Fossil herbivore stable isotopes reveal middle Pleistocene hominin palaeoenvironment in ‘Green Arabia’

Abstract

Despite its largely hyper-arid and inhospitable climate today, the Arabian Peninsula is emerging as an important area for investigating Pleistocene hominin dispersals. Recently, a member of our own species was found in northern Arabia dating to ca. 90 ka, while stone tools and fossil finds have hinted at an earlier, middle Pleistocene, hominin presence. However, there remain few direct insights into Pleistocene environments, and associated hominin adaptations, that accompanied the movement of populations into this region. Here, we apply stable carbon and oxygen isotope analysis to fossil mammal tooth enamel (n = 21) from the middle Pleistocene locality of Ti's al Ghadah in Saudi Arabia associated with newly discovered stone tools and probable cutmarks. The results demonstrate productive grasslands in the interior of the Arabian Peninsula ca. 300-500 ka, as well as aridity levels similar to those found in open savannah settings in eastern Africa today. The association between this palaeoenvironmental information and the earliest traces for hominin activity in this part of the world lead us to argue that middle Pleistocene hominin dispersals into the interior of the Arabian Peninsula required no major novel adaptation.

Isotopic evidence for initial coastal colonization and subsequent diversification in the human occupation of Wallacea

“…The precipitation of carbonate minerals is likely to be more of a problem in the context of more porous materials, such as bone 43,44 . Subtle differences noted in faunal enamel apatite during fossilization noted here, including increased BAI and decreased A-carbonate on phosphate index, have also been demonstrated in other studies, including within the tropics of South Asia, and have been argued to be a product of the reduction in organic material within the apatite matrix through time 31,38,45 . Such change is not considered to have major impacts on overall enamel apatite structure or stable carbon and oxygen isotope measurements from enamel 45 , as further suggested by the preservation of expected ecological differences in the enamel here and elsewhere 29,31 .…”

“…Ample terrestrial and marine animal remains also allow us to build the first detailed paleoecological and palaeoenvironmental records for Pleistocene Wallacea and test assumptions in relation to: (1) pure C 3 terrestrial environments on Timor and Alor in the past; (2) the δ 13 C distinction between available terrestrial and marine resources; and (3) environmental shifts across the Pleistocene-Holocene boundary proposed elsewhere in Southeast Asia (e.g., 5,37 ). The preservation of a subsection of the analysed tooth enamel samples was also checked using Fourier transform infrared spectroscopy (FTIR) as per Roberts et al 31,38 .…”

A taxonomic and taphonomic study of Pleistocene fossil deposits from the western Nefud Desert, Saudi Arabia

“…Throughout the Pleistocene the Arabian Peninsula underwent a series of pluvial phases that transformed much of its deserts into well-watered semiarid grasslands (Rosenberg et al, 2011(Rosenberg et al, , 2013Drake et al, 2013;Breeze et al, 2015Breeze et al, , 2016Jennings et al, 2015;Parton et al, 2015Parton et al, , 2018Groucutt et al, 2015bGroucutt et al, , 2018Roberts et al, 2018). These conditions facilitated the dispersal of a variety of novel taxa into Arabia, including hippos, elephants, large carnivores, and waterbirds (McClure, 1984;Thomas et al, 1998;Stimpson et al, 2016;Stewart et al, 2019aStewart et al, , 2019bGroucutt et al, 2018).…”

“…90 ka (Groucutt et al, 2018) and recently discovered lithic artefacts demonstrate that hominins dispersed into Arabia as early as ca. 500–300 ka (Roberts et al, 2018; Stewart et al, 2019a).…”

“…Considering the importance of the Arabian Peninsula in hominin prehistory, and the regular occurrence of spatially associated lithic artefacts and fossils at relict lake and river sites within the Arabian interior (e.g., Delagnes et al, 2012; Scerri et al, 2015; Breeze et al, 2017; Groucutt et al, 2018; Roberts et al, 2018; Stewart et al, 2019a), it is crucial that we develop an understanding of the preservational pathways that skeletal elements in these environments might take. Fortunately, the need for taphonomic frameworks with which to study large vertebrate fossil assemblages has long been recognised and a wealth of actualistic and naturalistic landscape studies within tropical settings have been conducted and applied to questions surrounding hominin and animal landscape use, interactions, and behaviour (e.g., Behrensmeyer, 1978; Behrensmeyer and Dechant Boaz, 1980; Blumenchine, 1986, 1988, 1989; Domínguez-Rodrigo, 2001; Faith and Behrensmeyer, 2006; Faith, 2007).…”