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

在15,000年前的上一个冰河时代末期，美洲有许多种类的大型哺乳动物(更新世巨型动物)，它们比现代塞伦盖蒂的物种更加多样化。大约在那个时候，它们很快就灭绝了。关于大型猫科动物、大象、马、骆驼和地懒等动物为什么突然消失，存在很大争议。一些科学家将其归咎于气候变化，而另一些科学家则将其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种群波动：他们计算了很久以前产生的微小孢子，这些孢子只在大量的粪便中生长，现在保存在湖泊沉积物中。这些孢子在沉积岩心中的突然消失是更新世大型动物消失的一个很好的标志。在这项提案中，科学家们将调查巴拿马、巴西和秘鲁遗址中大型动物种群数量下降的时间，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，科学家们将能够确定气候变化或人类的到来是否最有可能导致大灭绝。上一次冰河时代的结束是最近一次，气候变暖的速度几乎与现代条件下一样快，降水制度存在巨大的不稳定性。研究物种灭绝事件和气候突然变化之间的潜在联系，显然与现代关注的问题有关。观察几千年前哪些气候变化引发了人口减少或恢复，这对农业政策和保护都有影响。同样，确定过去600万年来最大的哺乳动物灭绝事件是否可以归因于人类的行为，与我们如何看待我们与自然界的关系有关。最后，该项目将对学生进行古生态学方面的培训，并制作材料供广大观众传播。

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.