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Pleistocene hominin dispersals out of, and back into, Africa necessarily involved traversing the diverse and often challenging environments of Southwest Asia 1 – 4 . Archaeological and palaeontological records from the Levantine woodland zone document major biological and cultural shifts, such as alternating occupations by Homo sapiens and Neanderthals. However, Late Quaternary cultural, biological and environmental records from the vast arid zone that constitutes most of Southwest Asia remain scarce, limiting regional-scale insights into changes in hominin demography and behaviour 1 , 2 , 5 . Here we report a series of dated palaeolake sequences, associated with stone tool assemblages and vertebrate fossils, from the Khall Amayshan 4 and Jubbah basins in the Nefud Desert. These findings, including the oldest dated hominin occupations in Arabia, reveal at least five hominin expansions into the Arabian interior, coinciding with brief ‘green’ windows of reduced aridity approximately 400, 300, 200, 130–75 and 55 thousand years ago. Each occupation phase is characterized by a distinct form of material culture, indicating colonization by diverse hominin groups, and a lack of long-term Southwest Asian population continuity. Within a general pattern of African and Eurasian hominin groups being separated by Pleistocene Saharo-Arabian aridity, our findings reveal the tempo and character of climatically modulated windows for dispersal and admixture. Dated palaeolake sequences show that there were at least five Pleistocene hominin expansions into the Arabian interior, coinciding with windows of reduced aridity between 400 and 55 thousand years ago.

Columbus crater in the Terra Sirenum region of the Martian southern highlands contains light‐toned layered deposits with interbedded sulfate and phyllosilicate minerals, a rare occurrence on Mars. Here we investigate in detail the morphology, thermophysical properties, mineralogy, and stratigraphy of these deposits; explore their regional context; and interpret the crater's aqueous history. Hydrated mineral‐bearing deposits occupy a discrete ring around the walls of Columbus crater and are also exposed beneath younger materials, possibly lava flows, on its floor. Widespread minerals identified in the crater include gypsum, polyhydrated and monohydrated Mg/Fe‐sulfates, and kaolinite; localized deposits consistent with montmorillonite, Fe/Mg‐phyllosilicates, jarosite, alunite, and crystalline ferric oxide or hydroxide are also detected. Thermal emission spectra suggest abundances of these minerals in the tens of percent range. Other craters in northwest Terra Sirenum also contain layered deposits and Al/Fe/Mg‐phyllosilicates, but sulfates have so far been found only in Columbus and Cross craters. The region's intercrater plains contain scattered exposures of Al‐phyllosilicates and one isolated mound with opaline silica, in addition to more common Fe/Mg‐phyllosilicates with chlorides. A Late Noachian age is estimated for the aqueous deposits in Columbus, coinciding with a period of inferred groundwater upwelling and evaporation, which (according to model results reported here) could have formed evaporites in Columbus and other craters in Terra Sirenum. Hypotheses for the origin of these deposits include groundwater cementation of crater‐filling sediments and/or direct precipitation from subaerial springs or in a deep (∼900 m) paleolake. Especially under the deep lake scenario, which we prefer, chemical gradients in Columbus crater may have created a habitable environment at this location on early Mars.

How much did rainfall have to decrease to trigger the collapse of Lowland Classic Maya civilization during the Terminal Classic Period? This collapse is a well-cited example of how past climate change—in this case, drought—can disrupt a population. Evans et al. measured the isotopic composition of water in Lake Chichancanab, Mexico, to quantify how much precipitation decreased during that period. Annual rainfall must have fallen by around 50% on average and by up to 70% during peak drought conditions. Science , this issue p. 498 The collapse of Lowland Classic Maya civilization during the Terminal Classic Period was triggered by a 50% reduction in rainfall. The demise of Lowland Classic Maya civilization during the Terminal Classic Period (~800 to 1000 CE) is a well-cited example of how past climate may have affected ancient societies. Attempts to estimate the magnitude of hydrologic change, however, have met with equivocal success because of the qualitative and indirect nature of available climate proxy data. We reconstructed the past isotopic composition (δ 18 O, δD, 17 O-excess, and d-excess) of water in Lake Chichancanab, Mexico, using a technique that involves isotopic analysis of the structurally bound water in sedimentary gypsum, which was deposited under drought conditions. The triple oxygen and hydrogen isotope data provide a direct measure of past changes in lake hydrology. We modeled the data and conclude that annual precipitation decreased between 41 and 54% (with intervals of up to 70% rainfall reduction during peak drought conditions) and that relative humidity declined by 2 to 7% compared to present-day conditions.

To date, the most complete paleolake‐level reconstructions for the late Pleistocene water bodies that once occupied the Dead Sea depression have been based on the combination of dating of lake sediments and terrestrial materials. However, despite these major accomplishments, there is still limited spatial control regarding the water levels, suggesting some degree of uncertainty concerning the magnitude and rate of lake‐level changes. Here, we re‐examine the late Pleistocene lake‐level changes in the Dead Sea during the transition from paleolake Lisan to the present‐day Dead Sea. We rely on systematic dating of fossil stromatolites including 84 radiocarbon and 15 U‐series ages, stable‐isotope measurements, paleobiology, high‐resolution topography, and numerical modeling to assess lake‐level changes. Our results indicate that the highstand of paleolake Lisan was of shorter duration and the transition between Lake Lisan and the Dead Sea occurred at least 5 Kyrs earlier than previously indicated. By refining the timeline and accuracy of lake‐level positions during the transition paleolake Lisan—Dead Sea, our study offers new insights into the regional and local paleo‐climatic conditions during the last glacial period in this region. Plain Language Summary Index points, reflecting the unique position of the water levels in space and time, have been broadly used in marine realms to reconstruct past sea‐level changes. Here we study lake‐level variations using index points based on geomorphic and biological markers collected along the western and eastern coasts of the Dead Sea. Previous studies indicate that during the last glacial period (20–30 ka), the Dead Sea depression was filled by paleolake Lisan, which lasted 10 Kyrs. As it dried, dozens of paleo‐shorelines remained etched in the landscape. Lake level index points estimated from 99 radiometric ages in these paleo‐shorelines suggest that Lisan's highstand was shorter and the transition to the Dead Sea occurred 5 Kyrs earlier than previously thought. These novel results suggest an initial and wet period followed by drier conditions, altering the regional paleo‐climatic narrative during the last glacial period. Key Points Lake paleo‐shorelines and fossil stromatolites are used to reconstruct lake‐level changes during the transition paleolake Lisan‐Dead Sea Fossil stromatolites were dated using radiocarbon and U‐series applying temporal and vertical corrections The transition between paleolake Lisan and the Dead Sea occurred ∼5 Kyrs earlier than estimated by previous reconstructions

Despite more than half a century of hominin fossil discoveries in eastern Africa, the regional environmental context of hominin evolution and dispersal is not well established due to the lack of continuous palaeoenvironmental records from one of the proven habitats of early human populations, particularly for the Pleistocene epoch. Here we present a 620,000-year environmental record from Chew Bahir, southern Ethiopia, which is proximal to key fossil sites. Our record documents the potential influence of different episodes of climatic variability on hominin biological and cultural transformation. The appearance of high anatomical diversity in hominin groups coincides with long-lasting and relatively stable humid conditions from ~620,000 to 275,000 years bp (episodes 1–6), interrupted by several abrupt and extreme hydroclimate perturbations. A pattern of pronounced climatic cyclicity transformed habitats during episodes 7–9 (~275,000–60,000 years bp ), a crucial phase encompassing the gradual transition from Acheulean to Middle Stone Age technologies, the emergence of Homo sapiens in eastern Africa and key human social and cultural innovations. Those accumulative innovations plus the alignment of humid pulses between northeastern Africa and the eastern Mediterranean during high-frequency climate oscillations of episodes 10–12 (~60,000–10,000 years bp ) could have facilitated the global dispersal of H. sapiens . Over the past 620,000 years, three distinct phases of climate variability in eastern Africa coincided with shifts in hominin evolution and dispersal, according to an analysis of environmental proxy records from a core collected in the Chew Bahir basin of Ethiopia.

The surface environment of early Mars had an active hydrologic cycle, including flowing liquid water that carved river valleys 1 – 3 and filled lake basins 4 – 6 . Over 200 of these lake basins filled with sufficient water to breach the confining topography 4 , 6 , causing catastrophic flooding and incision of outlet canyons 7 – 10 . Much past work has recognized the local importance of lake breach floods on Mars for rapidly incising large valleys 7 – 12 ; however, on a global scale, valley systems have often been interpreted as recording more persistent fluvial erosion linked to a distributed Martian hydrologic cycle 1 – 3 , 13 – 16 . Here, we demonstrate the global importance of lake breach flooding, and find that it was responsible for eroding at least 24% of the volume of incised valleys on early Mars, despite representing only approximately 3% of total valley length. We conclude that lake breach floods were a major geomorphic process responsible for valley incision on early Mars, which in turn influenced the topographic form of many Martian valley systems and the broader landscape evolution of the cratered highlands. Our results indicate that the importance of lake breach floods should be considered when reconstructing the formative conditions for Martian valley systems. Lake breach flooding rapidly eroded almost a quarter of the volume of incised valleys on early Mars, influencing the topography of the wider Martian landscape.

[...]researchers from a range of fields, including Earth science, palaeoanthropology and archaeology, have theorized that major habitat changes might have profoundly affected hominin populations by altering the availability of resources, and thereby influencing biological and behavioural pressures2,3. In investigations of habitat variability over millions of years, one of the most notable problems is that terrestrial records of habitat information - such as that obtained from sedimentary outcrops and palaeolake drill cores - are often limited in terms of the time frames of data available. [...]fieldwork to gather such records is geographically biased, with only partial coverage of the regions that hominins inhabited. By contrast, the central eastern African record is viewed as having gaps in the availability of fossils and in archaeological data, suggesting to the authors that this region is less likely to have harboured a gradual species transition or diversification compared with southern Africa.

Hydrologic loads can stimulate seismicity in the Earth’s crust 1 . However, evidence for the triggering of large earthquakes remains elusive. The southern San Andreas Fault (SSAF) in Southern California lies next to the Salton Sea 2 , a remnant of ancient Lake Cahuilla that periodically filled and desiccated over the past millennium 3 – 5 . Here we use new geologic and palaeoseismic data to demonstrate that the past six major earthquakes on the SSAF probably occurred during highstands of Lake Cahuilla 5 , 6 . To investigate possible causal relationships, we computed time-dependent Coulomb stress changes 7 , 8 due to variations in the lake level. Using a fully coupled model of a poroelastic crust 9 – 11 overlying a viscoelastic mantle 12 , 13 , we find that hydrologic loads increased Coulomb stress on the SSAF by several hundred kilopascals and fault-stressing rates by more than a factor of 2, which is probably sufficient for earthquake triggering 7 , 8 . The destabilizing effects of lake inundation are enhanced by a nonvertical fault dip 14 – 17 , the presence of a fault damage zone 18 , 19 and lateral pore-pressure diffusion 20 , 21 . Our model may be applicable to other regions in which hydrologic loading, either natural 8 , 22 or anthropogenic 1 , 23 , was associated with substantial seismicity. Analysis of new geologic and palaeoseismic data using a 3D finite-element model suggests that the past six major earthquakes on the southern San Andreas Fault were probably triggered by highstands of ancient Lake Cahuilla.

The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012–2014 HSPDP coring campaign.

Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores 1 ; these interhemispheric connections may have existed during previous glacial cycles. Analysis of a continuous and independently dated record of glaciation in the tropical Andes spanning 700,000 years shows that Andean glaciation follows patterns of global ice volume change, with a periodicity of approximately 100,000 years.