An Analysis and Timeline

Abstract

This theory proposes that Denisovans, an archaic hominin group closely related to Neanderthals, may have been the earliest hominin migrants to the Americas. A 130,000-year-old archaeological site in California suggests hominin activity long before anatomically modern humans are known to have left Africa. During this period, Denisovans inhabited Siberia and may have crossed the Beringia land bridge, establishing ephemeral populations in North America. These groups likely died out without descendants but left behind physical traces. Later, modern humans who interbred with Denisovans in Eurasia crossed into the Americas in intermittent migration waves taking place possibly as early as 37,000 years ago. Genetic findings in a 1,500-year-old skeleton from Uruguay confirm persistent Denisovan ancestry in Indigenous populations, supporting the idea of earlier, layered migrations. This model complicates the standard peopling narrative and opens new avenues for understanding pre-Clovis human history in the Americas.

Introduction

The traditional “Clovis-first” model, which posited that anatomically modern humans (Homo sapiens) first entered the Americas approximately 13,000 to 15,000 years ago via the Bering land bridge and dispersed southward through an ice-free corridor or coastal routes, has significantly fallen out of favor in contemporary paleoanthropology. Over the past two decades, accumulating archaeological and genetic evidence, initially viewed with skepticism but now increasingly supported, has dramatically expanded the timeline of human migration into the Americas, revealing a far older and more complex history of hominin presence on the continent.

One of the most controversial data points is the Cerutti Mastodon site in Southern California, dated to approximately 130,000 years ago (Holen et al., 2017). The site contains apparent tool-modified mastodon remains, far predating the earliest known presence of modern humans in Siberia, and calls into question which hominin species, if any, might have made such a crossing at that time. Modern humans are not known to have migrated out of Africa before ~120,000 years ago (Liu et al., 2015; Oppenheimer, 2012), and there is no evidence of their presence in northeastern Asia or Beringia at the time in question. In contrast, the Denisovans, an archaic hominin group known from genomic and limited fossil evidence, were already established in Siberia and parts of East Asia by 130,000 years ago (Reich et al., 2010; Slon et al., 2018). During this period, fluctuating sea levels rendered the Beringia land bridge intermittently traversable (Hopkins, 1982), potentially enabling Denisovan populations to explore or migrate into the North American continent.

This paper explores the possibility that Denisovans, rather than Homo sapiens, may have been the first hominins to set foot in the Americas. Drawing on archaeological timelines, genomic studies, and paleoenvironmental data, I argue that Denisovan populations could have crossed into North America via Beringia during Marine Isotope Stage 5e (~130,000 years ago), leaving ephemeral but significant traces. These populations likely went extinct, but their presence helps explain both the early mastodon site and later genetic signatures of Denisovan ancestry found in some Indigenous American populations, including a recently analyzed 1,500-year-old skeleton from Uruguay (Lindo et al., 2022) that exhibited elevated Denisovan ancestry, exceeding Neanderthal levels. Furthermore, evidence from New Mexico distinctly places modern human presence in the Americas as early as 37,000 years ago (Rowe et al., 2021), reinforcing the possibility of earlier migrations and layered waves of hominin movement.

To support this theory, I present a chronological framework outlining key migration events, interbreeding episodes, and environmental conditions to posit in a reinterpretation of the peopling of the Americas not as a singular event, but as a complex, multi-species process extending back over 100,000 years.

Peopling the Americas: Expanding the Timeline

The dominant model of the peopling of the Americas has long held that anatomically modern humans migrated from northeastern Asia into North America via the Bering land bridge approximately 15,000–16,000 years ago, during the late Pleistocene. This view was largely shaped by associations with the Clovis culture and reinforced by early genetic studies of Indigenous American populations (Goebel et al., 2008). However, a growing body of archaeological evidence has increasingly pushed this date back. Sites such as Monte Verde in Chile (~18,500 years ago) and Bluefish Caves in the Yukon (~24,000 years ago) provided the first major challenges to the “Clovis-first” hypothesis (Dillehay, 1997; Bourgeon et al., 2017).

More recent discoveries have further widened this window. Notably, Rowe et al. (2021) reported evidence of human-modified mammoth remains from New Mexico, dated to approximately 37,000 years ago – well before even the earliest accepted Homo sapiens migrations into the Americas. Such findings support the existence of pre-Clovis migrations and hint at a far more complex and staggered set of dispersals than previously understood.

A landmark discovery published in 2021 and further confirmed in 2024 adds yet another layer to this growing timeline. Human footprints found at White Sands National Park in New Mexico have been dated to between 21,000 and 23,000 years ago, firmly establishing that sustained human activity occurred during the Last Glacial Maximum (Bennett et al., 2021; 2024). These footprints, among the oldest securely dated evidence of Homo sapiens in the Americas, challenge the idea that glacial barriers prevented earlier migration, instead reinforcing the plausibility of earlier migration routes and lending further credence to the idea of multi-layered waves of entry.

Even more dramatically, the Cerutti Mastodon site in California, dated to ~130,000 years ago, presents signs of bone breakage patterns consistent with lithic tool use by hominins (Holen et al., 2017). While the claim remains controversial, the methodological rigor of the dating and the site context have made it difficult to dismiss outright. The site’s age poses a fundamental challenge: it cannot be reconciled with the conventional timeline of Homo sapiens migration out of Africa.

While archaeological sites like Monte Verde and White Sands increasingly affirm the presence of humans in the Americas well before the Clovis period, they also underscore a striking logistical reality: reaching these locations by foot from Beringia would have required not only significant time but sustained adaptability across vastly different environments. From the Alaskan entry point, a journey to central New Mexico, let alone to southern Chile, would span thousands of kilometers and likely many generations. The fact that people were living in Chile by ~18,500 years ago suggests that early migrants either moved with remarkable speed or, more likely, that the peopling of the Americas occurred far earlier than traditional models allow. This spatial-temporal gap reinforces the plausibility of layered migratory waves and intermittent occupation, including the possibility of even earlier, now-extinct populations such as Denisovans contributing to this dispersal framework. It also lends further weight to the coastal migration hypothesis, given the difficulty of inland routes during glacial maxima, and suggests that archaeologists should anticipate not just one origin point or corridor but a patchwork of adaptive routes over tens of thousands of years.

Denisovans and the Siberian Nexus

Denisovans, first identified through genetic analysis of remains from Denisova Cave in Siberia, represent a sister lineage to Neanderthals that diverged roughly 400,000 to 500,000 years ago (Reich et al., 2010). Fossil and genomic evidence places Denisovans in Siberia, the Tibetan Plateau, and Southeast Asia between 200,000 and 50,000 years ago (Meyer et al., 2012; Chen et al., 2019). Their presence in ecologically varied and high-altitude regions has led scholars to suggest they were both adaptable and wide-ranging.

While Denisovan fossil evidence remains limited, genetic traces of their presence extend far beyond known sites. Significant Denisovan ancestry appears in modern populations across Oceania, East Asia, and, notably, in some Indigenous groups in the Americas (Skoglund & Reich, 2016). The genetic signal implies admixture with Homo sapiens occurred in East or Southeast Asia before humans dispersed into the Americas.

During periods of low sea level, including Marine Isotope Stage 5e (~130,000 years ago), the Bering land bridge connected northeastern Asia to Alaska, providing a viable (though harsh) migration route for Pleistocene megafauna and, potentially, archaic hominins such as the Denisovans (Hopkins, 1982). If Denisovans reached northeastern Siberia, as some researchers posit, they may have had both the temporal and ecological opportunity to enter the Americas, even if only in small, ephemeral waves.

Interbreeding, Legacy, and Ghost Lineages

One of the most transformative insights in recent paleoanthropology is the recognition that anatomically modern humans interbred with multiple archaic hominin groups. The discovery of a first-generation hybrid offspring of a Neanderthal mother and a Denisovan father (Slon et al., 2018) confirmed that interbreeding was not incidental but recurrent.

Genomic analyses now suggest that Denisovans interbred with Homo sapiens on at least two separate occasions – once in mainland Asia and again in Southeast Asia – leaving detectable ancestry in modern humans (Browning et al., 2018). These findings have profound implications for the ancestry of Indigenous American populations. Some studies show low but measurable Denisovan admixture in South American groups (Skoglund et al., 2015), although this signal has been complicated by subsequent population movements.

The recent discovery of significant Denisovan ancestry in a 1,500-year-old individual from Uruguay (Lindo et al., 2022) significantly complicates our understanding of Denisovan genetic legacy in the Americas. Lindo and colleagues’ genomic analysis reveals that this ancient individual possessed notably higher levels of Denisovan DNA relative to Neanderthal DNA, a ratio not commonly observed in ancient American genomes studied to date. This unusual genomic signature raises important questions regarding the persistence and distribution of Denisovan ancestry across American populations, particularly in regions far removed from known early migration entry points such as Beringia.

Lindo et al. suggest several possible explanations for this elevated Denisovan signature. First, it might indicate a major admixture event occurring in ancestral populations prior to entry into the Americas, resulting in sustained higher levels of Denisovan ancestry in certain lineages. It could alternatively reflect more complex regional population dynamics, such as secondary admixture events occurring within the Americas, potentially involving remnant populations carrying substantial Denisovan ancestry from earlier migrations. This hypothesis implies that Denisovan genetic influence in the Americas may not have been uniformly diluted over time but instead persisted regionally or was periodically refreshed by contacts with isolated groups.

Moreover, this finding underscores the possibility that the distribution of Denisovan ancestry across indigenous populations in the Americas may be uneven and more complex than previously modeled. Rather than being a simple genetic echo of admixture events that occurred exclusively in Asia, the elevated Denisovan ancestry in this Uruguayan individual points toward a deeper, potentially multi-layered genetic history within South America itself, possibly extending back to the earliest human migrations into the continent.

Future studies, particularly those employing high-resolution paleogenomic methods on ancient human remains throughout the Americas, will be critical in determining the timing, routes, and complexity of Denisovan admixture. This Uruguayan case thus opens an important new window into the prehistoric genomic landscape of the Americas, highlighting the need to reconsider traditional migration models to accommodate more nuanced patterns of interbreeding, population isolation, and genetic persistence.

Taken together, these findings support a model of complex, layered hominin dispersals, punctuated by interbreeding and extinction. This challenges linear narratives and opens space for considering Denisovans as potential participants in the earliest episodes of human presence in the Americas.

Methods

This paper employs a synthetic, cross-disciplinary methodology that draws on paleoarchaeological, paleogenomic, and paleoenvironmental research to reassess the timing and identity of early hominin presence in the Americas. Rather than relying on a single site or genetic dataset, the argument integrates:

1. Archaeological findings from North and South America, especially those predating Clovis-era models;
2. Genetic analyses of Denisovan admixture across modern and ancient populations;
3. Paleogeographic reconstructions of the Beringia land bridge during Marine Isotope Stage 5e and other low-sea-level intervals.

The analysis proceeds by aligning dated sites and admixture signals with known Denisovan dispersal patterns, in order to evaluate whether small-scale Denisovan migration into the Americas during the late Middle Pleistocene is a plausible explanatory model. The framework also considers extinction dynamics, ghost lineages, and the retention of archaic DNA in later Homo sapiens populations to understand how early Denisovan presence might persist genetically but not culturally or morphologically.

Chronological analysis

The earliest and most contentious evidence for hominin presence in the Americas comes from the Cerutti Mastodon site in Southern California, dated to approximately 130,000 years ago (Holen et al., 2017). The site’s pattern of bone breakage, consistent with lithic tool use, has no clear association with either Homo sapiens or Neanderthals, neither of which are believed to have been present in northeast Asia at that time. However, Denisovans, known to have occupied Siberia during this period (Reich et al., 2010), present a compelling candidate. Given the climatic context of Marine Isotope Stage 5e, when sea levels were low and Beringia was intermittently exposed (Hopkins, 1982), Denisovans could have plausibly crossed into North America in small, mobile groups.

While no physical Denisovan remains have been found in the Americas, the idea of a brief, low-population migration is not incompatible with the archaeological record. Such a migration would likely have left behind few direct traces, particularly if the populations did not persist or expand. This model helps contextualize the Cerutti site as part of a “failed migration” or short-lived presence, rather than a direct ancestral source for later Indigenous populations.

Between 60,000 and 40,000 years ago, anatomically modern humans began dispersing widely across Eurasia, encountering and interbreeding with Denisovans along the way (Browning et al., 2018). Genetic studies suggest that Denisovan admixture occurred at least twice: once in mainland Asia and once in Southeast Asia. Intriguingly, low levels of Denisovan DNA have also been detected in several Indigenous American populations, particularly in South America (Skoglund et al., 2015). While this is typically attributed to admixture events that took place before Homo sapiens crossed Beringia, emerging evidence is suggesting a more complex narrative. Several controversial archaeological sites in Alaska and the Yukon, including the Old Crow Basin, Chandalar River, and possibly even layers beneath Bluefish Caves, have yielded lithics and modified faunal remains dated to between 80,000 and 100,000 years ago, predating accepted timelines for Homo sapiens in the region. These findings raise the possibility that small, short-lived Denisovan populations may have crossed into North America during glacial periods when the Bering Land Bridge was exposed. The persistence of Denisovan ancestry in a 1,500-year-old skeleton from Uruguay (Lindo et al., 2022), which carried more Denisovan than Neanderthal DNA, lends further weight to this theory and suggests a major admixture event as early as 40,000 years ago. Whether this genetic legacy reflects deep inheritance from an early Homo sapien population with substantial Denisovan ancestry, or direct Denisovan migration into the Americas, remains unresolved.

By around 37,000 years ago, modern humans had established a presence in North America, as evidenced by clear signs of mammoth butchery at the Hartley Mammoth site in New Mexico (Rowe et al., 2021). This early date significantly challenges the traditional Clovis-first model by extending the timeline for human occupation far earlier than previously accepted. The existence of this site supports the notion of an extended, successful period of human habitation preceding Clovis culture. Although speculative, it is conceivable that admixed populations – modern humans carrying substantial Denisovan ancestry – were among these early migrants, reflecting complex population dynamics in Late Pleistocene Asia prior to crossing into North America. While direct DNA evidence from the site itself is lacking, this possibility aligns with known genetic admixture events in Eurasia before this period.

More recently, fossilized human footprints discovered at White Sands National Park in New Mexico have been dated to between 23,000 and 21,000 years ago (Bennett et al., 2021; 2024). These footprints, the oldest securely dated physical evidence of Homo sapiens in North America, provide direct behavioral insight into life during the Last Glacial Maximum, challenging prior assumptions that ice sheets made the continent inaccessible. Their existence implies long-term human presence that predates Clovis culture by several millennia and supports the notion of early, sustained habitation.

Similarly, the Monte Verde site in southern Chile, dated to around 18,500 years ago (Dillehay, 1997), provides unambiguous evidence of human settlement deep in South America. Its excellent preservation,  including wooden structures, medicinal plants, and hearths, reinforces the possibility of a coastal migration route and underscores the sheer temporal and geographic breadth of early occupation. The fact that humans reached the southern cone of the continent thousands of years before Clovis culture suggests either an exceptionally rapid dispersal or, more likely, a far earlier entry into the Americas than most models accommodate.

Taken together, these data points support a model of layered migration: a Denisovan exploratory or fringe presence in the Americas around 130,000 years ago, followed by extinction; Homo sapiens migration into Asia and subsequent admixture with Denisovans; and a final, sustained wave of modern human migration into the Americas beginning around 37,000 years ago, carrying traces of earlier archaic contact.

Layered migration

The suggestion that Denisovans, rather than Homo sapiens, may have been the earliest hominin visitors to the Americas emerges not from speculation, but from a growing reexamination of Pleistocene hominin dispersal patterns. While direct archaeological and genetic evidence remains limited, this hypothesis gains plausibility in light of mounting challenges to traditional models of human migration into the New World. A suite of pre-Clovis archaeological sites now firmly establishes that anatomically modern humans were present in the Americas well before the once-dominant 15,000-year threshold. Securely dated footprints from White Sands, New Mexico (21,000–23,000 years ago; Bennett et al., 2021; 2024), and the well-preserved remains at Monte Verde, Chile (~18,500 years ago; Dillehay, 1997), confirm sustained Late Pleistocene occupation. Yet even these earlier sites are temporally distant – by over 100,000 years – from the controversial Cerutti Mastodon site in Southern California, dated to approximately 130,000 years ago.

Cerutti remains among the most contentious findings in North American archaeology. While critics argue the bone modifications could result from non-anthropogenic processes such as sediment pressure or faunal trampling, Holen et al. (2017) provide a detailed taphonomic assessment that systematically rules out these alternatives. If one accepts the site’s dating and the patterning of bone breakage as evidence of hominin agency, the central question is no longer if hominins were present in North America at that time, but which hominins.

By 130,000 years ago, Homo sapiens had not yet reached northeast Asia, and Neanderthals remained largely confined to Europe and western Asia. The only hominin lineage known to occupy the relevant spatial and temporal window is the Denisovans. Their presence in the Altai region of Siberia (Reich et al., 2010; Slon et al., 2018), alongside genetic and morphological evidence for ecological breadth and high-altitude adaptability (Chen et al., 2019), supports the possibility of a wider Denisovan range than the fossil record currently documents. Crucially, sea levels during Marine Isotope Stage 5e (~130 ka) rendered the Bering land bridge intermittently accessible (Hopkins, 1982), opening a plausible corridor for low-density Denisovan forays into the western Americas.

Such a scenario does not displace later waves of Homo sapiens migration, but rather enriches the broader framework of early human presence in the Americas. The archaeological record increasingly supports a model of layered migration: some populations leaving deep but ephemeral traces, others persisting and dispersing widely. Within this model, the Cerutti site may represent not a chronological anomaly but instead an early (and likely short-lived) episode in a much older and more complex narrative of hominin movement across continents.

The Case for Denisovan Mobility

The Denisovan fossil record is notoriously limited, but their genetic legacy is expansive, spanning from Siberia to Papua New Guinea. This suggests they were more geographically widespread than current fossil finds would imply. Their ability to survive at high altitudes, as demonstrated by a Denisovan genome recovered from the Tibetan Plateau (Chen et al., 2019), reflects physiological and cultural adaptability – traits that would support long-distance movement, including the potential crossing of Beringia during low sea level periods.

Beringia, while ecologically challenging, was not an insurmountable barrier. During Marine Isotope Stage 5e, the climate in this region may have been comparatively hospitable, and megafaunal migration routes across Beringia were well established. Small groups of Denisovans could have followed these corridors, temporarily establishing themselves in what is now western North America. The absence of further archaeological evidence may reflect the low population size, technological simplicity, or ecological marginality of such groups, factors that also characterize failed or fringe migrations in other prehistoric contexts.

Importantly, the confirmed fossilized footprints from White Sands, New Mexico, dating to 21,000–23,000 years ago, demonstrate that Homo sapiens not only entered North America earlier than previously accepted but may have done so during a period once thought impassable due to ice sheets. These tracks serve as direct, behaviorally rich evidence of human presence, reinforcing the argument that multiple migratory pulses occurred and that long-term occupation may have preceded Clovis by tens of thousands of years (Bennett et al., 2021; 2024).

One of the most compelling pieces of evidence in favor of early Denisovan presence in the Americas is genetic: the presence of Denisovan ancestry in Indigenous American populations. While most researchers attribute this to admixture in Asia before Homo sapiens entered the Americas, the genetic distribution is not entirely consistent with this model. South American populations in particular display slightly elevated Denisovan signals compared to northern populations, despite expected dilution through bottlenecks and founder effects (Skoglund & Reich, 2016).

Recent archaeological findings further complicate the picture. Several controversial sites in eastern Beringia, including Old Crow Basin, Chandalar River, and the deeper strata of Bluefish Caves, have produced lithic tools and faunal remains that some researchers interpret as evidence of hominin activity dating from approximately 80,000 to 100,000 years ago. These dates precede the known arrival of anatomically modern humans in northeast Asia, raising the possibility that these occupations reflect short-lived incursions by Denisovan groups during glacial periods when the Bering Land Bridge was exposed. While the artifact status of some materials is debated, the timing and geography align with what is known about Denisovan range and climate-accessible corridors.

The discovery of Denisovan ancestry in a 1,500-year-old individual from Uruguay (Lindo et al., 2022) complicates the narrative by confirming that Denisovan ancestry persisted well into the late Holocene in South America, likely the result of deep ancestral admixture. This particular individual carried more Denisovan than Neanderthal ancestry, an unusual genetic signature that supports the idea of a substantial admixture event possibly dating back ~40,000 years. This suggests either a deep and persistent Denisovan genetic legacy in the Americas, or more recent introgression from an as-yet-undetected population of archaic-human-descended individuals. Taken together with the archaeological hints of earlier Beringian presence, the presence of Denisovan DNA in late Holocene individuals supports the possibility that Denisovan-derived lineages were not merely inherited from admixture events in Asia, but may have had more direct regional roots.

Counterarguments and Constraints

Skeptics may rightly point out that there is no direct physical evidence – no Denisovan skeletal remains, tools, or habitation sites – in the Americas. This is a valid limitation. However, this absence must be weighed against two considerations: first, that the fossil record is highly fragmentary and biased toward certain depositional environments; and second, that known Denisovan remains themselves are extremely limited even within Asia, their home range. Moreover, models of small-scale, exploratory, or failed migrations are consistent with other examples in the Pleistocene. Neanderthals, for example, appear to have made brief forays into areas they did not permanently inhabit. A small group of Denisovans entering North America and dying out without major demographic impact would leave precisely the sort of faint archaeological and genetic traces we currently see, if any.

Conclusion and Future Research

Rather than viewing the peopling of the Americas as a singular event, this theory encourages a layered model: one that acknowledges a likely Denisovan crossing around 130,000 years ago; their subsequent extinction; Homo sapien–Denisovan admixture in Asia around 50,000-40,000 years ago; and a later, successful Homo sapiens migration into the Americas beginning ~37,000 years ago, carrying the genomic legacy of their archaic ancestors. This framework accounts for the Cerutti site without invoking implausibly early Homo sapien migration. It also integrates paleoenvironmental, archaeological, and genomic data into a coherent, if still hypothetical, scenario of early human movement and interaction.

This paper has proposed a layered model of early hominin presence in the Americas, with Denisovans as plausible candidates for the earliest wave of migration across the Bering land bridge. While conventional models of peopling emphasize a singular Homo sapiens migration during the Late Pleistocene, emerging evidence from archaeology, genetics, and paleoenvironmental reconstructions complicates this picture. The Cerutti Mastodon site, dated to 130,000 years ago, cannot be easily dismissed and remains difficult to reconcile with modern human timelines. However, it fits plausibly within a scenario of limited Denisovan movement into North America during Marine Isotope Stage 5e, when ecological and geographical conditions may have briefly permitted such a crossing.

The Denisovan genetic legacy, traced across Southeast Asia, Oceania, and the Americas, demonstrates that this archaic population was both widespread and reproductively compatible with Homo sapiens. The detection of Denisovan DNA in both ancient and present-day Indigenous American populations, particularly in South America, adds further weight to the possibility of direct or indirect Denisovan involvement in the earliest layers of American population history. While no Denisovan fossils have yet been discovered in the Americas, the extreme scarcity of their remains even within Asia cautions against dismissing their presence based on absence alone.

Future research must address several key questions to test the strength of this hypothesis. First, renewed excavation and reanalysis of early North American sites, especially those predating Clovis culture, may help clarify the extent and nature of hominin activity prior to 40,000 years ago. Second, advanced paleogenomic work, including high-resolution mapping of archaic DNA segments in Indigenous populations, may help distinguish between Denisovan ancestry acquired in Asia and ancestry potentially inherited from archaic populations present in the Americas. Third, paleoenvironmental reconstructions of Beringia during MIS 5e and related periods can refine our understanding of when and how migrations might have occurred.

Ultimately, a Denisovan presence in the Americas would not displace the importance of later Homo sapiens migrations, but rather deepen our understanding of hominin dispersal, extinction, and interconnection. It would affirm that the story of human presence in the Americas is older and more complex than previously imagined – one not solely of Homo sapiens, but of archaic cousins who ventured far and whose genetic shadows linger still.

timeline

130,000 years ago: Early Hominin Activity in North America
A controversial archaeological site in Southern California (Cerutti Mastodon site) has been dated to approximately 130,000 years ago and presents signs of hominin-modified mastodon remains (Holen et al., 2017). This site predates the generally accepted timeline for anatomically modern human migration out of Africa. Meanwhile, Denisovans occupied parts of Siberia, as evidenced by remains from the Denisova Cave in the Altai Mountains (Reich et al., 2010; Slon et al., 2018). During interglacial periods, such as Marine Isotope Stage 5e (~130 ka), the Bering land bridge intermittently connected Asia and North America, theoretically enabling Denisovan migration (Hopkins, 1982).

~100,000–80,000 years ago: New Denisovan Forays into Eastern Beringia
Several controversial archaeological sites in Alaska and the Yukon, such as Old Crow Basin, Chandalar River, and deep layers at Bluefish Caves, have yielded lithic artifacts and faunal remains interpreted by some researchers as evidence of hominin activity during this period (Morlan, 2003; Bourgeon et al., 2017). These sites predate the known presence of Homo sapiens in northeast Asia, raising the possibility of short-lived Denisovan incursions into eastern Beringia via an exposed Bering Land Bridge. While no fossils confirm the species involved, the dates precede Homo sapiens’ arrival in northeast Asia, pointing to Denisovans as likely candidates. These early incursions may not have led to lasting populations but could explain traces of Denisovan ancestry in later American genomes, especially in the south.

~120,000–60,000 years ago: Homo sapien Dispersal from Africa
Current fossil and genetic evidence places the initial dispersal of anatomically modern humans (Homo sapiens) out of Africa no earlier than 120,000 years ago, with the bulk of migration occurring after 70,000 years ago (Liu et al., 2015; Oppenheimer, 2012). There is no evidence of Homo sapiens in Siberia or Beringia by 130,000 years ago.

~70,000–38,000 years ago: Widespread Denisovan–Homo sapiens Interbreeding in Siberia and East Asia
Genetic studies reveal that Homo sapiens interbred with Denisovans at least twice in Asia, including one major episode in mainland Siberia (Browning et al., 2018). Estimates place major admixture events between 44,000 and 38,000 years ago. Following these admixture events, human populations with Denisovan ancestry began migrating northeastward during a period when Beringia was partially exposed. These admixed groups may have contributed to the elevated Denisovan genetic signal later found in Indigenous South American populations (Lindo et al., 2022).

~37,000 years ago: Modern Humans Enter the Americas?
New archaeological findings in New Mexico provide evidence of modern human activity in North America around 37,000 years ago, predating the Clovis culture and traditional peopling models (Rowe et al., 2021). These migrants very likely carried Denisovan DNA acquired through earlier admixture in Asia.

~24,000–18,500 years ago: Pre-Clovis Coastal and Interior Occupation
Monte Verde in southern Chile (~18,500 years ago) and Bluefish Caves in the Yukon (~24,000 years ago) provide critical evidence of early human presence both deep in South America and in the subarctic north. Monte Verde’s remarkable preservation of organic tools, hearths, and plant remains supports the theory of a coastal migration route and was instrumental in overturning the “Clovis-first” hypothesis that previously dominated paleoanthropology theory (Dillehay, 1997).

22,400-20,700 years ago: Fossil Footprints in White Sands, New Mexico
Dozens of fossilized human footprints discovered in White Sands National Park provide direct evidence of sustained human presence in North America during the Last Glacial Maximum (Bennett et al., 2021; 2024). This finding pushes back the earliest securely dated presence of Homo sapiens in the Americas and challenges the assumption that glacial barriers made earlier migration impossible.

1,500 years ago: Persistence of Denisovan Ancestry
Genomic analysis of a 1,500-year-old individual from Uruguay revealed greater Denisovan than Neanderthal ancestry, according to Lindo et al. (2022), suggesting that Denisovan DNA persisted in South American populations far longer than previously confirmed. This supports the hypothesis of a substantial admixture event at least 40,000 years ago.

This evidence supports the hypothesis that Denisovans may have crossed into North America via Beringia around 130,000 years ago, establishing small populations that ultimately went extinct but predated modern human migration. Later Homo sapien migrations around 37,000 years ago carried traces of Denisovan DNA, potentially from Siberian admixture, which continues to persist in Indigenous American populations.

Three-wave migration across beringia (135,000–13,000 ya)

1. MIS 6–5e (~135,000–115,000 ya): Initial Denisovan Incursion

• Glacial phase before ~130 ka exposed Beringia fully, providing a plausible corridor.
• Candidate migration: Small, likely short-lived Denisovan groups.
• Archaeological anchor: This position aligns temporally with the Cerutti Mastodon site (~130 ka), which could represent ephemeral Denisovan presence.

2. MIS 4 (~80,000–60,000 ya): Beringia Exposed, Denisovan Re-Entry

• Beringia becomes partially exposed again due to glacial sea-level drop.
• Candidate migration: Small, likely short-lived Denisovan groups.
• Old Crow Basin, Chandalar River, and deep strata at Bluefish Caves yield lithics and modified faunal remains that some interpret as signs of hominin activity from this period (Morlan, 2003; Bourgeon et al., 2017).
• While no fossils confirm the species involved, the dates precede Homo sapien arrival in northeast Asia, pointing to Denisovans as likely candidates. These early incursions may not have led to lasting populations but may have contributed to traces of Denisovan ancestry in later American genomes, especially in the south (e.g., Lindo et al., 2022).

3. MIS 2 (~25,000–14,000 ya): Late Migration, Clovis-Associated Groups

• During the Last Glacial Maximum, Beringia is at its widest and most stable, enabling large-scale migration.
• This wave includes ancestors of the Clovis and post-Clovis cultures, likely with reduced Denisovan ancestry due to admixture dilution, bottlenecks, and time.
• This falls in line with the genetic and archaeological consensus of most Indigenous American lineages tracing back to this phase.

Citations:

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Posted 09 July 2025.