BiologicalJournal of the Linnean Society (1W5), 56: 377-404. With 9 figures
l l e Pitcairn Islands: biogeography, ecology and prehistory
Edited by T. G. Benton and T. Spencer
Henderson Island prehistory: colonization and
extinction on a remote Polynesian island
MARSHALL I. WEISLER
Department of Anthropology, University of Otago, P. 0. Box 56, Dunedin, New Zealand
Situated at the extreme margin of the Indo-West Pacific biotic province, the four islands of
the isolated Pitcairn Group hold interest for biogeographers and archaeologists alike. Human
settlement may have been as early as the 8th century AD for the uplifted limestone island
of Henderson, the most pristine island of its kind. An archaeological survey of the Pitcairn
Islands is provided, while Henderson is examined in detail. Recent extensive excavations
provide a record of change during 600 years of human occupation. Adaptation to the
ecologically-margnal conditions is documented by artefacts, more than 150 000 vertebrate
bones, molluscs and subfossil plant remains recovered from stratigraphic contexts. The effects
of prehistoric human occupation on the pristine environment are revealed by Polynesian
plant and animal introductions, bird extinctions and range reductions, possible over-predation
of marine molluscs, exploitation of sea turtles, and large-scale burning for swidden agriculture.
The origin of human colonists is documented by analysing imported artefacts by geochemical
characterization (x-ray fluorescence analysis). The human abandonment of Henderson, by the
seventeenth century, is viewed in the context of prehistoric regional dynamics.
0 I!W5 The Imnean Society of 1.ondon
ADDITIONAL KEY WORDS:-Prehistory - archaeology - Oceania - Polynesia
Group - Henderson Island - adaptation - extinctions - x-ray fluorescence.
-
Pitcairn
CONTENTS
Introduction . . . . . . . . .
Henderson Island: constraints to human habitation
The archaeological landscape . . . . .
Henderson
. . . . . . . .
Pitcairn . . . . . . . . .
Ducie
. . . . . . . . .
Oeno . . . . . . . . . .
Summary . . . . . . . . .
Prehistoric Polynesian occupation . . . .
Rockshelters and caves
. . . . .
Coastal midden . . . . . . .
Gardening sites . . . . . . .
Crypt
. . . . . . . . .
Chronology . . . . . . . .
Six centuries of human adaptation on Henderson
Human impacts to island landscapes . . .
Long-distance interaction . . . . . .
Conclusion
. . . . . . . . .
Acknowledgements
. . . . . . .
References
. . . . . . . . .
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0 1995 The Linnean Society of London
378
M. I. WEISLER
INTRODUCTION
Henderson is one of a group of islands in Polynesia that is characterized
by its relative geographic isolation and margnal ecological conditions for
sustaining human settlement. Despite its geographic isolation near the extreme
limit of human colonization of the Pacific islands, the Pitcairn Group, settled
as early as the 8th century AD, was part of a larger prehistoric interaction
sphere that included Mangareva, some 400 km to the west. Indeed, with
poorly developed soils, sporadic rainfall, no permanent source of potable
water, a land area limited by karst topography, and a low diversity of
terrestrial and marine life, it is a wonder that Henderson was occupied in
the first place. I maintain that it is only within the regional context of
southeast Polynesia (defined here as the islands of the Pitcairn Group and
Mangareva) that the colonization and settlement of Henderson can be
understood.
Four questions will be addressed in this paper: (1) When was Henderson
settled? (2) Where was the source of the colonists? (3) How did people
subsist and what effects did they have on the pristine island? (4)Why was
Henderson abandoned after at least 600 years of occupation? Where relevant,
data from archaeological investigations of other islands in the Pitcairn Group
will be presented. First, it is important to describe the setting that awaited
the first colonists of Henderson.
HENDERSON ISLAND: CONSTRAINTS TO HUMAN HABITATION
Henderson is not only marginal for habitation in terms of its distance to
high volcanic islands which display a greater range of resources, but the
island lacks many of the conditions that could foster a thriving human
population over long periods of time. The details of the island’s natural
history have been described in various papers in this volume. Here, however,
I draw attention to the geological, and terrestrial and marine resource base
that constrained human habitation.
The geographic isolation of Henderson, as well as its position in reference
to prevailing winds and ocean currents, were key determinants in the kinds
of plants and animals that could arrive and flourish. So too for human
populations that navigated the waters and sailed into the dominant southeast
tradewinds from Mangareva and points west (Irwin, 1992). Once humans set
foot on Henderson, they found a landscape with ready-made shelters in the
form of uplifted, wave-cut notches that were used for human habitation as
well as for burials.
The rapid uplift history of Henderson only provided sufficient time for
the formation of narrow beaches along the north and east coasts, and small
pocket-beaches at the northwest margin. The North Beach, in the lee of 33 m
high cliffs that encircle the island, provided the best protection from the
often intense southeast tradewinds, while the south has sheer cliffs with
difficult access from the sea. Only one narrow reef passage, less than about
HENDERSON ISLAND PREHISTORY
379
3 m across, is located at each of the beaches, and is best negotiated during
calm conditions at high tide.
Situated at the extreme margin of the Indo-West Pacific biotic province
(Kay, 1984), Henderson’s marine fauna is depauperate and is reflected in the
low diversity of edible molluscs and fish. Important gastropods are Turbo
spp. and secondarily, Neritu spp., CeZlunu sp., and Putelloidea sp. Useful
bivalves are limited to Triducnu and Isognomon which also provided raw
material for adze and fishhook manufacture, respectively. Inshore fish provided
the bulk of marine-based protein in the human diet and included species in
the families of Acanthuridae, Carangidae, Kuhliidae, Labridae, Serranidae
and Lutjanidae. The green sea turtle (CheZoniu mydas) nests on all the beaches
from January to March, and is most numerous on the east coast; this was
an important seasonally abundant resource.
Elevated limestone islands such as Henderson have characteristically poor
soils and only support a limited range of plant species. Pockets of soil with
high humus content are located near the northern and eastern plateau
margins, while a large swale in the northeast section of the island contains
the largest expanse of arable land. This area was probably the one used for
cultivation of potatoes during historic times (Maude, 1951: 63).
Rainfall approaches 1700 mm annually, but its pattern is unpredictable
from one month to another making gardening ventures a risky proposition.
Despite these constraints, the Polynesian introduced shrub ( Cordyline fiuticosu)
is found along the east, north, and northwest margins of the plateau and,
in some instances, marks prehistoric gardening locales. Pundunus tectoris
dominates the inland community and provides leaves that were used for
plaiting matts, thatching for house construction, and edible fruits and aerial
roots-the latter of little food value. The coastal community also included
isolated trees of Cordiu subcordutu and small stands of Thespesiu populneu that
were valued commodities for house construction and for fuel. The Polynesian
introduced candlenut tree (Aleurites rnoluccunu) was reported on Henderson in
1912 and 1922 (Paulay & Spencer, 1989: I I ) , but today the endocarps are
only found in prehistoric habitation deposits. The modern impacts to
Henderson’s flora are predominantly in the form of harvesting wood by
the Pitcairners for carving curios. Targeted species are miro (Thespesiu
populneu) and tou (Cordiu subcordutu), the removal of which appears to
have favoured the vigorous growth of pandanus within the inland coastal
community.
Sea birds are undoubtedly the most important terrestrial food resource on
Henderson where gadfly petrels (Pterodromu spp.) are the most abundant.
Young, flightless chicks from nesting colonies, especially on the north margin
of the plateau, were easy prey for human inhabitants. Other sea birds, such
as boobies (Sulu spp.), frigates (Fregutu minor), fairy terns (Gygis ulbu), and
red-tail tropicbirds (Phuethon rubricaudu), are found along the coasts and
augmented prehistoric human diets, but were of secondary importance. Of
the four endemic land birds, the Henderson rail (Pormnu utru), lory ( K n i
stepheni), and fruit dove (Ptilinopus insularis) provided food-and in the case
of the latter two species-brightly coloured feathers. Introduced by the
Polynesians, the Pacific rat (Ruttus exulum) is a significant predator of gadfly
petrel chicks (Weisler et al. 1991; Brooke, 1995).
380
M. I. WEISLER
THE ARCHAEOLOGICAL LANDSCAPE
Henderson
Henderson is truly a marginal environment in terms of sustainable marine
and terrestrial resources and in its physical landscape. While I do not argue
a strict ‘environmental determinst’ paradigm, one cannot overlook the obvious
limitations posed by narrow coastal flats, habitation areas with difficult access
from the sea and by overland routes, and an island interior with thick shrubs
covering a sharp, limestone karst topography. Among Polynesian settlement
patterns, Henderson is unique for its near total absence of a ‘built environment’
for the island lies within East Polynesia where the size and architectural
variability of domestic, religious, and agricultural features reached their
greatest complexity (e.g. Bellwood, 1979; Green, 1970; Kirch, 1984). On
Henderson, however, built architecture is very limited. Unfortunately, there
is no other environmentally similar Polynesian settlement pattern to contrast
with Henderson. Makatea Island (148’15’W and 15”50’S), in the Tuamotus,
would be interesting to compare, but no archaeological research has been
qonducted there. At this time, the archaeological landscape of Henderson
provides one of the only examples of a near-complete settlement pattern
survey of a resource-poor, ecologically-marginal tropical Polynesian island.
The archaeological research programme was conducted over two field
seasons that lasted a total of 5 months. The survey objectives of the initial
field season, conducted from 1 March to 5 May 1991, were to survey the
coastal areas with transects into the rugged interior, while during portions of
the second season, 1 January to 13 March 1992, the coastal survey was
completed on the East Beach and extended to the south end. The results
are summarized below by broad formal site classes that include: rockshelters
and caves, a coastal midden, gardening areas, and architectural sites.
A rockshelter is defined here as a natural cavity with its width greater
than depth; caves are deeper than they are wide. They both must be large
enough for a person to enter. All inhabited rockshelters and caves on
Henderson are found within 50 m of the sea on all the coastlines. They
are, moreover, concentrated on the North and East Beaches with only one
on the south end and two at the West Beach (Fig. 1). Most rockshelters and
caves are the products of wave erosion where landforms were subsequently
uplifted, but only some can be labelled as ‘classic’ wave-cut notches. Other
cavities are formed within old reef spur and groove topography, or eroded
at the intersection of differentially cemented strata. Table 1 lists the area of
rockshelters and caves. In most cases, area is calculated as true floor area
and not simply the product of the greatest depth multiplied by the width.
Functionally, this formal class contains habitation locales, burial sites, and at
least one cave with a water drip that, if present prehistorically, was
undoubtedly used.
Only one coastal midden, located on the North Beach, was discovered
rather fortuitously during the survey. The site parallels the coast for c. 300 m
and is situated between the base of the cliffs and the beach crest. At the
base camp while excavating a latrine, kitchen refuse pit, and smaller holes
for stabilizing a table, Expedition personnel unknowingly uncovered subsurface
cultural deposits consisting of dark grey sediment with shellfish, bone and
HENDERSON ISLAND PREHISTORY
I
-19'
I
I
38 1
I
Young limestone unit
Majorlminor cliffs1
"F breaks
of slope
Ridge topography
(from aerial photography)
21'
128"20'W
19'
18'
Figure 1. Archaeological sites recorded on Henderson Island.
artefacts. This chance discovery gave increased impetus to an extensive
auguring programme that was planned for all beaches in areas where the
width of the coast and protection from high surf could permit habitation;
this precluded the North West Beach and many areas along the east coast
and strongly indicated that the North Beach was the primary settlement area
on the island.
M. I. WEISLER
382
TABT.E
1. Henderson Island archaeological sites
Site No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Function'
major habitation
burial/minor hab.
major habitation
minor habitation
major habitation
major habitation
minor habitation
major habitation
minor habitation
major habitation
major habitation
major habitation
minor habitation
burial
burial
burial
minor habitation
minor habitation
minor habitation
gardening area
minor habitation
minor habitation
gardening area
gardening area
minor habitation
minor habitation
gardening area
stone slab crypt
Area my
Mapped
Excavated
90
7.5
64
120
9900
115
37.5
40
20
37
225
182
12
28
15
25.5
17.5
18
12
400+
8.8
7.8
54+
40+
8
6
400+
1
' Major and minor habitation designations determined by the relative
density of surface artefacts and midden, and observations of subsurface
areas from crab burrows and erosional features.
Situated along the margins of the plateau above the rockshelters and caves
are relic stands of the Polynesian introduced ti plant (Cordyline fiuticosa). Ti
is propagated by cuttings of the stalk or root and was often planted near
dwellings in Polynesia (Buck, 1930: 548; Handy, 1940: 205); perhaps this
accounts for its close association with habitation sites on Henderson. It was
an extremely useful plant, providing leaves for clothing, wrapping food for
cooking, and roots with a sweet carbohydrate-rich food with medicinal value
(Buck, 1938: 211-212, 1944: 76; Handy, 1940; Malo, 1951; Merlin, 1989).
The lower rhizomes (tubers) of ti were often an emergency root crop in
Polynesia (Handy, 1940: 206; Merlin, 1989: 30) and may also account for
its extensive distribution on Henderson. It was also recovered from prehistoric
contexts in many archaeological sites on the island (Jon Hather, personal
communication). Left to flourish unattended, stands of ti could provide an
important caloric adjunct during periods of uncertain food resources.
Four suspected gardening areas were excavated: two on the eastern margin
of the plateau and two locales above habitation sites on the North Beach.
Sites HEN-20, 23, 24, and 27 in Figure 1 mark the locations of excavated
ti stands on Henderson. Suspected gardening areas were identified by relic
stands of ti growing above thick vegetation on the plateau. Once these areas
were cleared, soil pockets and stone clearing mounds were often found and
HENDERSON ISLAND PREHISTORY
3x3
are similar in appearance to dryland agricultural features in leeward regions
of the Hawaiian Islands and parts of New Zealand.
Unlike other Polynesian settlement patterns where the use of stone for
building domestic and religious structures and agricultural systems was carried
to remarkable limits, stones for building domestic structures on Henderson
was limited to only four examples. A low stacked wall was erected
perpendicular to the prevailing tradewinds at the south coast rockshelter to
provide protection from the elements. At the North Beach midden, slabs of
beachrock formed a pavement as part of a domestic structure. At the seaward
edge of the vegetation line at the North Beach, six beachrock slabs were
used to form a rectangular vault, possibly for a secondary burial. Similar
vault features have been reported from Temoe, Mangareva (Emory, 1939:
44). Additionally, stone clearance mounds have been identified at gardening
areas on the North and East Beaches and are simply the product of increasing
gardening space and perhaps creating windbreaks. The limited use of building
stones on Henderson is not surprising given the general paucity and poor
quality of material. Cobble and boulder-sized stones are scattered on the
plateau as erosional products of uplifted reef detritus. The best building
stones and densest concentrations near habitation sites were observed along
the edge of the plateau above the East Beach just north of HEN-23. Although
few architectural sites were constructed, there was ample rock there to build
fishing shrines or other religious sites, especially considering the expansive
views from this portion of the island.
In sum, the settlement pattern of Henderson reflects the environmental
constraints imposed by the narrow beaches, distribution of habitable caves
and rockshelters, and limited pockets of arable soil. Every cave and rockshelter
that could support human habitation was use prehistorically.
Pitcairn
All archaeologists have been impressed with the quantity of flaked stone
artefacts found throughout Pitcairn Island, thus evoking claims by some that
Pitcairn was a ‘quarry island’. In this scenario, the island was visited
repeatedly by different groups for fashioning adze preforms for return to
their home island. This may, however, simply be a result of a small island
having a large accessible quarry that was extensively utilized. One can
imagine other quarries in Samoa, Hawaii, or the Marquesas that would
suggest similar claims if these islands were of diminutive size. Furthermore,
the archaeological evidence of intensive habitation is found throughout the
island where any reasonably flat land contains prehistoric habitation remains.
Settlements are concentrated at Adamstown and Tedside, while the relatively
level central region of the island-at
Flatlands, Taro Ground, and Aute
Valley-has deep soil and was undoubtedly the productive core of the
island (Fig. 2). Although timber resources were probably more extensive
prehistorically, tree crops, such as breadfruit, are found today at Tedside and
Adamstown reflecting current as well as recent historic use. This pattern
may, indeed, have some antiquity as the gulches that drain the central region
issuing at Down Fence and Bounty Bay have deep layers of silt with
dispersed charcoal suggesting upland burning for agricultural clearance.
384
M. I. WEISLER
Figure 2. Archaeological sites on Pitcairn Island. Intensive prehistoric habitation areas are
located at Adamstown and Tedside.
Pitcairn is surrounded by rocky, steep coastlines where the small embayment
at West Harbor provides the only safe landing; a major habitation and stoneworking site is located just inland at Water Valley. This may have been a
convenient place to bring fine-grained basalt adze preforms from the Tautama
quarry for finishing and grinding. Other important stone resources include
the volcanic glass deposits at Down Rope; scoria for abrading tools is located
at Jinser Valley and Red Hole (Fig. 2). Despite its small size, Pitcairn had
the best stone-tool resources in the region and was a source of cultivated
foods and probably large trees for canoe making.
Ducie
The most isolated island in the Pitcairn Group, Ducie has not been
archaeologically investigated although it is unlikely that it has any prehistoric
cultural deposits. The small islands of this low atoll lie unprotected from
seasonal storms that could scour and remove deposits. With its lack of fresh
water and edible plants, and extreme isolation, only small migrant groups
could have been sustained on the bountiful marine resources. The presence
of the Pacific rat (Rattus exuluns) suggests that Ducie was visited prehistorically.
Oeno
With the assistance of Graham Wragg, Oeno Atoll was surveyed during
four days in April, 1992. Transects were walked across the island, while the
HENDERSON ISLAND PREHISTORY
:w
wave-cut perimeter was inspected for buried cultural deposits. Shovel tests
were excavated throughout the island, but no cultural deposits were located.
Only a small beachrock cairn was discovered near the high water mark and
excavation produced no other cultural material or confirmation of its age.
From discussions with the Pitcairners-who visit the island regularly for short
durations-and examination of the coastal geomorphology, it is likely that
any prehistoric deposits would have been removed by shoreline erosion.
Summary
Despite its isolation from neighbouring islands, the Pitcairn Group has a
broad range of archaeological sites exemplifying human adaption to
ecologically marginal environments. That as much evidence of human use is
extant on Henderson and Pitcairn attests to the ability of prehistoric
Polynesians to withstand these harsh conditions such as unpredictable rainfall,
limited soils, rugged terrain, narrow reefs, and low species diversity.
PREHISTORIC POLYNESIAN OCCUPATION
The objectives of the first season were to test excavate a range of site
classes (e.g. caves and rockshelters, coastal midden and suspected gardening
area) in order to determine the depth and complexity of the cultural deposits,
collect datable material to determine the occupation span, and sample cultural
content. These preliminary excavations totalled 5.5 m' and, although limited
in areal extent, provided a solid basis for designing the strategy of the
second season. These latter objectives included: (1) excavations at the largest
and oldest habitation site, the coastal midden located at the North Beach;
(2) expanded excavations at some rockshelters and further subsurface sampling
of sites on all the coasts; and (3) determination of the areal extent of burning
for prehistoric agricultural practices by excavation of gardening sites on the
north and east plateau associated with major habitation areas. Additionally,
larger subsurface samples were needed to collect imported artefacts, Polynesian
introduced subfossil plant remains, and bones of extinct birds, all associated
within clear datable contexts.
All cultural deposits were excavated stratigraphically with thicker layers
divided into 5 cm levels for finer vertical control. Most layers were drysieved through 6.4 mm mesh, while 3.2 mm and 1.6 mm mesh were used
for additional sampling. Especially at HEN-1, wet sieving with 6.4 mm and
3.2 mm mesh was necessary to process exceptionally dark cultural layers
where sediment adhered to abundant cultural material.
The summary results of the site excavations, totalling nearly 42 m2 from
the two seasons, are described below by site class, while the portable artefacts
and other cultural material are presented in following sections.
Rockshelters and caues
A total of ten rockshelter and cave sites were excavated from all the
coasts totalling c. 24 m' (Fig. 3). The interior surface of most sites consisted
of scattered shellfish, bones, shell artefacts, and various pieces of wood. At
386
M. I. WEISLER
Figure 3. Prehistoric cave habitation (HEN-1) on Henderson’s north coast. Note excavated
area to the right of centre.
sites with frequent water drips, moist conditions produced a green mould on
the ceilings, walls and surface objects. In some cases, circular depressions up
to 1 m in diameter revealed-after excavation-subsurface earth ovens, while
smaller, oblong pits were made by nesting seabirds (e.g. Pterodroma spp.).
Thickness of cultural deposits ranged from 10 cm to c. 65 cm. Consisting
of loose, calcareous sediments, the deposits were easily excavated with a
trowel. In fact, the top 15 cm of some sites contained so much organic
matter that mere walking on the site surface depressed the ground up to 8
cm (Fig. 4). Subsurface features included small scoop hearths, larger earth
ovens associated with abundant charcoal and beachrock oven stones, Isognomon
pearl shell fishhook and Tridacna adze manufacturing activity areas.
Coastal midden
Situated along the north coast at the most protected beach of Henderson
is a large coastal midden measuring 9900 m2. It is probably no coincidence
that the Expedition’s main base camp was located precisely on top of an
intensively used portion of the site. This locale provided easy access to the
reef passage and protection from the prevailing tradewinds on one of the
widest sections of the beach. The entire site is covered with sterile, windblown
sand and is not visible from the surface. Preliminary work was completed
during the first field season (Weisler, 1994a: 88) and subsequent intensive
investigations included excavation of 1 m2 units placed at 50 m intervals
near the base of the cliffs parallel to the coast. Situated perpendicular to this
transect (i.e. north-south), additional units were spaced every 25 m from the
base of the cliffs towards the beach. In total, 16 m2 and numerous auger
holes were required to define the limits of the site.
HENDERSON ISLAND PREHISTORY
3x7
Figure 4. Stratigraphy of HEN-10, unit 1, west sidewall. Note the thin, discrete cultural layers.
The hearth visible in the lower profile yielded a radiocarbon age AD 1280-1430 (calibrated,
see Table 2).
The stratigraphy consisted of very loose, calcareous sediments with varying
amounts of shellfish, bone and artefacts to a maximum depth of about
85 cm. Unlike the rockshelters where thin lenses and multiple cultural layers
were the rule (see Fig. 4), the coastal midden displayed primarily one thick,
dark cultural layer grading to grey, then into the sterile, white subsoil.
Features included scoop hearths, earth ovens, post holes, refuse dumps, a
flat beachrock pavement, and a basalt adze working area. A large array of
imported materials was encountered: basalt flakes, adze preforms and finished
specimens; Pinctada pearl shell fishhooks and worked shell; and volcanic
oven stones. The largest number of bones from the extinct pigeon (Ducula
new sp.) were recovered.
The duration of site occupation is a key issue in Henderson archaeology
for it is important to decipher whether the island was occupied seasonally
for short periods of time, or if there was a permanent resident population.
In this regard, the presence of postmoulds associated with a beachrock
pavement suggests a substantial structure and some order of long-term
habitation, rather than site visitation for short durations. The sheer size of
the coastal midden, approaching 10000 m2, rivals the size of sites found on
high volcanic islands throughout the Pacific. The notion of long-term
habitation-for at least some habitation sites on Henderson-is strengthened
further by the identification of gardening sites that are discussed below.
Gardening sites
Four gardening locales were excavated: two each on the north and east
edges of the plateau. The nature of gardening practices implies some order
of longer-term occupation since crops such as sweet potato (Ipomoea sp.) or
388
M. I. WEISLER
Cordyline fiuticosa would require months to mature. These sites were initially
discovered after observing stands of the Polynesian introduced shrub ( Cordyline).
Subsequently, the densely vegetated areas surrounding the Cordyline stands
were cleared, thus revealing soil pockets between bedrock outcrops and
several stone mounds resulting from expanding the cultivated area. Test
excavations were conducted to determine soil depth and collect dispersed
charcoal for radiocarbon dating. Subsurface dispersed charcoal was found at
all gardening sites. It is assumed that charcoal found in this depositional
context results from burning the area; this is an effective technique of
removing unwanted vegetation prior to planting cultigens.
An AMS date from HEN-23 on the east plateau suggests that widespread
burning was initiated as early as AD 1174 (see Table 2). It is likely that the
plateau areas adjacent to major habitation sites-especially those which
currently support stands of Cordylin+were burned repeatedly during the
human occupation of the island.
CVPt
A small beachrock stone slab crypt (HEN-28) was discovered just below
the vegetation line on the North Beach after a recent cyclone. It measures
1.05 m by 0.51 m and 0.60 m deep and excavation revealed only a sterile
sandy matrix. These structures often contain human burials as seen recently
on Temoe (see also Emory, 1939).
Chronology
The prehistoric settlement of Henderson and Pitcairn was part of the
concluding chapter in the colonization of the hundreds of islands spanning
the vast Pacific ocean. Dating sites in the Pitcairn Group could inform on
the probable periods of settlement of islands to the west, such as Mangareva
and the Tuamotu archipelagoes, where little archaeological research has been
published (but see Weisler, in press). Consequently, the dating of initial
settlement of Henderson could determine the rate of colonization for the
southeastern Pacific in addition to anchoring the cultural-historical sequence
of the island.
Table 2 presents all the archaeological radiocarbon samples for the Pitcairn
Group including four samples processed by previous investigators (Schubel
& Steadman, 1989; Sinoto, 1983). The 29 samples processed as part of the
Expedition-and those of Schubel & Steadman (1989)-were analysed by
Beta Analytic Inc., Miami, Florida. After extraction of rootlets the samples
were given alternate acid, alkali, acid soakings to remove carbonates and
humic acids. The following benzene syntheses and counting proceeded
normally. Calibration ages reported are the extreme ranges at two standard
deviations using Stuiver & Reimer (1993) for conventional radiocarbon age
determinations (Stuiver & Polach, 1977), and rounded to the nearest 10 years
for samples with standard deviations greater than 50 years (Stuiver & Reimer,
1993).
Figure 5 illustrates the Henderson radiocarbon age determinations plotted
as the oldest range at two sigma by century. While Table 2 lists the specific
HENDERSON ISLAND PREHISTORY
389
TABLE
2. Archaeological radiocarbon age determinations for the Pitcairn Group
Lab No.'
______
Pitcairn
1-5629
1-5630
B-62940
B-62937
Henderson
B-45596
B-45603
B-59005
B-25244
B-59983
1-6344
B-59008
B-62261
B-59013
B-45599
B-59984
B-59985
B-45601
B-45598
1-6343
B-590 15
B-45600
B-25245
B-59001
B-45602
B-59009
B-59003
B-59010
B-59014
B-59007
B-62939
B-590 12
B-62941
B-62938
B-45597
B-59011
Provenience'
Conventional
I4C Age3
cal B P
~~
Adamstown
Adamstown
Water Valley
Down Fence
5-013
11-1/10
5-514
8-surface
1-1/10
1-base of 3
5-1614
23-112
11-2/5
3-213
5-1/12
5-1116
10-116
3-211
1-top of 2
21-112
10-111
8-11.1-.3 m
1-112
11-1/3
6-114
5-116
6-119
11-612
5-1414
12-213
8-415
7-111
22-1/2
20-112
8-111
cal AD3
~
~-
615+ 105
5902 105
180550
140+70
703-470
700-470
303-0
300-0
1220-1480
1250-1480
1647- 1955
1650- 1955
1120+50
970_+60
940 5 80
870 70
840+ 100
790+ 110
710+70
700 & 90
700 f 50
670 5 60
660+110
630 f 90
630 60
570+60
495 105
450 f 70
450 80
400 k 60
400 _+ 70
400 f80
380 f50
380 f 70
360 f 40
360 f50
330 + 60
310+50
290 f 60
270+50
270+ 70
200 k 55
170+60
1170-929
970-740
1050-670
950-670
950-560
930-540
740-540
776-529
705-555
690-540
790-510
730-510
670-520
660-5 10
660-304
620-310
620-3 10
540-300
540-300
540-290
5 17-302
540-290
509-302
513-297
5 10-0
501-0
500-0
460-0
500-0
420-0
310-0
780- 1021
980-1210
900-1280
1110-1290
1000-1390
1020- 1410
1210-1 4 10
1174-1421
1245- 1395
1260-1410
1160-1440
1220-1440
1280- 1430
1290-1440
1290- 1650
1330- 1640
1330-1650
1420- 1650
1410-1650
1410- 1660
1433-1648
1420- 1660
1441- 1648
1437-1 653
1440- 1950
1449-1952
1450- 1950
1490- 1954
1450- 1950
1530-1950
1645- 1955
+
+
+
+
'B-25244 and B-25245 (Schubel & Steadman, 1989); 1-6343 and 1-6344 probably not corrected
for '3C/12C(Sinoto, 1983).
Site-unit/level unless otherwise stated.
3Conventional radiocarbon age after Stuiver & Polach (1977).
4Calculated at two sigma and rounded to the nearest 10 years for samples with a standard
deviation greater than 50 years using method A (Stuiver & Reimer, 1993).
calibrated ages, this plot demonstrates the general nature and trend of the
occupational sequence. I have argued elsewhere that colonization of Henderson
may have been as early as the 8th century AD by citing the maximum
range of the oldest sample (Weisler et al. 1991; Weisler 1993a, 1994a). Based
on basal dates from HEN-5 and 11-from
the north and east coasts,
respectively-colonization of Henderson clearly took place by AD 1050,
although settlement perhaps two centuries earlier would not be unreasonable.
During the next 500 years, all the coasts evidenced some nature of occupation,
whether sporadic or permanent, and there is a constant increase in population.
The largest dip in the curve seen in Figure 5 reflects the fact that samples
M. I. WEISLER
390
Frequency
6
I
Inferred
4 /
4
0
700
A
,
1
I
1
I
1
800
900
1000
1100
1200
1300
1400
1500
1600
1700AD
Figure 5. Frequency of Henderson radiocarbon age determinations and cessation of voyaging
noted by the change from imported to locally produced artefacts. The dip at AD 1300
reflects the age of samples selected from the basal and top layers of sites. Samples plotted
at the oldest range at two sigma by century.
for dating were selected from the basal and top or terminal cultural layer
from most excavated sites. Consequently, the dip reflects a lack of samples
and not a decrease in prehistoric occupation. Regardless of how the
radiocarbon corpus is manipulated by calibration programmes and illustrative
plots, human occupation of Henderson spanned six centuries beginning by
at least c. AD 1050.
As a footnote, radiocarbon dating for the settlement of Pitcairn is still a
matter of speculation. The oldest dates thus far suggest occupation by the
13th century AD (Table 2). Given the better conditions for human habitation
on Pitcairn-stone resources, especially permanent water, excellent soils, and
a greater possibility for food production-the island should have an occupation
span that rivals Henderson.
SIX CENTURIES OF HUMAN ADAPTATION O N HENDERSON
The adaptation to Henderson’s restricted range of resources is most telling
in the kinds and frequency of artefacts manufactured and used during more
than 600 years of occupation. The inventory of the Henderson artefactsnumbering more than lfi00 to date-is in progress and detailed analyses will
be presented elsewhere. Here, however, I describe the major artefact classes
in reference to the historical sequence of Henderson’s occupation.
Fishhooks
Numerous fishhooks, both finished forms and unfinished specimens, were
found at most habitation sites (Fig. 6). Rotating forms were most numerous,
while a single jabbing hook was recovered (Weisler, 1994a: 92). The fishhooks
from the earliest part of the sequence were made from imported Pinctada
marguritzfra, probably from Mangareva where the largest stocks of this species
HENDERSON ISLAND PREHISTORY
39 1
-
0
5 cm
Figure 6. Henderson pearl shell fishhooks. Top two rows made from imported pinctada, while
specimens in the third row are made of local Isognomon. Bottom row illustrates some of the
stages in Isognomon fishhook manufacture.
are found. These hooks also share stylistic dimensions with some Mangarevan
fishhooks (Green, 1960). Made from locally available Isognomon valves, these
fishhooks were recovered from the latter part of the Henderson sequence,
Figure 6, bottom row, illustrates some of the stages in the manufacture of
these specimens.
Worked pearl shell
Resulting from the manufacture of fishhooks, worked pearl shell is found
throughout the Henderson sequence. Pinctada was found only in the lower
and earliest deposits and suggested some fishhooks were manufactured locally
with imported material. Isognomon pearl shell is most numerous towards the
M. I. WEISLER
302
E
G
6
-
0
cm
Figure 7. Flaked stone artefacts from Henderson. A-D, volcanic glass flakes and cores; E,
limestone flake; F, basalt awl (arrow points to used tip); G, basalt adze with broken cutting
edge; H, basalt adze preform; I, Triducnu adze preform.
end of Henderson’s occupation and demonstrates an adaptation to this species
with small valves.
Basalt adzes
Fine-grained volcanic rock is an important raw material for adze
manufacturing because of its conchoidal fracturing properties and the ability
of the stone to be honed to a sharp cutting edge. Specimens included
finished forms of quadrangular cross-section (Fig. 7G), a common style during
HENDERSON ISLAND PREHISTORY
393
late prehistory in Polynesia. Several complete cutting edges were also found
attesting to adze use and discard. These artefacts were recovered from the
first few hundred years of the sequence. Geochemical analysis documents
the Tautama, Pitcairn basalt quarry as the source of all of these artefacts.
Tridacna adzes
This artefact class appears late in the Henderson sequence and demonstrates
an adaptation to a restricted range of raw materials. Included here are
finished adzes as well as blanks and preforms. They are made from valves
of the Tridacna maxima clam which rarely exceeds 25 cm long (measured
posterior to anterior). Consequently, the thickest portion of the valve at the
hinge was used. The dorsal fold of exceptionally large valves was also
utilized.
Tridacna valves were available from three sources on Henderson: (1) as
fossilized specimens from the plateau; (2) valves removed from beachrock
deposits; and (3) as fresh specimens or recent beach wash-ups (Weisler,
1994a). With 200000+ years of weathering, it is unlikely that fossil shells
were utilized. These shells are characteristically light and bear evidence of
weathering pits rendering them useless for adzes. It is more likely that valves
removed from beachrock deposits, live specimens, and recent wash-ups were
the preferred raw material. Thin-section analysis may confirm raw material
source (Moir, 1990).
Basalt adze preforms
These artefacts are significant in that they indicate that unfinished tools
were brought from Pitcairn to Henderson for final grinding and sharpening.
The products of a flake reduction strategy, these artefacts are generally small
and quadrangular in cross-section (Fig. 7H).
Polished basalt Jlakes
This artefact class results either from spalls that are removed from the
cutting edge of the adze during use and are relatively small and thin, or
larger specimens that are often the by-products of reworking adzes that have
been broken or require edge preparation and resharpening. All of these
artefacts originated from Tautama, Pitcairn except one that may be from an
unknown source in Mangareva (Weisler, 1993a: 225).
Unmodijied jlakes
The most numerous of the volcanic artefacts, unmodified basalt flakes are
the by-products of manufacturing adzes from basalt cores, adze blanks and
preforms. Some primary flakes exhibit the cortex or original weathered
surface of the stone. Consequently, most manufacturing stages of basalt adzes
are represented on Henderson from cores to finished adzes and the resulting
unmodified basalt flakes. Large limestone flakes were occasionally found at
some habitation sites (Fig. 7E).
Basalt awl
A typical basalt awl is made from an expanding flake where one point
exhibits polishing from use against soft material such as wood (Fig. 7F).
394
M. I. WEISLER
While only a few of these artefacts were found on Henderson, they are
ubiquitous on Pitcairn.
Volcanic glass
Typically small sharp flakes used for delicate cutting tasks (Fig. 7A-D),
the volcanic glass from Henderson habitation sites is only found during the
first few hundred years of occupation. Geochemical analysis of 14 Henderson
artefacts and numerous volcanic glass sources throughout Polynesia point to
the Down Rope, Pitcairn quarry as the source of raw material (Weisler,
1993a: 238). The Down Rope source is an ignimbrite with characteristic
‘patches’ of welded grey and black glass. It is macroscopically identifiable
with pieces weighing as little as 0.1 g.
Ouen stones
These cobble-sized stones are heated and used for baking food in
underground ovens. Vesicular basalt rocks are most prized since they retain
heat longer and can be used repeatedly. The source of these stones was
Pitcairn as well as Mangareva. Beachrock, limestone, and Tridacna valves
were used exclusively during late prehistory when volcanic rock was no
longer available. This material fractures after heating and has a limited uselife. Consequently, they are found in abundance at most habitation sites.
Coral abraders
Used primarily for reducing and shaping pearl shell for fishhook
manufacture, abraders are grouped here according to cross-section: triangular
for grooving and cutting; rounded, oval, plano-convex and quadrangular for
shaping and smoothing (see illustrations in Weisler, 1994a: 96). The artefacts
were found throughout the sequence, but rounded forms seem to predominate
in late prehistory. The raw material was sub-rounded, tabular cobbles that
are readily found on all beaches, but are most numerous on the East Beach.
Miscellaneous prehistoric artefacts
A small cowry shell (Cypraea isabella) ground on the dorsum suggests use
as an ornament. Bird bone humeri were ground to a point for use as awls
and a single incised human tooth was an unusual find (all illustrated in
Weisler, 1994a: 92).
Historical artefacts
An assortment of glass bottles, metal fragments, a cork life preserver, a
ceramic fragment of a pot, and leather shoes and chaps were found as
surface finds at East Beach sites. This is precisely the side of the island
where 19th century sailing ships could get trapped against the prevailing
tradewinds and driven onto the reef. Two whole bottles were found at HEN10: one a square-sided case gin bottle and the other may have been used
to store kerosene; they date between 1820 to 1870.
HENDERSON ISLAND PREHISTORY
305
The vertebrate sample
The vertebrate sample from Henderson is the largest from southeast
Polynesia, containing in excess of 150000 bones from controlled, stratigraphic
excavations. I present here a general discussion of the remains while Wragg
provides further details of the avifauna (Wragg, 1995; see also Weisler, 1994:
96-97; Wragg & Weisler, 1994). Detailed analysis will be presented elsewhere.
The marine environment probably supplied the major portion of protein
to the diet of Henderson’s prehistoric inhabitants, although land birds, and
especially sea birds, provided an important source of food. Gadfly petrel
(Pterodroma spp.) colonies are located near the margin of the plateau near
several cave and rockshelter habitations on the north coast where flightless
chicks and nesting adults could have been easily caught. A petrel colony is
also located on the south end near a rockshelter that served, in part, as a
station for collecting these birds. Along with petrels, other sea birds recovered
from habitation sites included noddys (Anous spp.), shearwaters (Puflnus spp.),
red-tailed tropicbirds (Phaethon rubricauda), boobies (Sula dactylatra), frigatebirds
(Fregata minor), and fairy terns (Gygis alba).
Bones of Henderson’s four surviving endemic land birds were recovered
from many habitation sites. The brightly coloured feathers of the lory (Vini
stepheni) and fruit dove (Ptilinopus insularis) may have been important exchange
items from Henderson to residents of Pitcairn and Mangareva. The role of
the diminutive warbler (Acrocephalus vaughani) is less certain as a food item,
while the rail, or crake, (Porzana atra) is one of the few flightless species in
the eastern Pacific to survive prehistoric human predation.
Bird extinctions on Pacific islands have attracted much attention in recent
years (Anderson, 1989; Olson & James, 1982, 1984; Steadman, 1989) and
preliminary examination of the avian assemblages from Henderson adds
another important example of the role of humans in causing species
reductions. Although it is not a simple matter to identify the causes of
extinction events in the archaeological record (Weisler & Gargett, 1993),
several taxa disappeared from the prehistoric sequence during the human
habitation of Henderson suggesting that predation and habitat alteration may
have had negative effects on the following species: ground dove (Gallicolumba
new sp.), extinct pigeon (Ducula new sp.), Christmas shearwater (Puflnus
nativitatis), black-winged petrel (Pterodroma nigipennis), and the Polynesian
storm petrel (Nesofiegetta filiginosa) (Wragg & Weisler, 1994).
The most numerous of the vertebrate fauna were predictably those of fish
(Table 3 ) . As is true of most Pacific island assemblages, the inshore
species are well-represented and include bones of shark and possibly
rays (Elasmobranchii), Acanthuridae, Carangidae, Epinephelinae, Diodontidae,
Holocentridae, Kuhliidae, Labridae, Lutjanidae, Pomacentridae, Scaridae, and
Serranidae. In addition to the ‘special’ bones used for identification of tropical
Pacific fish (Leach, 1976), otoliths (Weisler, 199%) were also used permitting
nine species-level identifications: Abudefduf sordidus, Acanthurus leucopareius,
Adioryx adamanensis, Ephinephelus faciatus, E. tauvina, Kuhlia marginata, Lutjanus
bohar, Myripristis berndti, and Variola louti.
Sea turtles (Chelonia mydas) nest on all the beaches, but are most numerous
today on the east coast-precisely where their bones were found in greatest
numbers in the habitation sites (cf. Table 3). Indeed, HEN-11 is where turtles
M. I. WEISLER
3Y 6
T;\ici.e 3 . Bone midden from selected Henderson sites
Coast
Site
Unit
~
~~
~~
~~~
Taxon wt(gms)
Sea Turtle
(cf Chelonia mydas)
Plg
North
1
1
East
11
3
South
21
1
1,019 (23)
3,335 (76)
15
263(17)
1,298 (82)
20 (1)
1,376(8)
15,879 (90)
319 @)
159 (55)
126 (44)
2 (1)
4,369
1,58 1
17,574
287
~~
Taxon, ct(ll/o)
Bird
Fish
Pacific Rat
(Ratlus exulans)
Total
~
Northwest
8
3
~~
105
11.8
0
0.4
6.182.5
0
0
0
(Sus scroji)
All values rounded to the nearest whole number.
were probably taken when they came ashore to deposit eggs. Recovery of
turtle eggshell fragments from the cultural layers of HEN-11 documents use
of the site during the nesting months from January to March.
Bones of mammals from Henderson sites included Pacific rat (Rattus exulans)
and the first documentation of pig (Sus scrofa). Rat bones are found at most
sites, but are best recovered by screening the deposits with 3.2 mm mesh
or finer. Pig was found at several units from the coastal midden (HEN-5)
and one occurrence at HEN-1.
Human bones were collected from the surface of burial sites HEN-2 (North
Beach) and HEN-14 on the East Beach and as individual bones from
excavations at HEN-3, 5 and 6. Sara Collins (Bishop Museum, Honolulu)
calculated the minimum number of individuals from 98 bones that included:
10 adults more than 30 years of age (5 male, 4 female, 1 unknown); 3
young adults between the ages of 17-22 years (2 probably female, 1
unknown); and 4 children less than 10 years old, all of unknown sex. Many
of the bones were Mongoloid, possibly of Polynesian stock. Rebecca Cann
and associates are currently conducting mitochondria1 DNA analysis to
determine ancestry.
Molluscs
Twenty-seven taxa of marine molluscs were identified as food remains
from habitation sites. Table 4 presents the distribution of the top eight taxa
at selected sites, one from each of the coasts. Gastropods are dominant with
Turbo accounting for as much as 98% of shellfish weight at one site; other
univalves include Nerita, Patelloidea, Cellana, Cerithiidae and Drupa. With the
possible exception of Cerithiidae, these are all taxa commonly found in high
energy environments exposed to surge and wave-action along the nearshore.
Bivalves were represented by species that also served as raw material for
fishhook and adze manufacture: Isognomon and Pinctada, and Tridacna,
respectively.
Future analyses will include measurements of the ubiquitous Turbo to
determine if there is a reduction in size over time, implying human
HENDERSON ISLAND PREHISTORY
3!)7
T.wix 4. Shellfish midden from selected Henderson sites
Coast
Site
Unit
Northwest
East
North
6
8
3
South
21
10
1
1
~
1
~
Taxon: wt('io)
Cellana sp.
Cerithiidae
Drupa spp.
Haliotus sp.
Isognomon sp.
Nerita spp.
Patelloidea sp.
Turbo spp.
All others
Total
0
0
13 (4)
0
27 (8)
1
4
61 (17)
9 (3)
226 (64)
10 ( 3 )
3fi 1
11
8
25
5
54
7,141 (98)
28
7,272
4
418 (15)
73 (3)
3 (2)
0
0
0
0
3 (2)
0
6
42 (2)
7
2,191 (79)
35 ( I )
0
122 ( 9 5 )
0
128
2,776
Weight in grams. All other values rounded to the nearest whole number.
predation pressure. However, the distribution of Cerithiidae (mostly Cerithium
tuberculiferum) from at least one East Beach site appears to be an example
of over predation of these taxa that live in sand and coral detritus (Fig. 8).
While not an important food item, terrestrial gastropods inform on
prehistoric subsistence practices by indicating habitat disturbance from
widespread burning for land clearance and agricultural pursuits (Christensen
& Kirch, 1981, 1986) and documenting extinction events. Humanly transported
taxa can signal the arrival of introduced plants such as taro (Colocasia) that
arrive in the sediments packed around these important cultigens. Several
extinct taxa have been identified at the lower levels of HEN-6 (Richard
Preece, personal communication).
Subfossil plant remains
In addition to containing a large array of well-preserved bone and mollusc
remains, the dry and protected nature of Henderson's cave and rockshelter
sites provide ideal conditions for the preservation of floral material. In
collaboration with Jon Hather (University of London) three groups of plant
remains were collected from secure stratigraphic contexts for analysis: (1)
1000
2
100
.+
10
1
I
I
2
3
1
4
I
I
I
5
6
7
8
Layer
A
Cerithium
0
Turbo spp.
Figure 8. Distribution by layer of Cerithium and Turbo spp. marine molluscs from east coast
site HEN-10, unit 1, illustrating a possible case of over-predation.
398
M. I. WEISLER
uncharred and wood charcoal; (2) seeds and drupes; and (3) leaf matter. It
is planned to analyse the temporal distribution of taxa from at least one site
from each of the coasts. Analysis is in progress, but several observations can
be made. Important Polynesian plants introduced prehistorically to Henderson
included: candlenut (Aleurites) endocarps; Cordyline leaves; coconut ( Cocus
nucifera) wood, husk and endocarp; swamp taro ( Cyrtosperma chamissonis) leaves
whose identification extends the eastern limit of its distribution; banana (Musa
sp.) leaves; possibly taro (Colocasia) leaves, and Hibiscus wood. Whether
Pandanus was present on the island prior to human arrival is likely, but
certain varieties for plaiting may have been humanly transported; charred
drupes have been identified. Found associated with an earth oven, it is
interesting to note that a few leaves of Cordyline were found knotted, the
remains of a leaf bundle that is still a common practice for wrapping food
prior to baking in underground ovens.
Wood charcoal identifications are only complete for HEN-10 on the east
coast, but Tournefortia and the hardwood, Pemphis, were two taxa undoubtedly
used for fuel. Pandanus, Baringtonia, and Hernandia were also identified in
addition to the Gymnosperm, cf. Norfolk Island Pine (Araucaria heterophylla,)
which was probably utilized from a beached log. A few seeds of Nesoluma
were identified.
HUMAN IMPACTS TO ISLAND LANDSCAPES
One may begin by asking: are there any pristine islands left in the world?
If any island supported humans-whether
occupied currently or during
prehistory-then the answer is assuredly no. However, the more important
question is one of degree. That is, how pristine (or pure) are insular settings?
In this latter regard, Henderson stands alone as being the last ‘pristine’
elevated limestone island in the world (Fosberg, Sachet & Stoddart, 1983;
Wells &Jenkins, 1988). Despite this distinction, the landscape we see today
reflects more than 600 years of purposeful manipulation by Polynesians who
sought to transform Henderson into a habitable landscape.
The notion of ‘transported landscapes’ reflects the active pursuit of Pacific
islanders who introduced the compliment of plants and animals necessary to
sustain life as well as the purposeful transformation of the landscape. O n
Henderson, this included introducing such important cultigens as swamp taro
( Cyrtosperma chamissonis), banana (Musa sp.), ti (Cordyline fjuticosa), and possibly
taro (Colocasia sp.). Integral tree species that provided food, fuel, and raw
materials for structures and portable artefacts comprised coconut ( Cocos
nucifera), possibly the screw pine (Pandanus tectoris), miro (nespesia populnea),
tou (Cordia subcordata) and Hibiscus. The indirect transfer of some cultigens
may also be inferred from the presence of several species of anthropophilic
land snails that may have been inadvertently transported in the sediment
adhering to the roots of some plants (Kirch, 1984: 56). Identification of
Gastrocopta pediculus, Lamellidea oblonga, and Tornatellides oblungus may provide
important clues in this regard should they be documented from prehistoric
cultural deposits. The effect of the introduction of new plant species to
Henderson will never be known in precise terms. But we may speculate that
HENDERSON ISLAND PREHISTORY
399
changes were inevitable to the species composition of the coastal communities
where human habitation was concentrated.
That the Polynesians sought to transform their environment is further
documented by the evidence for large-scale burning of the northern and
eastern margins of the plateau immediately inland of habitation sites. Dates
from dispersed charcoal found amongst relic stands of Cordyline suggest that
burning for agricultural clearance was an important aspect of the subsistence
base. This may have affected the distribution and succession of plant taxa
as well as cause reduction in habitat for birds. The extinction and species
range reduction of birds throughout the Pacific has been attributed to burning
for swidden agriculture (Steadman, 1989). On Henderson, the extinction of
a pigeon (Ducula new sp.), ground dove (Gallicolumba new sp.), and range
reductions of the Christmas shearwater (Pu@nis nativitatis), black-winged petrel
(Pterodroma nigr$ennis), Polynesian storm petrel (Nesojkgetta filiginosa), and
Pacific swallow (Hirundo tuhitica) have been documented (Wragg & Weisler,
1994). In this latter regard, the prehistoric Polynesian introduction of the
Pacific rat (Rattus exulans) is a significant predator of gadfly petrel chicks
(Weisler et al., 1991; Brooke, 1995).
In addition to the introduction of plants, several pieces of pig (Sus scrofi)
bone were recovered from the major coastal midden and a rockshelter on
the north coast. It is unlikely, on present evidence to determine whether this
represents butchered food that was brought to the island, or a small extant
population that lived on Henderson. The need for water and ample fodder
suggests that few, if any, pigs would have survived without human intervention.
The terrestrial environment speaks of many changes over the past 600
years, but the effects of human predation on the marine fauna is also
suggested. The over-predation of the gastropod ( Cerithium tuberculiferum) is
documented in at least one East Beach site where it disappears completely
from the sequence. That this mollusc recovered after island abandonment is
attested to by its presence today.
We do not know, at present, the role of prehistoric sea turtle consumption
and how it may have effected the abundance of this species today. Are the
low numbers of nests recorded on the East Beach (Brooke, 1995) a reflection
of near decimation 500 years ago? Judging from evidence from other Pacific
islands, it is likely that Henderson’s human population would have taken full
advantage of this easily caught and seasonally plentiful resource, thus altering
population levels.
In summary, the evidence from the prehistoric human occupation of
Henderson strongly suggests that changes have occurred to the terrestrial as
well as marine environments. Both intentional and inadvertent plant and
animal introductions, habitat alteration through widespread burning on the
plateau margins and overpredation of molluscs, and possibly turtles and
birds, have, indeed, shaped the present richness and diversity of Henderson’s
biota.
LONG-DISTANCE INTERACTION
That ecologically marginal islands such as Henderson were occupied during
prehistoric times is a tribute to the colonization strategies employed by
400
M. I. WEISLER
Polynesians. However, the ability to sustain communities on isolated landfalls
is a complex issue that can be addressed by documenting the frequency,
scale and temporal duration of exotic artefacts imported to Henderson.
Despite the isolation of the Pitcairn Group, archaeological evidence documents
that at least Pitcairn and Henderson were part of a prehistoric interaction
sphere that included Mangareva.
Differences in natural resource distributions were often an inducement for
trade, exchange, and other forms of social interaction. Considering the
Pitcairn Group and Mangareva as a regional interaction sphere, certain
disparities exist in the resource base of each group. For example, the lagoon
at Mangareva contains the largest stocks of black-lipped pearl shell (Pznctudu
rnurguritiferu), a raw material used for fishhook manufacture, vegetable peelers,
and ornaments. Additionally, Mangareva would have been an important
source for cultigens and domesticated animals since these Polynesian
introductions were carried across the Pacific from west to east.
Fine-grained basalt has a limited distribution throughout the Pacific and
was a vital raw material for fashioning stone tools, especially adzes. Studies
of adze material in Polynesia have documented the movement of these
artefacts over distances exceeding 1000 km (Best et u l , 1992; Weisler, 1993a).
The largest source of fine-grained basalt is located at the Tautama quarry,
Pitcairn. Additionally, volcanic glass is also found nearby at Down Rope.
The islands of Henderson, Oeno, and Ducie provide excellent opportunities
to document imported volcanic artefacts since the exposed portions of the
islands are non-volcanic. In addition to fine-grained basalt and volcanic glass,
vesicular basalt oven stones could have been imported from either Pitcairn
or Mangareva.
With volcanic tools and pearl shell brought to Henderson, it, in turn,
could have supplied seasonally abundant turtles and brightly coloured feathers
in exchange. The latter would have been especially important during late
prehistory when bird stocks may have been at their lowest on Pitcairn and
Mangareva due to habitat alteration and predation by the highest human
population levels.
To determine the role of external contacts in sustaining communities on
Henderson, it was necessary to document the presence and source of exotic
artefacts. One hundred and eight volcanic artefacts were analysed by nondestructive energy dispersive x-ray fluorescence (EDXRF) and included adzes
in various stages of production, polished and unmodified flakes, and volcanic
glass flakes and cores, Additionally, 17 fire-altered vesicular basalt oven
stones were analysed by destructive wavelength x-ray fluorescence. For sample
preparation, equipment, and operating conditions see Weisler (1993a).
Figure 9 (upper) is a bivariate plot of selected unmodified basalt flakes
demonstrating that the Tautama quarry was the source of most of this
material. Within the quarry, chemical distinctions are made between Group
A and C; the latter where only a few artefacts derive. At least one flake
could have come originally from as yet an unknown source of Mangareva.
The bivariate plot of volcanic oven stones (Fig. 9, lower) illustrates the multiple sources of these artefacts from Pitcairn and Mangareva. Since no tholeiitic
volcanics exist on Pitcairn, all such rocks derive from Mangarevan sources.
Since much of the evidence of prehistoric interaction is in the form of
HENDERSON ISLAND PREHISTORY
40 1
90
GroupC A
m
80
0
e
Tautama, Pitcairn
70
0
2
a
Ha'a'upa'upa,
Marquesas
60
X
A
k
&
50
*
.
I
I
40
30
I
I
I
I
I
I
I
I
50
60
70
80
90 100 110
Nb/Sr x 1000
I
120
130
140
150
45
46
47
SiO,
50
51
52
8
7-
%
z
+
6-
Alkalic
5-
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b?
43-
43
44
48
49
Figure 9. Upper panel, bivariate plot of Henderson unmodified basalt flakes. Most artefacts
originated from the Tautama quarry, while a few may be from unknown Mangarevan sources.
Lower panel, bivariate plot of Henderson oven stones showing Pitcairn and Mangareva
sources.
perishable commodities (such as feathers, cultigens, pig and turtle meat, and
even marriage partners), volcanic artefacts are a powerful means to demonstrate
external contacts within the Pitcairn-Mangarevan region and throughout
Polynesia as well (Weisler, 199310). Sources of many of the Henderson
artefacts have been established and their temporal distribution on the island
suggests that voyaging between islands ceased sometime after AD 1450
(calibrated; Fig. 5).
CONCLUSION
It remains to be discussed why Henderson was abandoned after at least
600 years of human occupation. To answer this question, it is important, if
not vital, to examine Henderson within the context of southeast Polynesia.
As an ecologically-marginal and isolated island, Henderson, at initial
402
M. I. WEISLER
colonization, would have provided shores teaming with fish, and a landscape
with tens of thousands of easily caught sea birds. It is these very conditions
of abundance that prompted Anderson to suggest that one incentive for
human colonization of the Pacific was the eastern push to discover unoccupied
islands with unclaimed, abundant resources (Anderson, 1992). But, once
colonized, sustained human occupation of marginal landfalls would depend
on regular inter-island voyages that connected resource-poor islands such as
those of the Pitcairn Group, with high volcanic islands with more diverse
resources. That regular communication took place between Henderson, and
Pitcairn and Mangareva has been documented by the presence of imported
commodities such as pearl shell and volcanic artefacts from colonization to
about AD 1450. After that time, and until island abandonment some 200
years later, voyaging between islands ceased possibly due to events that took
place on Mangareva.
I have made the case elsewhere (Weisler, 1993a, 1994a) that during late
prehistory, Mangareva not only experienced its highest human population
levels, but coupled with a depleted resource base, could not continue to
support long-distance voyaging that required large ocean-going sailing vessels,
skilled crews, food supplies, and exchange commodities. By late prehistory,
swidden agricultural practices in Mangareva had caused massive slope erosion
reducing the possibility of sustaining important tree crops such as breadfruit,
and may have affected the number of large trees that could have been used
for canoe manufacture. This may have been why early historic visitors to
Mangareva noted the lack of canoes and use of only rafts (Beechey, 1831;
Buck, 1938).
Although the data are sketchy at best, a similar situation may have
developed on Pitcairn where massive episodes of landscape degradation have
been documented during late prehistory. The environmental crises on
Mangareva and Pitcairn would have precluded sustained and regular voyaging
between islands. With low population levels on Henderson, the communities
would have been more susceptible to environmental problems such as
unpredictable rainfall, prolonged drought, and storms that would prohibit
access to marine resources. Additionally, small populations would be more
prone to the effects of inbreeding and their ability to withstand diseases
(Williamson & Sabath, 1984).
The detailed archaeological study of Henderson provides a firm foundation
in which to understand the historical processes that have led to the biotic
diversity seen on the island today. The use of Henderson by the Pitcairners
to harvest wood for curio production is merely the current episode in the
use of this ecologically-marginal landfall, a process of settlement and
exploitation that began more than 800 years ago.
ACKNOWLEDGEMENTS
A project of this size and duration owes much to many people, and I am
sure I will miss mentioning a few here. First, I thank the organizers (Michael
Brooke, Tim Benton and Tom Spencer) for their invitation to join such a
broadly represented, interdisciplinary Expedition. In the field, gratitude is
extended to my archaeological assistants: Neal Oppen, Michelle Langer, Liz
Senear, and especially Chino Lewis and Mandy Merklein on Henderson;
HENDERSON ISLAND PREHISTORY
403
and on Pitcairn, Glen Buffett, Adon Butterfield, and Mary Pavicich. Graham
Wragg assisted during portions of the survey and excavations as well.
Financial support for analysing the archaeological collections and some travel
was provided by the Wenner-Gren Foundation for Anthropological Research,
Inc., and the Stahl Foundation and Robert H. Lowie Scholarship at the
University of California, Berkeley. Travel to the Linnean Society meeting
and funds for dating some radiocarbon samples were provided by the
Expedition. Collaborations with various specialists were justly rewarding: Jon
Hather (University of London), subfossil plant remains; Sara L. Collins
(Bishop Museum, Honolulu) for analysis of human bones; Graham Wragg
(Oxford University), bird bone identifications; Alan Ziegler (consultant,
Honolulu, Hawaii) identifications of rat and turtle bones; and Judith Ogden,
artefact illustrations. I thank also Peter Gathercole and Yosi Sinoto for
enjoyable discussions on Pitcairn and Henderson archaeology and for
providing copies of their field notes. At the University of California, Berkeley:
Patrick V. Kirch, Kent Lightfoot (Anthropology Department) and Ian S. E.
Carmichael and Tim Teague (Geology Department) assisted in various stages
of the research. And, of course, anyone who has had the memorable
experience of landing on this remote speck of land could only approximate
an adequate thanks to the people of Pitcairn.
My visits to the islands as part of the Sir Peter Scott Commemorative
Expedition were generously supported by the following major sponsors: The
Royal Society, International Council for Bird Preservation, British
Ornithologists’ Union, J. A. Shirley, Foreign & Commonwealth Office UK,
UNESCO; all other sponsors are acknowledged in the expedition report of
1992. This is paper 53 of the Sir Peter Scott Commemorative Expedition to
the Pitcairn Islands.
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