Evolutionary history of Castanea sativa in the Caucasus driven by Middle and Late Pleistocene paleoenvironmental changes.

Due to global climate cooling and aridification since the Paleogene, members of the Neogene flora were extirpated from the Northern Hemisphere or were confined to a few refugial areas. For some species, the final reduction/extinction came in the Pleistocene, but some others have survived climatic transformations up to the present. This has occurred in Castanea sativa, a species of high commercial value in Europe and a significant component of the Caucasian forests' biodiversity. In contrast to the European range, neither the historical biogeography nor the population genetic structure of the species in its isolated Caucasian range has been clarified. Here, based on a survey of 21 natural populations from the Caucasus and a single one from Europe, we provide a likely biogeographic reconstruction and genetic diversity details. By applying Bayesian inference, species distribution modelling and fossil pollen data, we estimated (i) the time of the Caucasian-European divergence during the Middle Pleistocene, (ii) the time of divergence among Caucasian lineages and (iii) outlined the glacial refugia for species. The climate changes related to the Early-Middle Pleistocene Transition are proposed as the major drivers of the intraspecific divergence and European-Caucasian disjunction for the species, while the impact of the last glacial cycle was of marginal importance.

The ROCEEH Out of Africa Database (ROAD): A large-scale research database serves as an indispensable tool for human evolutionary studies.

Large scale databases are critical for helping scientists decipher long-term patterns in human evolution. This paper describes the conception and development of such a research database and illustrates how big data can be harnessed to formulate new ideas about the past. The Role of Culture in Early Expansions of Humans (ROCEEH) is a transdisciplinary research center whose aim is to study the origins of culture and the multifaceted aspects of human expansions across Africa and Eurasia over the last three million years. To support its research, the ROCEEH team developed an online tool named the ROCEEH Out of Africa Database (ROAD) and implemented its web-based applications. ROAD integrates geographical data as well as archaeological, paleoanthropological, paleontological and paleobotanical content within a robust chronological framework. In fact, a unique feature of ROAD is its ability to dynamically link scientific data both spatially and temporally, thereby allowing its reuse in ways that were not originally conceived. The data stem from published sources spanning the last 150 years, including those generated by the research team. Descriptions of these data rely on the development of a standardized vocabulary and profit from online explanations of each table and attribute. By synthesizing legacy data, ROAD facilitates the reuse of heritage data in novel ways. Database queries yield structured information in a variety of interoperable formats. By visualizing data on maps, users can explore this vast dataset and develop their own theories. By downloading data, users can conduct further quantitative analyses, for example with Geographic Information Systems, modeling programs and artificial intelligence. In this paper, we demonstrate the innovative nature of ROAD and show how it helps scientists studying human evolution to access datasets from different fields, thereby connecting the social and natural sciences. Because it permits the reuse of "old" data in new ways, ROAD is now an indispensable tool for researchers of human evolution and paleogeography.

Cooling-induced expansions of Afromontane forests in the Horn of Africa since the Last Glacial Maximum.

Understanding the changing plant ecosystems that existed in East Africa over the past millennia is crucial for identifying links between habitats and past human adaptation and dispersal across the region. In the Horn of Africa, this task is hampered by the scarcity of fossil botanical data. Here we present modelled past vegetation distributions in Ethiopia from the Last Glacial Maximum (LGM) to present at high spatial and temporal resolution. The simulations show that, contrary to long-standing hypotheses, the area covered by Afromontane forests during the Late Glacial was significantly larger than at present. The combined effect of low temperatures and the relative rainfall contribution sourced from the Congo Basin and Indian Ocean, emerges as the mechanism that controlled the migration of Afromontane forests to lower elevations. This process may have enabled the development of continuous forest corridors connecting populations that are currently isolated in mountainous areas over the African continent. Starting with the Holocene, the expansion of forests began to reverse. This decline intensified over the second half of the Holocene leading to a retreat of the forests to higher elevations where they are restricted today. The simulations are consistent with proxy data derived from regional pollen records and provide a key environmental and conceptual framework for human environmental adaptation research.

Palaeobotanical evidence reveals the living conditions of Miocene Lufengpithecus in East Asia.

BACKGROUND: Understanding the relationship between human evolution and environmental changes is the key to lifting the veil on human origin. The hypothesis that environmental changes triggered the divergence of humans from apes (ca. 9.3-6.5 million years ago, Ma) has been poorly tested because of limited continuous environmental data from fossil localities. Lufengpithecus (12.5-6.0 Ma) found on the southeastern margin of the Tibetan Plateau (SEMTP) across the ape-human split provides a good chance for testing this hypothesis. RESULTS: Here, we reconstructed the habitats of L. keiyuanensis (12.5-11.6 Ma) with comprehensive vegetation, climate, and potential food web data by palaeobotanical evidence, together with other multidisciplinary data and partly tested the environment-driven hypothesis by revealing the living conditions of Lufengpithecus. CONCLUSION: A detailed comparison of hominoids on different continents reveals their behaviour and fate divergence across the ape-human split against the background of global climate change, i.e., the stable living conditions of SEMTP not only provided a so-called 'refuge' for arboreal Lufengpithecus but also acted as a 'double-edged sword', preventing their further evolution while vegetation shifts in East Africa probably stimulated the emergence of human bipedalism, and the intense climatic changes in Europe possibly prevented those hominoids from surviving that time interval. Our findings provide interesting insight into the environmental impacts on the behavioural evolution of hominoids.

Sedimentary ancient DNA metabarcoding as a tool for assessing prehistoric plant use at the Upper Paleolithic cave site Aghitu-3, Armenia.

Current knowledge about Paleolithic human plant use is limited by the rare survival of identifiable plant remains as well as the availability of methods for plant detection and identification. By analyzing DNA preserved in cave sediments, we can identify organisms in the absence of any visible remains, opening up new ways to study details of past human behavior, including plant use. Aghitu-3 Cave contains a 15,000-yearlong record (from ∼39,000 to 24,000 cal BP) of Upper Paleolithic human settlement and environmental variability in the Armenian Highlands. Finds from this cave include stone artifacts, faunal remains, bone tools, shell beads, charcoal, and pollen, among others. We applied sedimentary ancient DNA (sedaDNA) metabarcoding to the Aghitu-3 sedimentary sequence and combined this with pollen data to obtain a temporal reconstruction of plant assemblages. Our results reveal a stratification of plant abundance and diversity where sedaDNA reflects periods of human occupation, showing higher diversity in layers with increased human activity. Low pollen concentrations combined with high sedaDNA abundance indicate plant remains may have been brought into the cave by animals or humans during the deposition of the lower two archaeological horizons. Most of the recovered plants are reported to be useful for food, flavor, medicine, and/or technical purposes, demonstrating the potential of the environment around Aghitu-3 Cave to support humans during the Upper Paleolithic. Moreover, we identified several specific plant taxa that strengthen previous findings about Upper Paleolithic plant use in this region (i.e., for medicine and the manufacturing and dyeing of textiles). This study represents the first application of plant sedaDNA analysis of cave sediments for the investigation of potential plant use by prehistoric humans.

Mapping Early Pleistocene environments and the availability of plant food as a potential driver of early Homo presence in the Guadix-Baza Basin (Spain).

The Guadix-Baza Basin, in SE Spain, harbors hominin fossils and lithic artifacts dated to ca. 1.4-1.3 Ma, representing the first hominin habitat in the Iberian Peninsula and possibly in Western Europe. Recent palynological studies have described a high diversity of plant taxa and biomes existing in the basin at the time of hominin presence. However, the relationship between these hominins and their environment has not been fully explored. Two novel methodologies are developed. The first method maps the distribution of the Early Pleistocene vegetation units based on paleobotanical and paleogeographic data. The second method assesses the availability of edible plant parts using a combination of Early Pleistocene and modern taxa lists. The resulting vegetation maps reveal a great diversity of vegetation types. During dry (glacial) periods, the vegetation of the basin was represented mostly by steppes, with the appearance of forested vegetation only in the mountainous regions. During humid (interglacial) periods, Mediterranean woodlands represented the dominant vegetation, accompanied by deciduous and conifer forests in the areas of higher altitude. The lake system present in the basin also allowed for the presence of marshland vegetation. The assessment of the availability of edible plant parts reveals that early Homo could have found a high number of resources in marshland and riparian environments throughout the year. Mediterranean woodlands and deciduous forests also provided numerous edible plant parts. During dry periods, the availability of plant resources decreased heavily, but the prevalence of marshland and riparian vegetation and of forested vegetation in the areas of higher altitude could have sustained hominin communities during harsher climatic periods. However, the disappearance of the lake system and an increase of aridity after the Mid-Pleistocene Transition and during the Middle Pleistocene probably led to an impoverishment of plant resources available to early Homo in the Guadix-Baza Basin.

The earliest evidence for Upper Paleolithic occupation in the Armenian Highlands at Aghitu-3 Cave.

With its well-preserved archaeological and environmental records, Aghitu-3 Cave permits us to examine the settlement patterns of the Upper Paleolithic (UP) people who inhabited the Armenian Highlands. We also test whether settlement of the region between ∼39-24,000 cal BP relates to environmental variability. The earliest evidence occurs in archaeological horizon (AH) VII from ∼39-36,000 cal BP during a mild, moist climatic phase. AH VI shows periodic occupation as warm, humid conditions prevailed from ∼36-32,000 cal BP. As the climate becomes cooler and drier at ∼32-29,000 cal BP (AH V-IV), evidence for occupation is minimal. However, as cooling continues, the deposits of AH III demonstrate that people used the site more intensively from ∼29-24,000 cal BP, leaving behind numerous stone artifacts, faunal remains, and complex combustion features. Despite the climatic fluctuations seen across this 15,000-year sequence, lithic technology remains attuned to one pattern: unidirectional reduction of small cores geared towards the production of bladelets for tool manufacture. Subsistence patterns also remain stable, focused on medium-sized prey such as ovids and caprids, as well as equids. AH III demonstrates an expansion of social networks to the northwest and southwest, as the transport distance of obsidian used to make stone artifacts increases. We also observe the addition of bone tools, including an eyed needle, and shell beads brought from the east, suggesting that these people manufactured complex clothing and wore ornaments. Remains of micromammals, birds, charcoal, pollen, and tephra relate the story of environmental variability. We hypothesize that UP behavior was linked to shifts in demographic pressures and climatic changes. Thus, by combining archaeological and environmental data, we gain a clearer picture about the first UP inhabitants of the Armenian Highlands.

Monsoon versus uplift in southwestern China--Late Pliocene climate in Yuanmou Basin, Yunnan.

Yuanmou Basin of Yunnan, SW China, is a famous locality with hominids, hominoids, mammals and plant fossils. Based on the published megaflora and palynoflora data from Yuanmou Basin, the climate of Late Pliocene is reconstructed using the Coexistence Approach. The results indicate a warm and humid subtropical climate with a mean annual temperature of ca. 16-17°C and a mean annual precipitation of ca. 1500-1600 mm in the Late Pliocene rather than a dry, hot climate today, which may be due to the local tectonic change and gradual intensification of India monsoon. The comparison of Late Pliocene climate in Eryuan, Yangyi, Longling, and Yuanmou Basin of Yunnan Province suggests that the mean annual temperatures generally show a latitudinal gradient and fit well with their geographic position, while the mean annual precipitations seem to be related to the different geometries of the valleys under the same monsoon system.

Millennial-scale vegetation dynamics in an estuary at the onset of the Miocene Climate Optimum.

Pollen analyses have been proven to possess the possibility to decipher rapid vegetational and climate shifts in Neogene sedimentary records. Herein, a c. 21-kyr-long transgression-regression cycle from the Lower Austrian locality Stetten is analysed in detail to evaluate climatic benchmarks for the early phase of the Middle Miocene Climate Optimum and to estimate the pace of environmental change.Based on the Coexistence Approach, a very clear signal of seasonality can be reconstructed. A warm and wet summer season with c. 204-236 mm precipitation during the wettest month was opposed by a rather dry winter season with precipitation of c. 9-24 mm during the driest month. The mean annual temperature ranged between 15.7 and 20.8 °C, with about 9.6-13.3 °C during the cold season and 24.7-27.9 °C during the warmest month. In contrast, today's climate of this area, with an annual temperature of 9.8 °C and 660 mm rainfall, is characterized by the winter season (mean temperature: -1.4 °C, mean precipitation: 39 mm) and a summer mean temperature of 19.9 °C (mean precipitation: 84 mm).Different modes of environmental shifts shaped the composition of the vegetation. Within few millennia, marshes and salt marshes with abundant Cyperaceae rapidly graded into Taxodiaceae swamps. This quick but gradual process was interrupted by swift marine ingressions which took place on a decadal to centennial scale. The transgression is accompanied by blooms of dinoflagellates and of the green alga Prasinophyta and an increase in Abies and Picea. Afterwards, the retreat of the sea and the progradation of estuarine and wetland settings were a gradual progress again.Despite a clear sedimentological cyclicity, which is related to the 21-kyr precessional forcing, the climate data show little variation. This missing pattern might be due to the buffering of the precessional-related climate signal by the subtropical vegetation. Another explanation could be the method-inherent broad range of climate-parameter estimates that could cover small scale climatic changes.