Collapse: How Societies Choose to Fail or Succeed (17 page)

occupied? Winds and currents would probably have ruled out a direct voy
age to Easter from the Marquesas, which supported a large population and
do seem to have been the immediate source for Hawaii's settlement. In
stead, the jumping-off points for the colonization of Easter are more likely
to have been Mangareva, Pitcairn, and Henderson, which lie about halfway between the Marquesas and Easter, and the fates of whose populations will
be the story of our next chapter (Chapter 3). The similarity between Easter's
language and Early Mangarevan, the similarity between a Pitcairn statue
and some Easter statues, the resemblances of Easter tool styles to Mangare
van and Pitcairn tool styles, and the correspondence of Easter Island skulls
to two Henderson Island skulls even more closely than to Marquesan skulls
all suggest use of Mangareva, Pitcairn, and Henderson as stepping-stones.
In 1999 the reconstructed Polynesian sailing canoe
Hokuk'a
succeeded in
reaching Easter from Mangareva after a voyage of 17 days. To us modern
landlubbers, it is literally incredible that canoe voyagers sailing east from Mangareva could have had the good luck to hit an island only nine miles
wide from north to south after such a long voyage. However, Polynesians knew how to anticipate an island long before land became visible, from the flocks of nesting seabirds that fly out over a radius of a hundred miles from
land to forage. Thus, the effective diameter of Easter (originally home to
some of the largest seabird colonies in the whole Pacific) would have been a
respectable 200 miles to Polynesian canoe-voyagers, rather than a mere
nine.

Easter Islanders themselves have a tradition that the leader of the expedition to settle their island was a chief named Hotu Matu'a ("the Great Par
ent") sailing in one or two large canoes with his wife, six sons, and extended
family. (European visitors in the late 1800s and early 1900s recorded many
oral traditions from surviving islanders, and those traditions contain much evidently reliable information about life on Easter in the century or so be
fore European arrival, but it is uncertain whether the traditions accurately
preserve details about events a thousand years earlier.) We shall see (Chap
ter 3) that the populations of many other Polynesian islands remained in
contact with each other through regular interisland two-way voyaging after
their initial discovery and settlement. Might that also have been true of
Easter, and might other canoes have arrived after Hotu Matu'a? Archaeologist Roger Green has suggested that possibility for Easter, on the basis of similarities between some Easter tool styles and the styles of Mangarevan
tools at a time several centuries after Easter's settlement. Against that possibility, however, stands Easter's traditional lack of dogs, pigs, and some typi-

cal Polynesian crops that one might have expected subsequent voyagers to have brought if those animals and crops had by chance failed to survive in
Hotu Matu'a's canoe or had died out soon after his arrival. In addition, we
shall see in the next chapter that finds of numerous tools made of stone
whose chemical composition is distinctive for one island, turning up on another island, unequivocally prove interisland voyaging between the Mar
quesas, Pitcairn, Henderson, Mangareva, and Societies, but no stone of
Easter origin has been found on any other island or vice versa. Thus, Easter
Islanders may have remained effectively completely isolated at the end of
the world, with no contact with outsiders for the thousand years or so sepa
rating Hotu Matu'a's arrival from Roggeveen's.

Given that East Polynesia's main islands may have been settled around
a.d.
600-800, when was Easter itself occupied? There is considerable uncer
tainty about the date, as there is for the settlement of the main islands. The published literature on Easter Island often mentions possible evidence for
settlement at
a.d.
300-400, based especially on calculations of language di
vergence times by the technique known as glottochronology, and on three radiocarbon dates from charcoal in Ahu Te Peu, in the Poike ditch, and in
lake sediments indicative of forest clearance. However, specialists on Easter
Island history increasingly question these early dates. Glottochronological
calculations are considered suspect, especially when applied to languages with as complicated histories as Easter's (known to us mainly through, and
possibly contaminated by, Tahitian and Marquesan informants) and Man-
gareva's (apparently secondarily modified by later Marquesan arrivals). All
three of the early radiocarbon dates were obtained on single samples dated
by older methods now superseded, and there is no proof that the charcoal
objects dated were actually associated with humans.

Instead, what appear to be the most reliable dates for early occupation of
Easter are the radiocarbon dates of
a.d.
900 that paleontologist David
Steadman and archaeologists Claudio Cristino and Patricia Vargas obtained
on wood charcoal and on bones of porpoises eaten by people, from the oldest archaeological layers offering evidence of human presence at Easter's
Anakena Beach. Anakena is by far the best canoe landing beach on the island,
the obvious site at which the first settlers would have based themselves. The
dating of the porpoise bones was done by the modern state-of-the-art radio
carbon method known as AMS (accelerator mass spectrometry), and a
so-called marine reservoir correction for radiocarbon dating of bones of
marine creatures like porpoises was roughly estimated. These dates are likely to be close to the time of first settlement, because they came from

archaeological layers containing bones of native land birds that were exter
minated very quickly on Easter and many other Pacific islands, and because
canoes to hunt porpoises soon became unavailable. Hence the current best
estimate of Easter's settlement is somewhat before
a.d.
900.

What did the islanders eat, and how many of them were there?

At the time of European arrival, they subsisted mainly as farmers, grow
ing sweet potatoes, yams, taro, bananas, and sugarcane, plus chickens as
their sole domestic animal. Easter's lack of coral reefs or of a lagoon meant
that fish and shellfish made a smaller contribution to the diet than on most
other Polynesian islands. Seabirds, land birds, and porpoises were available
to the first settlers, but we shall see that they declined or disappeared later.
The result was a high-carbohydrate diet, exacerbated by the islanders' com
pensating for Easter's limited sources of fresh water by copiously drinking
sugarcane juice. No dentist would be surprised to learn that the islanders
ended up with the highest incidence of cavities and tooth decay of any
known prehistoric people: many children already had cavities by age 14, and
everyone did by their 20s.

Easter's population at its peak has been estimated by methods such as
counting the number of house foundations, assuming 5 to 15 people per
house, and assuming one-third of identified houses to have been occupied
simultaneously, or by estimating the numbers of chiefs and their followers
from the numbers of platforms or erected statues. The resulting estimates
range from a low of 6,000 to a high of 30,000 people, which works out to an
average of 90 to 450 people per square mile. Some of the island's area, such as the Poike Peninsula and the highest elevations, was less suitable for agri
culture, so that population densities on the better land would have been
somewhat higher, but not much higher because archaeological surveys
show that a large fraction of the land surface was utilized.

As usual anywhere in the world when archaeologists debate rival esti
mates for prehistoric population densities, those preferring the lower esti
mates refer to the higher estimates as absurdly high, and vice versa. My own
opinion is that the higher estimates are more likely to be correct, in part be
cause those estimates are by the archaeologists with the most extensive
recent experience of surveying Easter: Claudio Cristino, Patricia Vargas, Ed-
mundo Edwards, Chris Stevenson, and Jo Anne Van Tilburg. In addition,
the earliest reliable estimate of Easter's population, 2,000 people, was made
by missionaries who took up residence in 1864 just after an epidemic of

smallpox had killed off most of the population. And that was after the kidnapping of about 1,500 islanders by Peruvian slave ships in 1862-63, after
two previous documented smallpox epidemics dating back to 1836, after
the virtual certainty of other undocumented epidemics introduced by regu
lar European visitors from 1770 onwards, and after a steep population crash
that began in the 1600s and that we shall discuss below. The same ship
that brought the third smallpox epidemic to Easter went on to the Mar
quesas, where the resulting epidemic is known to have killed seven-eighths
of the population. For these reasons it seems to me impossible that the
1864 post-smallpox population of 2,000 people represented the residue of a
pre-smallpox, pre-kidnapping, pre-other-epidemic, pre-17th-century-crash
population of only 6,000 to 8,000 people. Having seen the evidence for in
tensive prehistoric agriculture on Easter, I find Claudio's and Edmundo's
"high" estimates of 15,000 or more people unsurprising.

That evidence for agricultural intensification is of several types. One
type consists of stone-lined pits 5 to 8 feet in diameter and up to 4 feet deep that were used as composting pits in which to grow crops, and possibly also
as vegetable fermentation pits. Another type of evidence is a pair of stone dams built across the bed of the intermittent stream draining the southeast
ern slope of Mt. Terevaka, in order to divert water onto broad stone plat
forms. That water diversion system resembles systems for irrigated taro
production elsewhere in Polynesia. Still further evidence for agricultural in
tensification is numerous stone chicken houses (called
hare mod),
mostly up
to 20 feet long (plus a few 70-foot monsters), 10 feet wide, and 6 feet high,
with a small entrance near the ground for chickens to run in and out, and
with an adjacent yard ringed by a stone wall to prevent the precious chick
ens from running away or being stolen. If it were not for the fact that
Easter's abundant big stone
hare moa
are overshadowed by its even bigger
stone platforms and statues, tourists would remember Easter as the island of stone chicken houses. They dominate much of the landscape near the
coast, because today the prehistoric stone chicken houses
—all 1,233 of them—are much more conspicuous than the prehistoric human houses,
which had only stone foundations or patios and no stone walls.

But the most widespread method adopted to increase agricultural out
put involved various uses of lava rocks studied by archaeologist Chris
Stevenson. Large boulders were stacked as windbreaks to protect plants
from being dried out by Easter's frequent strong winds. Smaller boulders
were piled to create protected aboveground or sunken gardens, for growing
bananas and also for starting seedlings to be transplanted after they had

grown larger. Extensive areas of ground were partly covered by rocks placed
at close intervals on the surface, such that plants could come up between the rocks. Other large areas were modified by so-called "lithic mulches," which
means partly filling the soil with rocks down to a depth of a foot, either by carrying rocks from nearby outcrops or else by digging down to and break
ing up bedrock. Depressions for planting taro were excavated into natural
gravel fields. All of these rock windbreaks and gardens involved a huge ef
fort to construct, because they required moving millions or even billions of
rocks. As archaeologist Barry Rolett, who has worked in other parts of Poly
nesia, commented to me when he and I made our first visit to Easter to
gether, "I have never been to a Polynesian island where people were so desperate, as they were on Easter, that they piled small stones together in a circle to plant a few lousy small taro and protect them against the wind! On the Cook Islands, where they have irrigated taro, people will never stoop to
that effort!"

Indeed, why did farmers go to all that effort on Easter? On farms in the
northeastern U.S. where I spent my boyhood summers, farmers exerted themselves to carry stones
out
of fields, and would have been horrified at
the thought of intentionally bringing stones
into
the fields. What good does
it do to have a rocky field?

The answer has to do with Easter's windy, dry, cool climate that I already
described. Rock garden or lithic mulch agriculture was invented indepen
dently by farmers in many other dry parts of the world, such as Israel's
Negev desert, southwestern U.S. deserts, and dry parts of Peru, China, Ro
man Italy, and Maori New Zealand. Rocks make the soil moister by covering
it, reducing evaporative water loss due to sun and wind, and replacing a
hard surface crust of soil that would otherwise promote rain runoff. Rocks
damp out diurnal fluctuations in soil temperature by absorbing solar heat
during the day and releasing it at night; they protect soil against being
eroded by splashing rain droplets; dark rocks on lighter soil warm up the
soil by absorbing more solar heat; and rocks may also serve as slow-time-
release fertilizer pills (analogous to the slow-time-release vitamin pills that some of us take with breakfast), by containing needed minerals that gradu
ally become leached out into the soil. In modern agricultural experiments in the U.S. Southwest designed to understand why the ancient Anasazi
(Chapter 4) used lithic mulches, it turned out that the mulches yielded big advantages to farmers. Mulched soils ended up with double the soil mois
ture content, lower maximum soil temperatures during the day, higher
minimum soil temperatures at night, and higher yields for every one of 16