Investigating the timing and consequences of Pleistocene megafaunal population collapse in the Neotropics

在最后一个冰河时代结束时，也就是15000年前，美洲有许多种大型哺乳动物（更新世巨型动物），它们比现在的塞伦盖蒂更多样化。大约在那个时候，它们很快就灭绝了。关于为什么大型猫科动物、大象、马、骆驼和地懒等动物突然消失，存在很多争议。一些科学家将其归咎于气候变化，而另一些则归咎于人类猎人的到来。在过去的几年里，古生态学家开发了一种新的方法来研究这些灭绝的哺乳动物的数量波动：他们计算很久以前产生的微小孢子，这些孢子只在大量的粪便上生长，现在保存在湖泊沉积物中。这些孢子在沉积物岩心中的突然消失是更新世巨型动物消失的一个很好的指示。在这项提案中，科学家们将调查巴拿马、巴西和秘鲁等地巨型动物数量下降的时间，并将它们与过去气候变化的非常详细的记录以及考古记录进行比较。通过这样做，科学家将能够确定是气候变化还是人类的到来最有可能导致了大灭绝。最后一次冰河期的结束是最近的一次，当时气候变暖的速度几乎与现代条件下一样快，降水制度也存在巨大的不稳定性。调查灭绝事件与气候突变之间的潜在联系与现代关注的问题明显相关。观察一下，如果有的话，气候变化在几千年前引发了人口减少或恢复，这对农业政策和保护产生了影响。同样，确定过去600万年中最大的哺乳动物灭绝事件是否可以归咎于人类行为，与我们如何看待我们与自然世界的关系有关。最后，该项目将训练学生在古生态学和制作材料传播给广大观众。

At the end of the last ice age, 15,000 years ago, the Americas had many species large mammals (Pleistocene megafauna) that were more diverse than those of the modern Serengeti. About that time, they quickly became extinct. There is much controversy about why animals such as big cats, elephants, horses, camels and ground sloths suddenly disappeared. Some scientists blame climate change, while others blame the arrival of human hunters. In the last few years, paleoecologists have developed a new way to investigate the population fluctuations of these extinct mammals: they count microscopic spores that were produced long ago, grew only on large amounts of dung, and are now preserved in lake sediments. The sudden disappearance of these spores in sediment cores is an excellent indicator of the disappearance of the Pleistocene megafauna. In this proposal, scientists will investigate the timing of the megafaunal population decline at sites in Panama, Brazil and Peru, and compare them with very detailed records of past climate change, and with the archaeological record. By doing so, scientists will be able to determine if climate change or the arrival of humans most likely caused the mass extinction.The end of the last ice age was the most recent time when climates warmed almost as rapidly as under modern conditions, and there was huge instability in precipitation regimes. Investigating the potential link between extinction events and abrupt climate change has clear relevance to modern concerns. To observe which, if any, climate changes triggered population reductions or recoveries thousands of years ago, has repercussions for agricultural policy as well as conservation. Similarly, establishing whether the largest mammalian extinction event in the last 6 million years can be assigned to human actions is relevant to how we perceive our relationship to the natural world. Finally, the project will train students in paleoecology and produce materials for dissemination to large audiences.