Southeast Asia has emerged as an important region for understanding hominin and mammalian migrations and extinctions. High-profile discoveries have shown that Southeast Asia has been home to at least five members of the genus Homo1-3. Considerable turnover in Pleistocene megafauna has previously been linked with these hominins or with climate change4, although the region is often left out of discussions of megafauna extinctions. In the traditional hominin evolutionary core of Africa, attempts to establish the environmental context of hominin evolution and its association with faunal changes have long been informed by stable isotope methodologies5,6. However, such studies have largely been neglected in Southeast Asia. Here we present a large-scale dataset of stable isotope data for Southeast Asian mammals that spans the Quaternary period. Our results demonstrate that the forests of the Early Pleistocene had given way to savannahs by the Middle Pleistocene, which led to the spread of grazers and extinction of browsers-although geochronological limitations mean that not all samples can be resolved to glacial or interglacial periods. Savannahs retreated by the Late Pleistocene and had completely disappeared by the Holocene epoch, when they were replaced by highly stratified closed-canopy rainforest. This resulted in the ascendency of rainforest-adapted species as well as Homo sapiens-which has a unique adaptive plasticity among hominins-at the expense of savannah and woodland specialists, including Homo erectus. At present, megafauna are restricted to rainforests and are severely threatened by anthropogenic deforestation.

中文翻译：

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东南亚巨型动物和人类灭绝的环境驱动因素

东南亚已成为了解人类和哺乳动物迁徙和灭绝的重要地区。备受瞩目的发现表明，东南亚至少有五个 Homo1-3 属成员。更新世巨型动物群的大量周转以前与这些古人类或气候变化有关4，尽管该地区经常被排除在巨型动物群灭绝的讨论之外。在非洲传统的古人类进化核心中，建立古人类进化的环境背景及其与动物群变化的关联的尝试长期以来一直受到稳定同位素方法学的影响5, 6。然而，此类研究在东南亚很大程度上被忽视了。在这里，我们展示了跨越第四纪的东南亚哺乳动物稳定同位素数据的大规模数据集。我们的研究结果表明，早更新世的森林已经让位于中更新世的稀树草原，这导致了食草动物的传播和浏览器的灭绝——尽管地质年代学上的限制意味着并非所有的样本都可以解析到冰期或间冰期。大草原在晚更新世后退，到全新世完全消失，取而代之的是高度分层的封闭冠层雨林。这导致了适应雨林的物种以及智人（在人类中具有独特的适应性可塑性）的优势，而牺牲了热带草原和林地专家，包括直立人。目前，巨型动物仅限于热带雨林，并受到人为砍伐森林的严重威胁。