Burning Bush. Stephen J. Pyne

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СКАЧАТЬ ambulatory weed, a species nurtured in the Pleistocene, a torch-carrying pyrophile—was well adapted. Of all creatures humans were prepared to survive in a disturbed environment, and humans became in turn a contributing disturbance. Whether the Aborigine hunted megafauna to extinction, or whether he burned away critical environments, or whether he favored some species who subsequently outcompeted rivals, or whether he only hastened an irrevocable decline driven by distant sunspots and Milankovitch wobbles in the Earth’s orbit, he was an important, an unprecedented presence. While his hunting mimicked other carnivores and his torch mimicked lightning fire, the rapidity, the purposes, and the scale of those actions made his abrupt arrival new and troubling. The Aborigine did not move passively into niches vacated by climatic extinction: some of those niches he created and others he actively sustained. As Josephine Flood argues, “the weight of circumstantial evidence favors human hunters as the decisive factor” in the revolution that was Pleistocene Australia.¹⁴

      The interpretation of prehistoric fire history is anchored by two deep sediment cores. One comes from Lynch’s Crater on the eastern coast of Cape York Peninsula; the other, from Lake George in the tablelands of New South Wales. The Lynch’s Crater sequence dates back 140,000 years. During glacial maxima, scleroforest advanced somewhat on rainforest and charcoal lightly laced the preserved pollen. Then, around 40,000 years ago, the charcoal content abruptly increased tenfold and rainforest elements melted away before scleroforest. Thereafter, the charcoal content shrank to a lower, steadier level, then peaked after the last glacial maximum (c. 20,000 years ago). It disappeared when, after relentlessly wet conditions were reestablished, rainforest reclaimed the site around 8,000 years ago.¹⁵

      The Lake George core dates back 350,000 years. Steppe grassland typified the glacial maxima, while Casuarina woodland characterized the interglacials. There is some charcoal preserved in the interglacial sediments, but around 130,000 years ago the oscillation ends; charcoal content quadruples; scleroforest, with a heavy eucalypt component, dominates the biota, resisting the climatic pressures to submerge the site under rainforest. A steady rhythm of burning persists unchanged into the Holocene. The overall quantity of preserved charcoal rises slightly. It is clear that ignition is now chronic, that the large amplitudes in the preserved charcoal contents signify droughts that allowed average fires to become extensive. It is suggested that the sudden magnification of burning prior to the last interglacial represents anthropogenic firing. If so, it is the earliest record of human presence in Australia—and an isolated artifact. More reasonable is the persistence of burning throughout the last glacial epoch, through wet and dry periods both, a regularity for which natural causes are an unlikely explanation.¹⁶

      Other evidence testifies to remarkable changes around the whole continent at about 40,000 years ago. There are preserved hearths at Devil’s Lair in the southwest, at Lake Mungo in western New South Wales, and at Keilor in Victoria—all of which date from 38,000 to 32,000 years ago. Many hearth sites from around the continent date to around 20,000 years ago. Among indirect, geomorphic evidence there are charcoal-laden deposits (“red alluvium”) laid down by streams along the Darling Scarp that date to 37,000–28,000 years ago; charcoal lenses washed into the Koonalda Cave of the Nullarbor Plain, probably around 30,000–20,000 years ago; charcoal, silt, even charred wood deposited along the Darling and Lachlan drainages of the southeast around 21,000 years ago. In Tasmania even uplands were occupied and fired by 20,000 years ago and held in partial defiance of a returning interglacial climate. A major resurgence of burning and destabilized soils materializes around 7,000 ago; it is speculated that new lands, more heavily forested, were being opened to exploitation and burning. With the onset of roughly contemporary climate conditions around 6,000 years ago, that pattern of chronic firing, broken occasionally by drought-borne conflagrations, continues. Whatever else happened in Old Australia—whatever processes contributed to the extermination of its megafauna—anthropogenic fire was on the scene. If it did not contribute to the wave of extinction, it did reshape the environment in ways that made a megafaunal reconquest unlikely.

      The subtlety and universality of anthropogenic fire makes it difficult to evaluate. There is no way to avoid its presence in Pleistocene Australia, yet there is no way to assess its full impact. Perhaps it is enough to say that anthropogenic fire was there, that it was ubiquitous, that it was capable of interacting with the rest of the Australian environment in ways that no other human implement could. It made the environment after the arrival of Homo fundamentally different from that which existed prior to Homo. Whether or not Aborigines actively destroyed megafauna or the megafaunal habitat through the use of fire, they certainly changed the conditions by which that environment could be repopulated. They changed the rules of the game. They made it impossible for the old species to regroup and reclaim their old niches. The Aboriginal firestick may well have been the smoking gun of Pleistocene extinctions.

      It has often been observed that in Australia, unlike its closest analogue, America, no new megafauna replaced those that were lost. But this is not quite true: the versatile, omnivorous Homo seized those niches—not in one locale, but across the whole spectrum of Old Australia; not a single biota, but all of them. A variety of human cultures replaced the variety of Pleistocene creatures. Some forty species of megafauna were lost, but some seven hundred tribes of Aborigines, organized into perhaps two hundred linguistic groups, took their place. The specificity of their differences was fantastic; it is said that a tribe on one side of Sydney Harbor could not communicate with a tribe on the other. Once humans moved in, once anthropogenic fire was established, they were difficult to dislodge. In the new regime some creatures would thrive, and some would suffer. Their relationship to Homo—and to anthropogenic fire—would determine much of their relative standing. “The land the English settled was not as God made it,” archaeologist Sylvia Hallam concluded. “It was as the Aborigines made it.”¹⁷

      Increasingly, as climate stabilized to roughly its present conditions around 6,000 years ago, human history drove natural history. The isolation of Australia discouraged other biotic invaders. Some new anthropogenic elements apparently intruded around 4,000 years ago, but otherwise Aboriginal existence was remarkably stable. Only other humans could dislodge what humans had fashioned. That did not occur until European colonization, which set in motion a biotic revolution that swept across Aboriginal Australia as the Pleistocene had Old Australia. Apart from outright extinctions, there was a profound restructuring of habitats such that indigenes, including the Aborigine, found it all but impossible to reoccupy old sites. Inevitably, fire was a vital catalyst. Once more it became for humans a point of entry, a tool of landscape modification, a weapon of interspecific (and intercultural) warfare. The history of this second invasion, as of the first, is one equally illuminated by fire and obscured by smoke.

       “THIS THEIR PLACE OF DWELLING WAS ONLY A FIRE”

      With uncanny mimicry, the genus Homo recapitulated the experience of the genus Eucalyptus. From an origin in other environments, humans adapted to the unique circumstances of Old Australia. Their total numbers were never extraordinary, but the specificity of their adaptations was astonishing. Societies of small endogamous clans favored genetic drift; their physical variability remained high. In effect, they became sclermorphs, discovering cultural equivalents to sclerophylly. With language the Aborigine possessed a means by which information and experience could be stored outside genetic codes. With nomadism, Aborigines could exploit the various resources made available at different places and at different times, overcoming the nutrient impoverishment or aridity of particular sites. With fire, the Aborigine could manipulate the dynamics of entire biotas.¹⁸

      Like the eucalypts, Aborigines were uniquely indigenous to Australia. Genetic marker studies suggest that Aborigines have no close affinities with other human groups. The closest affinities—and they are based on traits that date back to very early origins—are to Southeast Asian and Melanesian peoples. Rather, the Australians developed in Australia. If they did not receive fresh genetic stock from outside sources, neither did they export their own. Until Europeans arrived, the isolation of Aboriginal Australia was almost total: nothing came in, and nothing left. Early colonization by the Aborigines СКАЧАТЬ