Crawford Lake owes its extraordinary preservative powers to an unusual physical quirk. It is a meromictic lake, meaning its water column never fully mixes with the lakebed. Because the deep waters remain undisturbed, sediment settling from the surface is laid down in neat, alternating layers of calcite and organic-rich laminae, each pair representing a single year of deposition. Matthew Emery, co-first author of the study and assistant professor of anthropology at Binghamton University, compared the structure to the growth rings of a tree. Like those rings, each sediment layer can be dated to a specific year, offering an exceptionally well-preserved, year-by-year account of environmental change. That annual resolution, combined with the lake’s status as one of the most intensively studied lakes in the world, gave the sedaDNA team an unparalleled opportunity to test their methods against decades of established palaeoecological evidence.

The technique at the heart of the study descends from methods originally developed to hunt far older quarry. Researchers used capture enrichment, a process in which genetic baits made of RNA are designed to bind to the DNA of target species if those genetic fragments are present in a sample. The RNA baits also attach to magnetic beads, allowing scientists to literally reel in their target DNA with a magnet. Emery noted that these approaches were first engineered to chase down extinct Pleistocene megafauna and extinct hominin relatives such as Neanderthals and Denisovans. Now, they are being applied to lake mud to trace human-environment interactions spanning recent centuries and reaching deep into geological time. Bait sets can be combined to target hundreds or even thousands of species genomes simultaneously, making the approach far more efficient than random shotgun sequencing, and allowing researchers to choose in advance which organisms they want to search for in the archive.

The reconstructed timeline traces a dramatic arc of human influence. In the period before local agriculture, the sedaDNA records a landscape shaped only by natural processes. Between the 1200s and the 1500s, the genetic evidence confirms the presence of Indigenous peoples farming maize and sunflowers near the lake, a finding that aligns with archaeological evidence of Longhouse Peoples villages at the site. The data also captures site abandonment and the ecological succession that followed, and then documents the Euro-Canadian period, with renewed impacts from logging, lumbering, milling, and farming, culminating in the unmistakable global markers of industrialization in the upper layers, including fossil fuel remnants, plastics, artificial fertilizers, acid rain, and even plutonium. It was precisely this well-preserved contamination record that made Crawford Lake a leading candidate among geologists supporting the Anthropocene as a new geological epoch, a designation that was ultimately rejected even as the scientific debate continues.

Among the study’s most striking results is the recovery of genetic evidence invisible to traditional palaeoecological techniques. Cattle DNA appears in sediments dating to the early 1800s, providing new proof of cattle in the surrounding landscape that left no trace in the fossil or pollen record. Even more remarkably, the analysis detected two of the so-called Four Sisters crops, maize and sunflower, directly from lake core samples for the first time. Three Sisters agriculture is an Indigenous farming technique introduced to the Great Lakes region during the Late Woodland Period, roughly 1000 to 1650 CE, in which maize, beans, and squash are planted side by side in mutually beneficial combinations. When sunflower is added, the grouping becomes the Four Sisters. While fossil and pollen studies had previously confirmed beans and squash at the Crawford Lake village site, those two crops were absent from the lake sediments, a puzzle the researchers attribute to the dietary preferences of an unexpected intermediary.

That intermediary is the Canada goose. The sedaDNA record shows a sharp increase in Canada goose DNA during the periods of Indigenous agriculture, a pattern consistent with geese foraging in cultivated maize and sunflower fields and then roosting on Crawford Lake. Their droppings would have carried both nutrients and traces of the crops they had eaten into the water, likely driving repeated algal blooms from nutrient influxes that are also visible in the sedimentary genetic record. These eutrophication events, caused by excess nutrients in the water, may even have contributed to the abandonment of the site, which occurred on more than one occasion according to the timeline. After abandonment in the 1500s, the lake’s ecology gradually rebounded, with the record showing a return of pine trees, rabbits, deer, beavers, and loons, and a notable disappearance of maize. Today, similar blooms are more often driven by artificial fertilizers, but the Crawford Lake record shows that nutrient-driven algal booms have deep human roots.

The study also delivered surprises about the physics of DNA decay itself. One of the biggest revelations, according to co-first author Tyler Murchie, lead scientist of Biodiversity Genomics: Ancient DNA at the Hakai Institute and adjunct assistant professor of anthropology at McMaster University, is that older DNA is not necessarily more damaged. Some of the roughly 500-year-old lake sedaDNA from plants and animals at Crawford Lake proved more degraded than DNA tens to hundreds of thousands of years old recovered from permafrost sites in northwestern Canada, demonstrating that preservation conditions matter far more than age alone. The chemistry of a burial environment, whether frozen, waterlogged, mineral-rich, or oxygenated, can determine whether genetic fragments survive intact for millennia or crumble into unreadable noise within a few centuries. For a small lake in southern Ontario, the cold, still, stratified water column turned out to be an unexpectedly generous custodian of molecular history.

The research was not without technical limitations, and the team has been candid about them. The bait set used in the analysis, the PaleoChip Arctic v1.0, was designed for Pleistocene and early Holocene sites far older than the period of human activity at Crawford Lake, and the absence of beans and squash in the results may reflect a gap in that panel or the geese’s preference for maize and sunflower. The researchers are already working to improve their bait sets for better capture enrichment, with Murchie emphasizing the need for an Eastern Woodland panel for future targeted ancient DNA research in the region. The effort has momentum behind it: in January, co-senior author Hendrik Poinar, professor of anthropology at McMaster University, and Murchie received an NSERC Alliance grant to develop improved sedaDNA methods for permafrost and marine sediments, support the reconstruction of long-term terrestrial and marine ecosystem dynamics, and build the Canadian Ancient DNA Network.

Beyond its technical achievements, the study underscores the collaborative nature of modern environmental science. Poinar noted that the work was only possible through the combination of genetics, archaeology, traditional Indigenous knowledge, lake chemistry, and geochemistry, disciplines that together make the unknown a little more tangible and the past recoverable, almost like magic. The international team included scientists from McMaster University, the Hakai Institute, Brock University, the University of Alberta, and the University of British Columbia in Canada; Binghamton University and Arizona State University in the United States; and Stockholm University in Sweden. Emery described the layered sediment as a filing cabinet and a time capsule, each stratum holding the plants and animals that lived around the lake when it formed, readable straight down through the centuries as long as nothing has shuffled the order. As the debate over the Anthropocene continues, Crawford Lake’s genetic archive now offers a thousand-year benchmark against which humanity’s accelerating transformation of the natural world can be measured, one annual layer at a time.

Subject of Research: Sedimentary ancient DNA analysis reconstructing 1,000 years of human-environment interactions at Crawford Lake, Ontario

Article Title: Ancient DNA reveals 1,000 years of human–environment interactions at Crawford Lake

Article References: Ancient DNA reveals 1,000 years of human–environment interactions at Crawford Lake. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: ancient DNA, sedaDNA, Crawford Lake, Anthropocene, Indigenous agriculture, Three Sisters, eutrophication, capture enrichment, molecular ecology, palaeoecology, meromictic lake, environmental change

The Anthropocene concept was coined in recognition that human activities have ended the unusually benign environmental regime that characterized the Holocene, the epoch that encompassed the entire history of agriculture, cities and written civilization. But as the term migrated from stratigraphy into economics, politics, museum curation, education and the arts, it accumulated divergent and sometimes contradictory definitions. Some scholars stretch the Anthropocene back thousands or even tens of thousands of years to capture the cumulative footprint of early farming, mining and land clearance. The authors argue that while such extended interpretations portray the totality of anthropogenic change, they obscure the quantitatively established, dramatic rupture in Earth system behavior that began in the mid-twentieth century, and they cannot be defined in formal chronostratigraphic terms.

The technical case for the 1952 boundary rests on the stratigraphic record. Sediments deposited from the mid-twentieth century onward carry a distinctive and globally synchronous suite of signals: radionuclide fallout from atmospheric nuclear weapons testing, spheroidal carbonaceous fly-ash particles from fossil fuel combustion, a sharp rise in plastics and microplastics, and profound shifts in fossil assemblages driven by global species translocations and industrial agriculture. High-resolution analyses of archives such as the varved sediments of Crawford Lake in Canada have demonstrated that these markers appear together within a narrow time window, providing the kind of precise, correlatable geological evidence that formal epoch boundaries require. Human-driven environmental change of earlier millennia, by contrast, is diachronous and regionally variable, leaving no single globally synchronous horizon.

The authors emphasize that the distinction is not merely academic. A formally defined Anthropocene epoch enables quantitative and qualitative comparison between the stable Holocene and the increasingly unstable Anthropocene, a comparison already embedded in influential frameworks such as the planetary boundaries concept. That framework, which assesses how far humanity has pushed Earth system processes beyond safe operating limits, depends on a Holocene baseline against which modern departures can be measured. Six of nine planetary boundaries are currently judged to have been transgressed, and the annual Planetary Health Check tracks the deterioration. Without a stabilized Anthropocene definition, the authors warn, the conceptual foundation for such comparisons becomes blurred, weakening the scientific signal that policymakers most need to hear.

The Perspective also documents how deeply the Anthropocene idea has already penetrated institutions beyond geology. Dedicated research centers, policy programs and educational initiatives now bear its name. The United Nations Development Programme has framed new threats to human security in Anthropocene terms, the European Environment Agency has explored what it would mean to exit the Anthropocene, and the OECD’s PISA 2025 science framework incorporates agency in the Anthropocene as an educational goal. International law is grappling with the concept as well: the International Law Association’s committee on sea level rise has traced the implications of moving from Holocene assumptions of stable coastlines to an Anthropocene reality of rising seas, and the International Court of Justice issued a landmark advisory opinion on states’ obligations in respect of climate change in July 2025.

Underlying all of these applications is a single, consequential insight: the Earth system transformation of the Anthropocene is systemic, not piecemeal. Greenhouse gas accumulation, ocean warming and acidification, biodiversity loss, sediment cycle disruption, nutrient overloading and the spread of novel materials such as plastics and concrete are coupled processes, each amplifying the others. The authors argue that because the disruption is systemic, political responses must also be systemic rather than ad hoc. A unified Anthropocene epoch, they contend, would facilitate systematic, actionable climate and environmental policies by giving scientists, lawyers, economists and politicians a shared, precisely bounded reference point for what has changed and how quickly.

The geological evidence for that change is now overwhelming in its breadth. Humans have become the most significant global geomorphological driving force of the twenty-first century, moving more material than all natural erosion processes combined. The physical technosphere, the sum of human-made structures, machines and waste, has reached planetary scale, and its discarded products, from broiler chicken bones to concrete and plastics, are forming recognizable technofossils that will persist in the rock record. Earth’s sediment budget has been fundamentally reorganized, deltas and coastal wetlands are being transformed faster than they can adapt, and palaeontological signatures of the Anthropocene, including global species translocations and mass mortality assemblages, are demonstrably distinct from those of any previous epoch. Meanwhile, monitoring shows the acceleration continuing: record ocean temperatures in 2024, record-low Antarctic sea ice, warming-intensified drought, and documented declines in insect populations and wild mammal biomass.

The authors do not dismiss the value of broader, extended uses of the term. Environmental historians and archaeologists have shown that human reshaping of landscapes stretches back millennia, and understanding that deep history matters for questions of responsibility, equity and long-term change. But they insist that these interpretations represent a concept distinct from the Anthropocene epoch. Conflating the two, they argue, produces the worst of both worlds: the dramatic mid-twentieth-century rupture, which is the clearest and most politically urgent signal, gets diluted into a diffuse background of ancient impacts, while the genuine achievements of pre-industrial societies are recast as the origin of a crisis they did not cause. Clarity, they maintain, serves both scholarship and justice.

Looking forward, the Perspective maps out a research agenda in which a stabilized Anthropocene definition becomes a working tool across disciplines. In Earth science, it would sharpen the study of the anthropoclastic rock cycle, legacy contaminants re-released by melting glaciers, and the fate of microplastics as planetary markers. In law and governance, it would underpin efforts to adapt maritime boundaries, environmental obligations and international institutions to a planet no longer governed by Holocene assumptions. In education, it would anchor curricula that teach Earth system thinking and futures literacy. In the arts and humanities, it would provide a common chronological anchor for museums, exhibitions and imaginative work that seeks to make planetary change perceptible. The central purpose of a clear, formalized definition, the authors conclude, is to enable unified communication across the Earth sciences, social sciences, humanities, society and political and legal fora, so that the scale of the transformation can be grasped, debated and addressed with the seriousness it demands.

Subject of Research: Definition and interdisciplinary applications of the Anthropocene epoch

Article Title: Future directions for Anthropocene research and its applications

Article References: Zalasiewicz, J., Thomas, J. A., Cohen, K. M., Vidas, D., Sörlin, S., Waters, C. N., Head, M. J., Summerhayes, C. P., Leinfelder, R., Wallenhorst, N., Syvitski, J., McNeill, J. R., Robin, L., Williams, M., Cearreta, A., Ivar do Sul, J. A., Park, B. S., McCarthy, F. M. G., Han, Y., … Kuwae, M. (2026). Future directions for Anthropocene research and its applications. Nature Reviews Earth & Environment, 7(9), 633-646. https://doi.org/10.1038/s43017-026-00820-z

Image Credits: AI Generated

DOI: 10.1038/s43017-026-00820-z

Keywords: Anthropocene, Holocene, Great Acceleration, chronostratigraphy, planetary boundaries, Earth system science, Crawford Lake, technosphere, microplastics, geological epoch, environmental policy, international law

The technical heart of the argument lies in fallout from above-ground thermonuclear weapons testing. Beginning in the early 1950s, detonations of high-yield fusion devices injected artificial radionuclides into the stratosphere, from where they settled onto land, ice and ocean in a thin, worldwide veneer. Among these products, plutonium isotopes show a sharp global upturn in 1952, and because plutonium has no natural source in recent surface environments and is comparatively immobile once deposited, it functions as an exceptionally clean primary marker. In annually laminated lake sediments such as those of Crawford Lake in Ontario, Canada, the proposed golden spike locality, the plutonium rise can be pinned to a single annual varve, allowing correlation between archives worldwide with an uncertainty of a year or two, a precision almost unheard of in the deeper geological record.

Crucially, the plutonium signal does not stand alone. The researchers document what they call the Great Acceleration Event Array, a cluster of mid-century physical, chemical and biological signals that appear together in sediments across both hemispheres and every climatic belt. Spheroidal carbonaceous particles, microscopic spheres of elemental carbon produced only by burning coal and fuel oil at high temperature, appear in peat bogs, lake muds, coral skeletons and even an Antarctic ice core. Stable carbon and nitrogen isotopes shift as fossil fuel combustion and industrial fertiliser transformed the planet’s carbon and nitrogen cycles. Heavy metals including lead, mercury and arsenic climb sharply, plastic debris begins its geological journey, and invasive species restructure biological communities from the Baltic Sea to San Francisco Bay.

The scale of the underlying Earth system change is quantified with sobering figures. Atmospheric carbon dioxide now stands 51 percent above typical Holocene concentrations, while methane has risen 157 percent, driving global mean temperatures roughly 1.5 degrees Celsius above pre-industrial levels. Ice cores show that greenhouse gas levels remained within a narrow band for most of the past 11,700 years, the span of the Holocene Epoch, making the current departure both rapid and unusual when viewed against three decades of millennia of natural variability. The authors argue that these shifts overwhelm the regulatory feedbacks that previously stabilised the Earth system, and that this planetary threshold is exactly what an epoch boundary should record.

The choice of 1952 also serves a stratigraphic logic that goes beyond convenience. Earlier candidates for the start of the Anthropocene, such as the onset of agriculture millennia ago, the Columbian exchange of the sixteenth century or the Industrial Revolution of the late eighteenth century, produce signals that are diachronous, meaning they appear at different times in different places, and are often subtle or locally overprinted. By contrast, bomb fallout arrived essentially everywhere at once. The team acknowledges a rich pre-history of human impact, from early mining lead anomalies to deforestation, but insists that these belong to the characterisation of the Holocene, an epoch in which human influence, however real, never tipped the planetary machinery into a new state.

Formal recognition would require a Global boundary Stratotype Section and Point, the so-called golden spike, and Crawford Lake has been proposed for that role. Its sediments accumulate in varves, paired seasonal layers that permit year-by-year dating, and its small, sheltered basin records fallout with minimal disturbance. Supporting auxiliary sections, including Sihailongwan Maar Lake in northeastern China, Searsville Lake in California, Beppu Bay in Japan, the Palmer ice core from the Antarctic Peninsula, corals from Flower Garden Banks and North Flinders Reef, the Baltic Sea’s East Gotland Basin, a peatland at Śnieżka in Poland, the Ernesto Cave stalagmite in Italy and urban sediments at Vienna’s Karlsplatz, would anchor the boundary across marine, terrestrial, tropical and polar settings.

Not everyone is convinced, and the article engages frankly with the opposition. In 2024, the International Union of Geological Sciences declined to ratify the Anthropocene as an epoch, with critics arguing that the term works better as an informal concept or as a diachronous geological event rather than a precisely timed unit. Some have questioned whether an epoch lasting mere decades is proportionate to units that typically span millions of years. Waters and colleagues respond that geological units are defined by the quality of their boundary signals, not their duration, that the geological record is replete with brief intervals, and that the Anthropocene’s global synchronicity and uniqueness actually exceed the criteria applied to many ancient boundaries.

The stakes extend well beyond taxonomy. The authors argue that placing the Anthropocene on the Geological Time Scale would give scientists, educators and policymakers a common, rigorously defined reference point for the scale and abruptness of human-driven planetary change. It would confine the Holocene to its true character as an interval of unusual climatic stability, and would provide a unifying framework across disciplines from stratigraphy and ecology to Earth system science, in which the Anthropocene term is already used widely but inconsistently. Future geologists, they suggest, will encounter this interval whether or not it is formally named; the question is whether the present generation chooses to describe it with precision.

Whatever the formal outcome, the study reframes the Anthropocene from metaphor to measurement. By knitting together radionuclide fallout, industrial ash, isotope chemistry, microplastics, metals and biological invasions across a dozen independent archives, the researchers have assembled the kind of multi-proxy, globally correlated evidence that underpins every epoch boundary in the geological column. The plutonium horizon of 1952, they conclude, marks the moment humanity’s imprint became synchronous, permanent and unmistakable in the rocks, a stratigraphic signature distinct from everything that came before it in the Holocene.

The machinery behind formalising a new unit of geological time is deliberately slow and demanding. Under the guidelines of the International Commission on Stratigraphy, a candidate boundary must be fixed to a physical reference point in a rock, sediment or ice succession, and the marker chosen must be correlatable across environments as different as deep ocean basins and mountain glaciers. The plutonium fallout horizon satisfies this requirement in a way few markers ever have, because the same signal can be located in archives that preserve annual layers, giving geologists a common time line where older boundaries often carry uncertainties of thousands of years.

The comparison with the Holocene itself is instructive. That epoch was defined in 2009 using the NGRIP ice core in Greenland, with its base pinned to a climatic warming event recorded in ice chemistry. The proposed Anthropocene boundary follows the same logic but achieves finer resolution, since bomb-derived radionuclides can be measured at concentrations far below those of natural isotopes, and their abrupt appearance reflects a discrete historical process rather than a gradual climatic transition. This illustrates how the tools available to stratigraphers have expanded, allowing boundaries to be drawn with a precision that earlier generations of geologists could not have imagined.

The multi-proxy approach also guards against a familiar pitfall in correlation work: post-depositional alteration. Some radionuclides can migrate within sediments or soils, blurring a boundary in certain archives, which is why the authors pair the plutonium signal with particles and chemical shifts that are effectively immobile once buried. Spheroidal carbonaceous particles, for example, are preserved intact in peat and lake mud, while isotope shifts in carbon and nitrogen record the reorganisation of planetary biogeochemical cycles. When several independent signals align at the same level across a dozen archives, the likelihood that the alignment is coincidental becomes vanishingly small.

There is also a deeper scientific point about what the geological record preserves. Human activity has generated materials with no natural counterpart, from plastics to concrete to aluminium, and these are already accumulating in sediments that future investigators will treat exactly as present-day geologists treat ancient strata. Recognising the Anthropocene formally would simply bring the naming conventions of the time scale into line with what the sedimentary record is already registering, and would give the interval a defined base rather than leaving its start open to interpretation in every discipline that borrows the term.

Subject of Research: Stratigraphic evidence defining the Anthropocene as a formal geological epoch beginning in 1952.

Article Title: Defining the Anthropocene using precise geological evidence

Article References: Waters, C. N., Zalasiewicz, J., Turner, S. D., Head, M. J., McCarthy, F. M. G., Kuwae, M., Han, Y., Fiałkiewicz-Kozieł, B., Wagreich, M., DeLong, K. L., Kaiser, J., Borsato, A., Zinke, J., Williams, M., Thomas, E. R., Rose, N. L., Ivar do Sul, J. A., Gałuszka, A., Cundy, A. B., … Jeandel, C. (2026). Defining the Anthropocene using precise geological evidence. Nature Reviews Earth & Environment, 7(9), 612-632. https://doi.org/10.1038/s43017-026-00817-8

Image Credits: AI Generated

DOI: 10.1038/s43017-026-00817-8

Keywords: Anthropocene, stratigraphy, plutonium fallout, Crawford Lake, Geological Time Scale, golden spike, Holocene, Great Acceleration, thermonuclear testing, fly-ash particles, Earth system change, epoch definition