Hominin Populations Research Articles

The expression of the MIS 12 glacial stage in Southeastern Europe and its impact over the Middle Pleistocene hominins in Megalopolis Basin (Greece)

Southern Europe is hypothesized to have acted as a glacial refugium for hominin populations during the Pleistocene. Of particular importance is South-East Europe, which most likely played a dual role, both as refugium and dispersal corridor, especially during the Middle Pleistocene glaciations, when drastic climatic conditions led to major sea level drops in the Aegean. However, little is known about the palaeoenvironmental conditions at the time of hominin presence in this region, making these hypotheses difficult to test. Here we analyze biomarker data and leaf wax stable isotopic compositions of the MIS 12 Lower Palaeolithic site Marathousa 1 (Megalopolis Basin, Greece) to assess the climatic conditions accompanying the time of hominin presence in the area. Our data indicate a major cooling affecting the north Mediterranean/Aegean domain during this time interval, with lowest temperatures recorded between ∼440–432 ka. The glacial peak is associated with changes in vegetation (i.e., from more forested to more open landscape), reduction of humidity and water availability (i.e., moisture depletion, increased evaporation). Hominins are present at the Marathousa 1 location at the end of this interval (434–432 ka), confirming that the Megalopolis Basin served as a refugium for hunter-gatherer groups during periods of harsh climatic conditions. Additionally, the progressive cooling is associated with an important sedimentary hiatus between ∼465–440 ka reflected in all circum-Mediterranean records (both marine and continental), indicating a regional impact of the MIS 12 glaciation over surface processes.

Climatic variability in the Armenian Highlands as the backdrop to hominin population dynamics 50–25 ka

The impact of Late Pleistocene climatic oscillations, volcanism and the diverse terrain of the Armenian Highlands affected hominin population dynamics and movements through the region. To test different scenarios for the period 50–25 ka regarding expansion, adaptive response, intra-population interactions and extinction, we need local on-site paleoclimatic data found in association with hominin occupations. However, this approach has been hampered by the dearth and highly uneven spatiotemporal recovery of paleoclimatic data from prehistoric sites across the region. In this study, we analyze multiple assemblages of fossil micromammals from the Late Middle Paleolithic (LMP) Lusakert-1 rockshelter (two fossil-yielding strata; <55 ka) and Early Upper Paleolithic (EUP) Aghitu-3 Cave (four fossil-yielding strata; ∼39–24 ka) using geometric morphometric-aided taxonomy, to quantify the representation of different species among the abundant and diverse arvicoline genera (Microtus and Chionomys; mean = 58% of assemblages). We combined this approach with quantitative species-level paleoclimatic reconstructions (Bioclimatic Model; 14 rodent taxa) to determine changes in habitat composition as well as temperature and precipitation shifts during the Late Middle–Early Upper Paleolithic. Taphonomic analysis was conducted to establish isotaphonomy among the assemblages. The analysis shows higher than present-day absolute temperatures for the series of occupations at both Lusakert-1 and Aghitu-3, making it unlikely that hominin activity at the sites coincided with extreme cold-climate phases. A multivariate comparison of the taxonomic abundances (genus level) across a wider sample of regional Middle Paleolithic (MP) and Upper Paleolithic (UP) cave sites (Hovk-1, Kudaro-1, Mezmaiskaya, Satsurblia and Dzudzuana) indicates the possibility of cold-period occupation at only two of the sites, Mezmaiskaya Layers 3 and 2 and Kudaro-1 Layer 3. We surmise that the manufacturers of LMP lithic industries in the Caucasus were well adapted to these challenging environments, thus undermining arguments that rapid climate change through the LMP/EUP period could alone have determined the course of population dynamics in this region.

Hominin population bottleneck coincided with migration from Africa during the Early Pleistocene ice age transition

Two recently published analyses make cases for severe bottlenecking of human populations occurring in the late Early Pleistocene, one case at about 0.9 Mya based on a genomic analysis of modern human populations and the low number of hominin sites of this age in Africa and the other at about 1.1 Mya based on an age inventory of sites of hominin presence in Eurasia. Both models point to climate change as the bottleneck trigger, albeit manifested at very different times, and have implications for human migrations as a mechanism to elude extinction at bottlenecking. Here, we assess the climatic and chronologic components of these models and suggest that the several hundred-thousand-year difference is largely an artifact of biases in the chronostratigraphic record of Eurasian hominin sites. We suggest that the best available data are consistent with the Galerian hypothesis expanded from Europe to Eurasia as a major migration pulse of fauna including hominins in the late Early Pleistocene as a consequence of the opening of land routes from Africa facilitated by a large sea level drop associated with the first major ice age of the Pleistocene and concurrent with widespread aridity across Africa that occurred during marine isotope stage 22 at ~0.9 Mya. This timing agrees with the independently dated bottleneck from genomic analysis of modern human populations and allows speculations about the relative roles of climate forcing on the survival of hominins.

Changes in climate extremes in Zambia during green and dry Sahara periods and their potential impacts on hominid dispersal

Northern Africa experienced humid periods known as African humid periods or Green Sahara periods during the late Pleistocene and Holocene. The waxing and waning of the African Monsoon over the last several million years raises the question of how the climatic variability in the African Saharan region could have influenced the evolution and dispersion of hominins in Africa. Little is yet known about the changes in climate extremes in central southern Africa associated with these cycles and their potential impacts on human migration. In this study, we use a regional climate model to simulate archetypal Green and Desert Sahara periods under high and low boreal summer insolation and investigate the resulting changes in climate variability and extremes in South Tropical Africa, with a focus on Zambia. Our results indicate drier and warmer conditions under Green Sahara conditions relative to the Dry Sahara periods. In particular, an increase in the length of droughts and higher temperature extremes have been simulated over the Zambian region in the Green Sahara experiment. Our results suggest that during the Dry Sahara periods, Zambia may have offered better environmental conditions for hominin populations than the Central African Plateau (CAP). In contrast, the Green Sahara periods offered opposite conditions, potentially encouraging hominins to disperse through the large river valleys into the CAP and northward into the Sahel and Sahara.

Homo heterogenus: Variability in early Pleistocene Homo environments.

To understand the ecological dominance of Homo sapiens, we need to investigate the origins of the plasticity that has enabled our colonization of the planet. We can approach this by exploring the variability of habitats to which different hominin populations have adapted over time. In this article, we draw upon and synthesize the current research on habitats of genus Homo during the early Pleistocene. We examined 121 published environmental reconstructions from 74 early Pleistocene sites or site phases to assess the balance of arguments in the research community. We found that, while grasslands and savannahs were prominent features of Homo habitats in the early Pleistocene, current research does not place early Pleistocene Homo, in any single environmental type, but in a wide variety of environments, ranging from open grasslands to forests. Our analysis also suggests that the first known dispersal of Homo out of Africa was accompanied by niche expansion.

Early North African Acheulean techno-economic systems at Thomas Quarry I - L1 (Casablanca, Morocco).

North Africa is a key area for understanding cultural processes that led to the Acheulean pan - African emergence and expressions and the related hominin population dynamics. Unfortunately, little is known about the early Acheulean in this vast area of the African continent due to the scarceness of archaeological sites in stratigraphic context with reliable chronometric data, human remains, and technological analyses of the lithic industries. Here, we present the first comprehensive techno-economic analysis of the early Acheulean assemblage from Thomas Quarry I - Unit L1 (ThI-L1, Casablanca, Morocco), which is the earliest Acheulean site of North Africa, unambiguously dated to 1.3 Ma. Fieldwork has unearthed faunal remains and a lithic collection containing over 3800 artefacts, which represents one of the largest series for the early African Acheulean. The assemblage is mainly composed of quartzites and to a lesser extent of silicites, both abundantly available near the site. Previously published results of the silicite study revealed two different productions for the extraction of small flakes and of bladelet-like flakes. In this work, we analyse the techno-economic systems of the quartzite assemblage. Two distinct quartzite productions co-occur, one devoted to the manufacture of Large Cutting Tools (LCTs), the other focused on the extraction of small-medium sized flakes. LCTs were usually produced from large cobbles, less often from large flakes detached mainly using the entame core method. The main technical objective was to obtain large pointed tools and, more rarely, large tools with a transversal cutting edge. Results support the existence of a strong synergy between conceptual and operational schemes regulated by the ability to anticipate the final tool morphology and to apply standardized shaping procedures to manufacture recurrent morphotypes. Quartzite small-medium sized flakes were produced by a diversity of flaking methods adapted to the cobble blank morphologies and were not retouched. The results allow to assess that the earliest technical expression of the Acheulean in North Africa is characterised by a high diversification of the stone knapping outcomes, the complexity of the mental templates, and the flexible structure of the operational schemes.

Late Acheulean occupations at Montagu Cave and the pattern of Middle Pleistocene behavioral change in Western Cape, southern Africa

Patterns of so-called modern human behavior are increasingly well documented in an abundance of Middle Stone Age archaeological sites across southern Africa. Contextualized archives directly preceding the southern African Middle Stone Age, however, remain scarce. Current understanding of the terminal Acheulean in southern Africa derives from a small number of localities that are predominantly in the central and northern interior. Many of these localities are surface and deflated contexts, others were excavated prior to the availability of modern field documentation techniques, and yet other relevant assemblages contain low numbers of characteristic artifacts relative to volume of excavated deposit. The site of Montagu Cave, situated in the diverse ecosystem of the Cape Floral Region, South Africa, contains the rare combination of archaeologically rich, laminated and deeply stratified Acheulean layers followed by a younger Middle Stone Age occupation. Yet little is known about the site owing largely to a lack of contextual information associated with the early excavations. Here we present renewed excavation of Levels 21–22 at Montagu Cave, located in the basal Acheulean sequence, including new data on site formation and ecological context, geochronology, and technological variability. We document intensive occupation of the cave by Acheulean tool-producing hominins, likely at the onset of interglacial conditions in MIS 7. New excavations at Montagu Cave suggest that, while Middle Stone Age technologies were practiced by 300 ka in several other regions of Africa, the classic Acheulean persisted later in the Fynbos Biome of the southwestern Cape. We discuss the implications of this regionalized persistence for the biogeography of African later Middle Pleistocene hominin populations, for the ecological drivers of their technological systems, and for the pattern and pace of behavioral change just prior to the proliferation of the southern African later Middle Stone Age.

How are Ideas about Evolution Evolving?

Exciting new studies in human evolution are appearing rapidly, transforming scientific understanding of how the human community took form. A 2018 article by archaeologist Eleanor Scerri and colleagues, for example, identifies key debates on this topic. They ask: When and how did Homo sapiens become a species? How important were subgroups and migration in human evolution? And while Scerri cannot yet propose a specific date or place for the origin of Homo sapiens, she reveals certain misunderstandings in earlier thinking about human populations, then points to new directions in interpretation. Scerri argues that paleontology shows varied physical populations with varied material culture, geographically spread through Africa. She notes genetic evidence suggesting that the lineage for Homo sapiens traces back to 500 ka (where “ka,” in this essay, means “thousand years ago”); she also suggests human admixture with other hominin populations in Africa.

Extreme glacial cooling likely led to hominin depopulation of Europe in the Early Pleistocene.

The oldest known hominin remains in Europe [~1.5 to ~1.1 million years ago (Ma)] have been recovered from Iberia, where paleoenvironmental reconstructions have indicated warm and wet interglacials and mild glacials, supporting the view that once established, hominin populations persisted continuously. We report analyses of marine and terrestrial proxies from a deep-sea core on the Portugese margin that show the presence of pronounced millennial-scale climate variability during a glacial period ~1.154 to ~1.123 Ma, culminating in a terminal stadial cooling comparable to the most extreme events of the last 400,000 years. Climate envelope-model simulations reveal a drastic decrease in early hominin habitat suitability around the Mediterranean during the terminal stadial. We suggest that these extreme conditions led to the depopulation of Europe, perhaps lasting for several successive glacial-interglacial cycles.

Exploring Acheulean biface diversity in the central Narmada Valley, Madhya Pradesh, India

Central India occupies a pivotal place in the study of the Indian Palaeolithic. It is rich in Lower Palaeolithic records, with over 300 occurrences reported, and the region's antiquity is at least 800 Ka or older. The central Narmada Valley remains one of the crucial regions in Central India with a high frequency of Acheulean sites, which are primarily observed in the regolith deposits derived from the Vindhyan Supergroup. It is observed that most of the Acheulean sites are to the north of the Narmada River, and with fewer sites to the south. One possible reason could be that multiple hominin populations occupied this region, and the central Narmada Valley acted as a corridor for multidirectional movement in the past. This paper presents preliminary research on different lithic bifacial forms at various Acheulean sites in the central Narmada Valley. This study presents an analysis of 733 bifaces which are typologically divided into cleavers (57.1%), handaxes (35.1%) and miscellaneous (7.8%) specimens. The spatial distribution of these biface forms shows that cleavers are prominently present in the Northern zone, while handaxes are more prevalent in the Central zone. This research discusses various technological aspects of Acheulean bifacial technology in the central Narmada Valley and provides broad implications regarding the hominin occupation in the Indian Subcontinent.

Archaeological evidence for two culture diverse Neanderthal populations in the North Caucasus and contacts between them.

Neanderthals were widespread during the Middle Palaeolithic (MP) across Europe and Asia, including the Caucasus Mountains. Occupying the border between eastern Europe and West Asia, the Caucasus is important region regarding the Neanderthal occupation of Eurasia. On current radiometric estimates, the MP is represented in the Caucasus between about 260-210 ka and about 40 ka. Archaeological record indicates that several culture diverse MP hominin populations inhabited the Caucasus, but the region complex population history during this period remains poorly understood. In this paper, we identify for the first time the archaeological evidence indicating contacts between two culture diverse MP Neanderthal populations in the North Caucasus and discuss the nature of these contacts. Basing on the lithic assemblages that we excavated at Mezmaiskaya cave in the north-western Caucasus (Kuban River basin) and Saradj-Chuko grotto in the north-central Caucasus (Terek River basin), dating from MIS 5 to MIS 3, and comparative data from other MP sites in the Caucasus, we identify two large cultural regions that existed during the late MP in the North Caucasus. The distinctive toolkits and stone knapping technologies indicate that the MP assemblages from Mezmaiskaya cave and other sites in the west of North Caucasus represent a Caucasian variant of the Eastern Micoquian industry that was wide spread in central and eastern Europe, while the assemblages from Saradj-Chuko Grotto and other sites in the east of North Caucasus closely resemble the Zagros Mousterian industry that was wide spread in the Armenian Highlands, Lesser Caucasus and Zagros Mountains. The archaeological evidence implies that two culture diverse populations of Neanderthals settled the North Caucasus during the Late Pleistocene from two various source regions: from the Armenian Highlands and Lesser Caucasus along the Caspian Sea coast, and from Russian plain along the Sea of Azov coast.

Paleoenvironments and climate at Nahal Me'arot (Mount Carmel, Israel) during the Middle and Late Pleistocene: The herpetofauna of Tabun Cave and el-Wad Terrace

The Paleolithic record of the Levant encompasses several key changes in human population dynamics and human biological and cultural evolution. These processes are frequently linked to climatic shifts, but high-resolution and long-term paleoenvironmental and paleoclimatic records often come from off-site sources, hindering the correlation with human developments observed in the archaeological sites. This paper aims to reconstruct the long-term paleoenvironmental and paleoclimatic records of the Middle and Late Pleistocene Nahal Me'arot, Mount Carmel, Israel, using the archaeological herpetofauna assemblages from the Middle Paleolithic (MP) of Tabun Cave (layers C and B; using 18 stratigraphically ordered beds in total) and the Early Natufian of el-Wad Terrace (EWT), and employing the habitat weighting and mutual climate range methods. To strengthen our control of the correlation between the observed variation and the changing environment we also add a modern sample from the same location. We provide a systematic description of the finds and employ taphonomic and taxonomic analyses, which enabled us to identify three major accumulation agents that differentially affected the various samples: raptor predation predominantly in Tabun C, natural entrapment and death in Tabun B, and human consumption in Natufian EWT.The studied Tabun sequence exhibits changes in temperature and humidity. These are more apparent in the lower part (Tabun C), where the driest spell of our sequence also occurred, than in its upper part (Tabun B), and potentially coincide with the succession of two different hominin populations in the site. The correlation with regional off-site records remains challenging. Yet, given the available dates for the layers immediately underlying our driest sample, this dry fluctuation can be cautiously correlated with one of the dry phases apparent in the isotope records at the end of MIS 6. In the Terminal Pleistocene, the Early Natufian EWT reconstruction shows a wetter and cooler climate than the present day, with favorable Eastern Mediterranean vegetation, possibly enabling the long-term sedentary habitation that is suggested for this phase. Finally, our results testify to the general resilience of amphibian and reptile communities through the sequence but also to the rising impact of human activities on the reptile community during the Natufian.

The Role of Large Mammals as Vitamin C Sources for MIS 3 Hominins

The acquisition of large prey by hominins living during the Marine Isotope Stage 3, including Neanderthals and Anatomically Modern Humans, had nutritional and bioenergetic implications: these contain high fat amounts, provide a high energy return, and the strategies and skills required to acquire small prey were different from those required to acquire the former. Vitamin C availability at several MIS 3 periods could have had a strong seasonal variability and would have been decisive for hominin groups’ survival. During the cold periods of the MIS 3, Paleolithic hominins had variable available amounts of vitamin C-containing plants only in the short summers, and for the remainder of the year, viscera would have been their best source of vitamin C. Meanwhile, the dependence on small mammals could have caused an erratic distribution of viscera to be consumed by such hominins, thus leading to chronic scurvy, and compromising their survival. Then, the hunting of large mammals would have helped to meet the daily vitamin C needs, besides an efficient energy supply. Therefore, the decline of large prey during the MIS 3 could have been critical for hominins survival, and thus the efficient exploitation of alternative vitamin C-rich food resources such as birds and aquatic animals could have favored the evolutionary success of hominin populations.

Palaeoenvironmental changes in the southwestern Mediterranean (ODP site 976, Alboran sea) during the MIS 12/11 transition and the MIS 11 interglacial and implications for hominin populations

The transition from the Marine Isotope Stage (MIS) 12 glacial (ca. 478–424 ka BP) to the MIS 11 interglacial (ca. 424–365 ka BP) is one of the most remarkable climatic shifts of the Middle Pleistocene and is regarded as a phase of major behavioural innovation for hominins. However, many of the available pollen records for this period are of low resolution or fragmented, limiting our understanding of millennial-scale climatic variability. We present a high-temporal resolution pollen record that encompasses the period between MIS 12 and MIS 10 (434–356 ka BP), recovered from the Ocean Drilling Program (ODP) Site 976 in the Alboran Sea. This study aims to provide new insights into the response of vegetation during the transition and to highlight patterns of climatic variability during MIS 11.The ODP Site 976 pollen record shows the shift from glacial to interglacial at 426 ka BP, highlighted by the transition from Pinus, herbaceous and steppic taxa to temperate and Mediterranean taxa. A climatic optimum for temperate and Mediterranean taxa is identified around 426–400 ka BP, equivalent to substage MIS 11c and synchronous with the maxima in SSTs, greenhouse gas concentrations and insolation. A phase with increased Pinus and Cedrus indicates the return to colder and more arid conditions during substage MIS 11b (400–390 ka BP). Substage MIS 11a (390–367 ka BP) is marked by a period of short-term warming followed by gradual cooling, until the return of glacial conditions during MIS 10. Forest contractions have been linked with high- and moderate-intensity climate events also observed in other pollen records and proxies from the Mediterranean and North Atlantic.Our results confirm the intense shift during the MIS 12/11 transition and show that this region is sensitive to millennial-scale climatic variation during MIS 11. The forest contractions observed in our record during events of millennial-scale variability appear to be less intense than in the central and eastern Mediterranean. This suggests that the southwestern Mediterranean may have been less variable during periods of climatic deterioration, thereby representing a possible ecological niche for vegetation. This may have provided a source of subsistence for hominins during harsher conditions, thus contributing to their demographic expansion and technological innovations.

Déjà vu: on the use of meat resources by sabretooth cats, hominins, and hyaenas in the Early Pleistocene site of Fuente Nueva 3 (Guadix-Baza Depression, SE Spain)

The late Early Pleistocene archaeological site of Fuente Nueva 3 (Orce, Guadix-Baza Depression, SE Spain), dated to ~1.4 Ma, provides evidence on the subsistence strategies of the first hominin population that dispersed in Western Europe. The site preserves Oldowan tool assemblages associated with abundant remains of large mammals. A small proportion of these remains show cut marks and percussion marks resulting from defleshing and bone fracturing, and a small proportion of bones also show tooth marks. Previous taphonomic studies of FN3 suggested that the hominins had secondary access to the prey leftovers abandoned by sabretooth cats and other primary predators. However, a recent analysis by Yravedra et al. (2021) of the frequency of anthropogenic marks and tooth marks has concluded that the hominins had primary access to the carcasses of a wide variety of ungulate prey, even though the frequency of evisceration marks is strikingly low. In this rebuttal, we analyse the patterns of bone preservation in FN3, which show that the exploitation of bone marrow by the hominins after hammerstone breakage was a usual activity at the site. Our study also reviews the evidence available on the lesser abilities of sabretooth cats for carcass processing compared to pantherine felids. This reinforces the hypothesis that primary predators provided the hominins the opportunity to scavenge sizeable chunks of meat and bone marrow of their prey carcasses before the arrival of hyaenas. Finally, we also provide new inferences on resource availability and competition intensity among the members of the carnivore guild in FN3, which reinforce our interpretation that a secondary access by the Oldowan hominins to the prey leftovers of sabretooth cats was an optimal foraging strategy in the Guadix-Baza Depression.

Towards an astronomical age model for the Lower to Middle Pleistocene hominin-bearing succession of the Sangiran Dome area on Java, Indonesia

Well-dated paleoanthropological sites are critical for studying hominin evolution and dispersal, especially when related to regional or global climate change. For the rich hominin fossil record of Africa, this has been facilitated by the development of high-resolution astronomically tuned age models. So far, such age models are lacking for the Pleistocene of SE Asia with its similarly rich fossil hominin record. This study aims to develop an astronomical age model for the classical Sangiran Dome area of central Java, using a semi-quantitative grain size record of the hominin-bearing Sangiran and Bapang Formations. Two initial age models were established based on two different sets of tie points and approaches (constant sedimentation rate and Bayesian age modelling). These models, which correspond to the paleoanthropological short and long chronologies for the arrival of Homo erectus on Java, were used to convert the grain size record into a time series for time series analysis. The preferred initial age model was then used as a starting point to correlate or tune the grain size record to the LR04 benthic δ18O isotope stack. This tuning was constrained by the sudden switch in grain size from obliquity to double obliquity related cycles; this switch can be linked to the onset of the Mid-Pleistocene Transition at ∼1.2 Ma marked by a similarly abrupt change in ice age history. Two slightly different astronomical age models are presented, while a one cycle hiatus at the base of the Grenzbank cannot be excluded. These age models are in better agreement with the short paleoanthropological chronology, arguing for a late arrival of H. erectus on Java. Finally, such astronomical age models, when finalized, will provide the accurate, precise, and high-resolution age control required to gain insight into the influence of both regional and global climate change on the Pleistocene paleoenvironment and potentially the hominin population of Java.

The Possible Time and Region of Host Switches of Ancient Malaria Parasites with Reference to the Pliocene–Quaternary Archaeological Sites in Africa

AbstractAbout 96% of all malaria deaths occur in Africa, and the malignant falciparum malaria also originated on the continent. Although falciparum malaria only appeared in the Holocene period, it can be hypothesized that the transfer of malaria parasites from other primates to humans occurred several times in history parallel to human evolution. This study develops the model that examines the possible coexistence of the potential original host apes, human ancestors, and the diverse anopheline mosquito species; and how, where, and when the host switch of these parasites from great apes to humans occurred. Based on the Pliocene-early Pleistocene archaeological sites, it was found that certain early hominin populations could have lived in malaria areas where the anopheline mosquito fauna was moderately diverse. The people of the Lupemban Culture, as well as the Greenlandian and Northgrippian human populations of East and West-Central Africa, lived close to the high diversity of anopheline fauna and the territories of such great apes as Gorilla gorrilla. African mid-Holocene cultures likely came in contact with gorilla populations — the original hosts of Plasmodium falciparum — along the coasts of the Gulf of Guinea and the East African Rift Valley during their migration to southern Africa. The host switch of the ancestor of the falciparum malaria parasite likely occurred in these regions.

A process-based approach to hominin taxonomy provides new perspectives on hominin speciation.

A longstanding debate in hominin taxonomy is that between "lumpers" and "splitters." We argue that both approaches assume an unrealistically static model of speciation. Speciation is an extended process, of which fossils provide a record. Fossils should be interpreted in a more dynamic framework than is the norm. We introduce the process-based approach (PBA), in which we suggest that "splitters" recognize and name units at an earlier stage of speciation than "lumpers" do. The "determinants" of speciation can control the rate at which population isolates form, or the rate at which these complete the speciation process, or both. Embedded in the PBA, differences between existing lumped and split taxonomies are a heuristic tool to study these processes. We apply the PBA to show that not all hominin populations reached later stages of the speciation process and that populations have a disproportionate likelihood of doing so from ∼3.1 to ∼1.5 Ma. We outline and discuss resulting new research questions.

The relevance of late MSA mandibles on the emergence of modern morphology in Northern Africa

North Africa is a key area for understanding hominin population movements and the expansion of our species. It is home to the earliest currently known Homo sapiens (Jebel Irhoud) and several late Middle Stone Age (MSA) fossils, notably Kébibat, Contrebandiers 1, Dar-es-Soltane II H5 and El Harhoura. Mostly referred to as “Aterian” they fill a gap in the North African fossil record between Jebel Irhoud and Iberomaurusians. We explore morphological continuity in this region by quantifying mandibular shape using 3D (semi)landmark geometric morphometric methods in a comparative framework of late Early and Middle Pleistocene hominins (n = 15), Neanderthals (n = 27) and H. sapiens (n = 145). We discovered a set of mixed features among late MSA fossils that is in line with an accretion of modern traits through time and an ongoing masticatory gracilization process. In Northern Africa, Aterians display similarities to Iberomaurusians and recent humans in the area as well as to the Tighenif and Thomas Quarry hominins, suggesting a greater time depth for regional continuity than previously assumed. The evidence we lay out for a long-term succession of hominins and humans emphasizes North Africa’s role as source area of the earliest H. sapiens.

Reconstructing Hominin Diets with Stable Isotope Analysis of Amino Acids: New Perspectives and Future Directions.

Stable isotope analysis of teeth and bones is regularly applied by archeologists and paleoanthropologists seeking to reconstruct diets, ecologies, and environments of past hominin populations. Moving beyond the now prevalent study of stable isotope ratios from bulk materials, researchers are increasingly turning to stable isotope ratios of individual amino acids to obtain more detailed and robust insights into trophic level and resource use. In the present article, we provide a guide on how to best use amino acid stable isotope ratios to determine hominin dietary behaviors and ecologies, past and present. We highlight existing uncertainties of interpretation and the methodological developments required to ensure good practice. In doing so, we hope to make this promising approach more broadly accessible to researchers at a variety of career stages and from a variety of methodological and academic backgrounds who seek to delve into new depths in the study of dietary composition.