Page 109 - Encyclopedia Of World History Vol IV

1410 berkshire encyclopedia of world history

historical observations show that more complex rigs, in- Faunal Devastation
cluding the lateen sail with its fixed mast, halyards, and When colonists reached uninhabited islands,they broached
balance boards, were only reaching the Central Pacific in ancient and fragile ecosystems with devastating results.
the seventeenth and eighteenth centuries, long after the The scale of the assault was realized as early as 1843
colonization of East and South Polynesia, it can be hy- when remains of extinct giant birds (moa) were found in
pothesized that the New Zealand rig was used through- Maori middens. Evidence of anthropogenic change has
out Remote Oceanic colonization. continued to accumulate ever since. Extinction of terres-
Although quite simple, this rig could be repaired at sea trial vertebrates is widely documented. Large flightless
and set in high- or low-aspect shapes. It avoided the mas- birds became extinct in Pleistocene New Ireland. The
sive stresses on gear, especially on fragile pandanus sails giant megapode, or brush fowl; a land crocodile, Meko-
of windward sailing, and it could be demounted instantly suchus inexpectatus; and a giant horned tortoise disap-
in high winds or squalls. However, sailing with this rig peared in New Caledonia, and the giant iguana and
must have been relatively slow and highly dependent on megapode in Tonga. Recent research shows that numer-
fair winds. The question then arises of how the settle- ous species disappeared with the arrival of people in Fiji.
ment of Remote Oceania was achieved by vessels that These included another land crocodile, Volia athollander-
could not sail into the prevailing trade winds. soni; a giant iguana and tortoise; a giant frog; two large
Westerly winds occur briefly but frequently so they megapode species; another giant megapode, Megavi-
cannot explain the long pauses in the colonizing se- tiornis altirostris; and a giant flightless pigeon, similar to
quence. However, there was also long-term variation in the dodo. In New Zealand nearly forty species of birds,
the frequency of westerly winds of El Niño origin. Proxy including thirteen species of moas, disappeared.This rep-
measures of the frequency and intensity of El Niño con- resents a 50 percent decline in the number of bird taxa
ditions, including long-term records of loess production breeding on the mainland, and similar losses were sus-
in China, of changes in ocean circulation, and of sedi- tained on Hawaii and elsewhere in East Polynesia, from
ment deposition in lakes, indicate that El Niño frequen- the central archipelagos to the margins. Extinctions oc-
cies were unusually high about 3000 BCE, 1400–500 curred rapidly, although perhaps not as quickly on large
BCE, 400–900 CE, and 1100–1700 CE. Dispersal out of islands as the fifty years after human colonization pre-
Southeast Asia, the Lapita expansion, and movement into ferred for moa extinction in one scenario. As well as ex-
East Polynesia approximate this pattern. They were all tinction, there was also depletion and range contraction
largely west-to-east movements. East-to-west movements among other taxa. Some seal species occur in the earli-
into Central Micronesia and to South Polynesia occurred est archaeological sites in subtropical Polynesia, but by
at intervening periods during the “normal” pattern of the eighteenth century, they were found only in New Zea-
trade wind dominance. In summary, migration in land, where their breeding ranges had contracted almost
Remote Oceania may have been restricted to downwind to the subantarctic under hunting pressure.
sailing at slow average speeds on long passages. Suc- These data show that faunal collapse in Remote Ocea-
cessful voyaging would have been significantly more dif- nia was rapid and early.The typical pattern is for remains
ficult, with much lower rates of success than is envisaged of extinct taxa to be found in sites that date to the initial
in traditionalist and neotraditionalist hypotheses. It was century or two of human settlement and thereafter to be
probably undertaken uncommonly at times when winds absent. Extinction, at least among the larger-bodied taxa,
were predominantly adverse, but occasional significant was density-independent, that is, small human popula-
episodes of frequent wind reversals would have provided tions of widely varying density distribution could still
conditions that enhanced the probability of colonizing devastate indigenous faunas very quickly. In addition, it
success toward the east. is now clear that the process was virtually universal. So