ABSTRACT

Human migration in response to past climate change has been recorded globally. The pastoralist Todas are believed to have colonised the higher elevations (>2000 m asl) of the Nilgiris, Western Ghats, India, after ∼2000 cal. yr BP. During the late Quaternary, climate-induced vegetation shifts in tropical montane forest-grassland mosaic of the Nilgiris have been well-documented using stable carbon isotopes and pollen, but there have been no corresponding investigations of human activity. We used several proxies to infer the human ecology of this region. Radiocarbon-dated (∼22,000 cal. yr BP to the present) peat from Sandynallah (2200 m asl) was used to reconstruct fire history, animal abundance, and human presence since the Last Glacial Maximum (LGM). While macro-charcoal records fires at the LGM, macro- and micro-charcoal indicate intense fire at ∼3500 cal. yr BP, coprophilous fungal spores indicate abundant herbivorous mammals, n-alkane signatures point to arid grassland vegetation, and steroid biomarkers show human faecal remains for the first time. We infer that a pastoralist people, most likely the Todas, migrated to the montane Nilgiris along with their buffaloes in response to prolonged or abrupt climate change in peninsular India ∼3500 cal yr BP or ~1500 years prior to what historical accounts assume.

摘要

全球范围内都记录了为应对过去的气候变化而进行的人类迁移。据信，大约 2000 cal 之后，牧民 Todas 已经在印度西高止山脉的尼尔吉里斯 (Nilgiris) 的高海拔地区 (>2000 m asl) 定居。年血压。在第四纪晚期，尼尔吉里斯热带山地森林-草原马赛克中气候引起的植被变化已使用稳定的碳同位素和花粉得到充分记录，但没有对人类活动进行相应的调查。我们使用了几个代理来推断该地区的人类生态。Sandynallah（海拔 2200 米）的放射性碳年代测定法（距今约 22,000 cal. yr BP）泥炭被用于重建自末次盛冰期 (LGM) 以来的火灾历史、动物丰度和人类存在。当 LGM 上的大型木炭记录火时，宏观和微观木炭表明约 3500 cal 的强烈火灾。yr BP，粪便真菌孢子表明有大量食草哺乳动物，正烷烃特征指向干旱的草地植被，类固醇生物标志物首次显示人类粪便遗骸。我们推断，一个游牧民族，很可能是托达人，随着印度半岛长期或突然的气候变化，与他们的水牛一起迁移到尼尔吉里斯山区，时间比历史记载假设的时间早约 3500 cal yr BP 或约 1500 年。