The research was led by Kelly Graf, professor of anthropology at the University of Kansas, who co-wrote the paper with Ted Goebel, KU professor of anthropology and department chair, doctoral student Mia Harbort, undergraduate Mason Sewing, and other colleagues from the United States and Europe. Graf began traveling to the site in 2013 and returned every year until the COVID-19 pandemic interrupted fieldwork, with subsequent seasons in 2021, 2023 and 2025. As director of the excavation project, she secured several National Science Foundation grants totaling 400,000 dollars to support the work. The effort has yielded more than 80,000 archaeological specimens, an assemblage that includes a unique hafted-biface form, tools made from bone and antler, a diverse array of animal remains, and remarkably well-preserved activity areas where ancient camp tasks can still be read from the ground.

To understand why the site matters, it helps to picture the world of the late Pleistocene. The Bering Land Bridge formed about 35,000 years ago, when sea levels dropped far enough to expose the continental shelf between Siberia and Alaska, and it remained above water until rising seas submerged it around 12,000 years ago. During that window, a region larger than many modern countries served as both a corridor and a homeland. Today the area around the Shég’ Xdaltth’i’ site is cloaked in spruce forest, but during the final millennia of the Ice Age it was covered in shrub-tundra vegetation, a cold, open landscape in which hardy plants, large herbivores and the people who hunted them coexisted along the Tanana River, one of the major river systems of interior Alaska.

The faunal record from the site shows that its residents were skilled hunters of Ice Age megafauna. Mammoth, bison and horse, all three of which are now extinct, appear in the assemblage alongside caribou, a species that survives today and remains a critically important resource for Indigenous communities across Alaska. Graf noted that caribou has always been a vital resource for the region’s Indigenous peoples, a continuity that stretches back to the very occupations her team has excavated. The combination of extinct and extant prey in a single site illustrates the breadth of the late-glacial subsistence economy and the flexibility hunters needed to survive in a subarctic environment where seasons were extreme and resources patchy.

Among the most evocative discoveries is a large stone anvil found within a dwelling feature. Around it, the excavators found bison bones that had been deliberately broken apart, along with numerous quartz and quartzite hammerstones, the tools used to fracture the bone. Graf explained that the pattern suggests people were using these stones to fully process the bones in order to extract marrow and likely to render grease, a calorie-rich food product that would have been essential in a northern winter. All of this activity, she said, was taking place near a large earth oven, a heated pit used for slow cooking. Together, the anvil, the hammerstones, the shattered bones and the oven preserve a frozen moment of camp life: a group processing an animal carcass into fat and marrow, likely sharing the results around a hearth.

Other key finds point to the sophistication of the site’s inhabitants. Bird bones were fashioned into needles, evidence of tailored clothing sewn from hides, an indispensable technology for people enduring Ice Age winters in a treeless landscape. The team also recovered numerous diamond-shaped bifacial points, which Graf suggested may have served as the sharpened tips of weapons. The shape is distinctive: she said it is the only site in Alaska that features this clear diamond form, and the only other places from this period with such points in a northern context lie on the Russian side of the land bridge. That distribution carries a striking implication. As Graf put it, it suggests people traveled across the Bering Land Bridge to, and possibly from, this location, making the site a potential waypoint in the back-and-forth movements that ultimately populated two continents.

Technically, the site contributes to a long-running debate about how and when humans moved from Asia into the Americas. Beringian archaeological occupations are concentrated in an area only slightly larger than the U.S. state of Maryland, which makes each well-documented site disproportionately valuable. The three components at Shég’ Xdaltth’i’, separated by roughly a thousand years, span the transition from the late-glacial period into the early Holocene, capturing what researchers describe as settling-in behavior: the process by which newly arrived populations learned the geography, established recurring camps, and developed the toolkits and food-processing strategies suited to a far northern setting. The presence of a dwelling feature, organized activity areas and repeated occupations indicates that this was a base camp, a place to which people returned, rather than a brief hunting stop.

The publication, titled “Highlights from an early base camp in Beringia 13,800 years ago: Shég’ Xdaltth’i’ and the Late Pleistocene Peopling of Alaska,” appears in Science Advances, a peer-reviewed journal. The research is an observational study of the archaeological record, and the authors declare no competing interests. For Graf, who has been at the University of Kansas since 2022 and specializes in Ice Age archaeology, environmental archaeology and the peopling of the Americas, the fascination began in an undergraduate North American archaeology class. She recalled falling in love with the Bering Land Bridge concept: people hunting megafauna and traveling from one massive continent to another across exposed continental shelf, studying extinct animals and the tools hunters used to take them. She described getting caught up in the wonder of that vision.

Beyond the individual artifacts, Graf frames the work as part of a larger effort to understand human evolution and adaptation. What began as a mere handful of individuals in a small region has expanded to more than 8 billion people in a fraction of geological time, a trajectory she finds remarkable given humanity’s meager beginnings as hunter-gatherers. Studying how early Beringians coped with the exigencies of Ice Age life, she argues, informs how humans have always adapted and responded to challenges. The more we learn about the evolution of the Homo sapiens species, she said, the more we can understand ourselves today. In that sense, the broken bison bones, the sewing needles and the diamond-shaped points on an Alaskan ridge are not just relics of a distant past but evidence of the problem-solving capacities that carried our species across a vanished land bridge and, eventually, around the entire world.

For now, the Shég’ Xdaltth’i’ site stands as one of the clearest windows into the lives of the people who stood at the threshold of the Americas nearly 14,000 years ago. Its 80,000-plus specimens continue to be analyzed, and each field season adds detail to the picture of a community that hunted mammoth and caribou, rendered grease from bone beside earth ovens, sewed tailored clothing with bone needles, and carried weapon technology across a land bridge that no longer exists. The name given to the site by Alaska Native Athabascan speakers, “they were there,” proves an apt summary of what the archaeology shows: a resilient group of hunter-gatherers, present on that ridge through centuries of change, leaving behind the material record of how they lived.

Subject of Research: Late Pleistocene archaeology of a 13,800-year-old base camp in Beringia, Alaska, and its evidence for the peopling of the Americas

Article Title: Bering Land Bridge base camp reveals what life was like nearly 14,000 years ago

Article References: Bering Land Bridge base camp reveals what life was like nearly 14,000 years ago. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Bering Land Bridge, Beringia, Alaska archaeology, Shég’ Xdaltth’i’, Pleistocene, megafauna, hunter-gatherers, peopling of the Americas, Tanana River, Science Advances, University of Kansas, late-glacial

The significance of Shég’ Xdaltth’í’ lies not only in its age but in its character. Unlike kill sites or short-term hunting camps, which dominate the archaeological record of Late Pleistocene Beringia, this location functioned as a settled base camp—a place where people returned repeatedly over generations. Sustained occupation of this kind implies a degree of stability and familiarity with the landscape that challenges older models of rapid, restless migration. The inhabitants were not simply passing through; they were living, working, and maintaining a community in the subarctic interior of what is now Alaska during a pivotal moment in human history, when the last ice age was loosening its grip on the northern hemisphere.

The excavation team applied rigorous geoarchaeological methods to establish the site’s chronology and formation history. Careful documentation of the stratigraphic sequence allowed researchers to distinguish the oldest cultural layer from later deposits, while a series of radiocarbon dates anchored the earliest occupation to approximately 13,800 calendar years before present. This dating framework is critical, because it places the site’s foundation within the narrow window when interior Alaska was becoming habitable as glacial conditions eased. The stratigraphic integrity of the deposits means that the artifacts and ecological remains within the oldest layer can be confidently associated with a single, well-defined period of use, rather than a jumbled mixture of occupations spanning millennia.

The artifact assemblage itself is the heart of the discovery. More than 80,000 items from the oldest layer include stone tools, debitage from tool manufacture, and other material traces of daily life. Among these, one artifact class stands out for its analytical importance: a distinct hafted-biface form, a type of stone projectile point or knife blade designed to be attached to a handle or shaft. Hafted bifaces are among the most culturally diagnostic artifacts in Paleolithic archaeology, because their specific shapes and manufacturing techniques were transmitted through teaching and tradition rather than reinvented by each generation. When similar forms appear at sites separated by vast distances, archaeologists consider this strong evidence of shared cultural heritage or direct contact between populations.

That is precisely what the researchers found. The hafted-biface forms and other tools at Shég’ Xdaltth’í’ resemble those recovered from Beringian sites located further to the west, in the region of the Bering Land Bridge that once connected northeastern Asia to Alaska. During the Late Pleistocene, sea levels were substantially lower, exposing a broad plain—sometimes called Beringia—that stretched for hundreds of kilometers between the two continents. If the tool forms at the Alaskan site match those from western Beringian sites, the implication is that the people who established this base camp carried with them a technological tradition rooted in Asia, preserving a trans-Beringian cultural connection even after their ancestors had crossed into the New World.

At the same time, the assemblage contains artifacts that echo traditions known from much further south in temperate North America. Some pieces resemble forms associated with pre-Clovis, Clovis, Folsom, and Late Paleoindian complexes—the successive fluted-point and projectile-point traditions that define the early archaeological record of the American midcontinent and beyond. This dual character makes Shég’ Xdaltth’í’ an unusually valuable data point. It sits at a geographic and chronological crossroads, showing both the Asian-derived heritage of Beringia’s first peoples and hints of the technological developments that would spread southward as populations expanded into the Americas. Few sites anywhere in the North American Arctic preserve this combination of affinities in a single, well-dated context.

The ecological remains from the site add another dimension to the story. Analysis of animal and plant materials recovered from the oldest layer provides a picture of the environment in which these early Beringians lived and the resources they relied upon. Interior Alaska at the end of the Pleistocene supported a mosaic of open habitats that sustained large herbivores and the human hunters who pursued them. Documenting which species were present and exploited helps researchers reconstruct subsistence strategies at the base camp and assess how a settled, multi-generational occupation could be supported in a subarctic setting. Such paleoecological data are essential for understanding not just where people were, but how they made a living once they arrived.

The broader context of the discovery is a long-running and sometimes contentious debate in New World archaeology: how and when did humans first travel from Asia to the Americas? The classic model long held that the Clovis culture, dating to roughly 13,000 years ago, represented the first successful colonization of the continents. That consensus has eroded over recent decades as sites across both North and South America have yielded credible evidence of earlier human presence. Today, many researchers accept that people were in the Americas well before Clovis, but the routes, timing, and genetic relationships of these early populations remain actively debated. Sites in Beringia—the presumed staging ground for the entire dispersal—are therefore of outsized importance to resolving these questions.

In an accompanying Focus article, archaeologist Spencer Pelton discusses why discoveries like Shég’ Xdaltth’í’ are reviving what he calls an old idea in New World archaeology: the Beringian standstill hypothesis. According to this model, populations that entered the North American continent between roughly 20,000 and 15,000 years ago were halted in Beringia, unable to move southward until the massive ice sheets that blocked interior routes began to retreat. Only then could they continue their journey into temperate North America. A long-used base camp in interior Alaska, occupied at just the moment when southern routes were opening, fits neatly with this scenario. It suggests that Beringia was not merely a corridor people rushed through, but a homeland where founding populations lived for extended periods before dispersing to the south.

As research at Shég’ Xdaltth’í’ continues, the site is poised to become a key reference point for studies of the initial peopling of the Americas. Its combination of secure dating, exceptional artifact preservation, ecological evidence, and demonstrable cultural affinities spanning Beringia gives scientists an unusually complete window onto life at the gateway to the New World. Whether the trans-Beringian connection implied by its tools reflects direct contact across the land bridge, shared ancestry, or both, the base camp demonstrates that the earliest Alaskans were participants in a far-flung cultural world—one that stretched from the plains of Asia to the frontiers of an unexplored continent. In that sense, the site’s Athabascan name proves prophetic: they were there, and the traces they left are now rewriting the opening chapters of American history.

Subject of Research: Late Pleistocene archaeology of a 13,800-year-old base camp in Alaska and its evidence for trans-Beringian cultural connections during the peopling of the Americas

Article Title: Late Pleistocene site in Alaska yields evidence of a trans-Beringian cultural connection

Article References: Late Pleistocene site in Alaska yields evidence of a trans-Beringian cultural connection. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Shég’ Xdaltth’í’, Beringia, Bering Land Bridge, Late Pleistocene, peopling of the Americas, Alaska archaeology, hafted bifaces, base camp, Clovis, pre-Clovis, Science Advances, radiocarbon dating

The research team collected scale-leaf tissue from M. callistoma in Shiyan, Hubei Province, and sequenced it on an Illumina HiSeq 4000 platform at a mean depth of over 900-fold. Assembly with GetOrganelle and polishing with Pilon produced a single circular plastome of 29,784 base pairs with a GC content of 30.8 percent. That figure might sound unremarkable until compared with a typical photosynthetic plant, whose plastome runs roughly 150,000 base pairs and carries more than a hundred genes. The M. callistoma plastome contains just 40 genes: 20 protein-coding genes, 16 transfer RNAs, and four ribosomal RNAs. Strikingly, the canonical quadripartite structure found in almost all land plant plastids, with two inverted repeats separating large and small single-copy regions, is entirely absent. No inverted-repeat boundaries could be detected at all.

The gene inventory tells the story of a genome in terminal decline. Every photosynthetic function has been erased. There are no photosystem subunits, no NADH dehydrogenase genes, no cytochrome b6f complex components, no ATP synthase subunits, and no rubisco large subunit. What remains is essentially a minimal housekeeping kit: ten genes for small ribosomal subunit proteins, seven for large subunit proteins, and just three other coding genes, infA, matK, and accD. Four of the retained genes carry a single intron. This is the genomic signature of an organelle whose core reason for existence, photosynthesis, has been outsourced to fungal partners, leaving relaxed selection to strip away everything the plant no longer needs.

To place this genome in context, the researchers compiled published plastomes from 30 mycoheterotrophic species across six families, ranging from orchids such as Gastrodia and Lecanorchis to the bizarre holoparasites Sciaphila and Mitrastemon. The comparison revealed a spectrum of decay. Sciaphila thaidanica and Mitrastemon yamamotoi carry plastomes of only about 20 kilobases, among the smallest known in flowering plants, while at the other extreme some Burmannia species retain genomes approaching 100 kilobases. GC content showed a weak but statistically significant positive correlation with genome size, suggesting that as these genomes shrink, their nucleotide composition shifts in parallel. Within Monotropoideae itself, Pterospora andromedea holds the largest plastome at roughly 40 kilobases, while the more recently diverged Monotropa uniflora has the smallest at about 27 kilobases.

Whole-genome alignments exposed another dimension of decay: the collapse of synteny, the conserved order of genes along the chromosome. Among Monotropoideae species, gene order is scrambled, particularly in Hypopitys, Monotropsis, Monotropastrum, and Monotropa. Fragment loss has accumulated in more recently diverged lineages, so that even within the genus Monotropa, where synteny is relatively well preserved, the overall picture across the subfamily is one of progressive disintegration. Ancestral-state reconstruction across the 30 species showed that losses of the large genes ycf1 and ycf2 occurred convergently among eudicot lineages, while all sampled Monotropa species lacked rps23, pointing to a lineage-specific loss within that genus.

The phylogenomic analysis went beyond genome description to resolve long-standing questions about relationships within Ericaceae. Using a concatenated alignment of plastid protein-coding genes nearly 48,000 base pairs long, with Actinidia chinensis as an outgroup, the team recovered a well-supported split into two major clades. Clade 1 united Pyroloideae, Arbutoideae, and Monotropoideae, with Pyroloideae branching earliest and Monotropoideae emerging as the youngest lineage. Within Monotropoideae, the sampling covered 10 of the 12 recognized genera and achieved maximum bootstrap support of 100 for the backbone. Pterospora and Sarcodes occupied successive early-branching positions, followed by Pleuricospora, while a clade of Monotropsis, Monotropastrum, and Monotropa was sister to a group containing Allotropa, Hemitomes, Pityopus, and Hypopitys. Clade 2 comprised the core Ericaceae, subdivided into Vaccinioideae and Ericoideae.

Divergence dating with fossil calibrations placed the split between Pyroloideae and the remaining subfamilies at approximately 67.77 million years ago, in the latest Cretaceous. Arbutoideae and Monotropoideae diverged around 66.57 million years ago, and diversification within Monotropoideae began about 63.35 million years ago, immediately after the end-Cretaceous extinction. The genus-level splits came much later: Sarcodes and Pterospora separated roughly 45.79 million years ago, Monotropsis split from the lineage leading to Monotropa and Monotropastrum about 39.73 million years ago, and those two genera diverged about 26.74 million years ago. The rapid radiation of Rhododendron and Vaccinium, by contrast, occurred only around 1 to 2 million years ago.

Perhaps the most striking finding concerns geography. Ancestral-range estimation using the DIVALIKE+J model in RASP placed the most recent common ancestor of Clade 1 in Asia during the late Cretaceous to early Cenozoic. From there, the lineage dispersed to North America, most plausibly across the Bering Land Bridge, which connected the continents from the latest Cretaceous into the early Paleocene, when a warm, humid belt of deciduous broadleaf forest stretched across the region. Then came a remarkable reversal: the ancestor of the Monotropsis, Monotropastrum, and Monotropa lineage appears to have dispersed back to Asia during the late Eocene to early Oligocene, around 39.70 million years ago, giving rise to the East Asian endemics Monotropastrum humile and Monotropa callistoma. The ghost plants, in other words, crossed the world twice.

The comparative analysis also yielded a testable hypothesis about the order in which plastid genes are lost as plants abandon photosynthesis. Across the 30 species examined, the ndh genes were absent everywhere, followed by photosystem, cytochrome, rubisco, and ycf3/4 genes, then the RNA polymerase genes, then atp genes, and finally the ribosomal, transfer RNA, and housekeeping genes such as accD, clpP, and matK. The sole exception was Burmannia cryptopetala, which retains atp genes, a pattern associated with mixotrophic or partially parasitic lifestyles. The team proposes that the degree of a plant’s absolute dependence on fungal hosts correlates with the breadth of plastid gene loss, with Monotropa, whose plastid genes evolve roughly 13 times faster than its nuclear genes, representing an advanced stage of degradation in which even clpP has been discarded.

Yet the decay is not random, and that is the deeper lesson of the study. Housekeeping genes persist with remarkable consistency: accD, which catalyzes the first committed step of fatty acid biosynthesis and is essential for building the plastid’s own membranes, was retained in every single mycoheterotrophic species examined. The retention of matK across all Monotropoideae and Burmanniaceae, despite its patchy record in orchids, and the lineage-specific survival of ycf1 and ycf2 in some orchids and Burmanniaceae but not others, show that different lineages face different residual functional constraints. The endpoints of plastid genome reduction form a spectrum rather than a single destination, ranging from the streamlined but intact genomes of Monotropoideae to the complete loss of the plastid genome in Balanophora, which has transferred even accD to the nucleus. When an organelle’s core function is outsourced, its genetic system converges, again and again across independent lineages, toward the same extreme simplification. The ghost plants of Asia and North America, silent and white beneath the forest canopy, are carrying out that experiment in real time, and their genomes are the record.

Subject of Research: Plastome evolution and phylogenomics of the mycoheterotrophic subfamily Monotropoideae (Ericaceae)

Article Title: Phylogenomics Clarifies Plastome Reduction and Phylogenetic Relationships in Monotropoideae

Article References: Deng, G., Duan, K., Xiang, N., Gao, F., Zhan, P., Shu, R., Lin, Q., Zuo, Q., & Yuan, T. (2026). Phylogenomics Clarifies Plastome Reduction and Phylogenetic Relationships in Monotropoideae. Ecology and Evolution, 16(10), Article e74449. https://doi.org/10.1002/ece3.74449

Image Credits: AI Generated

DOI: 10.1002/ece3.74449

Keywords: Monotropoideae, mycoheterotrophy, plastome reduction, Ericaceae, Monotropa callistoma, phylogenomics, Bering Land Bridge, biogeography, gene loss, relaxed selection, ghost plants, divergence dating