Weakened AMOC related to cooling and atmospheric circulation shifts in the last interglacial Eastern Mediterranean.

There is limited understanding of temperature and atmospheric circulation changes that accompany an Atlantic Meridional Overturning Circulation (AMOC) slowdown beyond the North Atlantic realm. A Peqi'in Cave (Israel) speleothem dated to the last interglacial period (LIG), 129-116 thousand years ago (ka), together with a large modern rainfall monitoring dataset, serve as the base for investigating past AMOC slowdown effects on the Eastern Mediterranean. Here, we reconstruct LIG temperatures and rainfall source using organic proxies (TEX86) and fluid inclusion water d-excess. The TEX86 data show a stepwise cooling from 19.8 ± 0.2° (ca. 128-126 ka) to 16.5 ± 0.6 °C (ca. 124-123 ka), while d-excess values decrease abruptly (ca. 126 ka). The d-excess shift suggests that rainfall was derived from more zonal Mediterranean air flow during the weakened AMOC interval. Decreasing rainfall d-excess trends over the last 25 years raise the question whether similar atmospheric circulation changes are also occurring today.

Climatic and environmental conditions in the Western Galilee, during Late Middle and Upper Paleolithic periods, based on speleothems from Manot Cave, Israel.

Early Ahmarian, Levantine Aurignacian and Post-Levantine Aurignacian archeological assemblages show that the karstic Manot Cave, located 5 km east of the Mediterranean coast in the Western Galilee region of Israel, was intensively occupied during the Early Upper Paleolithic. The coexistence of these rich archaeological layers with speleothems in Manot Cave provides a window of opportunity for determining the relationships between climatic conditions and the nature of human activity and mobility patterns in the Western Galilee region during the Early Upper Paleolithic period. This study, based on four stalagmites that grew almost continuously from ∼75 to 26.5 ka, covers most of the last glacial, and overlaps with the human occupation of the cave. The speleothems oxygen (δ18O) and carbon (δ13C) isotopic records indicate that climate and environmental conditions fluctuated during the last glacial, some of which correspond with Dansgaard-Oeschger (D-O) cycles 12, 10, 7 and Heinrich (H) events VI and V. Consistent with independent evidence from botanic and faunal remains, these climatic shifts brought about significant environmental changes in the region, ranging from dominant thick Mediterranean forest to more open landscape. A good correlation with less negative δ13C values is most pronounced during the Early Ahmarian time period, but there was also a change to less negative δ13C values during the Levantine Aurignacian and Post-Levantine Aurignacian industries in the Levant. These positive δ13C shifts suggest that environmental transformation towards a more open grassy landscape dominated by C4 vegetation might have played an important role in the development of these cultural entities (mainly the Early Ahmarian) in Manot Cave region.

Climate stability and societal decline on the margins of the Byzantine empire in the Negev Desert.

Understanding past human settlement of inhospitable regions is one of the most intriguing puzzles in archaeological research, with implications for more sustainable use of marginal regions today. During the Byzantine period in the 4th century CE, large settlements were established in the arid region of the Negev Desert, Israel, but it remains unclear why it did so, and why the settlements were abandoned three centuries later. Previous theories proposed that the Negev was a "green desert" in the early 1st millennium CE, and that the Byzantine Empire withdrew from this region due to a dramatic climatic downturn. In the absence of a local climate archive correlated to the Byzantine/Early Islamic transition, testing this theory has proven challenging. We use stable isotopic indicators of animal dietary and mobility patterns to assess the extent of the vegetative cover in the desert. By doing so, we aim to detect possible climatic fluctuations that may have led to the abandonment of the Byzantine settlements. The findings show that the Negev Desert was not greener during the time period under investigation than it is today and that the composition of the animals' diets, as well as their grazing mobility patterns, remained unchanged through the Byzantine/Early Islamic transition. Favoring a non-climatic explanation, we propose instead that the abandonment of the Negev Byzantine settlements was motivated by restructuring of the Empire's territorial priorities.

Resolving seasonal rainfall changes in the Middle East during the last interglacial period.

Paleorainfall proxy records from the Middle East have revealed remarkable patterns of variability since the penultimate glacial period (140 ka), but the seasonality of this signal has been unresolvable. Here, seasonal-resolution oxygen isotope data from Soreq Cave speleothems suggest that summer monsoon rainfall periodically reaches as far north as Israel-well removed from the modern monsoon-at times (∼125, 105 ka) that overlap with evidence for some of the earliest modern human migrations out of Africa. These seasonal proxy data are corroborated by seasonal-resolution model output of the amount and oxygen-isotope ratio of rainfall from an isotope-enabled climate model. In contrast to the modern regional climate where rainfall is delivered predominantly in winter months along westerly storm tracks, the model suggests that during extreme peaks of summer insolation-as occurs during the last interglacial (e.g., 125, 105 ka)-regional rainfall increases due to both wetter winters and the incursion of summer monsoons. This interpretation brings clarity to regional paleoproxy records and provides important environmental context along one potential pathway of early modern human migration.

Response to Comment on "The earliest modern humans outside Africa".

Our original claim, based on three independent numerical dating methods, of an age of ~185,000 years for the Misliya-1 modern human hemi-maxilla from Mount Carmel, Israel, is little affected by discounting uranium-series dating of adhering crusts. It confirms a much earlier out-of-Africa Homo sapiens expansion than previously suggested by the considerably younger (90,000 to 120,000 years) Skhul/Qafzeh hominins.

Evidence for a humid interval at ∼56-44 ka in the Levant and its potential link to modern humans dispersal out of Africa.

This study provides a detailed reconstruction of the paleoenvironmental conditions that prevailed during one of the periods of modern human migration out of Africa and their occupation of the Eastern Mediterranean-Levant during the Late Middle Paleolithic-Early Upper Paleolithic. Tracing the past vegetation and climate within the Eastern Mediterranean-Levant region is largely based on a south-eastern Mediterranean marine pollen record covering the last 90 kyr (core MD-9509). The various palynomorphs were linked to distinct vegetation zones that were correlated to the two climate systems affecting the study area: the low-latitude monsoon system and the North Atlantic-Mediterranean climate system. The bioprovince palynological markers show that during the period between ∼56 and 44 ka, which covers the early part of Marine Isotope Stage 3 (MIS 3), there was an increase in transportation of pollen from Nilotic origin and a rise in dinoflagellate cyst ratios. These changes coincided with maximum insolation values at 65°N, which led to an enhancement in Nile River discharge into the Eastern Mediterranean following the intensification of the African monsoonal system. At the same time, the rise in Mediterranean arboreal pollen values (broadleaved, coniferous and deciduous temperate trees) is most likely driven by increased precipitation related to the intensification of the North Atlantic-Mediterranean climate system. The ∼56-44 ka wet event coincides with Dansgaard-Oeschger interstadials 14 and 12 and with a warming phase in the Levant, as evidenced by the melting of permafrost along the higher elevations of Mount Hermon. We suggest that African modern humans were able to cross the harsher arid areas due to the intensification of the monsoonal system during the first part of MIS 3, and inhabit the Eastern Mediterranean-Levant region where climatic conditions were favorable (wetter and warmer), even in the currently semiarid/steppe regions.

The earliest modern humans outside Africa.

To date, the earliest modern human fossils found outside of Africa are dated to around 90,000 to 120,000 years ago at the Levantine sites of Skhul and Qafzeh. A maxilla and associated dentition recently discovered at Misliya Cave, Israel, was dated to 177,000 to 194,000 years ago, suggesting that members of the Homo sapiens clade left Africa earlier than previously thought. This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of Homo sapiens around 220,000 years ago. The Misliya maxilla is associated with full-fledged Levallois technology in the Levant, suggesting that the emergence of this technology is linked to the appearance of Homo sapiens in the region, as has been documented in Africa.

A new research strategy for integrating studies of paleoclimate, paleoenvironment, and paleoanthropology.

Paleoanthropologists (scientists studying human origins) universally recognize the evolutionary significance of ancient climates and environments for understanding human origins. Even those scientists working in recent phases of human evolution, when modern humans evolved, agree that hunter-gatherer adaptations are tied to the way that climate and environment shape the food and technological resource base. The result is a long tradition of paleoanthropologists engaging with climate and environmental scientists in an effort to understand if and how hominin bio-behavioral evolution responded to climate and environmental change. Despite this unusual consonance, the anticipated rewards of this synergy are unrealized and, in our opinion, will not reach potential until there are some fundamental changes in the way the research model is constructed. Discovering the relation between climate and environmental change to human origins must be grounded in a theoretical framework and a causal understanding of the connection between climate, environment, resource patterning, behavior, and morphology, then move beyond the strict correlative research that continues to dominate the field.

Levantine cranium from Manot Cave (Israel) foreshadows the first European modern humans.

A key event in human evolution is the expansion of modern humans of African origin across Eurasia between 60 and 40 thousand years (kyr) before present (bp), replacing all other forms of hominins. Owing to the scarcity of human fossils from this period, these ancestors of all present-day non-African modern populations remain largely enigmatic. Here we describe a partial calvaria, recently discovered at Manot Cave (Western Galilee, Israel) and dated to 54.7 ± 5.5 kyr bp (arithmetic mean ± 2 standard deviations) by uranium-thorium dating, that sheds light on this crucial event. The overall shape and discrete morphological features of the Manot 1 calvaria demonstrate that this partial skull is unequivocally modern. It is similar in shape to recent African skulls as well as to European skulls from the Upper Palaeolithic period, but different from most other early anatomically modern humans in the Levant. This suggests that the Manot people could be closely related to the first modern humans who later successfully colonized Europe. Thus, the anatomical features used to support the 'assimilation model' in Europe might not have been inherited from European Neanderthals, but rather from earlier Levantine populations. Moreover, at present, Manot 1 is the only modern human specimen to provide evidence that during the Middle to Upper Palaeolithic interface, both modern humans and Neanderthals contemporaneously inhabited the southern Levant, close in time to the likely interbreeding event with Neanderthals.

Archaeological horizons and fluvial processes at the Lower Paleolithic open-air site of Revadim (Israel).

In this paper we present new data pertaining to the paleo-landscape characteristics at the Acheulian site of Revadim, on the southern coastal plain of Israel. Sedimentological, isotopic, granulometric and micromorphological studies showed that the archaeological remains accumulated in an active fluvial environment where channel action, overbank flooding and episodic inundation occurred. Measurements of total organic matter and its carbon isotopic composition indicate that the hominin activity at the site started at a period of relatively drier conditions, which coincided with erosion of the preceding soil sequence. This process led to the formation of a gently-undulating topography, as reconstructed by a GIS model. Later deposition documents relatively wetter conditions, as indicated by carbon isotopic composition. Formation processes identified at the site include fluvial processes, inundation episodes that resulted in anaerobic conditions and formation of oxide nodules, as well as small-scale bioturbation and later infiltration of carbonate-rich solutions that resulted in the formation of calcite nodules and crusts. The combination of micro-habitats created favorable conditions that repeatedly drew hominins to the area, as seen by a series of super-imposed archaeological horizons. This study shows that site-specific paleo-landscape reconstructions should play an important role in understanding regional variation among hominin occupations and in extrapolating long-term behavioral patterns during the Middle Pleistocene.

The stratigraphy of the Middle Stone Age sediments at Pinnacle Point Cave 13B (Mossel Bay, Western Cape Province, South Africa).

Pinnacle Point Cave 13B (PP13B) has provided the earliest archaeological evidence for the exploitation of marine shellfish, along with very early evidence for use and modification of pigments and the production of bladelets, all dated to approximately 164 ka (Marean et al., 2007). This makes PP13B a key site in studies of the origins of modern humans, one of a handful of sites in Africa dating to Marine Isotope Stage 6 (MIS 6), and the only site on the coast of South Africa with human occupation confidently dated to MIS 6. Along with this MIS 6 occupation there are rich archaeological sediments dated to MIS 5, and together these sediments are differentially preserved in three different areas of the cave. The sediments represent a complex palimpsest of geogenic, biogenic, and anthropogenic input and alteration that are described and interpreted through the use of a variety of macrostratigraphic, micromorphologic, and geochemical techniques. Three independent dating techniques allow us to constrain the age range of these sediments and together provide the stratigraphic context for the analyses of the material that follow in this special issue.

Early human use of marine resources and pigment in South Africa during the Middle Pleistocene.

Genetic and anatomical evidence suggests that Homo sapiens arose in Africa between 200 and 100 thousand years (kyr) ago, and recent evidence indicates symbolic behaviour may have appeared approximately 135-75 kyr ago. From 195-130 kyr ago, the world was in a fluctuating but predominantly glacial stage (marine isotope stage MIS6); much of Africa was cooler and drier, and dated archaeological sites are rare. Here we show that by approximately 164 kyr ago (+/-12 kyr) at Pinnacle Point (on the south coast of South Africa) humans expanded their diet to include marine resources, perhaps as a response to these harsh environmental conditions. The earliest previous evidence for human use of marine resources and coastal habitats was dated to approximately 125 kyr ago. Coincident with this diet and habitat expansion is an early use and modification of pigment, probably for symbolic behaviour, as well as the production of bladelet stone tool technology, previously dated to post-70 kyr ago. Shellfish may have been crucial to the survival of these early humans as they expanded their home ranges to include coastlines and followed the shifting position of the coast when sea level fluctuated over the length of MIS6.