The earliest Ethiopian wolf: implications for the species evolution and its future survival.

In 2017, a hemimandible (MW5-B208), corresponding to the Ethiopian wolf (Canis simensis), was found in a stratigraphically-controlled and radio-isotopically-dated sequence of the Melka Wakena paleoanthropological site-complex, on the Southeastern Ethiopian Highlands, ~ 2300 m above sea level. The specimen is the first and unique Pleistocene fossil of this species. Our data provide an unambiguous minimum age of 1.6-1.4 Ma for the species' presence in Africa and constitutes the first empirical evidence that supports molecular interpretations. Currently, C. simensis is one of the most endangered carnivore species of Africa. Bioclimate niche modeling applied to the time frame indicated by the fossil suggests that the lineage of the Ethiopian wolf faced severe survival challenges in the past, with consecutive drastic geographic range contractions during warmer periods. These models help to describe future scenarios for the survival of the species. Projections ranging from most pessimistic to most optimistic future climatic scenarios indicate significant reduction of the already-deteriorating territories suitable for the Ethiopian Wolf, increasing the threat to the specie's future survival. Additionally, the recovery of the Melka Wakena fossil underscores the importance of work outside the East African Rift System in research of early human origins and associated biodiversity on the African continent.

Modelling effects of inter-group contact on links between population size and cultural complexity.

Human populations rely on cultural artefacts for their survival. Populations vary dramatically in the size of their tool repertoires, and the determinants of these cultural repertoire sizes have been the focus of extensive study. A prominent hypothesis, supported by computational models of cultural evolution, asserts that tool repertoire size increases with population size. However, not all empirical studies have found such a correlation, leading to a contentious and ongoing debate. As a possible resolution to this longstanding controversy, we suggest that accounting for even rare cultural migration events that allow sharing of knowledge between different-sized populations may help explain why a population's size might not always predict its cultural repertoire size. Using an agent-based model to test assumptions about the effects of population size and connectivity on tool repertoires, we find that cultural exchange between a focal population and others, particularly with large populations, may significantly boost its tool repertoire size. Thus, two populations of identical size may have drastically different tool repertoire sizes, hinging upon their access to other groups' knowledge. Intermittent contact between populations boosts cultural repertoire size and still allows for the development of unique tool repertoires that have limited overlap between populations.

Continuity and change in lithic techno-economy of the early Acheulian on the Ethiopian highland: A case study from locality MW2; the Melka Wakena site-complex.

Recent research has made great strides clarifying the chronology, temporal span, and geographic and technological patterning of the Acheulian in eastern Africa. However, highland occurrences of the Acheulian remain under-represented and their relationship to cultural dynamics in the Rift are still poorly understood. Recently, a stratified sequence of four archaeological layers, recording Acheulian occupations dated between ~1.6 Ma and ~1.3 Ma, has been discovered in locality MW2 of the Melka Wakena site-complex (south-central Ethiopian highlands). This database enabled a systematic exploration of the question of tempo and mode of technological changes at a local sequence, allowing, for the first time, comparison with other highland sites as well as in the Rift. The detailed techno-economic study presented in this study shows that the early Acheulian at the locality was characterized by the co-existence of lithic reduction sequences for small debitage and for flake-based Large Cutting Tool production. In the early, ~1.6 Ma assemblage, a strategy of variable raw material exploitation and technological emphasis on small debitage were coupled with production of few crude bifacial elements. These shifted at ~1.4 Ma towards a preferential and intensive exploitation of a highly knappable glassy ignimbrite and emphasis on Large Cutting Tool production, including higher investment in their techno-morphological aspects. The MW2 sequence tracks lithic technological trends observed in the Rift, with only a short time lag. Diachronic changes in the raw material economy and land use patterns may have occurred at MW2 earlier than previously reported for the Acheulian on the highlands. The behavioral dynamics gleaned from the early Acheulian assemblages at MW2 are important for our understanding of the diachronic changes in the abilities of Acheulian hominins to exploit the diverse geographic and ecological habitats of eastern Africa and beyond.

Disease transmission and introgression can explain the long-lasting contact zone of modern humans and Neanderthals.

Neanderthals and modern humans both occupied the Levant for tens of thousands of years prior to the spread of modern humans into the rest of Eurasia and their replacement of the Neanderthals. That the inter-species boundary remained geographically localized for so long is a puzzle, particularly in light of the rapidity of its subsequent movement. Here, we propose that infectious-disease dynamics can explain the localization and persistence of the inter-species boundary. We further propose, and support with dynamical-systems models, that introgression-based transmission of alleles related to the immune system would have gradually diminished this barrier to pervasive inter-species interaction, leading to the eventual release of the inter-species boundary from its geographic localization. Asymmetries between the species in the characteristics of their associated 'pathogen packages' could have generated feedback that allowed modern humans to overcome disease burden earlier than Neanderthals, giving them an advantage in their subsequent spread into Eurasia.

Persistent Neanderthal occupation of the open-air site of 'Ein Qashish, Israel.

Over the last two decades, much of the recent efforts dedicated to the Levantine Middle Paleolithic has concentrated on the role of open-air sites in the settlement system in the region. Here focus on the site of 'Ein Qashish as a cases study. Located in present-day northern Israel, the area of this site is estimated to have been >1300 m2, of which ca. 670 were excavated. The site is located at the confluence of the Qishon stream with a small tributary running off the eastern flanks of the Mt. Carmel. At the area of this confluence, water channels and alluvial deposits created a dynamic depositional environment. Four Archaeological Units were identified in a 4.5-m thick stratigraphic sequence were dated by Optically Stimulated Luminescence (OSL) to between-71 and 54 ka, and probably shorter time span-~70-~60 ka. Here we present the diverse material culture remains from the site (lithics, including refitted sequences; modified limestone pieces; molluscs; faunal remains) against their changing paleogeographic backdrop. Skeletal evidence suggests that these remains were associated with Neanderthals. The large-scale repeated accumulation of late Middle Paleolithic remains in the same place on the landscape provides a unique opportunity to address questions of occupation duration and intensity in open-air sites. We find that each occupation was of ephemeral nature, yet presents a range of activities, suggesting that the locale has been used as a generalized residential site rather than specialized task-specific ones. This role of 'Ein Qashish did not change through time, suggesting that during the late Middle Paleolithic settlement system in this part of the southern Levant were stable.

One size does not fit all: Group size and the late middle Pleistocene prehistoric archive.

The role of demography is often suggested to be a key factor in both biological and cultural evolution. Recent research has shown that the linkage between population size and cultural evolution is not straightforward and emerges from the interplay of many demographic, economic, social and ecological variables. Formal modelling has yielded interesting insights into the complex relationship between population structure, intergroup connectedness, and magnitude and extent of population extinctions. Such studies have highlighted the importance of effective (as opposed to census) population size in transmission processes. At the same time, it remained unclear how such insights can be applied to material culture phenomena in the prehistoric record, especially for deeper prehistory. In this paper we approach the issue of population sizes during the time of the Lower to Middle Paleolithic transition through the proxy of regional trajectories of lithic technological change, identified in the archaeological records from Africa, the Levant, Southwestern and Northwestern Europe. Our discussion of the results takes into consideration the constraints inherent to the archaeological record of deep time - e.g., preservation bias, time-averaging and the incomplete nature of the archaeological record - and of extrapolation from discrete archaeological case studies to an evolutionary time scale. We suggest that technological trajectories of change over this transitional period reflect the robustness of transmission networks. Our results show differences in the pattern and rate of cultural transmission in these regions, from which we infer that information networks, and their underlying effective population sizes, also differed.

Prehistoric Perspectives on "Others" and "Strangers".

Social "connectivity" through time is currently considered as one of the major drivers of cultural transmission and cultural evolution. Within this framework, the interactions within and between groups are impacted by individuals' distinction of social relationships. In this paper, we focus on changes in a major aspect of social perceptions, "other" and "stranger." As inferred from the archaeological record, this perception among human groups gained importance during the course of the Pleistocene. These changes would have occurred due to the plasticity of cognitive mechanisms, in response to the demands on behavior along the trajectory of human social evolution. The concepts of "other" and "stranger" have received little attention in the archaeological discourse, yet they are fundamental in the perception of social standing. The property of being an "other" is defined by one's perception and is inherent to one's view of the world around oneself; when shared by a group it becomes a social cognitive construct. Allocating an individual the status of a "stranger" is a socially-defined state that is potentially transient. We hypothesize that, while possibly entrenched in deep evolutionary origins, the latter is a relatively late addition to socio-cognitive categorization, associated with increased sedentism, larger groups and reduced territorial extent as part of the process of Neolithization. We posit that "others" and "strangers" can be approached from contextual archaeological data, with inferences as regards the evolution of cognitive social categories. Our analysis focused on raw material studies, observations on style, and evidence for craft specialization. We find that contrary to the null hypothesis the archaeological record implies earlier emergence of complex socio-cognitive categorization. The cognitive, cultural and social processes involved in the maintenance and distinction between "others" and "strangers" can be defined as "self-domestication" that is still an on-going process.

The first Neanderthal remains from an open-air Middle Palaeolithic site in the Levant.

The late Middle Palaeolithic (MP) settlement patterns in the Levant included the repeated use of caves and open landscape sites. The fossil record shows that two types of hominins occupied the region during this period-Neandertals and Homo sapiens. Until recently, diagnostic fossil remains were found only at cave sites. Because the two populations in this region left similar material cultural remains, it was impossible to attribute any open-air site to either species. In this study, we present newly discovered fossil remains from intact archaeological layers of the open-air site 'Ein Qashish, in northern Israel. The hominin remains represent three individuals: EQH1, a nondiagnostic skull fragment; EQH2, an upper right third molar (RM3); and EQH3, lower limb bones of a young Neandertal male. EQH2 and EQH3 constitute the first diagnostic anatomical remains of Neandertals at an open-air site in the Levant. The optically stimulated luminescence ages suggest that Neandertals repeatedly visited 'Ein Qashish between 70 and 60 ka. The discovery of Neandertals at open-air sites during the late MP reinforces the view that Neandertals were a resilient population in the Levant shortly before Upper Palaeolithic Homo sapiens populated the region.

Across the Gap: Geochronological and Sedimentological Analyses from the Late Pleistocene-Holocene Sequence of Goda Buticha, Southeastern Ethiopia.

Goda Buticha is a cave site near Dire Dawa in southeastern Ethiopia that contains an archaeological sequence sampling the late Pleistocene and Holocene of the region. The sedimentary sequence displays complex cultural, chronological and sedimentological histories that seem incongruent with one another. A first set of radiocarbon ages suggested a long sedimentological gap from the end of Marine Isotopic Stage (MIS) 3 to the mid-Holocene. Macroscopic observations suggest that the main sedimentological change does not coincide with the chronostratigraphic hiatus. The cultural sequence shows technological continuity with a late persistence of artifacts that are usually attributed to the Middle Stone Age into the younger parts of the stratigraphic sequence, yet become increasingly associated with lithic artifacts typically related to the Later Stone Age. While not a unique case, this combination of features is unusual in the Horn of Africa. In order to evaluate the possible implications of these observations, sedimentological analyses combined with optically stimulated luminescence (OSL) were conducted. The OSL data now extend the radiocarbon chronology up to 63 ± 7 ka; they also confirm the existence of the chronological gap between 24.8 ± 2.6 ka and 7.5 ± 0.3 ka. The sedimentological analyses suggest that the origin and mode of deposition were largely similar throughout the whole sequence, although the anthropic and faunal activities increased in the younger levels. Regional climatic records are used to support the sedimentological observations and interpretations. We discuss the implications of the sedimentological and dating analyses for understanding cultural processes in the region.

Isotopic evidence for Last Glacial climatic impacts on Neanderthal gazelle hunting territories at Amud Cave, Israel.

The Middle Paleolithic site of Amud Cave, Israel, was occupied by Neanderthals at two different time periods, evidenced by two chronologically and stratigraphically distinct depositional sub-units (B4 and B2/B1) during MIS 4 and MIS 3, respectively. The composition of both hunted large fauna and naturally-deposited micromammalian taxa is stable at the site over time, despite a ∼ 10 ky gap between the two occupation phases. However, while gazelle is the most ubiquitous hunted species throughout the occupation, isotopic analysis showed that there is a marked change in Neanderthal hunting ranges between the early (B4) and late (B2/B1) phases. Hunting ranges were reconstructed by comparing oxygen, carbon, and strontium isotopes from gazelle tooth enamel with modern isotope data from the Amud Cave region. This region is characterized by extensive topographic, lithological, and pedological heterogeneity. During the early occupation phase negative oxygen isotope values, low radiogenic (87)Sr/(86)Sr ratios, and low Sr concentrations reveal restricted gazelle hunting in the high elevations west of Amud Cave. In the late occupation phase, hunting ranges became more diverse, but concentrate at low elevations closer to the site. Climatic proxies indicate that conditions were drier in the early occupation phase, which may have pushed gazelle populations into higher, more productive foraging areas. This study showed that Neanderthals adjusted their hunting territories considerably in relation to varying environmental conditions over the course of occupation in Amud Cave. It highlights the utility of multiple isotope analysis in enhancing the resolution of behavioral interpretations based on faunal remains and in reconstructing past hunting behaviors of Paleolithic hominins.

Raw material selectivity in Late Pliocene Oldowan sites in the Makaamitalu Basin, Hadar, Ethiopia.

We report the results of an analysis of raw material selection patterns in the assemblages from two Late Pliocene in situ archaeological localities in the Makaamitalu Basin (Hadar, Ethiopia). While the same local conglomerate was used as a raw material source for both archaeological occurrences, different selection criteria are identified. At A.L. 894, selection for quality is subtle and the clearest selection is against non-homogeneous raw materials. In the A.L. 666 assemblage, higher-quality raw materials were selected and some rare raw materials reached the locality from unknown sources. A comparison between the Makaamitalu and other Oldowan assemblages reveals an overall shift toward higher complexity of both selectivity and transport behaviors from ca. 2.0 Ma onward, contrasting a typo-technological conservatism that pertains until ~1.6 Ma. It is hypothesized that an increase in complexity of behaviors related to raw material selection and acquisition involved changes in the intensity and fidelity of technological knowledge transmission.

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.