By the 1950s, when sociocultural anthropologists first began studying the peoples who inhabited the Central Highlands of New Guinea, they recognized that most of these densely populated communities subsisted on sweet potatoes (Ipomoea batatas). The problem this presented was the fact that sweet potatoes were a New World crop from South America. Short of some early trans-Pacific contact between Melanesia and South America, these sweet potatoes must have reached Melanesia sometime after Magellan’s voyage in 1519-20. James B. Watson suggested that the arrival of sweet potatoes had triggered a revolution in the highlands that brought these communities from hunting to horticulture in a few centuries. Watson assumed that lowland and coastal peoples in New Guinea may have long had horticulture involving taro and other crops, but proposed that introduction of sweet potatoes had led to an ‘Ipo-moean revolution’, leading to rapid growth of populations and population densities in the highlands as well as development of intensive exchange networks.
Excavations at Kuk plantation in the Western Highlands by Golson and his colleagues led to discovery of early drainage ditches in what had been a swampy area in the Western Highlands as early as 10 000 BP. Golson also found evidence of an early digging stick in one of these ditches, suggesting that millennia before the arrival of the sweet potato, New Guinea Highlanders were cultivating root crops such as taro. What makes this site so important archaeologically is Kuk was essentially isolated in the middle of the New Guinea highlands from and independent of other centers of agricultural evolution in China, the Indus valley, the fertile crescent, and the
Nile. Moreover, unlike these other areas at Kuk early inhabitants depended on root crops - and perhaps tree crops - rather than cereal grains.
Brookfield and White had also challenged Watson’s model arguing for a much longer and more gradual evolution of horticulture than the later had envisioned. More recent excavations at Kuk suggest that the transition from foraging to horticulture was a complex process extending over several thousand years. Denham and his colleagues find early cultivation at 10 000 BP, mounding appears about 7000 BP, and full blown network of drainage ditches from beginning around 4400 BP. They have also documented domestication of bananas at Kuk about 7000 BP. (Kuk has also been nominated as a World Heritage Site.)
Susan Bulmer’s excavations at Kiowa in the Western Highlands and White’s excavations at Kafiavana in the Eastern Highlands produced pig bones with carbon dates of 5000-6000 BP, suggesting that pigs were introduced to the island from Southeast Asia through human agency. The low intensity of pig husbandry found in many parts of New Guinea makes it difficult to determine whether such early pigs were feral or domesticated. Even today in the Western Province, the domestic pig herds are heavily interbred with the feral herds, since domestic boars are gelded. But if taro and other root crops were being grown in the highlands, there is no reason to discount the possibility that some of this production was used to domesticate a semiferal herd from an early date.
Golson and his colleagues accepted the Ipomoean Revolution as having important consequences for agriculture, pig husbandry, exchange systems, and rapid population growth, along some of the lines Watson had suggested. But they have demonstrated that the shift from hunting to horticulture had begun nearly 10 000 years earlier than Watson had imagined. The key feature of the Ipomoean revolution was that sweet potatoes grow much faster than taro and provided much greater yields, thereby allowing more food for both human and pig populations, which lead to human population densities more than 500 per km2 in some areas and the emergence intensified horticulture, production of surpluses, and coordinated exchange systems of thousands of pigs in the Te and Moka exchange networks that swept through the highlands valleys.
Another likely consequence of agricultural intensification in the New Guinea highlands was the creation of vast anthropogenic grasslands first suggested by Harold Brookfield and developed more systematically by Geoffrey Hope and J. M. B. Smith. More recent advances in palynology and residue analysis have confirmed that the expansion of grasslands as linked to the intensification of horticulture, but much of this expansion has arisen over the past millennium or so.
In a similar way, current studies have focused attention on tree crops as an important aspect of early plant domestication. Arboriculture was probably far more important in the lowland rainforests than archaeologists had previously believed. Cultural anthropologists have come to recognize that sago, the most important lowland crop, is tended and weeded in a very nonintensive way to produce greater yields and to speed up or slow down the timing of maturation. Other tree crops such as breadfruit, pandanus, galip, and other fruits and nuts are often planted and minimally tended, yet they yield important edible products for a generation or more.
Such studies have emerged primarily in the lowlands and coastal areas once archaeologists recognized that the landscapes we see today are fairly recent phenomena. Swadling had noted that when sea levels rose after the last glacial maximum it produced a huge bay in what is now the Sepik and Ramu Rivers. But silt from the mountains over the past 6000 years has filled in this bay to produce the current coastline. Similarly, Terrell has suggested that what now appears as a long straight shoreline at Aitape was once a complex series of islands and lagoons complete with a rich array of food resources. Kyle Latinis has argued that in such environments trees likely played a much more important role than other cultigens. Andrew Fairbairn has built on these studies and those at Kuk to suggest the need for more intensive archaeobotanical methods to understand the evolution of horticulture and plant use in Melanesia.
World History
