Human Interaction with North American Pleistocene Proboscideans

在美国国家科学基金会的支持下，费舍尔博士将研究一系列猛犸象和乳齿象的牙本质纹层，它们生活在大约12,000到10,000年前的北美。费舍尔博士之前的工作表明，这些物种的象牙和面颊牙齿显示出记录个体生活史细节的牙本质薄片。连续的层压顺序代表每年一次、每两周一次和每天一次的牙本质增生周期。对这些模式的分析得出了季节性死亡率、年龄、性别、生长率、性成熟年龄和产犊的数据。这些因素对动物遭受的生态压力的性质和程度很敏感，并显示出对改变的营养状态和/或捕食压力做出反应的可预测模式。有了这样的数据，费舍尔博士将在这两个物种灭绝之前量化它们的生活史踪迹。他将把结果与一系列环境中现存大象的数据进行比较。在此基础上，他将确定导致猛犸象和乳齿象在更新世末期灭绝的因素。众所周知，在上一个冰河世纪的末期，北美的许多动物物种灭绝了。虽然这一事实是毋庸置疑的，但原因尚未确定。虽然一些科学家认为，环境变化本身就是罪魁祸首，但另一些科学家指出，这些重大灭绝似乎与北美人类狩猎群体的出现相吻合，并认为过度狩猎导致了它们的灭绝。他认为，费舍尔博士将收集的数据可以区分这些可能的原因。这项研究之所以重要，有几个原因。它将为古人类学家提供对史前人类行为和生存模式的洞察。它还将阐明人类捕食、环境交换和物种灭绝之间的关系，这是一个当今具有重大意义的问题。

With National Science Foundation support Dr. Fisher will study tusk dentin laminations in a series of mammoths and mastodonts which lived between ca. 12,000 and 10,000 years ago in North America. Prior work by Dr. Fisher has shown that the tusks and cheek teeth of these species exhibit dentinal laminations that record details of individual life history. Successive orders of lamination represent annual, fortnightly and daily cycles in accreted dentin. Analyses of these patterns yield data on seasonal mortality, age, sex, growth rates, age at sexual maturity and calving. These factors are sensitive to the nature and degree of ecological stress to which the animal had been subjected and demonstrate predictable patterns of response to altered nutritional status and/or predation pressure. With such data Dr. Fisher will quantify these life history trails for the two species just before their time of extinction. He will compare the results with data from extant elephants from a range of environments. On this basis he will determine the factors which led to the extinction of mammoths and mastodonts at the end of the Pleistocene. It has long been known that the end of the last Ice Age saw the extinction of many species of animals in North America. While this fact is undisputed the cause has yet to be determined. While some scientists argue that environmental change alone is responsible, others note that these major extinctions seem to coincide with the appearance of human hunter gathers in North America and believe that overhunting led to their demise. The data Dr. Fisher will collect allows, he believes, for a distinction between these possible causes. This research is important for several reasons. It will provide paleoanthropologists with insight into prehistoric human behavior and subsistence patterns. It will also shed light on the relationships between human predation, environmental exchange and species extinction, a problem of major significance today.