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In the last few decades, advances in understanding and modeling climate have paralleled the growth of an impressive log of radiocarbon dates and quantitative analyses of climatic indicators including pollen, tree rings, and lake levels. At the same time, archeological research has given us an impressive assemblage of cultural information. We also have the tools for sorting out the diverse sources of variance in our datasets. The time has come to begin to integrate these lines of scientific endeavor to produce a mutually coherent picture of at least one of the mechanisms that have affected the history of humankind, and one that undoubtedly will affect the future as well.  相似文献   

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Sea change     
Williams N 《Current biology : CB》2007,17(11):R392-R393
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《Physiologia plantarum》1992,85(3):A79-A81
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Explicit density-dependence differs from density-vagueness in the sort of regulation imposed on populations. Explicit density-dependence implies regulation toward a central equilibrium point, whereas density-vagueness implies population change away from the two extremes of extinction and immense densities. Density-vagueness does not much concern regulation within the broad range of medial densities; it is 'liberal'.  相似文献   

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