Genome-scale sequencing and analysis of human, wolf, and bison DNA from 25,000-year-old sediment

sedimix : A workflow for the analysis of hominin nuclear DNA sequences from sediments

Summary

Sediment DNA--the ability to extract DNA from archaeological sediments-- is an exciting new frontier in ancient DNA research, offering the potential to study individuals at a given archaeological site without destructive sampling. In recent years, several studies have demonstrated the promise of this approach by recovering hominin DNA from prehistoric sediments, including those dating back to the Middle or Late Pleistocene. However, a lack of open-source workflows for analysis of hominin sediment DNA samples poses a challenge for data processing and reproducibility of findings across studies. Here we introduce a snakemake workflow, sedimix , for processing genomic sequences from archaeological sediment DNA samples to identify hominin sequences and generate relevant summary statistics to assess the reliability of the pipeline. By performing simulations and comparing to published studies, we show that sedimix has high sensitivity and precision. sedimix offers a reliable and adaptable framework to aid in the analysis of sediment DNA datasets and improve reproducibility across studies.

Availability and Implementation

sedimix is available as an open-source software with the associated code and user manual available at https://github.com/jierui-cell/sedimix Contact: Jierui Xu ( jierui.xu@berkeley.edu ) Supplementary information: Supplementary data are available at Bioinformatics online.

More than dirt: Sedimentary ancient DNA and Indigenous Australia

The rise of sedimentary ancient DNA (sedaDNA) studies has opened new possibilities for studying past environments. This groundbreaking area of genomics uses sediments to identify organisms, even in cases where macroscopic remains no longer exist. Managing this substrate in Indigenous Australian contexts, however, requires special considerations. Sediments and soils are often considered as waste by-products during archaeological and paleontological excavations and are not typically regulated by the same ethics guidelines utilised in mainstream 'western' research paradigms. Nevertheless, the product of sedaDNA work-genetic information from past fauna, flora, microbial communities and human ancestors-is likely to be of cultural significance and value for Indigenous peoples. This article offers an opinion on the responsibilities of researchers in Australia who engage in research related to this emerging field, particularly when it involves Indigenous communities. One aspect that deserves consideration in such research is the concept of benefit sharing. Benefit sharing refers to the practice of ensuring that the benefits that arise from research are shared equitably with the communities from which the research data were derived. This practice is particularly relevant in research that involves Indigenous communities, who may have unique cultural and spiritual connections to the research material. We argue that the integration of Traditional Knowledges into sedaDNA research would add enormous value to research and its outcomes by providing genomic outputs alongside and within the rich context of multimillennia oral histories.

Contextualizing the Upper Paleolithic of the Armenian Highlands: New data from Solak-1, central Armenia

As a potential corridor connecting Southwest Asia with western and northern Europe, the Armenian Highlands and southern Caucasus hold great potential for increasing our understanding of Upper Paleolithic behavioral and cultural variability. However, given the dearth of Upper Paleolithic sites, we lack the data necessary to answer basic questions regarding the timing and nature of the Upper Paleolithic in this region. Solak-1 is an open-air site located along the upper Hrazdan Valley (1635 m above sea level) in central Armenia. The site preserves a rich Upper Paleolithic lithic assemblage produced almost exclusively on obsidian and is just the fourth Upper Paleolithic sequence in Armenia. The goal of this study is to present geoarchaeological, chronometric, and technological analyses of the Solak-1 site to integrate the site into the regional Upper Paleolithic sequence. Solak-1 is composed of six lithostratigraphic units (LUs 1-6) comprising recently reworked (LUs 1-2), pedogenically modified (LUs 3-5), and primary (LU 6) loess. A single-grain postinfrared infrared stimulated luminescence date of 27.73 ± 3.63 ka was obtained from LU 4. This age is comparable to regional Middle Upper Paleolithic sites in Armenia and Georgia. Technotypological analyses indicate a lithic assemblage dominated by the production of bladelets and bladelet tools from formal and informal cores. Geochemical sourcing of the obsidian highlights a predominance of local raw material use, with rare transport of artifacts over 185 linear km. These results add an important new datapoint to the Upper Paleolithic record of the Armenian Highlands, offering additional insights into technotypological patterning within this period.

Rapid change in red cell blood group systems after the main Out of Africa of Homo sapiens

Despite the advances in paleogenomics, red cell blood group systems in ancient human populations remain scarcely known. Pioneer attempts showed that Neandertal and Denisova, two archaic hominid populations inhabiting Eurasia, expressed blood groups currently found in sub-Saharans and a rare "rhesus", part of which is found in Oceanians. Herein we fully pictured the blood group genetic diversity of 22 Homo sapiens and 14 Neandertals from Eurasia living between 120,000 and 20,000 years before present (yBP). From the ABO, Rh, Kell, Duffy, Kidd, MNS, Diego, H, secretor and Indian systems, we noted that the blood group allele diversity in the Neandertals remained unchanged since 120,000 yBP, while H. sapiens conquered Eurasia with blood group alleles presently exclusive to non-African populations, suggesting they may have differentiated right after the Out of Africa, between 70,000 and 45,000 yBP. Notably, Ust'Ishim possessed unknown alleles that may illustrate the lost genetic heritage of the early Eurasians. Lastly, Neandertals shared a unique Rh haplotype from which we updated the current RHD phylogeny. The contribution of this study is twofold. It enlightens the expansion patterns of H sapiens and recalls the anthropological effectiveness of genetic polymorphisms currently being surveyed for transfusion safety and pregnancy monitoring.

Pre-processing of paleogenomes: mitigating reference bias and postmortem damage in ancient genome data

We investigate alternative strategies against reference bias and postmortem damage in low coverage paleogenomes. Compared to alignment to the linear reference genome, we show that masking known polymorphic sites and graph alignment effectively remove reference bias, but only starting from raw read files. We next study approaches to overcome postmortem damage: trimming, rescaling, and our newly developed algorithm, bamRefine (github.com/etkayapar/bamRefine and zenodo.org/records/14234666), masking reads only at positions possibly affected by PMD. We propose graph alignment coupled with bamRefine as a simple strategy to minimize data loss and bias, and urge the community to publish FASTQ files.

A sedimentary ancient DNA perspective on human and carnivore persistence through the Late Pleistocene in El Mirón Cave, Spain

Caves are primary sites for studying human and animal subsistence patterns and genetic ancestry throughout the Palaeolithic. Iberia served as a critical human and animal refugium in Europe during the Last Glacial Maximum (LGM), 26.5 to 19 thousand years before the present (cal kya). Therefore, it is a key location for understanding human and animal population dynamics during this event. We recover and analyse sedimentary ancient DNA (sedaDNA) data from the lower archaeological stratigraphic sequence of El Mirón Cave (Cantabria, Spain), encompassing the (1) Late Mousterian period, associated with Neanderthals, and (2) the Gravettian (c. 31.5 cal kya), Solutrean (c. 24.5-22 cal kya), and Initial Magdalenian (d. 21-20.5 cal kya) periods, associated with anatomically modern humans. We identify 28 animal taxa including humans. Fifteen of these taxa had not been identified from the archaeozoological (i.e., faunal) record, including the presence of hyenas in the Magdalenian. Additionally, we provide phylogenetic analyses on 70 sedaDNA mtDNA genomes of fauna including the densest Iberian Pleistocene sampling of C. lupus. Finally, we recover three human mtDNA sequences from the Solutrean levels. These sequences, along with published data, suggest mtDNA haplogroup continuity in Iberia throughout the Solutrean/Last Glacial Maximum period.

Genetic Polymorphism of Y-Chromosome in Turkmen Population from Turkmenistan

This study investigates the Y-chromosome genetic diversity of the Turkmen population in Turkmenistan, analyzing 23 Y-STR loci for the first time in a sample of 100 individuals. Combined with comparative data from Turkmen populations in Afghanistan, Iran, Iraq, Russia, and Uzbekistan, this analysis offers insights into the genetic structure and relationships among Turkmen populations across regions across Central Asia and the Near East. High haplotype diversity in the Turkmen of Turkmenistan is shaped by founder effects (lineage expansions) from distinct haplogroups, with haplogroups Q and R1a predominating. Subhaplogroups Q1a and Q1b identified in Turkmenistan trace back to ancient Y-chromosome lineages from the Bronze Age. Comparative analyses, including genetic distance (RST), median-joining network, and multidimensional scaling (MDS), highlight the genetic proximity of the Turkmen in Turkmenistan to those in Afghanistan and Iran, while Iraqi Turkmen display unique characteristics, aligning with Near Eastern populations. This study underscores the Central Asian genetic affinity across most Turkmen populations. It demonstrates the value of deep-sequencing Y-chromosome data in tracing the patrilineal history of Central Asia for future studies. These findings contribute to a more comprehensive understanding of Turkmen genetic ancestry and add new data to the ongoing study of Central Asian population genetics.

soibean: High-Resolution Taxonomic Identification of Ancient Environmental DNA Using Mitochondrial Pangenome Graphs

Ancient environmental DNA (aeDNA) is becoming a powerful tool to gain insights about past ecosystems, overcoming the limitations of conventional fossil records. However, several methodological challenges remain, particularly for classifying the DNA to species level and conducting phylogenetic analysis. Current methods, primarily tailored for modern datasets, fail to capture several idiosyncrasies of aeDNA, including species mixtures from closely related species and ancestral divergence. We introduce soibean, a novel tool that utilizes mitochondrial pangenomic graphs for identifying species from aeDNA reads. It outperforms existing methods in accurately identifying species from multiple closely related sources within a sample, enhancing phylogenetic analysis for aeDNA. soibean employs a damage-aware likelihood model for precise identification at low coverage with a high damage rate. Additionally, we reconstructed ancestral sequences for soibean's database to handle aeDNA that is highly diverged from modern references. soibean demonstrates effectiveness through simulated data tests and empirical validation. Notably, our method uncovered new empirical results in published datasets, including using porpoise whales as food in a Mesolithic community in Sweden, demonstrating its potential to reveal previously unrecognized findings in aeDNA studies.

Maximizing efficiency in sedimentary ancient DNA analysis: a novel extract pooling approach

In the last few decades, the field of ancient DNA has taken a new direction towards using sedimentary ancient DNA (sedaDNA) for studying human and mammalian population dynamics as well as past ecosystems. However, the screening of numerous sediment samples from archaeological sites remains a time-consuming and costly endeavor, particularly when targeting hominin DNA. Here, we present a novel high-throughput method that facilitates the fast and efficient analysis of sediment samples by applying a pooled testing approach. This method combines multiple extracts, enabling early parallelization of laboratory procedures and effective aDNA screening. Pooled samples with detectable aDNA signals undergo detailed analysis, while empty pools are discarded. We have successfully applied our method to multiple sediment samples from Middle and Upper Paleolithic sites in Europe, Asia, and Africa. Notably, our results reveal that an aDNA signal remains discernible even when pooled with four negative samples. We also demonstrate that the DNA yield of double-stranded libraries increases significantly when reducing the extract input, potentially mitigating the effects of inhibition. By embracing this innovative approach, researchers can analyze large numbers of sediment samples for aDNA preservation, achieving significant cost reductions of up to 70% and reducing hands-on laboratory time to one-fifth.

Archaeology meets environmental genomics: implementing sedaDNA in the study of the human past

Sedimentary ancient DNA (sedaDNA) has become one of the standard applications in the field of paleogenomics in recent years. It has been used for paleoenvironmental reconstructions, detecting the presence of prehistoric species in the absence of macro remains and even investigating the evolutionary history of a few species. However, its application in archaeology has been limited and primarily focused on humans. This article argues that sedaDNA holds significant potential in addressing key archaeological questions concerning the origins, lifestyles, and environments of past human populations. Our aim is to facilitate the integration of sedaDNA into the standard workflows in archaeology as a transformative tool, thereby unleashing its full potential for studying the human past. Ultimately, we not only underscore the challenges inherent in the sedaDNA field but also provide a research agenda for essential enhancements needed for implementing sedaDNA into the archaeological workflow.

Cervidae antlers exploited to manufacture prehistoric tools and hunting implements as a reliable source of ancient DNA

Antler is one of the primary animal raw materials exploited for technical purposes by the hunter-gatherer groups of the Eurasian Upper Palaeolithic (UP) all over the ecological range of deers, and beyond. It was exhaustively employed to produce one of the most critical tools for the survival of the UP societies: hunting weapons. However, antler implements can be made from diverse deer taxa, with different ecological requirements and ethological behaviours. Identifying the antler's origin at a taxonomic level is thus essential in improving our knowledge of humans' functional, practical and symbolic choices, as well as the human-animal interface during Prehistoric times. Nevertheless, palaeogenetics analyses have focused mainly on bone and teeth, with genetic studies of antler generally focused on modern deer conservation. Here we present the results of the first whole mitochondrial genome ancient DNA (aDNA) analysis by means of in-solution hybridisation capture of antlers from pre-Holocene archaeological contexts. We analysed a set of 50 Palaeolithic and Neolithic (c. 34-8ka) antler and osseous objects from South-Western Europe, Central Europe, South-Western Asia and the Caucasus. We successfully obtained aDNA, allowing us to identify the exploited taxa and demonstrate the archaeological relevance of those finds. Moreover, as most of the antlers were sampled using a minimally-invasive method, further analyses (morphometric, technical, genetic, radiometric and more) remain possible on these objects.

Late Pleistocene stickleback environmental genomes reveal the chronology of freshwater adaptation

Directly observing the chronology and tempo of adaptation in response to ecological change is rarely possible in natural ecosystems. Sedimentary ancient DNA (sedaDNA) has been shown to be a tractable source of genome-scale data of long-dead organisms1,2,3 and to thereby potentially provide an understanding of the evolutionary histories of past populations.4,5 To date, time series of ecosystem biodiversity have been reconstructed from sedaDNA, typically using DNA metabarcoding or shotgun sequence data generated from less than 1 g of sediment.6,7 Here, we maximize sequence coverage by extracting DNA from ∼50× more sediment per sample than the majority of previous studies1,2,3 to achieve genotype resolution. From a time series of Late Pleistocene sediments spanning from a marine to freshwater ecosystem, we compare adaptive genotypes reconstructed from the environmental genomes of three-spined stickleback at key time points of this transition. We find a staggered temporal dynamic in which freshwater alleles at known loci of large effect in marine-freshwater divergence of three-spined stickleback (e.g., EDA)8 were already established during the brackish phase of the formation of the isolation basin. However, marine alleles were still detected across the majority of marine-freshwater divergence-associated loci, even after the complete isolation of the lake from marine ingression. Our retrospective approach to studying adaptation from environmental genomes of three-spined sticklebacks at the end of the last glacial period complements contemporary experimental approaches9,10,11 and highlights the untapped potential for retrospective "evolve and resequence" natural experiments using sedaDNA.

Non-invasive real-time genomic monitoring of the critically endangered kākāpō

We used non-invasive real-time genomic approaches to monitor one of the last surviving populations of the critically endangered kākāpō (Strigops habroptilus). We first established an environmental DNA metabarcoding protocol to identify the distribution of kākāpō and other vertebrate species in a highly localized manner using soil samples. Harnessing real-time nanopore sequencing and the high-quality kākāpō reference genome, we then extracted species-specific DNA from soil. We combined long read-based haplotype phasing with known individual genomic variation in the kākāpō population to identify the presence of individuals, and confirmed these genomically informed predictions through detailed metadata on kākāpō distributions. This study shows that individual identification is feasible through nanopore sequencing of environmental DNA, with important implications for future efforts in the application of genomics to the conservation of rare species, potentially expanding the application of real-time environmental DNA research from monitoring species distribution to inferring fitness parameters such as genomic diversity and inbreeding.

aMeta: an accurate and memory-efficient ancient metagenomic profiling workflow

Analysis of microbial data from archaeological samples is a growing field with great potential for understanding ancient environments, lifestyles, and diseases. However, high error rates have been a challenge in ancient metagenomics, and the availability of computational frameworks that meet the demands of the field is limited. Here, we propose aMeta, an accurate metagenomic profiling workflow for ancient DNA designed to minimize the amount of false discoveries and computer memory requirements. Using simulated data, we benchmark aMeta against a current state-of-the-art workflow and demonstrate its superiority in microbial detection and authentication, as well as substantially lower usage of computer memory.

Genome-wide analysis of a collective grave from Mentesh Tepe provides insight into the population structure of early neolithic population in the South Caucasus

Despite the localisation of the southern Caucasus at the outskirt of the Fertile Crescent, the Neolithisation process started there only at the beginning of the sixth millennium with the Shomutepe-Shulaveri culture of yet unclear origins. We present here genomic data for three new individuals from Mentesh Tepe in Azerbaijan, dating back to the beginnings of the Shomutepe-Shulaveri culture. We evidence that two juveniles, buried embracing each other, were brothers. We show that the Mentesh Tepe Neolithic population is the product of a recent gene flow between the Anatolian farmer-related population and the Caucasus/Iranian population, demonstrating that population admixture was at the core of the development of agriculture in the South Caucasus. By comparing Bronze Age individuals from the South Caucasus with Neolithic individuals from the same region, including Mentesh Tepe, we evidence that gene flows between Pontic Steppe populations and Mentesh Tepe-related groups contributed to the makeup of the Late Bronze Age and modern Caucasian populations. Our results show that the high cultural diversity during the Neolithic period of the South Caucasus deserves close genetic analysis.

Pleistocene mitogenomes reconstructed from the environmental DNA of permafrost sediments

Traditionally, paleontologists have relied on the morphological features of bones and teeth to reconstruct the evolutionary relationships of extinct animals.¹ In recent decades, the analysis of ancient DNA recovered from macrofossils has provided a powerful means to evaluate these hypotheses and develop novel phylogenetic models.² Although a great deal of life history data can be extracted from bones, their scarcity and associated biases limit their information potential. The paleontological record of Beringia³-the unglaciated areas and former land bridge between northeast Eurasia and northwest North America-is relatively robust thanks to its perennially frozen ground favoring fossil preservation.^4,5 However, even here, the macrofossil record is significantly lacking in small-bodied fauna (e.g., rodents and birds), whereas questions related to migration and extirpation, even among well-studied taxa, remain crudely resolved. The growing sophistication of ancient environmental DNA (eDNA) methods have allowed for the identification of species within terrestrial/aquatic ecosystems,^6-12 in paleodietary reconstructions,^13-19 and facilitated genomic reconstructions from cave contexts.^8,20-22 Murchie et al.^6,23 used a capture enrichment approach to sequence a diverse range of faunal and floral DNA from permafrost silts deposited during the Pleistocene-Holocene transition.²⁴ Here, we expand on their work with the mitogenomic assembly and phylogenetic placement of Equus caballus (caballine horse), Bison priscus (steppe bison), Mammuthus primigenius (woolly mammoth), and Lagopus lagopus (willow ptarmigan) eDNA from multiple permafrost cores spanning the last 30,000 years. We identify a diverse metagenomic spectra of Pleistocene fauna and identify the eDNA co-occurrence of distinct Eurasian and American mitogenomic lineages.

Ancient Metagenomic Studies: Considerations for the Wider Scientific Community

Like modern metagenomics, ancient metagenomics is a highly data-rich discipline, with the added challenge that the DNA of interest is degraded and, depending on the sample type, in low abundance. This requires the application of specialized measures during molecular experiments and computational analyses. Furthermore, researchers often work with finite sample sizes, which impedes optimal experimental design and control of confounding factors, and with ethically sensitive samples necessitating the consideration of additional guidelines. In September 2020, early career researchers in the field of ancient metagenomics met (Standards, Precautions & Advances in Ancient Metagenomics 2 [SPAAM2] community meeting) to discuss the state of the field and how to address current challenges. Here, in an effort to bridge the gap between ancient and modern metagenomics, we highlight and reflect upon some common misconceptions, provide a brief overview of the challenges in our field, and point toward useful resources for potential reviewers and newcomers to the field.

Ancient DNA diffuses from human bones to cave stones

Recent studies have demonstrated the potential to recover ancient human mitochondrial DNA and nuclear DNA from cave sediments. However, the source of such sedimentary ancient DNA is still under discussion. Here we report the case of a Bronze Age human skeleton, found in a limestone cave, which was covered with layers of calcite stone deposits. By analyzing samples representing bones and stone deposits from this cave, we were able to: i) reconstruct the full human mitochondrial genome from the bones and the stones (same haplotype); ii) determine the sex of the individual; iii) reconstruct six ancient bacterial and archaeal genomes; and finally iv) demonstrate better ancient DNA preservation in the stones than in the bones. Thereby, we demonstrate the direct diffusion of human DNA from bones into the surrounding environment and show the potential to reconstruct ancient microbial genomes from such cave deposits, which represent an additional paleoarcheological archive resource.

Integrating multi-taxon palaeogenomes and sedimentary ancient DNA to study past ecosystem dynamics

Ancient DNA (aDNA) has played a major role in our understanding of the past. Important advances in the sequencing and analysis of aDNA from a range of organisms have enabled a detailed understanding of processes such as past demography, introgression, domestication, adaptation and speciation. However, to date and with the notable exception of microbiomes and sediments, most aDNA studies have focused on single taxa or taxonomic groups, making the study of changes at the community level challenging. This is rather surprising because current sequencing and analytical approaches allow us to obtain and analyse aDNA from multiple source materials. When combined, these data can enable the simultaneous study of multiple taxa through space and time, and could thus provide a more comprehensive understanding of ecosystem-wide changes. It is therefore timely to develop an integrative approach to aDNA studies by combining data from multiple taxa and substrates. In this review, we discuss the various applications, associated challenges and future prospects of such an approach.

Palaeogenetics: Dirt, what is it good for? Everything

Researchers in the ancient DNA community have suspected for well over a decade that ancient whole genomes can be found in sediments. Three new studies now provide such evidence and, with it, endless possibilities for future studies of sedimentary ancient DNA.