Hominid early migrations into Eurasia: a paleomagnetism-ESR perspective

Abstract

The so-called Early Middle Pleistocene Transition (EMPT), from 1.4 to 0.4 Ma, was a major revolution in the Quaternary. For about one million years several events including a progressive increase of climate oscillations, a change in orbital rhythm from 41 to 100 ka cycles, and an increase of the long term ice volume, led to dramatic changes in the biota including a major faunal turnover and hominid dispersal and speciation. An increase in Saharan terrigenous dust flux as observed in both the Mediterranean Sea and Arabian Sea, further supports the beginning and the role of the EMPT. Overall, the existing data reveal that the arrival of hominids to Europe was apparently favored by periods of extreme climate variability, conditions that are met as early as 1.4 Ma. Two major geomagnetic chrons are critical to identifying the EMPT interval in sedimentary sequences, including the Matuyama-Brunhes Boundary (0.78 Ma) and the Jaramillo Subchron (0.99-1.07 Ma), with the latter placed in the middle of the EMPT. Therefore, the Jaramillo is a key time marker that allows placing fossils and archaeological remains within the Early Pleistocene and EMPT. A number of European localities with important faunal remains have become “classic” references as the Jaramillo Subchron has been purportedly identified. We have re-evaluated such localities in order to assess the assumed chronology of the fossiliferous and/or archaeological record. Issues related to rockmagnetism, data quality, and remagnetization among other, make us to consider some of these sites with caution. Nevertheless, when combined with numerical dating methods such as Electron Spin Resonance, magnetic reversal stratigraphy has been proven to be a powerful tool to assign and to constrain chronology to sedimentary sequences that formed during the EMPT thanks to the presence of the Jaramillo Subchron.