Classic
efforts on the sediments
civilization,
collapse of Maya
the authors found evidence
of four multi-year
separated by some 40 to 50 years of
droughts,
more moderate
record (red) helps
conditions
to delineate
(top panel). The smoothed
these major droughts.
version
of this highly
detailed
climate
a century or more later. This pattern
is opposite to what
of abandonment
one might expect based on themodern
pattern of rainfall, which diminishes
markedly from south to north. Some
Mayanists have pointed to this incon
gruity as evidence against drought
All in the Timing
having played a significant role. How
Scholars generally agree that the termi
ever, an additional factor thatmust be
nal Classic collapse occurred firstin the considered is the availability and ac
cess to natural water sources, which
southern and central Yucatan lowlands
could have sustained the population
and thatmany areas of the northern
lowlands underwent theirown decline
during extended periods of drought.
indicate that the four droughts struck
around 760, 810, 860 and 910 a.D., but
quoting such precise dates is somewhat
misleading, given that the radiocarbon
technique has an uncertainty of about
?30 years for samples of this age.
During the peak of Maya civiliza
tion, as now, an important source of
freshwater for human activities was
from the natural underground aquifer.
This aquifer is generally more acces
sible in the northern end of the pen
insula, where theMaya were able to
reach thewater table at various sink
holes (places where the roof of an un
derground cavern had collapsed) or by
digging wells. However, as one moves
to the south, the landscape rises in el
evation, and the depth to the water
table increases, making direct access
to groundwater unfeasible, at least for
the Classic Maya with the technology
of their time. Thus themore southern
settlements,which were totally depen
dent on rainfall and reservoirs for their
water needs, were more likely to be
susceptible to the effects of prolonged
drought thanwere citieswith direct ac
cess to subsurface sources. This critical
difference helps explain why drought
could have caused greater problems in
the normally wetter south.
Although there is general agreement
that the abandonment ofmajor popu
lation centers began first in the south
and then spread to thenorth, Gill pro
posed a more controversial tripartite
pattern of collapse. Based on an analy
sis of the last recorded dates carved
into stone monuments known as ste
sites. Gill argued
lae at major Maya
that therewere, in fact, three phases
of drought-related collapse between
about 760 and 910 a.d., with a distinct
regional progression.
The firstphase, according toGill, oc
curred between 760 and 810. The sec
ond phase was largely over by about
860. The third and final phase termi
nated around 910. Noting a similarity
between the end dates of these three
phases and the timing of especially
severe cold spells in Europe (as evi
denced in Swedish tree-ring records),
Gill speculated that the abandonments
occurred rather abruptly at the end of
each phase, that theywere primarily
the result of droughts and that these
droughts were linked to the cold condi
tions at higher latitudes.
Gill's model of three phases of col
lapse, and especially the archaeologi
cal basis for their proposed
timing,
has been the subject of much debate.
There is considerable disagreement,
for example, over the interpretation of
the last dated inscriptions on stelae as
accurate records of city abandonment.
Furthermore, Gill considered only the
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settlements
7. Droughts
did not affect all Classic
Maya
were
Yucatan
in
the
northern
In
living
people
particular,
equally.
on seasonal
rains because
sinkholes,
dependent
only somewhat
Figure
caves
and
other
access
to
them with
provided
openings
was not, however,
easy. At right,
always
at Bol
Catherwood
(The Well
by Frederick
of this area of the
to which
residents
the lengths
natural
access
That
groundwater.
an 1844 engraving
shows
onchen)
northern
to groundwater,
went
to gain access
earlier.
centuries
had done
forebears
Maya
a complicated
one to negotiate
system of lad
more
the surface.
below
than 100 meters
descended
Yucatan
sometimes
just as their Classic
This "well"
required
ders, which
To the south,
and
of the land increases,
the elevation
however,
even harder
to reach
becomes
only
(top). Having
groundwater
era could not tap the deep ground
stone tools, Maya
of the Classic
on the seasonal
water of the south and had to depend
exclusively
in
surface
reservoirs.
collect
water
could
rains and whatever
they
(Diagram
adapted
from Gill
2000.)
largestMaya sites inhis original analy
sis. So there is certainly some room
the drought
for doubt. Nevertheless,
events we inferred from the Cariaco
Basin record match Gill's three phases
of abandonment remarkably well.
The onset of Gill's first phase at
about 760 a.D. is clearly marked in the
Cariaco record by an abrupt decrease
in inferred rainfall. Over the subse
quent 40 years or so, there appears to
have been a slight long-term drying
trend. This period then culminated in
a decade or more of severe
roughly
drought, which, within the limits of
our chronology, agrees well with the
end of Gill's firstphase. Societal col
lapse at this time was limited to the
western lowlands, a region with little
accessible groundwater and where the
inhabitants depended almost entirely
on rainfall to satisfy theirneeds.
The end of Gill's second phase of
collapse is also marked in the Caria
co Basin record by a distinct interval
of low titanium concentrations, sug
gesting an unusually severe drought
that lasted for three or four years. City
abandonment
during this phase of
collapse was largely restricted to the
southeastern portion of the lowlands, a
region where freshwater lagoons may
have provided a source ofwater up to
thatpoint.
328
American
Scientist, Volume
rul
According toGill, the third and final dermined the institution ofMaya
and
when
at
910
about
occurred
of
existing technologies
ership
collapse
phase
a.D., affectingpopulation centers in the rituals failed toprovide sufficientwater.
on
central and northern lowlands. And
Large population centers dependent
this control were abandoned and peo
low titanium values in the Cariaco
Basin sediments indicate yet another
ple moved sequentially eastward and
then northward during the successive
coincident period of drought, one that
more stable sources of
lasted for five or six years.
droughts to find
unlike what transpired
water.
Gill's
the
between
match
However,
Although
during previous intervals of too little
drought model and our findings isquite
no single cause is rainfall,which theMaya must certainly
good, we accept that
as com
a
have weathered before, the landscape
to
likely explain phenomenon
was
recent
as
In
his
decline.
the
during the final stages of collapse
Maya
plex
book Collapse: How Societies Choose to at carrying capacity (because of the
wet
Fail or Succeed, JaredDiamond
argues
growth ofMaya population during
ter times), and migration to areas less
that a confluence of factorsmay have
affected by drought was no longer pos
combined to doom theMaya. These
include an expanding population that sible. In short, they ran out of options.
was operating at or near the limits of
Climate inHuman History
available resources, environmental deg
The ability to combine geological
radation in the form of deforestation
and hillside erosion, increased internal archives with traditional archaeological
and historical information provides a
warfare and a leadership focused on
short-term concerns. (Sound familiar?) powerful means to examine the societal
Nevertheless, Diamond posits that cli
response to climate shifts of the distant
the socioeconomic
mate change, in the form of droughts,
past. Although
a
El Nino events or
to
recent
of
have
impacts
may
helped bring things
head, triggering a series of events that of the infamous Dust Bowl drought
of the 1930s are easy enough to study,
destabilized Maya society.
Some archaeologists have pointed
climatologists still know relatively little
about the consequences of older and
out that the control of water reserves
In
a centralized source of politi
longer-period changes in climate.
provided
recent years, however, high-resolution
cal authority for the rulingMaya elites.
records from ice cores, tree rings,
Periods of drought might thenhave un
93
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A
-
Figure 8. Independent
archaeologist
son B. Gill found that Classic
Maya
Richard
cities un
derwent
three phases of abandonment
One set
(green at left) appears to have been abandoned
by 810 A.D.; a second set (pink) by 860 A.D.; and
arang
Piedra --
a thirdset (purple)by 910 A.D. (left).These
of abandonment
remark
phases
correspond
ably well with the timing of severe droughts
revealed by the authors' examination
of deep
sea sediments.
civiliza
Although Classic Maya
tion underwent
this staged collapse, many of
these people
their descendants
survived?and
continue to populate
the region today, as does
MEXICO
..:rg~~~..
.-..'..:.......-
-
thisMaya woman
from the Chiapas
region of
Mexico
(above). (Map adapted from Gill 2000.
Note
that because
of space constraints, Gill's
.-.-.
...".
-..
indicated many smaller
published map, which
cities not reproduced here, did not show two
included
in his table
sites, Yaxha and Ucanal,
of abandonment
dates.)
corals and certain deep-sea and lake
sediments have begun to provide an
increasingly precise record of climate
change for the past fewmillennia.
The coincidence of drought and col
lapsewithin theMaya civilization is just
one example. In theAmerican South
west, tree-ringevidence fora prolonged
drying of climate between about 1275
and 1300 has long been
thought to play
a role in the
disappearance of the cliff
dwelling Anasazi
people. And there
are indications that similar
changes in
climate may have been responsible for
othermajor events inhuman
history as
well. The collapse of theAkkadian Em
about 4,200 years
pire inMesopotamia
the
decline
of
the
Mochica culture
ago,
incoastal Peru about 1,500 years ago and
the end of the Tiwanaku ctdture on the
Bolivian-Peruvian altiplano some 1,000
years ago have all now been linked to
persistent long-termdrought in those re
gions. Before the geological evidence for
these ancient droughts became available,
each of these cultural collapses, like that
of theMaya, had been interpreted
solely
in terms
of human
factors?warfare,
overpopulation, resource depletion.
The rise and fall of theClassic
Maya
provides a textbook example of human
social evolution. It is therefore signifi
cant to discover that the
history of the
Maya was so closely tied to environ
mental constraints. IfMaya
civiliza
tion could collapse under the
weight
of natural climate events, it is of more
than academic interest to ponder how
modern society will fare in the face of
an uncertain climate in the years ahead.
An understanding of how ancient cul
tures responded to climatic
changes in
the past may thus provide important
lessons forhumanity in the future.
Bibliography
Carr, R. F., and J.E. Hazard.
No. 11:Map
of the Ruins
1961. Tikal Report
of Tikal, El Veten,
Guatemala.
Mu
Philadelphia:
University
seum, University of Pennsylvania.
P. B. 2001. Cultural
to
deMenocal,
responses
climate change during the Late Holocene.
Science 292:667-673.
Diamond,
J.2005. Collapse: How
toFail or Succeed. New York:
Societies Choose
Viking.
Gill, R. B. 2000. The Great Maya Droughts: Water,
Life, and Death. Albuquerque:
University of
New Mexico
Press.
Haug, G. H., D. G?nther, L. C Peterson, D. M. Sig
man, K. A. Hughen and B. Aeschlimann. 2003.
Climate and the collapse of Maya civilization.
Science 299:1731-1735.
D. A., J.H. Curtis and M. Brenner.
Hodell,
1995. Possible
role of climate
in the col
civilization. Nature
lapse of Classic Maya
375:391-394.
For relevant Web
issue of American
links, consult
this
Scientist Online:
http:/ /www.ameri?anscientist.org/
IssueTOC/issue/741
2005
www.americanscientist.org
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All use subject to JSTOR Terms and Conditions
July-August