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By Root 2054 0

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 gradually 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 moisture content, lower maximum soil temperatures during the day, higher minimum soil temperatures at night, and higher yields for every one of 16 plant species grown—four times higher yields averaged over the 16 species, and 50 times higher yields of the species most benefited by the mulch. Those are enormous advantages.

Chris Stevenson interprets his surveys as documenting the spread of rock-assisted intensive agriculture on Easter. For about the first 500 years of Polynesian occupation, in his view, farmers remained in the lowlands within a few miles of the coast, in order to be closer to freshwater sources and fishing and shellfishing opportunities. The first evidence for rock gardens that he can discern appears around A.D. 1300, in higher-elevation inland areas that have the advantage of higher rainfall than coastal areas but cooler temperatures (mitigated by the use of dark rocks to raise soil temperatures). Much of Easter’s interior was converted into rock gardens. Interestingly, it seems clear that farmers themselves didn’t live in the interior, because there are remains of only small numbers of commoners’ houses there, lacking chicken houses and with only small ovens and garbage piles. Instead, there are scattered elite-type houses, evidently for resident upper-class managers who ran the extensive rock gardens as large-scale plantations (not as individual family gardens) to produce surplus food for the chiefs’ labor force, while all the peasants continued to live near the coast and walked back and forth several miles inland each day. Roads five yards wide with stone edges, running between the uplands and the coast, may mark the routes of those daily commutes. Probably the upland plantations did not require year-round effort: the peasants just had to march up and plant taro and other root crops in the spring, then return later in the year for the harvest.

As elsewhere in Polynesia, traditional Easter Island society was divided into chiefs and commoners. To archaeologists today, the difference is obvious from remains of the different houses of the two groups. Chiefs and members of the elite lived in houses termed hare paenga, in the shape of a long and slender upside-down canoe, typically around 40 feet long (in one case, 310 feet), not more than 10 feet wide, and curved at the ends. The house’s walls and roof (corresponding to the canoe’s inverted hull) were of three layers of thatch, but the floor was outlined by neatly cut and fitted foundation stones of basalt. Especially the curved and beveled stones at each end were difficult to make, prized, and stolen back and forth between rival clans. In front of many hare paenga was a stone-paved terrace. Hare paenga were built in the 200-yard-broad coastal strip, 6 to 10 of them at each major site, immediately inland of the site’s platform bearing the statues. In contrast, houses of commoners were relegated to locations farther inland, were smaller, and were associated each with its own chicken house, oven, stone garden circle, and garbage pit—utilitarian structures banned by religious tapu from the coastal zone containing the platforms and the beautiful hare paenga.

Both oral traditions preserved by the islanders, and archaeological