Human responses to hydroclimate fluctuations over the last 200 kyr in Ethiopia
Authors: Schäbitz Frank , Foerster Verena , Asrat Asfawossen , Cohen Andrew S. , Chapot Melissa S. , Dean Jonathan R. , Deino Alan , Deocampo Daniel M. , Duesing Walter , Günter Christina , Junginger Annett , Kaboth-Bahr Stefanie , Lamb Henry F. , Lane Christine , Leng Melanie J. , Opitz Stefan , Lupien Rachel , Roberts Helen M. , Bronk Ramsey Christopher , Rusell James ,   HSPDP and CRC806 Science team
Published: March 2020

&lt;p&gt;&lt;span&gt;Humans &lt;/span&gt;&lt;span&gt;have been adapting to more demanding habitats in the course of their evolutionary history&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;span&gt;Nevertheless&lt;/span&gt;&lt;span&gt;, environmental changes coupled with overpopulation naturally limit competition for resources. In order to find such limits, reconstructions of climate and &lt;/span&gt;&lt;span&gt;population changes &lt;/span&gt;&lt;span&gt;are increasingly used for the continent of our origin, Africa.&lt;/span&gt; &lt;span&gt;However, &lt;/span&gt;&lt;span&gt;continuous and high-resolution records of climate-human interactions are still scarce. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Using a 280 m sediment core from Chew Bahir*, a wide tectonic basin in southern Ethiopia,&lt;/span&gt; &lt;span&gt;we reconstruct the paleoenvironmental conditions during the development of &lt;em&gt;Homo sapiens.&lt;/em&gt; The complete multiproxy record of the composite core covers the last ~600 ka &lt;/span&gt;&lt;span&gt;, allowing tests of hypotheses about the influence of climate change on human evolution and technological innovation from the Late Acheulean to the Middle/Late Stone Age, and on dispersal within and out of Africa&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Here we present results from the uppermost 100 meters of the Chew Bahir core, spanning the last 200 kiloyears (ka). &lt;/span&gt;&lt;span&gt;The record shows two modes of environmental change that are associated with two types of human mobility. The first mode is a long-term trend towards a more arid climate, overlain by precession-driven wet-dry alternation. Through comparison with the archaeological record, humid episodes appear to have led to the opening of &amp;#8216;green&amp;#8217; networks between favourable habitats and thus to increased human mobility on a regional scale. The second mode of environmental change resembles millennial-scale Dansgaard-Oeschger and Heinrich events, which seem to coincide with enhanced vertical mobility from the Ethiopian rift to the highlands, especially in the time frame between ~65&amp;#8211;21 ka BP. The coincidence of climate change and human mobility patterns help to define the limiting conditions for early &lt;em&gt;Homo sapiens&lt;/em&gt; in eastern Africa.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;___________________&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;*&lt;/span&gt; &lt;span&gt;cored in the context of HSPDP (&lt;em&gt;Hominin Sites and Paleolakes Drilling Project&lt;/em&gt;) and CRC&amp;#160;&lt;/span&gt;&lt;span&gt;(&lt;em&gt;Collaborative Research &lt;/em&gt;&lt;em&gt;Centre&lt;/em&gt;) 806 &amp;#8220;&lt;em&gt;Our way to Europe&lt;/em&gt;&amp;#8221;&lt;/span&gt;&lt;/p&gt;