American Journal of Biological Anthropology

Uintatheres, mammals belonging to the extinct order Dinocerata, are among the most recognizable of all Paleogene ([~]66 - 23 Ma) organisms. Unmistakable for their bizarre skulls with multiple pairs of horns and saber-like upper canines, uintatheres have captivated paleontologists since the late nineteenth century. Since their initial discovery, uintatheres have been regarded as a classic example of dramatic sexual dimorphism in the fossil record, with males purported to be larger and possess more prominent horns and canines than females. However, the hypothesis that uintatheres were highly sexually dimorphic has never been formally tested. Here, I use traditional, linear morphometrics on a collection including most known skulls of Uintatherium anceps to quantify patterns of cranial variation within this taxon. Despite using a variety of traditional and novel statistical methods, I fail to detect any evidence of strong sexual dimorphism in Uintatherium. To verify my approach, I assembled a similarly sized dataset from Bison bison as an extant analog, and found strong, consistent evidence of sexual dimorphism. In light of these findings, as well as the current understanding of uintathere systematics and paleoecology, I argue that strong sexual dimorphism should not be treated as the null hypothesis for this clade.

Chimpanzees, amongst other primates, are characterized by the large variability of habitats they can be found in as well as a large behavioral, sometimes cultural diversity. Such observations have launched a decades-long debate on the roots of behavioral diversity, stressing the need to document this behavioral variability in context, such as by connecting closely related populations through localized analyses. This study presents the first comprehensive description of feeding ecology from the Mwera South chimpanzee (Pan troglodytes schweinfurthii) community in the Bugoma Central Forest Reserve, in Uganda, establishing a valuable baseline for this previously unstudied population and providing a comparative perspective on the populations of Western Uganda and Eastern Democratic Republic of Congo. By employing multiple methodological approaches, including direct observation and fecal analysis, we describe dietary composition, seasonal patterns, and environmental influences on feeding behavior. Characterizing the feeding ecology of this previously unstudied population is critical for examining how ecological factors might influence how feeding patterns evolve depending on resource availability or chimpanzee behavior, in particular by favoring analyses at the regional level. In addition, we can better evaluate to what extent behavioral differences between chimpanzee communities stem from ecological constraints and/or cultural transmission pathways. Our findings suggest that the Bugoma chimpanzees seat at the location of a historic cultural junction, opening a large array of questions about historic movements and cultural diffusion in Eastern chimpanzees.

The deepest phylogenetic divergence within crown birds (Neornithes) is that between the reciprocally monophyletic Palaeognathae and Neognathae. Extant palaeognath diversity comprises the iconic flightless "ratites" (ostriches, rhea, kiwi, cassowaries, and emu), as well as 46 species of volant tinamous in Central and South America (Billerman et al., 2020). Although the earliest stages of palaeognath evolution remain shrouded in mystery due to a sparse fossil record, a group of apparently volant extinct palaeognaths from the Paleogene of Europe and North America, the lithornithids, can help to clarify palaeognath origins. Here, we use high resolution microCT scanning to characterize the morphology of two lithornithid specimens from the early Eocene (Ypresian) London Clay Formation: the neotype of Lithornis vulturinus (NHMUK A5204), from the Isle of Sheppey, Kent, England, and a newly discovered clay nodule containing lithornithid postcranial remains from the nearby locality of Seasalter. This three-dimensional dataset reveals bones from the L. vulturinus neotype that are partially or completely covered by matrix, allowing us to redescribe this critical specimen in new detail and present a revised differential diagnosis of L. vulturinus. We refer the new specimen from Seasalter to L. vulturinus on the basis of apomorphies such as a proximally directed lateral process of the coracoid, caudally divergent lateral margins of the sternum, an arcuate deltopectoral crest, as well as its provenance from a nearby penecontemporaneous locality. The Seasalter specimen contains abundant postcranial material that provides new insight into bones damaged or missing in the neotype, including two undamaged scapulae bearing the hooked acromion that is a diagnostic feature of lithornithids, two complete coracoids, and a nearly complete three-dimensionally preserved sternum. Its estimated body mass is one third larger than that of the neotype, indicating intraspecific variation within L. vulturinus that may reflect sexual dimorphism. Molecular divergence dates and Cretaceous neognath fossils indicate the presence of total-clade palaeognaths before the K-Pg mass extinction event; detailed anatomical descriptions of Paleogene palaeognaths will assist in the identification of the first total-clade palaeognaths from the Cretaceous, and provide insight into how and when flight was independently lost among Cenozoic crown palaeognaths.

South Asia is central to debates on early human dispersals, particularly the Out of Africa model and Eurasian colonization. Studies of M haplogroups have been used to support both Northern and Southern route hypotheses, but current archaeological and genetic evidence in the region remains contradictory. In the present work, we find that in addition to haplogroup M lineages, a few R lineages exhibit ancient, locally rooted variation, with R30 being one of the widespread haplogroup of R lineages across South Asia. To better understand South Asian demographic history, we investigated the phylogeographic distribution of haplogroup R30, an indigenous lineage. We used 190 complete modern and ancient sequences from diverse mainland and island populations including incorporation of 44 newly generated sequences which enabled the refinement of the R30 phylogeny and the identification of a novel basal lineage, R30c. Bayesian and {rho}-based age estimates suggest that R30 originated in the Indian subcontinent ~50 kya. Early diversification likely occurred in Northern India, giving rise to R30b (~44 kya), while R30a and R30c differentiated primarily in Southern India. Several subclades of haplogroup R30 exhibit strong signatures of founder effects, particularly among the language isolate Vedda of Sri Lanka, Uru Kurumban of Southern India, and the populations of the Lakshadweep archipelago. Bayesian skyline analyses indicate long-term demographic stability followed by rapid lineage expansion ~20 kya and more recent declines consistent with localised drift and relatively recent founder events. The presence of early-diverging R30 lineages in Thailand and Indonesia further supports long-term connections between South and Southeast Asia. Overall, archaeological and genetic evidence point towards the multiple migrations for South Asia colonizations.

The fossil record is the most important tool in palaeosciences, so continually reviewing and attempting to reduce biases in its collection is necessary to curate the best possible record of past life on Earth. Biases in the fossil record are introduced through both biological processes and data collection. Here we have investigated the extent to which anthropocentric data collection has contributed to sampling bias in the assembly of the current fossil record. We have found that the current fossil record (represented in this study by the NOW database) is anthropocentrically biased, both temporally and spatially. Specifically, fossil locality density is higher in time periods when hominins are found, and in known hominin-bearing locations. This demonstrates the need to stop essentializing the narrative of human evolution in paleoscience to reduce bias in sampling of fossil localities.

The population of Madagascar exhibits a globally unique combination of African and Asian genetic ancestries. Previous studies have described the admixture history of Madagascar at island-wide scales [1,2], but less focus has been paid to fine-scale population structure across the island. We present new genome-wide genetic data from 192 individuals sampled across five regions of Madagascar. We identify population structure at extremely fine spatial scales ([~]10 km) among the Merina of the central highlands. By analysing subpopulations separately, we found one Merina group exhibited similarity to coastal populations in f4 ratios, estimated admixture dates, and pairwise FST distances, while another group was similar to other highland individuals in the same measures. This fine-scale substructure is likely associated with historical coastal-to-highland migration during the 18th and 19th centuries. In contrast, we also observe macro-scale structure in estimated timing of admixture across the island, with southeastern coastal groups exhibiting the earliest estimated admixture timings, and northern groups exhibiting the latest. This pattern corroborates previous results [1,2], and may suggest differing histories of admixture timing among Malagasy populations. Our results emphasise the importance of deep micro-geographic sampling to complement macro-scale analysis when characterising demographic history.

Five millennia ago, nomadic people from the North Pontic steppe left a profound impact on the course of Eurasian prehistory. However, little is known about their mobility patterns within their home region. To address this knowledge gap, we conducted a survey of the strontium isotope landscape of people interred in the 4th-3rd millennium BCE burial mounds (kurgans) of the western part of the North Pontic steppe. By analyzing the strontium signature in human bone and dentin, we established strontium baseline values for the region. We subsequently correlated enamel strontium ratios from 25 selected individuals with the baseline obtained and with published strontium data across the North Pontic steppe. Enamel strontium ratios show that some individuals interred in the northwest North Pontic fall within the regional baseline range, whereas others overlap with values reported for the eastern North Pontic steppe. In conjunction with carbon ({delta}13C) and nitrogen ({delta}15N) stable isotope data, we further determined that some individuals interred in the western Pontic steppe either spent the later part of life in the west Caspian steppe or were affected by physiological stress during lifetime. By integrating our data with published isotopic datasets, we produced a first baseline heatmap of the North Pontic steppe for the c. 4000-2000 BCE chronological period.

Small marsupials in the family Dasyuridae are a key component of Australias arid and semi-arid fauna, whose high species richness is proposed to reflect an opportunity-driven adaptive radiation. Despite growing interest in this group from both ecological and evolutionary perspectives, genomic data for most species is non-existent, or limited to a few marker loci. Here, we generated a chromosome-level reference genome and a de novo mitochondrial genome for the desert-dwelling Wongai ningaui (Ningaui ridei). The nuclear genome assembly is highly contiguous, with a scaffold N50 of 594.484 MB and high BUSCO gene recovery (93.84%). Additionally, we produced a draft assembly for the related, semi-arid slender-tailed dunnart (Sminthopsis murina). We then used these assemblies to explore the demographic histories of these species. We find evidence for contrasting patterns of population growth during the late Pleistocene and early Holocene, corresponding with differences in local climate, potentially consistent with differences in optimal habitat. The new genomic resources and demographic findings presented here provide a foundation for future studies on adaptive specialisation in this group of Australian marsupials. Significance StatementDasyurid marsupials are the primary carnivorous and insectivorous mammals in Australia. This diverse family includes species such as the endangered Tasmanian devil (Sarcophilus harrisii) and quolls (Genus Dasyurus), as well as an emerging laboratory model species, the fat-tailed dunnart (Sminthopsis crassicaudata). Despite the species richness within dasyurids, most species remain under-studied. This is particularly true of arid and semi-arid zone species, who are often small in size, live in remote habitats and are cryptic by nature. By creating genome assemblies for two dasyurid species, this study provides resources to support a variety of phylogenetic, population genetic and evolutionary developmental lines of research. Importantly, the studys finding that arid and semi-arid dasyurids show distinct trajectories of demographic change in response to historical climatic shifts may point to local adaptations with implications for the resilience of these species to ongoing and future climate change.

Dental morphology and wear patterns provide insight into the dietary adaptations and ecological niches of living and extinct herbivores. Traditional classification statistics such as Linear Discriminant Analysis (LDA) are limited by assumptions of linearity, normality, and homoscedasticity. This study quantifies mesowear, the shape of molar cusps resulting from occlusal wear, and evaluates the performance of non-linear machine learning models in predicting herbivore diets based on geometric morphometric (GMM) data from adult mandibular second molars (M2) in bovids. We applied Generalized Procrustes Analysis and Principal Component Analysis (PCA) to digitized occlusal shape coordinates from 132 M2 specimens across 64 species. Using the resulting principal component scores, we compared the classification accuracy of LDA with three non-linear models: Random Forest, K-Nearest Neighbors, and Gradient Boosting. While LDA achieved a cross-validated accuracy of just 31%, all non-linear models achieved 99% cross-validation accuracy and 90% test accuracy, demonstrating substantially improved performance. Misclassification analyses revealed that non-linear models more effectively captured complex shape differences, particularly among species with overlapping wear patterns. Our findings support the integration of machine learning with geometric morphometrics to quantify mesowear and improve dietary classification, providing a framework for robust paleoecological inference.

The morphology of the palate has long constituted the primary basis for differentiating between the two deepest clades of crown group birds, Neognathae and Palaeognathae. However, published literature on the bird palate is dominated by classical anatomical descriptions pre-dating the advent of contemporary three-dimensional imaging techniques, hindering our understanding of bird palate disparity and development. Pterygoid segmentation, the process by which the rostral portion of the pterygoid separates and fuses with the palatine during ontogeny in neognathous birds, remains a poorly understood aspect of avian cranial development despite giving rise to an important component of the cranial kinetic system. Here, we use micro-computed tomography to explore ontogenetic change of the palate during the process of pterygoid segmentation across an unprecedentedly broad taxonomic sample of immature and mature birds. We found that direct evidence of post-hatching pterygoid segmentation was restricted to the major avian subclade Neoaves. Based on morphological and topological similarities, we hypothesise that the rostral projection of the pterygoid observed in Anatidae/Anseres and potentially Anhimidae and Megapodiidae, which we term the hemipterygoid process, is homologous with the hemipterygoid of neoavians, though it does not undergo segmentation. We posit that the origin of a discrete hemipterygoid (as observable in some crownward stem-birds) originated prior to the origin of the process of pterygoid segmentation; however, it remains ambiguous whether pterygoid segmentation is a synapomorphy of Neornithes, Neognathae, or Neoaves. Overall, our study clarifies the process of avian pterygoid segmentation and raises new questions regarding the major morphological modifications that have characterised the evolutionary history of the avian bony palate.

This research provides original insights into the diversity of DNA extracted from samples collected in 1978 from the Turin Shroud, revealing its biological complexity through rigorous DNA and metagenomic analyses. Our findings highlight its preservation conditions and environmental interactions, offering valuable perspectives into the identified genetic variants, which originated from multiple biological sources. Several human mitochondrial DNA (mtDNA) lineages were identified, including K1a1b1a, which matches the 1978 official collectors mitogenome, H2a2 (i.e. the lineage of the mtDNA reference sequence rRCS), H1b, which is common in Western Eurasia, and H33, which is prevalent in the Near East and frequent among the Druze. Moreover, the reconstructed microbiome of the Shroud reveals a rich tapestry of multiple microbes commonly found on the human epidermis, as well as archaeal communities adapted to high salinity, and fungi including molds. This is indicative of the Shrouds preservation conditions over the centuries. Additionally, the presence of abundant Mediterranean endemic red coral, various cultivated plants (e.g. carrot, wheat, corn, bananas, and peanuts) and domesticated animals (e.g. cattle, pigs, chickens, dogs, and cats) provide a fascinating glimpse into the diverse biological sources of the contaminants that have accumulated on the Turin Shroud over time. Finally, radiocarbon dating of two distinct threads collected from the reliquary provides evidence of their use to repair the Shroud in the years 1534 and 1694 of the Common Era (CE). Significance statementAn in-depth metagenomic analysis was conducted on several linen strands collected from different areas of the body image of the Man of the Shroud during the official sampling in 1978. Our analyses revealed several human mtDNA lineages, including one common in Western Eurasia and another prevalent in the Near East. Additionally, the diversity of animal and plant species identified details the significant environmental contamination of the Shroud that likely occurred in recent centuries, particularly following the voyages of Marco Polo and Christopher Columbus. Radiocarbon dating of two distinct textile residuals from the Shrouds reliquary indicated a time range between 1451 and 1800 CE, overlapping with the period of its repair interventions.

The diversity of body shapes is one of the most prominent features of phenotypic variation in mammals. Yet, mammalian body shapes are poorly quantified and the underlying components contributing to its diversity as well as its relationship to other components of the skeleton are rarely tested. Here, we use lagomorphs (hares, rabbits and pikas) as a model system to (1) investigate which components of the skeleton contributed the most to body shape diversity, (2) examine the relationships between body shape and relative limb lengths, and (3) test how body size, ecotype, burrowing behavior, and locomotor mode influenced variation in lagomorph body shape and appendicular morphology. We quantified the body shape and functional proxies of the appendicular skeleton in 40 lagomorph species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we found the relative length of the ribs and elongation or shortening of the thoracic and lumbar regions contributed the most to body shape evolution across lagomorphs. Second, we found that only leporids (hares and rabbits) exhibited a significant relationship between limb length and body shape, where more elongate species exhibit relatively shorter forelimbs and hindlimbs. Lastly, we found that models incorporating body size were the best predictors of lagomorph body shape and the majority of the appendicular traits, whereas models incorporating burrowing behavior and locomotor mode were largely poor fits. Broadly, these results indicate that larger lagomorphs tend to exhibit more robust body shapes with longer, more gracile forelimbs, whereas smaller lagomorphs tend to exhibit more elongate body shapes with shorter, more robust forelimbs. Overall, this work contributes to the growing understanding of mammalian body shape evolution and demonstrates the importance of not omitting body size in ecomorphological analyses.

In their recent study entitled "Ancient DNA reveals the co-existence of domestic horses, donkeys and their hybrids in the prehistorical northwestern China", Li and colleagues (2026) report the genetic identification of three horses, three donkeys and four first-generation hinny hybrids dating to 400-160 BCE from the Mazongshan jade mining site in northwestern China. While a re-analysis of their ancient DNA sequence data confirms the horse and donkey identifications, it indicates that the four putative hinny specimens were, in fact, donkeys. This revision removes the primary evidence originally shown for the presence of hinnies at this site. Therefore, new data from the Mazongshan bone assemblage are required to support the proposed role of hinny hybrids as integral components of trans-regional trade networks during the Late Warring States and Early Han periods.

Comparative studies in evolutionary biology must account for trait non-independence arising from shared ancestry. While the phylogenetic signal of adult traits has been extensively studied, little is known about how conserved developmental trajectories are across species. Here, I quantify the phylogenetic signal (K) in the ontogeny of 35 traits across 157 primate species, spanning motor, cognitive, life-history, and dental development. Using Blombergs K statistic and a species-level mammalian phylogeny, I test two predictions: (i) that morphological (dental) traits exhibit the strongest phylogenetic signal, and (ii) that earlier-developing traits are more conserved. Results show that life-history traits are the most phylogenetically labile, while dental development is the most conserved (K = 0.7-2.6), with the eruption of the mandibular canine showing the highest signal (K = 2.6). Contrary to expectations, later-developing traits, particularly permanent teeth, display stronger phylogenetic conservation than earlier-developing deciduous teeth. These findings suggest that even within a single developmental system, the strength of phylogenetic constraint varies markedly with timing. The results provide an empirical foundation for identifying reliable temporal anchors in comparative primate ontogeny and have implications for interpreting maturational patterns in human evolution and the fossil record.

Ancient DNA has shown that a distantly-related "superarchaic" population interbred first with the ancestors of Neanderthals and Denisovans and later with Denisovans themselves. Other work has shown that a superarchaic population interbred with the African ancestors of all modern humans. But it is not yet clear whether these events involved the same superarchaic population. Here, we use the distribution of derived alleles among populations to evaluate hypotheses about superarchaics and their relationship to other hominins of the Pleistocene and Holocene. We find evidence for at least two distinct superarchaic populations. The one contributing to archaic Eurasian populations (Denisovans and Neanderthal-Denisovan ancestors) diverged earlier from the human lineage than did the one contributing to early moderns in Africa. These findings reveal previously unrecognized structure among hominin populations of the Pleistocene.

Characterized by the earliest use of pottery, the Jomon culture was a unique Neolithic culture that spread throughout the Japanese Archipelago. Previous archaeological evidence suggests that Jomon hunter-gatherers colonized the southernmost islands, the Ryukyu Archipelago, by approximately 7,000 years before present (YBP). However, genetic characteristics of the Ryukyu Jomon population and its contribution to the modern population have not been elucidated yet. In this study, we newly sequenced 273 modern and 25 ancient (6,700-900 YBP) whole genomes collected across the Ryukyu Archipelago. Our analysis demonstrated a genetic differentiation between the Hondo (Japanese mainland) and Ryukyu Jomon, dating back to [~]6,900 YBP. After the divergence from the Hondo Jomon, the Ryukyu Jomon experienced severe bottlenecks, with an effective population size of [~]2,000. Admixture between the Ryukyu Jomon and migrants from the historic Hondo population occurred [~]1,000 YBP, which corresponds to the widespread adoption of iron tools and agriculture in the Central Ryukyus. Different demographic histories between modern Hondo and Ryukyu populations resulted in different rates of Jomon ancestry in these populations. By providing a new perspective on the peopling of the Ryukyu Archipelago, this study significantly enhances our understanding of cultural transitions in the region.

The early evolutionary history of modern domestic horses (Equus caballus/E. ferus caballus), known as the DOM2 lineage, is well documented due to numerous archaeological and ancient DNA (aDNA) studies. Although many uncertainties remain in the domestication timeline, current evidence suggests that the domestication of modern horses began in the Pontic-Caspian steppe at least [~]2700 BCE (before common era), or even earlier. However, it is not known how long remnant wild horse populations survived or when domestic horses were introduced into Northern Europe. In this study, we review the current knowledge of horse domestication, focusing on Northern Europe. We analysed prehistoric horses from western Russia to assess the body sizes of wild horses from the Ivanovskaya site (5900-3800 BCE) in the Pontic-Caspian steppe, and the body weight of one Lithuanian wild horse (4000-3800 BCE). Additionally, we analysed body sizes of Late Bronze Age-Early Roman Age horses (1100 BCE-300 CE; common era) and re-analysed body sizes and estimated rider weights of historic domestic horses from Lithuania (100-1400 CE). We searched for pathological changes and signs of bit wear indicative of bridling. Furthermore, we investigated maternal genetic diversity by sequencing ancient mitochondrial DNA. We found that wild horses from Ivanovskaya were intermediate in body size between earlier and more recent horses of the Eurasian Steppe, and that the Lithuanian wild horse weighed only [~]270 kg and Late Bronze Age-Early Roman Age horses 200-300 kg. Lithuanian domestic horses were pony-sized (< 130 cm on average). Bit wear was confirmed on one tooth, the oldest domestic horse in Lithuania (799-570 cal BCE). Another tooth showed signs of the Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) condition. Mitochondrial DNA was successfully amplified from one Ivanovskaya wild horse along with 25 other ancient samples, including Lithuanias oldest domestic horse. mtDNA diversity was high, revealing several maternal lineages.

BackgroundAlpha satellites, a superfamily of AT-rich tandem repeats, are the primary DNA component of centromeres in Platyrrhini and Catarrhini. Analyses of the human genome suggest that centromeres behave like biological ridges, with new alpha satellite families expanding at the centromere core, splitting and displacing older ones towards the pericentromeres. The Cercopithecini tribe, which displays an unusual chromosomal evolution involving multiple chromosomal fissions and centromere formations, represents a promising model to enhance our understanding of alpha satellite DNA evolutionary history. We previously applied targeted sequencing to centromere DNA from two distant species drawn from the Cercopithecini terrestrial and arboreal lineages, and characterized six alpha satellite families exhibiting varying mean sequence identities. MethodsCombining classical and molecular cytogenetics, we mapped the chromosomal distribution of these alpha satellite families across 13 Cercopithecini, one Papionini, and one Colobinae species. A nuclear marker-based phylogeny provided an evolutionary framework for interpretation. ResultsOur phylogeny identifies the terrestrial and arboreal lineages, and a newly designated swamp clade. We observed significant interspecies variations in alpha satellite patterns, including differences in presence/absence and distinct chromosomal distribution patterns (centromeric, pericentromeric, or subtelomeric). Families previously described as heterogeneous (83-87% mean sequence identity) exhibit a centromeric position in the swamp lineage, which is characterized by conserved karyotypes. In contrast, these families show a pericentromeric distribution in the terrestrial and arboreal lineages, replaced at the centromere core by more homogeneous families (95-98% mean sequence identity). In the arboreal clade, which is characterized by highly fissioned karyotypes, putative evolutionary new centromeres show a unique co-occurrence of highly homogeneous and heterogeneous families. Conclusion & ImplicationsWe propose a comprehensive evolutionary scenario for alpha satellite DNA in Cercopithecini, where younger families arise at the centromere core, shift toward the pericentromeres as they age, and eventually face extinction. Our study suggests that alpha satellite DNA and chromosomes evolve in an interdependent manner, with satellite diversification and displacement occurring in parallel with chromosome fissions and centromere repositioning. This comparative cytogenomic approach provides both support for the human-based evolutionary model for alpha satellite DNA and novel temporal insights into its diversification dynamics. Beyond evolutionary genomics, our findings highlight the potential of alpha satellite DNA to complement systematic studies in deciphering complex primate evolutionary histories.

Human diversity did not only remain restricted to their socio-cultural and linguistic domains but also have penetrated deep inside their genetic root. Africa harbors more genetic diversity than any other part of the world. Diversification of the African lineages were complex, involving long-distance gene flow. Data from Africansis needed to better understand the origin and evolution of modern humans, the genetic basis local adaptation, and the evolution of complex traits and related diseases. This analysis formed the basis for this study of determining the origin and migration of the Ameru community in Kenya. Blood samples was collected from 132 male adults of 65 year and above. DNA was extracted and analyzed for the Hyper variable region 1and 2. The sequences were sequenced using Sanger sequence alignment and analyzed using Geneious. Phylogenetic analysis was done using Mega-X while haplotype analysis was done using DNASP software. L1 haplogroup (2.9%) was found among Igembe (7%), Tharaka (6%), and Chuka (7%) and is common in West, Central, and parts of East Africa. L2 haplogroup (6.7%) was present in all subgroups except Imenti and Tigania, indicating West and Central African maternal ancestry. L1 and L2 haplotypes indicate that most Ameru subgroups share partial maternal ancestry from West and Central Africa, while Imenti and Tigania have different maternal lineages. L0-L4 haplogroups indicate predominant East, Central, and West African maternal origins, with subgroups showing variation in haplotype frequencies (e.g., L1 and L2 in Igembe, Tharaka, Chuka; L3 in Tharaka, Mwimbi, Chuka; L4 across all subgroups). Subgroup differences suggest that certain communities, particularly Imenti, have distinct maternal lineages, with less contribution from L1, L2, and L3 but potential links to Afro-Asiatic groups via L4 (found in the Middle East). Non-African haplogroups (N and R) point to historical interactions or shared ancestry with populations in Eurasia and the Horn of Africa, primarily in Tigania and Imenti. Overally, the Ameru maternal gene pool is heterogeneous, shaped by multiple migration routes and interactions across East Africa and beyond, with subgroup-specific maternal histories.

Domestic dogs (Canis familiaris) display more morphological variation than any other mammal. Cranial morphology has been extensively studied, as have the relationships with function, development, genetics, veterinary medicine, and breed welfare. Postcrania remain comparatively understudied, despite well-documented breed-specific predispositions to musculoskeletal disease. Here, we apply three-dimensional landmark-free morphometrics to quantify the shape of 743 elements from 213 dogs, including the scapula, humerus, radius, ulna, pelvic girdle, femur, tibia, and fibula. We assess integration among limb elements and investigate drivers of shape variation within and between breeds. Across most breeds, limb bone shape is strikingly similar. Dachshunds, however, exhibit distinct morphology across all elements and one to two orders of magnitude greater variation than any other breed. Despite this disparity, integration remains high between all element pairs. Remarkably, we find no significant relationship between bone shape and body mass, age, or pathology, but comparison with historic specimens reveals marked changes in dachshund long bone shape over the past [~]150 years. These extreme differences are not shared by other sampled chondrodysplastic breeds, underscoring the need to understand morphological diversity beyond simple categorisation. These findings provide a quantitative framework for linking postcranial morphology with function, disease risk, and evidence-based improvements to canine welfare.