Abrupt climate change and its influences on hominin evolution during the early Pleistocene in the Turkana Basin, Kenya
Abrupt climate change and its influences on hominin evolution during the early Pleistocene in the Turkana Basin, Kenya
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DOI：
10.1016/j.quascirev.2020.106531
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发表时间：
2020-10
影响因子：
4
通讯作者：
R. Lupien;J. Russell;M. Grove;C. Beck;C. Feibel;A. Cohen
中科院分区：
文献类型：
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作者：
R. Lupien;J. Russell;M. Grove;C. Beck;C. Feibel;A. Cohen
人们假设气候的快速变化在古人类的进化中发挥着重要作用，但我们对短时间尺度的上里奥-更新世气候变化的了解还很有限。在这里，我们利用肯尼亚西图尔卡纳的湖泊沉积物，根据叶蜡生物标志物氢同位素比率 (δDwax) 重建了百年尺度的降水。我们分析了具有不同轨道配置（分别为 0.043 和 0.025 偏心率）的两个时间间隔（∼1.72 和 ∼1.60 Ma），以研究季节性日照强迫对高频气候变率和气候转变速率的影响。我们的数据表明，在夏季日照较低的情况下，千禧年尺度的气候变率会更强，这会导致高纬度冰川作用和热带非洲干旱。这表明，在已经极端的环境条件下，古人类可能被迫应对气候变化的加剧。此外，我们观察到在高振幅进动尺度日照变化下，不到 200 年的时间里，气候条件从干旱条件迅速转变为潮湿条件。这种转变的速率与非洲湿润期开始的一些代理记录中观察到的速率相似，表明图尔卡纳盆地对逐渐日照强迫的高度敏感性。这种突然的气候变化可能会引发古人类普遍行为特征的进化选择。
Rapid climate variability has been hypothesized to play an important role in hominin evolution, yet our knowledge of Plio-Pleistocene climate change on short timescales is poor. Here, we developed centennial-scale reconstructions of precipitation from leaf wax biomarker hydrogen isotope ratios (δDwax) using lacustrine sediment from West Turkana, Kenya. We analyzed two time intervals (∼1.72 and ∼1.60 Ma) with different orbital configurations (0.043 and 0.025 eccentricity, respectively) to examine the influence of seasonal insolation forcing on high-frequency climate variability and the rates of climate transitions. Our data indicate that under low summer insolation, which should induce high latitude glaciation and tropical African aridity, millennial-scale climate variability was stronger. This suggests that hominins may have been forced to contend with increased climate variability during already extreme environmental conditions. Additionally, we observe a rapid shift from arid to humid conditions occurring in less than 200 years under high-amplitude precessional-scale insolation change. The rate of this transition is similar to that observed in some proxy records of the onset of the African Humid Period, indicating high sensitivity to gradual insolation forcing in the Turkana Basin. Such abrupt climate changes could induce evolutionary selection for generalist behavioral traits in hominins.