Razib Khan's Unsupervised Learning

In 1985, I flipped open a dictionary in my elementary school library, and became completely distracted by a map in the front matter illustrating the distribution of modern Indo-European languages. I was nine years old and this was the first time I saw the term “Indo-European.” Both the term and the map perplexed me. Included were the two languages I knew: English and Bengali, the northwesternmost and easternmost of the Indo-European languages, respectively. What could possibly connect them across that vast geographical span? I certainly had never noted any similarities…until I paused to take a closer look. That weekend, library card in hand, I trudged off to the public library, thumbed through the card catalog until I found the entry for “Indo-European,” inspected it and followed it to the linguistics section. I was already a habitué of the adults’ section, but so far, had solely explored the science stacks. That day, I pulled down a tome whose details I scarcely recall, unfamiliar matters of philology mixed with prehistoric speculation. What I do remember to this day is that inside that doorstopper was a wealth of maps, language-family trees and long lists of word-comparisons laid out in tables (what I know now to be swadesh lists). Seeing the similarities in the core words across Indo-European languages explicitly outlined, the scales fell from my eyes. Below are some typical cognates in English, Bengali and Proto-Indo-European (PIE):

Once you have seen, you cannot unsee.

More than 40% of humans alive today speak an Indo-European language as their mother tongue, some 3.4 billion people (and well north of 50% if you count second-language learners). The top ten are:

It is notable that, for raw numbers, being on the margins seems to have redounded to the benefit of expansionist Indo-Europeans. Except for Russian, all top ten Indo-European languages count speakers positioned around the map’s fringes: the Indian subcontinent and Western Europe. In contrast, the Baltic languages, whose domains once stretched some 750 miles from northern Poland to the environs of modern Moscow, are now constrained to Latvia and Lithuania, counting only some 5 million speakers. In the early 20th century, the Indo-European languages’ widespread range inspired theories of world-conquering supermen, but is anyone prepared to claim Bengalis and Portuguese (but not Lithuanians or Armenians) are scions of some super race? Or is it simply that, as luck would have it, the ancestors of those peoples who pushed to Eurasia’s frontiers were better positioned to exploit ecological opportunities than their kin who remained hard by the core ancestral homelands?

The longstanding questions of why the Indo-Europeans rose to prominence and how they did so date back to the 19th century and continue to be debated today, as attested by the existence of entire departments devoted to the study of Indo-Europeans. After nearly two centuries of scholarly fascination with the topic, J. P. Mallory’s seminal 1989 In Search of Indo-Europeans engrossingly captured the field where it then was. A generation later, David Anthony’s 2007 The Horse, the Wheel and Language, became the essential must-read. But it was truly paleogenetics’ post-2010 emergence as a tool to explore Indo-Europeans’ prehistoric population movements that supercharged the rate of new discoveries and fast-tracked revisions of our understanding toward a final draft. Fifteen years later, researchers have settled many long-standing questions that had spawned decades of spirited debate. Early this year, Nick Patterson, an author of the 2015 letter to Nature, Massive migration from the steppe was a source for Indo-European languages in Europe, told me he felt they had wrapped up most of the major questions, with only details left to be sorted out.

Certainly since the fall of 2020, when I began writing extensively here about Indo-Europeans, our understanding of the dynamics of the origins, emergence and expansion of these people has come an immense distance. I started with pieces on ‌Aryan migration to India and the Yamnaya’s rise in 2021, among many others, before culminating in a January 2025 post celebrating the fruitful relationship between linguistics and genetics in settling the Indo-European question. Today it feels defensible to argue that we have made more progress in the last decade than in the previous two centuries toward understanding Indo-European prehistory.

If I was a schoolboy today, I might look at the map above, grab my iPad and turn to an AI-agent or search engine. And I might immediately find satisfying answers to most of the questions raised by the fantastic geographical range and cultural diversity of Indo-European language speakers. Just as in my own childhood, at this point archaeologists and linguists have been assembling a vast edifice of data and evidence to answer these questions for decades, if not centuries.

But what took these lingering open questions I discovered as an elementary schooler over the finish line as my children were passing through the same ages, was the intervention of large-scale genomics. Ancient DNA samples in hand, geneticists have finally been able to arrange that carefully collected accumulation of facts from linguistics and archaeology on a rigorous phylogenetic and demographic scaffold, creating a theoretical superstructure sturdy enough to finally decide the fundamental question: how did a small group of pastoralists 5,000 years ago so swiftly come to dominate half the Old World?

For much of the 20th century, a key issue of debate was where the Proto-Indo-Europeans first emerged and from whence they expanded outward until their sphere spanned half of Eurasia. The leading contenders ranged from Germany to India. Historical linguists looking at the word roots shared near universally across Indo-European languages argued that the ancestral population must have lived in a climate with cold winters, and been familiar with both beech trees and salmon, which made Europe or somewhere immediately adjacent most likely.

But in the last quarter of the 20th century, archaeologists, led by Oxford’s Colin Renfrew, argued for focusing research on early Neolithic Anatolia, because only the rise of agriculture could have driven the scale of cultural and demographic change that Indo-Europeans had clearly inflicted on their local forerunners. The shortcoming of that theory, from historical linguists’ perspective, was that the Indo-European languages remained too similar to align with the considerable time depth since agriculture’s rise; the Neolithic expansion out of Anatolia into Europe began nearly 10,000 years ago. But beginning in the first decade of the 21st century, a new group of scholars weighed in on the topic, deploying not classical comparative linguistic techniques but computational methods borrowed from phylogenetics. Using lexical data, they applied evolutionary models to understand how modern language distributions and relationships could have emerged, and exactly when they began to diversify from a common ancestor. Surprisingly to the linguistically informed,‌ computational evolutionary linguistics came down on the side of the archeologists, supporting an older origin for Indo-European languages, and so one that aligned well with an Anatolian homeland.

But sometimes simple access to data, plain and clear, can overturn even the most sophisticated, computationally intense modeling. In the mid-2010s David Reich’s and Eske Willerslev’s groups, in the US and Europe respectively, raced to retrieve and genetically test individuals buried in ancient Yamnaya kurgans, those great earthen mounds the Eurasian steppe peoples characteristically placed atop elite graves. With the millennia-old DNA, they ran a battery of analyses comparing the genetics of those Yamnaya to modern and other ancient populations. The results shocked both them and their archaeological and linguistic collaborators: nearly half of Northern Europeans’ ancestry today, a substantial minority of Southern Europeans’ (some 20-40%), and an average approaching 15% across highly variable South Asian populations (with rates rising as high as 35% among Brahmins in certain locales), could be modeled as descended from the fourteen genomes retrieved from nine kurgans.

It’s worth noting that whatever disagreements a faction of linguists and archaeologists might have had with Renfrew’s out-of-Anatolia thesis, they had always conceded that in demographic terms it was likely a cogent argument. Farming supports a much larger population than pastoralism, and so could serve as a more plausible demographic engine for such sweeping patterns of cultural change. And in The Horse, Wheel and Language archaeologist Anthony promulgated the view that Indo-Europeans expanded out of the steppe, expanding on the ideas of his mentor, Lithuanian archaeologist Marija Gimbutas, but even he posited an “elite transmission” dynamic, whereby Indo-European memes were far more impactful than Indo-European genes as small groups of horsemen hurtled westward.

The game changer of paleogenetics here lay not in complex and formal model-building: but in the devastating simplicity of DNA reads. Because not only does that Yamnaya DNA from the kurgans echo down through so many modern human populations; it was immediately apparent that it matched a known Corded Ware burial site in Poland holding literal genetic kin of those in the kurgan mounds. This definitively established that the Corded Ware’s long-debated roots ultimately lay in the Pontic steppe; they were Yamnaya with cultural adaptations and local genetic accretions. Later work from Reich’s group showed 90% population replacement in Britain around 2500 BC, and Kristian Kristiansen, a Willerslev collaborator, has written of the Yamnaya-descended Battle-Axe Culture totally replacing the Neolithic Funnelbeaker society in Scandinavia. Even the Indian subcontinent absorbed a substantial demographic impact, and this in a region that classical observers as far back as Herodotus believed was the most populous on earth (how little has changed!). About 20% of the ancestry of people in the northwestern quadrant of South Asia, home to nearly 300 million people today, can be traced back specifically to the Yamnaya (and fractions even higher if you stipulate steppe pastoralists more broadly). The fractions are lower in other parts of the subcontinent, but even at India’s far southern tip, castes like Tamil Brahmins harbor some 15% Yamnaya ancestry and the least steppe-enriched groups in Southern India still show high single-digit steppe ancestry rates.

A quick back-of-the-envelope calculation aggregating those proportions across all contemporary human populations, Old World and New, estimates the equivalent of some 700 million pure Yamnaya walking among us today. All this from a very small founding population, perhaps just a few allied tribes. A 2025 Reich-lab paper with a large dataset of Yamnaya genotypes estimates an initial ancestral breeding population of about 5,000 at the start of the major expansion phase out of their Pontic steppe homeland into Europe in 3000 BC (up from a population as small as 2,000 in 3500 BC, when we estimate the Yamnaya had truly coalesced as a coherent genetic population cluster). These estimates are usually lower bounds, counting the core minority of individuals who contributed to the genes of future Indo-European-speaking people. But breeding populations don’t tend to be off by more than an order of magnitude; there weren’t 50,000 Yamnaya of whom only 5,000 bred. Using standard rules of thumb, we can estimate some 10-20,000 Yamnaya in total, subdivided between a few tribes. This means 5,000 years ago, with the Yamnaya on the cusp of their world-altering expansion, as few as 10,000 nomads scattered between the Dnieper and Don rivers in what is today Ukraine were about to run the table from the Altai to the Atlantic. Contemporary observers, like their neighbors the Cucuteni-Trypillia people, who built some of the largest towns of the late Neolithic, ‌likely did not see the scattered nomadic Yamnaya as ‌a particularly portentous or formidable horde, and yet within less than a millennium they would go on to reshape the face of the entire Eurasian continent.

Sometimes the evidence is so overwhelming, it fairly demands a final verdict. The flood of ancient DNA and genetic analyses has allowed archaeologists and linguists to reconstruct the shape of the past with a fidelity unimaginable a generation ago. The sequence of migrations is now finally clear, written in genes, and told in the rise and fall of successive peoples. Between 3000 and 2900 BC, a new culture arrived in what is today Poland, long ago detected in archaeology’s traditional fashion by the propagation of a new pottery tradition. These were the Corded Ware, a people who would become the subject of a century of speculation in European archaeology. To the shock of many, it quickly became clear that genetically many Corded Ware were basically interchangeable with the people buried in the kurgans; some of the Corded Ware samples are actual close genetic kin to the steppe probands, second and third cousins who might even have known one another’s families by name. After 2900 BC, most of the Corded Ware also show a substantial minority (about 30%) of ancestry derived from the region’s previous occupants, the Neolithic Globular Amphorae Culture (GAC). A century later, in 2800 BC, this population moved north and west, into Scandinavia and Germany, abruptly supplanting the local Neolithic societies whose roots in the region went back millennia. After 2600 BC it was France, after 2500 BC Britain, after 2300 BC Italy and Spain. Each time, the ancient DNA record reflects an abrupt and radical shift. New pots signal new people. Because so few ancient remains have been genotyped there, the conclusions out of India are more tentative; however, the best evidence currently suggests Yamnaya ancestry appeared there after 2000 BC, as no Indian or Indian-related sample prior to that date harbors that heritage.

Since it’s no use longing to time-travel into the past, the best evidence we can hope for remains circumstantial, but it staggers the imagination how massive a demographic shift swept most of Eurasia between 3000 and 1000 BC. A small number of tribes from the bleak Pontic steppe largely replaced Northern Europe’s great megalith-building civilizations, overthrew Europe’s first literate society in Greece, the Minoans, and erased the memory of the people who had built the grand Indus Valley Civilization. The only remaining plausible candidate for who these people were is Indo-Europeans, ethnolinguistic forebears of today’s Europeans, Iranians and Indians alike.

Welcome back to the Unsupervised Learning Journal Club, an occasional feature for paying subscribers where I review interesting papers in human population genomics. In the spirit of a conventional journal club, after each post, interested subscribers can vote on papers for future editions.

Genghis Khan, the Golden Horde and an 842-year-old paternity test

Re-writing the human family tree one skull at a time

Ghost Population in the Machine: AI finds Out-of-Africa plot twists in Papuan DNA

Free subscribers can get a sense of the format from my ungated coverage of two favorite 2024 papers:

The other man: Neanderthal findings test our power of imagination

We were selected: tracing what humans were made for

Today we’re reviewing a Cell paper, Ancient DNA challenges prevailing interpretations of the Pompeii plaster casts (2024). The authors use paleogenetics to shine new light on the backgrounds of the famous victims of one of history’s best-known natural disasters. It comes out of Alissa Mitnick’s group at Max Planck Institute. The first author is Elena Pilli of the Università di Firenze.

“Its general appearance can best be expressed as being like an umbrella pine, for it rose to a great height on a sort of trunk and then split off into branches, I imagine because it was thrust upwards by the first blast and then left unsupported as the pressure subsided, or else it was borne down by its own weight so that it spread out and gradually dispersed. In places it looked white, elsewhere blotched and dirty, according to the amount of soil and ashes it carried with it.”

- Pliny the Younger, 79 AD, later recalling his distant view of Mt. Vesuvius’ volcanic plumes

In 79 AD, Imperial Rome’s first flowering had passed. Over a decade prior, Nero, the last of the Julio-Claudians, had committed suicide. The end of Rome’s first imperial dynasty left a leadership vacuum that sparked civil war, eventually bringing Vespasian to the throne. A humble Italian from a town northeast of Rome, Vespasian had no roots in the great city itself. Ironically, it was he who established the practice of the Roman sovereign bearing the title imperator; unlike his Julio-Claudian predecessors, his lineage was obscure, so his right to rule rested purely on military achievement and the power conferred upon him by his armies. Vespasian brought the empire back together under firm and pragmatic rule after the degeneracy of Nero’s reign and the disorder of civil war. After a decade on the throne, in the spring of 79, Vespasian died, to be succeeded by his son Titus. Roman historians would judge Titus’ short two-year reign kindly, but one of the first things he had to attend to was the eruption of Mount Vesuvius in southern Italy, the second major event that year to shake the empire after Vespasian’s death.

At 4,200 feet (1280 meters), Vesuvius today is regarded as a menacing presence looming silently over the bay south of Naples; it is a well-known active volcano. But 1,946 years ago, it had lain dormant for so long that in 23 AD when Strabo wrote about the region, he depicted the mountainside as covered in vineyards and farms, with small villages nestled around its base. In the 60s, the region had witnessed multiple large earthquakes, so when in the days leading up to that cataclysmic day in 79, multiple tremors shook the area, citizens apparently saw them as business as usual. Ancient Pompeii, on its southern slopes, and seaside redoubt Herculaneum, just to its west, were the larger towns in the region, wealthy, well-run Roman cities with a high quality of life in a time of relative peace for the empire. When their neighboring mountain began erupting, the citizens were caught unprepared. The next two days would subject the region to cataclysm on a scale few of us are equipped to fathom. More earthquakes punctuated days of inferno as a 21-mile high cloud continued hailing rock and ash on the cities around the clock; the power of the explosion itself is estimated to have released 100,000 times the thermal energy of the atomic bombings of Hiroshima and Nagasaki.

There are no known eyewitness accounts from survivors who escaped either town. Only the Roman jurist Pliny the Younger, an eyewitness of the eruption from safety kilometers away across the bay, recalled the day in letters to Tacitus written decades later. He recalled those rumblings in the days before the cataclysm, but noted that the region had been so seismically active the locals took no particular notice. Pliny observed the mass destruction and chaos from far off on the other side of the bay. His uncle, Pliny the Elder (the famous encyclopedist and friend to Vespasian), sailed across the bay into the upheaval, and died attempting to aid those fleeing. Pliny the Younger describes seeing a giant plume of ash and pumice erupting above the distant mountain at 1 p.m. At that time, over 11,000 people ‌lived in Pompeii ‌and some 5,000 in Herculaneum. Most seem to have survived, scattering across the region. But ash and pumice buried both their vibrant cities overnight, sealing them up, in many ways fossilized as they had been on one arbitrary 79 AD afternoon (whose precise season is still debated, but was probably either late summer or early autumn), until antiquarians began excavating them in the 18th century.

Pyroclastic material, ash, pumice, and rock fragments, blanketed both Pompeii and Herculaneum. Pompeii, downwind of Vesuvius, apparently endured an uninterrupted rain of pumice (a steady downpour of small stones falling from the sky) from the eruption’s ash plume for 18 hours after the plume first formed. The air temperature increased to lethal levels over the day, and ash and stone continued to rain down on the city, all eventually entombing the sites. Herculaneum, in contrast, was upwind of Vesuvius and so escaped the initial pumice rain from the eruption plume. Closer to the base of the volcano though, overnight it was abruptly engulfed by a pyroclastic avalanche of mud, ash and superheated fumes moving at 100 mph; a flow of volcanic material super-heated to temperatures up to 500 degrees Celsius that carbonized wood furniture, doors, beds, bread and even an entire private library of papyrus scrolls, burying the town to a depth of 25 meters.

In Pompeii meanwhile, during the later phases of the eruption, the morning after the plume was first sighted, anyone who had remained in the city after the long downpour of pumice rain was doomed to be caught in the same sort of delayed pyroclastic surge as had suddenly engulfed Herculaneum overnight. But by the time the later round ‌hit Pompeii, the temperatures seem to have dropped to something closer to 300 degrees, which would prove a decisive adjustment from the levels during the cataclysmic avalanche that had doomed Herculaneum. Pompeii’s round of pyroclastic surges overwhelmed victims who were by then sheltering indoors from the pumice rain pelting their city, clearly catching them unawares, many cowering or huddling together inside.

Those relatively lower temperatures that killed Pompeii’s victims have made all the difference to science though; they mean that despite being abruptly engulfed and killed by the surge, this time the victims’ bodies did not immediately disintegrate, as they had in Herculaneum; instead the hail of ash and stone continued to steadily accumulate around them over the hours. In time, their bodies would decay, but by then the detritus of the eruption around them had long since fully cooled and hardened, leaving the solidified concrete-like mass studded with human-shaped cavities in the precise shapes in which they had been suddenly stilled. In 1863, Italian archaeologist Giuseppe Fiorelli realized that pouring plaster into these hollow voids would recapture the precise form of the humans who had died that day, yielding lifelike sculptures eternally suspended in the private moments and interactions at the instant tragedy engulfed them.

The 104 men, women and children who both perished in Vesuvius’ infernal aftermath, and whose final moments were then captured for us as if someone had pressed pause on a video, have gone on to fuel a century of archaeology. The possible life narratives their final moments suggest to the fertile human imagination have grown rich enough, whether those be a mother and child clinging together or a slave girl perhaps callously left behind to fend for herself, to serve as the basis for numerous documentaries in the late 20th and early 21st centuries. The vivid details amid calamity from what began as an ordinary day in two comfortable small cities have always offered an irresistibly human-scale counterpoint to the cold perfection of marble busts and the mute austerity of long since stripped amphitheaters that so often epitomize Roman antiquity’s material record.

The everyday objects preserved in the homes, the profane graffiti in public spaces, the rarity of ancient human bodies not laid lifelessly to rest, but frozen in the midst of living bring vividly to life the material reality of the vast majority of Roman citizens. For once we glimpse not the society’s storied generals and orators, but its humble farmers, merchants, potters, bakers and mothers. Certain of the most vividly captured among Pompeii’s doomed were in this way granted a belated afterlife far more evocative and enduring than the over 10,000 survivors who moved quickly enough to stream out of the doomed cities and reach safety at points north and south. The eloquence of those often anguished, unaffected final human gestures naturally move us to sympathize with them far more powerfully than we relate to those who fled. In lives abruptly cut short, they eventually had far more enduring legacies than actual eye-witness survivors lucky enough to live out the rest of their lives as refugees in other cities. The host of documentaries their remains inspired hinged on narratives spun out of the apparent pathos of their poignant final moments.

Today, though, we have at hand a powerful new way to understand those people of the past, no matter where we find them or how their final gestures strike us: their genetic interrelationships. Ancient DNA challenges prevailing interpretations of the Pompeii plaster casts, published in Cell, is the first comprehensive paleogenetic survey of multiple sets of remains (one single sample had been studied previously). When Italian archaeologists created the plaster casts, in some cases they unknowingly preserved remnants of bones within them. The research team for this study painstakingly probed the casts for traces of DNA adequate to sequence and were able to retrieve varying amounts from seven total casts, five of them in appreciable quantities. These casts had been the subject of scholarly analysis for decades, but now we could precisely delve into their genetic backgrounds and relationships.

One of the simplest things to test immediately upends some of our emotional interpretations of the figures and their poses: all five individuals are indisputably male, as attested by their Y chromosomes. This basic fact triggers revisions to some of the narratives their poses had always suggested. 1974 saw completion of the so-called House of the Golden Bracelet’s excavation. The private residence was a sumptuously decorated multi-level elite Pompeii home; its rooms yielded casts of four individual humans. The site was named for cast 52, who died wearing a massive 1.34-pound solid gold two-headed snake bracelet featuring a disk with the lunar goddess Selene, which was both evident in the relief of the cast and actually survived intact inside the cavity where its bearer’s remains decayed. An incomplete cast of a small child, cast 51, was positioned on the apparently recumbent figure’s lap. Given the opulent home, the extraordinary bracelet and the pose with figure 51 against her, archaeologists had posited that this was a wealthy mother sheltering in her home, protecting her child. Archaeologists surmised that another adult nearby, cast 50, was the father. The home’s fourth and final cast, number 53, expired alone in a different room, and was assumed to perhaps have become separated from the parents in chaotic final moments. The figure’s diminutive dimensions and a bulge at the crotch in the plaster, presumed to be a penis, suggested this child who died alone was a boy of about four. Archaeologists had imagined this whole grouping to be a nuclear family.

But genetic tests immediately found that individual 52, the maternal figure with the dramatic bracelet, had a Y chromosome and so was actually male. The figure we read as maternally protecting a child, was in fact a man. Next, comparison of individual 51, 52 and 53’s genomes show they are also clearly not biologically related (and even if individual 52 was instead the two children’s father, they would share his Y chromosome, which is also not the case). Though nuclear DNA was not retrievable for the individual in cast 50 (meaning we also cannot confirm sex), presumed to have been the father in the old model, mtDNA proved callable. Perhaps individual 50 was the mother of one of the children? Again this individual showed no genetic relationship to the others in the house (a cut and dried judgement, since humans inherit mtDNA from their mothers). So, genome-wide and mtDNA analysis now refutes five decades of conjecture that this was a conventional family unit, at least on any biological basis.

The number of Single Nucleotide Polymorphisms (SNPs) retrieved from each of the five is more than sufficient to assign biogeographic ancestry, for which we usually set a floor of 10,000 markers (even if a minimum of closer to 100,000 markers is preferable for more sophisticated methods). A PCA plot projecting the Pompeii individuals shows they were all of Mediterranean provenance, but not clustered together biogeographically. All the evidence then points to the three fully genotyped individuals in the House of the Golden Bracelet being entirely unrelated individuals (with the fourth being at least maternally unrelated), and what’s more, with a very diverse range of origins.

On this very special episode, Razib talks to paleoanthroplogists John Hawks and Chris Stringer. Hawks is a paleoanthropologist who has been a researcher and commentator in human evolutionary biology and paleoanthropology for over two decades. With a widely read weblog (now on Substack), a book on Homo naledi, and highly cited scientific papers, Hawks is an essential voice in understanding the origins of our species. He graduated from Kansas State University in 1994 with degrees in French, English, and Anthropology, and received both his M.A. and Ph.D. in Anthropology from the University of Michigan, where he studied under Milford Wolpoff. He is currently working on a textbook on the origins of modern humans in their evolutionary context. Hawks has already been a guest on Unsupervised Learning three times.

Chris Stringer is affiliated with the Natural History Museum in London. Stringer is the author of African Exodus. The Origins of Modern Humanity, Lone Survivors: How We Came to Be the Only Humans on Earth and Homo Britannicus - The Incredible Story of Human Life in Britain. A proponent since the 1970’s of the recent African origin of modern humans, he has also for decades been at the center of debates around our species’ relationship to Neanderthals. In the 1980’s, with the rise to prominence of the molecular model of “mtDNA Eve,” Stringer came to the fore as a paleoanthropological voice lending support to the genetic insights that pointed to our African origins. Trained as an anatomist, Stringer asserted that the fossil evidence was in alignment with the mtDNA phylogenies, a contention that has been broadly confirmed over the last five decades.

Razib, Hawks and Stringer discuss the latest work that has come out of Yuxian, China, and how it updates our understanding of human morphological diversity, and integrate it with the newest findings about Denisovans from whole genome sequencing. They talk about how we exist at a junction, with more and more data, but theories that are becoming more and more rickety in terms of explaining the patterns we see. Hawks talks about the skewing effect of selection on phylogenetic trees, while Stringer addresses the complexity of the fossil record in East Asia.

Related: Re-writing the human family tree one skull at a time and The cave where it happened: Denisova cavern’s congress of ancient peoples.

Subscribe now

Give a gift subscription

Share

Subscribe now

Give a gift subscription

Your time is finite. Your phone and the internet stand ready to help you squander it. Here are my latest picks for spending it well instead. Feel free to add more in the comments.

James Watson died on November 6th, 2025. Born in 1928, in his 97 years, he witnessed sea changes in culture, technology and of course science. Along with Francis Crick, he puzzled out the structure of DNA, the substrate of genetic inheritance. He, Crick and Maurice H. F. Wilkins shared the 1962 Nobel Prize in Medicine for that discovery. Watson was no one-trick pony; appointed director of Cold Spring Harbor Laboratory in 1968, he transformed it into one of America’s premier centers of biological discovery, steering it past its eugenicist past. In 1990, Watson helmed the Human Genome Project, departing after two years over a disagreement concerning gene patents. In 2013, the Supreme Court invalidated the concept of gene patents, coming down on the side Watson (and most geneticists, frankly) had always favored.

Americans had many reasons to know Watson better than Crick. First, and foremost, Watson was American, while Crick was English (though after 1977 Crick moved to the US from Cambridge, England. There, until his death in 2004,Crick devoted 30 years of his scientific career to neuroscience and understanding consciousness). Second, Watson was a more voluble, flamboyant and provocative figure than the more focused Crick. But perhaps most importantly, Watson wrote a scientific autobiography of their Nobel-prize winning discovery, The Double Helix: A Personal Account of the Discovery of the Structure of DNA. The Double Helix, a personal memoir, presented Watson’s particular perspective on how he and Crick discovered the structure of DNA. The book has gone through 213 printings in various editions and languages across the world, capped off by 2012’s Annotated and Illustrated Double Helix. People have faulted Watson’s narrative in various ways, most prominently for giving short shrift to Rosalind Franklin’s contributions, but it remains the definitive account of DNA’s discovery and the prose captures the excitement of biological science in a post-war England then just springing back to life and normalcy. If you want to understand how scientists came to grasp DNA’s structure, The Double Helix there is no better place to start, even acknowledging that it is not the entire story.

If Watson’s authorship of The Double Helix established his reputation and public stature, it was 1965’s The Molecular Biology of the Gene that most influenced working scientists and biology students. The elucidation of genetics’ physical mechanics, as opposed to observation of statistical regularities within pedigrees, revolutionized the field and established the foundation of contemporary molecular biology. Understanding DNA as a biological machine allowed researchers to re-conceptualize as biophysical processes abstractions like recombination and mutation, previously only inferred via patterns of traits transmitted through breeding lineages. And once genetics became a biophysical science, the methods of instrumentation and analysis could focus on its material variation in ways that paved the way for genomics’ advent. Genomics was stillborn, and the human genome could not have been mapped completely, until genetics became a molecular-biological discipline. It was Watson’s focus on establishing heredity’s physical basis that unlocked the key to the emergence of genomics, which in turn brought big data to genetic inference.

Not unlike James Watson, E. O. Wilson gained fame among the general public for his popular works and scientific controversies, from Sociobiology to his conflict with Harvard colleagues Stephen Jay Gould and Richard Lewontin. But before Wilson’s clashes with his left-wing peers in the department of Organismic Biology at Harvard, he had had tussles with a brash young James Watson in the 1950s. In Naturalist, Wilson’s autobiography, he relates how the co-discoverer of DNA had little use for traditional fields like taxonomy and anatomy, dismissing them as the domains of “stamp collectors.” The Watson-Wilson dispute in the 1950s prefigured the eventual fissure of Harvard’s biologists into ‌molecular and non-molecular factions (this bifurcation is actually now very common in American science). But Naturalist clarifies that the dispute was personal too; Watson was egotistical, bold and vocal, Wilson more soft-spoken, if nevertheless quietly self-assured.

Near the end of their lives, Watson and Wilson reconciled on personal terms, developing a friendship based on a shared fascination with biology’s power to explain the world around them and a tendency towards heterodox, and often incendiary pronouncements. Watson famously got in hot water in 2007 for asserting that the black-white IQ gap likely has a genetic basis. Wilson was never canceled on account of such topics, but it has become clear looking at his correspondence and talking to those who knew him that he held much the same views as Watson. But unlike DNA’s co-discoverer, the more prudent Wilson shared those opinions solely with intimates (Francis Crick’s personal correspondence makes it clear that Wilson also took Arthur Jensen’s side in the Jensen controversy).

The general public knew Watson and Wilson well during their lifetimes via their popular works. In contrast, W. D. Hamilton’s substantial oeuvre was known almost solely to scientists during his life, though after his 2000 death from malaria contracted during fieldwork Richard Dawkins eulogized him as the “most distinguished Darwinian since Darwin.” Hamilton’s ideas appear in most of Dawkins’ published works, as well as in Matt Ridley’s The Red Queen and The Origins of Virtue, but it is Hamilton’s volume 2 of his collected papers, Narrow Roads of Gene Land: Evolution of Sex, where he steps outside the narrower confines of science and comes alive as a human figure. Volume 2 of Narrow Roads of Gene Land was at a draft stage when Hamilton died, so his editors were powerless to force revisions that might have reduced its length and candor. It is true that Hamilton’s collected papers have overly indulgent introductions, are larded with biographical detail and myriad meandering asides, but it is in volume 2 that you can most easily discern the awkward and sensitive scholar described in other works like Ullica Segerstrale’s Nature’s Oracle: The Life and Work of W. D. Hamilton. Hamilton occupies a strange and gray space between Watson and Wilson, though his life paralleled that of the two American biologists. Hamilton, an evolutionary geneticist steeped in the mathematical formalism of R. A. Fisher and, in his leisure an enthusiastic naturalist in the British tradition, saw little to be gained from‌ embracing Watson’s molecular reductionism. But unlike Wilson, Hamilton was an evolutionary reductionist, working out complex and abstruse mathematical theories that would offer conceptual scaffolding to generations of empirical biologists. Though never entirely convinced of their completeness, Wilson describes encountering Hamilton’s ideas of inclusiveness in the 1960s in a scales-falling from his eyes moment that would eventually lead him to write Sociobiology: The New Synthesis.

More recently, Matt Ridley’s 1999 book Genome: The Autobiography of a Species in 23 Chapters, inspired a generation of geneticists to enter the field, while Siddhartha Mukherjee’s 2016 The Gene: An Intimate History gives a flavor of the field midway through its plunge deep into the genomic era. Genome was written at the tail end of the Human Genome Project, so though it anticipates questions like the number of genes to be found in the human genome; those details remained to be finalized at the time. Ridley’s book also came out before the genome-wide association era, and so includes no discussion of the surfeit of post-2005discoveries. Nevertheless, Genome already satisfyingly establishes the superstructure of genetics as it was to be understood in the first 25 years of the 21st century.

Mukherjee’s The Gene came out after the publication of the human genome, and the widespread deployment of genomic technologies toward understanding classical genetic questions. The Gene was also written four years into the CRISPR gene-editing revolution, and so could anticipate the probable future of writing-in-the-genome that will likely follow close upon reading-the-genome’s advent. Though Mukherjee reviews Mendelism’s historical origins, as a medical doctor, he is more interested in genetics’ practical applications to ameliorate human suffering. While Genome seems to reflect more of the evolutionary curiosities of British geneticists like W. D. Hamilton, The Gene favors Watson’s more hard-headed reductionist perspective with the aim of vanquishing the ailments that have plagued humanity for all of its history.

Two Hundred Years to Flatten the Curve. Charles C. Mann writes in The New Atlantis about how public health has transformed our lives. The US in particular took public health seriously beginning in the late 19th century because of the waves of immigration from Europe whom native-born Americans believed arrived bearing disease. This resulted in a public health push that arguably rendered the US world’s first society to drive urban infant mortality rates lower than rural ones.

Mamdani’s biggest challenges. The headquarters of the global capital, New York City, is now going to be governed by a man who is on record expressing deep misgivings about capitalism. As Noah Smith notes, finance ‌powers New York City’s fiscal health, but this is the same sector that Zohran Mamdani and his fellow travelers are most suspicious of.

The Sierra Club Embraced Social Justice. Then It Tore Itself Apart. The organization seems to have lost sight of why people donate to it. We’ve come a long way from, “The mountains are calling and I must go” to “One of the staff said, ‘That’s fine, Delia. But what do wolves have to do with equity, justice and inclusion?’”

The dirty secret of the Muslim world: The neglect of the history of Islamic slavery reflects a culture of American exceptionalism and a tradition of denial. This is just plain ignorance or intellectual dishonesty that it is a “dirty secret”; anyone who has read Islamic history even casually knows that sub-Saharan Africa, Europe and Central Asia were the hunting grounds of Muslim slavers.

China Started Separating Its Economy From the West Years Ago. They are ready for the trade war because they have been preparing for it.

Estimation and mapping of the missing heritability of human phenotypes. Blockbuster paper that surveys what we know from the UK Biobank about the heritability of phenotypes as understood through genomics.

Revisiting the Evolution of Lactase Persistence: Insights from South Asian Genomes. As in Europeans, it looks like there are some late (as recent as 1,000 years ago) selection events increasing the frequency of lactase persistence in the Indian subcontinent, though most of the variation in frequency across populations is a function of steppe ancestry.

Post-admixture selection favours Duffy negativity in the Lower Okavango Basin. Malaria has reshaped the genomes of Africans. First among these were agricultural populations, but these findings show that the same dynamic occurs with Khoisan people who mix advantageously with Bantus and invade the malarial zone.

The persistence and loss of hard selective sweeps amid ancient human admixture. Using deep learning on ancient genomes to reconstruct classical evolutionary dynamics that poor data quality and demographic phenomena like population bottlenecks might otherwise obscure.

There’s still no free lunch, free subscribers; my most in-depth pieces for this Substack remain beyond the paywall. Most recently, I delved into the genetics of successive waves of Greenland settlers and the recent publication of a second high-coverage Denisovan genome.

First, The cave where it happened: Denisova cavern’s congress of ancient peoples:

Although we now have genetic material from many more than a single Denisovan (for example, mitochondrial DNA from 10 individuals), because all the other samples have been comparatively incomplete, for paleogeneticists the high-quality whole genome from 2010 has continued to do the load-bearing work. This is the individual we call Denisova 3, sequenced at 30-fold coverage, meaning geneticists have sampled each region of her genome about thirty times to assure themselves of the accuracy of each position’s precise read. Not only is this excellent if we want to undertake deep evolutionary genomic analysis, it is modern medicine’s gold standard for medical-grade genetic inference (insurance companies traditionally require 30-fold coverage for whole-genome tests). Despite finding further fossils, attaining what they call environmental DNA (from debris where the group lived rather than even trace identifiable human remains) and snippets of sequence here and there from other Denisovans, the bulk of our genomic understanding of these enigmatic humans over the last 15 years has remained the legacy of Denisova 3. Until today.

Finally, at the end of 2025, a preprint reports a new high-quality whole-genome sequence, at 24-fold coverage: A high-coverage genome from a 200,000-year-old Denisovan. Though researchers found this individual, Denisova 25, at the same location, he is vastly older than Denisova 3, who died 65,000 years ago. Not only does this allow geneticists to probe deeper into the past (the rough estimate is that a staggering 5,400 generations separate Denisovan 25 from Denisova 3!), it finally allows for comparative genomic analyses, apples-to-apples high-quality genome to high-quality genome.

Denisovan 25 has already yielded fresh insights, from further confirmation of the carryover of pre-Denisovan humans into their lineage (and so ultimately, into parts of ours), to refinements in the understanding of Denisovan population structure and the timing of admixtures. The sequencing of a new Denisovan might not be as field-altering as the species’ 2010 discovery, but in 2025 we can say we are truly getting to grips with this people; we can now discern how many races they subdivided into, how many distinct times they mixed with different modern human populations and even the lineaments of their mysterious interactions among even more ancient and barely understood human lineages that preceded them into Asia.

Land acknowledgement, Greenland edition:

The Saga of the Greenlanders is a tale of daring and high adventure in strange and bleak landscapes. Texts went silent after 1408, while the archaeological record, with its paucity of material goods after 1300 and evidence of stress and dietary changes in some of the later remains, points to their saga’s final chapter closing not in triumph but sad, grinding defeat. Genetics confirms the medieval Norse left no long-term imprint on modern Greenlanders. Greenlanders today carry small amounts of ancestry from recent Danish male adventurers, but descend in the main from the Thule, the whale-hunters who swept so successfully across the Arctic. But the Saqqaq genome also shows that the Dorset suffered the same fate as the Norse, withering in their last centuries in the face of Thule expansion, even abandoning southern Greenland nearly a millennium before the Norse arrived. The parallel trajectories of these two groups, western and eastern, North American and European, show how the Thule were the exception. The Thule could withstand (and even flourish in) the most extreme climates that our species faced. From Neanderthals to Ancient North Eurasians, archaeology and genetics tell us that northern peoples have always teetered on the edge of existence, with the elements themselves an implacable enemy arrayed against their survival. The Norse were not exceptional failures, unable to adapt; rather, they faced the same formidable challenges of innumerable cultures that have pushed the northern limits of human occupation, going back nearly a million years. The centuries-long occupation of the Western and Eastern Settlements by the medieval Norse was simply the last of many failed attempts by humans of every stripe, all later to be overshadowed by the exceptional skills and talents of the Thule people in harnessing the resources of the north. In the end, the Norse defeat turns out to have actually been a footnote in someone else’s grand saga, a story of incredible resilience and outsized success, the tale of the Thule.

A 2025 feature for paying subscribers, the Unsupervised Learning Journal Club briskly reviews notable new papers or preprints. At the end of each edition, I invite subscribers to vote on papers/preprints for future editions.

Most recently, Ghost Population in the Machine: AI finds Out-of-Africa plot twists in Papuan DNA:

Papuans, in their splendid isolation, might seem to be of little interest to the broader narrative of human evolution and genetic history, but it is their very distance from the migrations and the rise and fall of empires that renders them notable. Until recently, New Guinea seems to only have ever been occupied by the first modern humans to settle the island, with nothing beyond minor changes upon Austronesians’ arrival to its shores 3,000 years ago. But in 2010 New Guinea and Papuans were suddenly thrust to the center of human evolutionary discoveries. In that year, researchers discovered upon sequencing that the genome from Denisova cave in Siberia matched about 5% of the New Guinean people’s ancestry (and almost none outside of Australasia). Then, in 2016, other researchers examining Papuan whole genomes concluded that the people might also harbor ancestry from an earlier out-of-Africa migration than the well-characterized expansion 50,000 years ago that swept from the Atlantic to the Pacific.

Previous editions:

Wealth, war and worse: plague’s ubiquity across millennia of human conquest

Where Queens Ruled: ancient DNA confirms legendary Matrilineal Celts were no exception

Eternally Illyrian: How Albanians resisted Rome and outlasted a Slavic onslaught

Homo with a side of sapiens: the brainy silent partner we co-opted 300,000 years ago

Brave new human: counting up the de novo mutations you alone carry

The wandering Fulani: children of the Green Sahara

Genghis Khan, the Golden Horde and an 842-year-old paternity test

Rewriting the Family Tree one skull at a time

For free subscribers: a sense of the format from my coverage of two favorite papers last year:

The other man: Neanderthal findings test our power of imagination

We were selected: tracing what humans were made for

All my podcasts go ungated two weeks after their Substack release. So I encourage subscribers on the free plan who’d like to automatically get them to subscribe to that podcast stream (Apple, Stitcher, and Spotify). If you want to listen on YouTube, please subscribe.

Here are podcasts since the last Time Well Spent:

• Sean Trende: 2025 elections and political demographics, past and future

• Alex Young: IQ, disease and statistical genomics

• Zineb Riboua: Zohran Mamdani and Third-Worldism ascendent

• Ed West: visitor from a dying empire

• Noah Smith: Japanese and American politics

• Coltan Scrivner: the evolution and psychology of horror

My own domain also has all my links and updates: https://www.razib.com

, including links to the few different podcasts I’ve contributed to or run, my total RSS feed, and my more mainstream or print articles when I remember to post them, my Twitter, the occasional guest appearance, etc.

• DM me

• Facebook message me

• Some of my past pieces for Palladium Magazine, The New York Times, Slate, Quillette and Nautilus.

Comments are open to all for this post, so if you have more reading/listening suggestions or tips on who I should be talking to or what you’ve been waiting to read about, put them here.

No one was looking for her or her kin when in 2010 scientists sequenced the genome of a woman who died in Siberia tens of thousands of years before modern humans arrived there. Digging into her genome, they beheld the first evidence of a whole new branch of humanity. From her genes alone, researchers identified the human population we now call Denisovans, drawing the name from that first source location, Denisova Cave, a cluster of high-vaulted caverns in central Siberia, north of the border with western Mongolia. To start, the team typed the woman’s mitochondrial DNA, tracing her direct maternal line. This was the first shock: her unknown human lineage was more distant from ours than Neanderthals are. Next, a whole-genome analysis, scanning all three billion base pairs, revealed more nuance. In fact, she was genetically more similar overall to Neanderthals than to our own out-of-Africa lineage; this realization spawned the neologism, “Neandersovans,” for the shared grouping of Neanderthals and Denisovans.

So this single genome from a woman interred in Denisova Cave brought the revelation that over 500,000 years ago a group of humans left Africa to spread out across Eurasia, trekking north and east, becoming Neanderthals and Denisovans respectively. With the abstruse arts of statistical genomics, researchers have since also inferred from that single genome that multiple admixture events with separate Denisovan lineages contributed trace ancestry to modern populations, from the Siberian Denisovans responsible for an average 0.15% of ancestry in East Asians today, to the southern Denisovans who contributed 4% of modern Papuan ancestry.

Even though a single genome is but a single human being born at a single point in time, at the molecular level, we truly cannot shake our past. The indelible ledger heredity smuggles into every genome makes any random being a decoder ring equipped to spill the population history of their species generations deep into their past. The millions of variable positions in any individual genome faithfully reflect population history, reporting highlights from an individual’s entire genealogy, allowing reconstruction of an entire vast lineage, with inferences fanning backward in an ever-branching ancestral tree.

Although we now have genetic material from many more than a single Denisovan (for example, mitochondrial DNA from 10 individuals), because all the other samples have been comparatively incomplete, for paleogeneticists the high-quality whole genome from 2010 has continued to do the load-bearing work. This is the individual we call Denisova 3, sequenced at 30-fold coverage, meaning geneticists have sampled each region of her genome about thirty times to assure themselves of the accuracy of each position’s precise read. Not only is this excellent if we want to undertake deep evolutionary genomic analysis, it is modern medicine’s gold standard for medical-grade genetic inference (insurance companies traditionally require 30-fold coverage for whole-genome tests). Despite finding further fossils, attaining what they call environmental DNA (from debris where the group lived rather than even trace identifiable human remains) and snippets of sequence here and there from other Denisovans, the bulk of our genomic understanding of these enigmatic humans over the last 15 years has remained the legacy of Denisova 3. Until today.

Finally, at the end of 2025, a preprint reports a new high-quality whole-genome sequence, at 24-fold coverage: A high-coverage genome from a 200,000-year-old Denisovan. Though researchers found this individual, Denisova 25, at the same location, he is vastly older than Denisova 3, who died 65,000 years ago. Not only does this allow geneticists to probe deeper into the past (the rough estimate is that a staggering 5,400 generations separate Denisovan 25 from Denisova 3!), it finally allows for comparative genomic analyses, apples-to-apples high-quality genome to high-quality genome.

Denisovan 25 has already yielded fresh insights, from further confirmation of the carryover of pre-Denisovan humans into their lineage (and so ultimately, into parts of ours), to refinements in the understanding of Denisovan population structure and the timing of admixtures. The sequencing of a new Denisovan might not be as field-altering as the species’ 2010 discovery, but in 2025 we can say we are truly getting to grips with this people; we can now discern how many races they subdivided into, how many distinct times they mixed with different modern human populations and even the lineaments of their mysterious interactions among even more ancient and barely understood human lineages that preceded them into Asia.

In science, you work with the data you can get, not the data you might want. For a host of reasons — geopolitical, archaeological and climatological — we have very little ancient DNA from Africa, despite the continent being the main stage for human evolution over the last two million years. Remote, singular Denisova Cave is at the other extreme; the single site is an embarrassment of riches. With the cavern complex’s relative surfeit of ancient Eurasian DNA, we have been able to piece together the dynamics of African evolution; never mind that Eurasian humans were not in Africa, their ancestors were, and those ancestors left their imprint on the genomes their descendants bore all across Eurasia. About a dozen humans have thus far been identified at the Denisova Cave location. The multi-chambered complex of caverns not only yielded the first Denisovan whole-genome, in 2014 researchers also found the first high-coverage Neanderthal there, known in the literature as the “Altai Neanderthal” (and which to this day, remains one of only three Neanderthals sequenced at over 20x coverage). Even more sensationally, in 2018 Denisova’s chambers yielded “Denny,” a young woman who lived 90,000 years ago, issue of a pure Neanderthal mother and Denisovan father. Finally, the caves have yielded 20,000-year-old DNA from a modern human of the “Ancient North Eurasian” (ANE) population. The characteristics that made the high-vaulted shelter a desirable home for our Eurasian cousins clearly still applied long after their disappearance and replacement by our single lineage.

Why is Denisova Cave such a fruitful hunting ground for paleoanthropology and paleogenetics? Part of the answer is clearly down to geology and climate, what ecologists would term “abiotic” parameters. For most of the last two million years the region was extremely cold and dry, with the cave surrounded by tundra steppe. And luckily for future researchers, cold, dry conditions favor the preservation of biological remains that might otherwise degrade, from DNA to coprolites. But evolutionary factors were also at play; Denisova Cave happens to straddle the extreme edges of both Neanderthal and Denisovan prehistoric ranges. For Neanderthals, it marked the eastern edge, for Denisovans it was apparently along their northwestern boundary. This means that the cave witnessed hundreds of thousands of years of congress between these two human groups, including matings recorded in the genes of the people who frequented the cave. Denny was only the clearest and most obvious case of this mixing. Denisova 25 attests not just to further instances of admixture from Neanderthals, but of other human lineages too that are yet unidentified ghosts in our understanding of ancient DNA.

A quick scan of the genome reveals Densiova 25 is clearly male; he has a Y chromosome. He clusters as expected with the other Denisovan males whose paternal lineage could be typed. The mtDNA lineage also clusters with other Denisovans. You will recall that since the Y and mtDNA lineages are not subject to recombination, they have since long before the genomic age been go-to’s for simple and elegant reconstruction of phylogenetic trees. The researchers dated the sample to some 219,000-232,000 years ago by comparing the mutations that define changes between Denisova 25 and the other dated Denisovans. Happily, comparing the entire genome of Denisova 25 to modern humans (again using those clock-like assumptions about rates of mutation accreted since last common ancestor) converges on roughly the same time span.

Though Denisova 3 and Denisova 25 are the only two high-quality genomes from the caverns recovered thus far, Denisova 2, 4, 8 and 11 each yielded enough material for simple phylogenetic analyses. Comparing numbers of shared and unshared genetic variants across the genomes, Denisova 8 and Denisova 25 are particularly genetically close, unsurprising since their positions within the sedimentary layers excavated date them to similar periods. Denisova 4 and 11 are noticeably more similar to Denisova 3 than to Denisova 8; again, no big surprise when you consider the times when their position suggests they lived. The newly discovered Denisovan genome is genetically closer to Neanderthal sequences than the 65,000-year-old Denisova 3 is, reflecting that the former bears more Neanderthal ancestry. Unlike the other samples mentioned here, Denisova 5 is a Neanderthal, and not a Denisovan human. Additionally, the new Denisova 25 individual’s genes are more similar to the Denisova 5 Neanderthal’s than to all other sequenced Neanderthals. Because this Neanderthal dates to about 60,000 years after Denisova 25 lived, the most likely explanation is that the ancestors of the Neanderthal labeled Denisova 5 had absorbed Denisovan ancestry specifically from a population related to Denisova 25.

A generation ago, many scholars of human evolution remained skeptical of hybridization between our species’ various lineages. They commonly believed Neanderthals and African humans had been separated too long for interbreeding to be viable. But after the 2010 publication of the Neanderthal genome, and the finding that all non-Africans (as well as ‌the vast majority of Africans!) have Neanderthal ancestry, all that changed. The addition of this second high-quality Denisovan genome, almost 150,000 years earlier in Denisova Cave’s eventful history, enriches our understanding of interactions between the various branches of our human family tree. Humans outside of Africa today average about 2% Neanderthal, while Denisova 3 was 1.8-2.5% and the far earlier Denisova 25 measured an estimated 3.6-5.2% Neanderthal. Additionally, Denisova 25 has Neanderthal admixture that is genetically equidistant to multiple Neanderthal genomes, indicating it derives from an unknown and yet unsampled Neanderthal lineage. Denisova 25 and 3’s high-quality genomes enable precise detection of Neanderthal ancestry segments interspersed in a sea of Denisovan ancestry. The average segment lengths, a reliable index correlating with time since mixture occurred, suggest that the Neanderthal ancestry input to both Denisova 25 and 3 arrived via several distinct events. In other words, Denisova Cave apparently played backdrop to repeated interactions between human lineages over tens of thousands of years. So now with hindsight, it isn’t entirely surprising that researchers stumbled upon Denny, a hybrid whose ancestry composition was probably far more common than originally assumed.

And yet even with samples from vastly different time periods, we identify pure Neanderthal and Denisovan individuals over and over in the cave, rather than witnessing the emergence of a new Neandersovan hybrid population. This implies that while Denisovan Cave was a meeting point, it proved more of a demographic sink than a transit junction between two populations. The hybridization events didn’t lead to enduring, discernible gene flow between Neanderthals and Denisovans as broader populations; rather, the local populations at Denisovan Cave emerged over and over again, only to go extinct repeatedly, leaving no longer-term legacy. The cave may have been optimal for the preservation of DNA, but in the depths of the ice age it was clearly a refuge in an incredibly harsh local ecology.

Among the most exciting upgrades granted us by a second high-quality genome is the chance to more fully delve into the possibility of “super-archaic” admixture in the broader Denisovan lineage. We want to settle whether Denisovans, whose ancestors arrived in eastern Eurasia less than a million years ago, might have mixed there with various earlier arrived human lineages. Think of the peoples who in an earlier era of scholarship were bracketed under the label Homo erectus. The earliest attested Homo outside of Africa seems to be fossils of the lineage labeled Homo georgicus at the Dmanisi site in Georgia 1.8 million years ago, and in short order, that hominin’s relatives spread eastward all the way to the Pacific. Meanwhile, most paleoanthropologists believe that human groups like the Flores hobbits and the diminutive Luzon hominins did not descend from the Neandersovan wave that arrived less than a million years ago, which suggests that they too would have predated Denisovans’ tenure, underscoring that prehistoric Asia was already quite speciose when the Denisovans’ ancestors arrived.

From a genomic perspective, it was clear from Denisova 3’s genome that compared to any Neanderthal, she shared fewer novel mutations with African humans and us, their modern descendants. Two possible models could explain this. One is gene flow between Neanderthals and our ancient Africans ancestors prior to 200,000 years ago, which would have cranked up the number of shared variants between Neanderthals and modern humans. The other alternative is that at some point Denisovans alone mixed with even more distantly related humans, super-archaics, genetically tugging them away from both Neanderthals and modern humans. The former hypothesis does have some support, the evidence from Y, mtDNA and whole genomes does indicate some ancient gene flow from our lineage into Neanderthals. But not enough to explain the entire extent of the genetic cleavage between our two groups and Denisovans.

Today Razib talks to Sean Trende. He is a prominent American political analyst who currently serves as the Senior Elections Analyst for RealClearPolitics, a position he has held since 2010. He is also a Fellow at the American Enterprise Institute (AEI) and a lecturer at The Ohio State University, where he earned his Ph.D. in political science in 2023. Before transitioning to full-time political analysis, Trende practiced law for eight years at firms including Kirkland & Ellis LLP and Hunton & Williams LLP, holding a J.D. and M.A. from Duke University and a B.A. from Yale University. Known for his expertise in election forecasting, redistricting, and political demographics, he authored the book The Lost Majority (2012), co-authored The Almanac of American Politics 2014, and served as a court-appointed special master to redraw Virginia’s legislative districts in 2021.

Trende and Razib first talk about the elections in the fall of 2025 in Virginia and New Jersey, and what they tell us about the elections next year. They also discuss the election of Zohran Mamdani in New York City, and the rise of populism on the Left and Right. Razib asks Trende about why political commentary often assumes single-party rule is about to happen, only to be refuted by the reality of the opposition's resurgence once these claims are made. They also talk about Trende’s distinctive personal background, and his perspective as a more centrist-libertarian commentator and professor in the political analyst field.

Subscribe now

Give a gift subscription

Share

In large precincts of left-leaning America, it has lately become commonplace for any official proceeding to be delayed until someone has intoned a somber statement of guilt acknowledging the locale’s legacy of colonization, its history as another people’s ancestral homelands (sometimes with such specificity as “since time immemorial”) and with homilies to such things as the “inherent sovereignty of indigenous people” who previously resided there. Such a self-serious ceremony could scarcely flourish (nor be so succinct and straightforward) anywhere but a continent with as few layers of human churn and conquest as North America.

But setting aside the specific bloody legacy of America’s European conquest and lingering questions of guilt and responsibility, it’s worth considering what a quarter century of genome-powered population genomics can now tell us about our upstart species’ general tendencies to usurp and wholly replace prior inhabitants. Is North America somehow unique? What do we know today about human patterns of replacement that we could not determine centuries ago when an informed person might have actually believed indigenous Native Americans had been in their “ancestral homelands” since time immemorial, rather than for some 15,000 years?

And what does it really mean to be indigenous, to be native, now that we can genuinely interrogate the layers of our species’ population history? What if a people whose genetic close kin we are accustomed to regarding as marginal or indigenous (with all the respect, compassion and pity that tend to so swiftly attach themselves to such designations) are the usurpers? What if they arrive last and are the last men standing? What if it is they who out-compete and supplant a locale’s entire contingent of long-time inhabitants? What if those vanished early inhabitants are Europeans? And what if when the dust settles, we see that the commonality of these johnny-come-latelies who out-compete long-time inhabitants and master a new locale, is not race, continent of origin or bellicosity, but simply an upgraded toolkit that runs circles around that of the locals’?

This is the case for Greenland, our subject today. We apply a genomic lens to the millennial saga of humanity’s quest to master one of the planet’s most unforgiving pieces of terrain. And if the non-European champions of our tale, the ancestors of Greenland’s 50,000 inhabitants today, supplanted both Norse and Dorset forerunners, is it time they draft a land acknowledgement? Or shall we defy chronology and regard them approvingly as native Greenlanders “since time immemorial”? Perhaps neither. Perhaps we can simply recognize that their story and their land’s long saga is proving to be among the most commonplace of human population plotlines.

Subscribe now

Give a gift subscription

* * * * *

In 1408, Thorsteinn Ólafsson and Sigríður Björnsdóttir, were joined as man and wife at Hvalsey Church, in modern-day Qaqortoq on the southern tip of Greenland. The bride and groom both had Icelandic origins, and we know of the wedding because of its mention in a surviving Icelandic letter dated 1409. Though their union at Hvalsey Church suggests they might have planned to make a life together in Greenland, settling down among the Norwegian-descended settlers who had by then retained a foothold along the great island’s fringes for over four centuries, the couple departed in 1410, returning to their native Iceland. Their nuptials mark the last written record of Europeans in Greenland before the modern era, though archaeological evidence suggests that presence persisted for several further decades before the ultimate extinction of the medieval Greenlandic Norse civilization.

The Hvalsey Church wedding was one of the final acts in the annals of a European outpost already old by the 15th century. In 982 AD, over four centuries prior, Icelanders exiled the landowner Erik the Red from their homeland for murdering his neighbor (Erik’s own father had fled Norway over a murder as well, bringing his wife and 10-year-old son to Iceland). Erik was prosperous, an important figure on the small island. He had followers who stood with him and were ready to follow him into exile. The small party ventured into the cold, rough seas of the North Atlantic with a boldness characteristic of the period’s pagan Norse. It was 180 miles beyond Iceland that he and his small party made landfall. There, they discovered the imposing landmass Erik would name Greenland. The world’s largest island, fully 30% the area of Australia, looms famously oversized on Mercator projections. But even scaled more accurately, Greenland remains three times the size of Texas. This vast near-continent is mostly a world of ice, over 80% of its surface covered by a permanent glacier that holds nearly 10% of the planet’s fresh water.

Erik the Red seems to have given Greenland its rather optimistic name as a marketing ploy, apparently presuming presciently that the name would better entice others to join him on a return voyage. In 985, his exile ended and he returned home. In short order, he had persuaded two dozen ships’-worth of his countrymen to join him sailing back into the untouched west. After 986, two primary European settlements were established in Greenland. These were blandly christened Eastern Settlement, Eystribyggð (site of Hvalsey Church) and Vestribyggð, for a smaller Western Settlement (which actually lies both to the north and west of Eystribyggð). In the generation after the initial colonization, Erik the Red’s son Leif brought Christianity to Greenland, having converted to the new religion at the court of the Norwegian king, Olaf Tryggvason. Lief converted his mother (though not his father), enlisting her to help build the first church in Greenland, easing Greenlanders’ integration into Latin Christendom, and eventually more formally into the kingdom of Norway. In 1124, Eystribyggð received its first resident bishop, a Norwegian named Arnald. A successor, Jón Árnason, appointed in 1189, would make a pilgrimage to Rome and meet Pope Innocent III in 1202 before returning to Greenland, illustrating just how integrated the Arctic Norse became with their cultural cousins in Europe, their island settlements marking the westernmost colonies of Christendom. But just as Europe was stretching itself west across the Atlantic, and establishing a beachhead approaching North America’s northeastern fringe, the New World was marching eastward, as it had for millennia. Greenland was not virgin territory when Europeans arrived; the Norse were actually newcomers in a land haunted by the remains of earlier peoples who had not been extirpated by fellow humans, but repulsed by the harshness of the unforgiving terrain itself.

Humans have occupied Greenland since at least as early as 2500 BC. But those earliest inhabitants did not venture across the Atlantic from Europe; they slipped east along the Arctic’s shores, following the north’s copious marine resources, including pods of seals, tempting targets for those foraging across an otherwise desolate landscape. Archaeology labels these polar societies “Paleo-Eskimo,” with the Saqqaq culture being the earliest. Part of the “small tools tradition,” they seem to have begun their migration eastward from a home base in eastern Siberia and western Alaska 5,000 years ago, until they reached the continent’s end in Greenland. As a world on the margins, Greenland’s population numbers have waxed and waned several times over. Norse timing was fortuitous; they arrived in Greenland at the beginning of the Medieval Climate Optimum, a period of warmer temperatures across the northern Atlantic begun in 950 AD, some seven centuries after the extinction of the last Paleo-Eskimo cultures on the island’s southern shores. However, the Norse had neighbors. Called Skræling in the Norse sagas, these were the Dorsets, and their existence beyond the limits of Christian civilization, in northern Greenland and the islands to the west, rendered them a shadowy menace to the medieval Greenlanders. But in a twist, neither of these two peoples, the Norse or the Dorset who inhabited Greenland in 1000 AD, would leave any lasting legacy. Modern Greenland was ultimately to be the easternmost outpost of the emerging Thule culture, which was sweeping across the northern Arctic by boat from a homeland in Alaska just as the Norse were tentatively exploring the North Atlantic. These whale hunters, in contrast to the agricultural Norse, flourished in Greenland’s colder temperatures after 1400, and it was they who would come to dominate the polar world of the north down to the present day.

Though the Paleo-Eskimos remain an obscure people outside the halls of Arctic archaeology, they represent something of a historical milestone for paleogeneticists, arguably present for the birth of that field as a branch of genomics, rather than just genetics. On February 10th, 2010, Ancient human genome sequence of an extinct Palaeo-Eskimo, appeared in Nature. This was the first ancient human genome to be fully sequenced, pipping the publication of the Neanderthal draft genome to the post by four months, and ushering in a decade-long competition between Eske Willerslev and David Reich, paleogenomics’ two dominant figures after Svante Pääbo transitioned to a more remote elder statesman status after 2010. But timing aside, the Willerslev group’s Nature publication remains notable just on scientific grounds, because with hindsight we can see that it anticipated a later key pattern gleaned from ancient DNA again and again: modern humans tend to replace each other with incredible regularity.

The sequenced individual was a member of the Saqqaq culture, one of the first Paleo-Eskimo societies in the Arctic and Greenland. He died 4,000 years ago, and his people buried him on an island off Greenland’s west coast. The most notable aspect of the Saqqaq genome at the time it was first analyzed is that the individual was not ancestral to modern Greenlanders; indeed genetically his closest matches in contemporary populations live on the far northeastern edge of Siberia, among the Chukchi and Koryak minorities, who occupy territories just across from Alaska in Russian Siberia. What paleogenomics has shown since the Saqqaq paper is that demographic prehistory often delivers such twists and lays bare unexpected distant connections; the genetic discontinuity that made waves in 2010 would surprise less today.

The Saqqaq, and their Dorset descendants are both genetically entirely unconnected to the Amerindians of North America to their south, and, surprisingly also to the Thule culture that would eventually supersede them across the American Arctic, giving rise to present-day Inuit societies from Alaska to Greenland. Additionally, the admixture plot above illustrates a Saqqaq affinity to the Nganasans, the Samoyedic tribe who occupy north-central Siberia’s Tamyr peninsula, just on the other side of the Urals from Europe’s northeastern corner. Importantly, the Nganasans’ Uralic language connects them to the west, to the Finnic peoples whose range eventually expanded to include the eastern Baltic. The Paleo-Eskimo and Uralic connection highlights the reality of a fully circumpolar world whose extent we are only just beginning to fathom via archaeology and genetics.

The Saqqaq genome’s sequencing also occurred at a critical juncture in our understanding of American prehistory. A generation ago, archaeologists knew the Clovis culture from Siberia had settled the Americas in a single pulse some 13,000 years ago. This common origin explained the general physical and genetic similarities of modern indigenous people across North and South America, from the Canadian north to Patagonia in the south, along with the massive megafaunal extinctions that swept the two continents just before the end of the last Ice Age 12,000 years ago. But excessively brittle regnant orthodoxies have a particular way of collapsing; first they weaken slowly, before imploding all at once; today, our understanding is in a state of flux and revision. Evidence from archaeology now makes nearly irrefutable that the New World saw many settlements long before the Clovis expansion, starting before the Last Glacial Maximum, over 20,000 years ago at White Sands in New Mexico and Chiquihuite Cave in Mexico. And though the overwhelming majority of the ancestry of American peoples derives from a single wave of foragers who pushed in about 15,000 years ago from the lost subcontinent of Beringia that spanned the seas between Alaska and Siberia, sophisticated modern genomic methods have discovered telltale but still poorly understood connections between South Americans and the peoples of Melanesia and Australia. The first-pass genetic analyses did discern this in broad strokes, but important details remain to be teased out of the DNA upon much more meticulous inspection. Nevertheless, the genetic methodologies before 2010 did correctly arrive at the truth that the Beringian wave nearly erased earlier genetic signatures south of the Arctic. By and large the earlier peoples left their artifacts, not their genes.

But what was true south of the Arctic, with a single great Amerindian diaspora entirely cut off from its Eurasian roots at the end of the last Ice Age, and then diversifying from initial shared heritage, is much less assured in the far north. To early 20th-century ethnographers working with the toolkit of cultural and physical anthropology’s descriptive tools, the Inuit people dominant in the Arctic seemed both quite physically and culturally distinct from the native peoples to their south. Together with the Aleuts of southwest Alaska, these Arctic peoples speak the related Eskaleut languages, tongues that differ greatly from the Na-Dene languages of North America’s northwestern quadrant. Save for its southeastern panhandle, the modern American state of Alaska illustrates the social and cultural differences between the Arctic and traditional Native America; the two groups of Inuit peoples, the Yupik and Inupiat, dominate the coastal zones, focusing on marine resources, while the Athabaskan-speaking tribes occupy the interior, hunting terrestrial big game like moose, the northernmost extension of North American foraging culture. The Yupik are also unique among American peoples in that they seem to have expanded into Asia as well: several thousand Siberian Yupik inhabit Russia’s far eastern Chukchi peninsula. Unlike the Yupik, who mostly reside in southwest Alaska, the Inupiaq Inuit of northern Alaska are part of an extensive related cultural zone that stretches out toward Greenland, where the Kalaallit branch are today known as “native” Greenlanders. But this ‌wide ethnolinguistic distribution is a relatively new configuration, as the Saqqaq genome’s stark differences from modern Greenlanders underscore.

This week on the Unsupervised Learning Podcast, Razib talks to returning guest Alex Young of UCLA and Herasight. Trained originally as a mathematician, Young studied statistics and computational biology at the University of Cambridge before doing a doctorate in genomic medicine and statistics at the Wellcome Trust Centre for Human Genetics, University of Oxford, under Peter Donnelly. He also worked at deCODE Genetics in Reykjavik and at Oxford with Augustine Kong, developing methods in quantitative and population genetics.

Razib and Young talk extensively about what we know about heritability and genomics in 2025, four years after their first conversation. In particular, they discuss what larger sample sizes, high-density genotype-arrays and whole-genome sequencing have told us about heritability and the ability to predict traits in individuals from their sequence. They discuss quantitative and behavioral traits like height, intelligence and risk of autism, and the differences between classical statistical genetical methods utilizing twins and modern molecular genomic techniques that attempt to fix specific physical markers as causal factors in characteristics of interest. In addition to his academic work, Young has also been consulting for the polygenic embryo-screening company Herasight, working on cutting-edge methods for genomic prediction in the context of in vitro fertilization. They dig deep into the new method Young and colleagues worked on that helps democratize embryo selection using genomics, ImputePGTA.

Subscribe now

Give a gift subscription

Share

Today on Unsupervised Learning Razib talks to Zineb Riboua, a research fellow and program manager of Hudson Institute’s Center for Peace and Security in the Middle East. She specializes in Chinese and Russian involvement in the Middle East, the Sahel, and North Africa, great power competition in the region, and Israeli-Arab relations. Riboua’s pieces and commentary have appeared in the Wall Street Journal, Foreign Policy, the National Interest, the Jerusalem Post and Tablet among other outlets. She holds a master’s of public policy from the McCourt School of Public Policy at Georgetown University. She did her undergraduate studies in France, where she attended French preparatory classes and HEC Paris’ Grande Ecole program. Her Substack is Beyond the Ideological.

Razib and Riboua discusses two pieces on her Substack today, Zohran Mamdani, Third-Worldism, and the Algerian Revolution and Zohran Mamdani and Islam as Language, American Third-Worldism. Riboua explains that contrary to some assertions Mamdani is not an Islamist, but neither is a standard-issue class-based socialist or an identitarian in the woke model that was ascendent a few years ago. Rather, Riboua’s contends that Mamdani, a “Third-Culture Kid,” emerges out of the post-colonial world that reframes the Marxist framework into a Western vs. non-Western dyad. Rather than the Islamist Iranian Revolution of 1979, she traces Mamdani’s intellectual lineage, that of anti-colonial Third-Worldism, to the Islam-inflected Algerian Revolution of the early 1960s. With conventional racial and gender identitarianism exhausted, Riboua contends that Third-Worldism is likely going to be the most potent force in the American Left over the next decade.

Subscribe now

Give a gift subscription

Share

This year I’ve introduced an occasional feature for paying subscribers, the Unsupervised Learning Journal Club where I offer a brisk review and consideration of an interesting paper in human population genomics.

In the spirit of a conventional journal club, after each post, interested subscribers can vote on papers for future editions. I’m open both to covering the latest papers/preprints and reflecting back on seminal publications from across these first decades of the genomic era.

Wealth, war and worse: plague’s ubiquity across millennia of human conquest

Where Queens Ruled: ancient DNA confirms legendary Matrilineal Celts were no exception

Eternally Illyrian: How Albanians resisted Rome and outlasted a Slavic onslaught

Homo with a side of sapiens: the brainy silent partner we co-opted 300,000 years ago

Brave new human: counting up the de novo mutations you alone carry

The wandering Fulani: children of the Green Sahara

Genghis Khan, the Golden Horde and an 842-year-old paternity test

Re-writing the human family tree one skull at a time

Free subscribers can get a sense of the format from my ungated coverage of two favorite 2024 papers:

The other man: Neanderthal findings test our power of imagination

We were selected: tracing what humans were made for

Today we’re reviewing a Nature paper which elucidates the deep evolutionary history of Papuans: Resolving out of Africa event for Papua New Guinean population using neural network (2025). It comes out of Mait Metspalu & Anders Eriksson’s joint groups at the University of Tartu. The first author is Mayukh Mondal, Institute of Clinical Molecular Biology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.

When Europeans first voyaged out into the world beyond their home continent in the 1400s and 1500s, they encountered populations of fellow humans previously unfathomed. Adrift amid unexpectedly vast new realms of human biodiversity, they groped for familiar qualifiers along which to sort their newly discovered kin. Christopher Columbus famously misidentified the natives of the New World as Indians, presuming he had reached the East Indies. A few decades later, and much further west, on the edge of Asia, Spanish Basque explorer Yñigo Ortiz de Retez, already a veteran of voyages throughout the New World and to such far flung holdings as the Philippines and the Spice Islands, named the island that spans the seas between Southeast Asia and Australia New Guinea. This was because the natives’ physical appearance, with dark pigmentation and tightly curled hair, led him to suspect a kinship with Africans of the Guinea coast, 11,000 miles away along the equator as the crow flies.

But despite its equatorial latitude, New Guinea, also known as Papua, differs significantly from Africa. Humanity’s original home continent has deserts, savannas and tropical rainforests. In contrast, while New Guinea’s coastal lowlands are all lush tropical forest, highlands dominate the spine of the isle. There, steep, ice-covered mountain peaks reach over 16,000 feet, high enough that they are capped by equatorial glaciers. These higher altitudes were ideal for horticulture, and so the island’s population’s highest concentration was found deep inland, beyond the ken of Europeans, who spent centuries pointedly skirting New Guinea’s malarial coasts along their voyages west and east. As late as the 1930s, European explorers were still discovering isolated valleys with hundreds of thousands of inhabitants, entire societies unknown to the outside world. Like Australia, New Guinea was a realm of exotic marsupial mammals; it was humans who brought the pigs, chickens and rats, and those only within the last 3,000 years.

For most of the past two million years, during the Ice Age, New Guinea and Australia both belonged to the continent of Sahul, a unified ecoregion. This long-time association explains the similarity in flora and fauna of the world’s second-largest island and its smallest continent. It also implies that the expansion of humans eastward into the western Pacific and beyond, to Australia, likely had a staging point in New Guinea, given both that locale’s proximity to Asia and its peripheral position within Oceania. But during the Holocene, about 10,000 years ago, as the world warmed and sea levels rose, Australia and New Guinea went their separate ways, as did their respective peoples and cultures. While Australia remained a continent of foragers, still living as their Paleolithic ancestors had until the arrival of Europeans en masse in the 19th century, New Guinea’s people abandoned a pure hunter-gatherer lifestyle over 7,000 years ago, turning instead to taro, yam and banana cultivation. By 2000 BC, Papuans began to re-engineer their landscape with ditches and vast clearings, evidence that by then they were expanding their system of agriculture at scale. On the edge of the Pacific, isolated from Eurasia’s social and cultural currents, New Guinea witnessed an independent farming revolution, in stark contrast to its Australian neighbors to the south.

Papuans, in their splendid isolation, might seem to be of little interest to the broader narrative of human evolution and genetic history, but it is their very distance from the migrations and the rise and fall of empires that renders them notable. Until recently, New Guinea seems to only have ever been occupied by the first modern humans to settle the island, with nothing beyond minor changes upon Austronesians’ arrival to its shores 3,000 years ago. But in 2010 New Guinea and Papuans were suddenly thrust to the center of human evolutionary discoveries. In that year, researchers discovered upon sequencing that the genome from Denisova cave in Siberia matched about 5% of the New Guinean people’s ancestry (and almost none outside of Australasia). Then, in 2016, other researchers examining Papuan whole genomes concluded that the people might also harbor ancestry from an earlier out-of-Africa migration than the well-characterized expansion 50,000 years ago that swept from the Atlantic to the Pacific.

So in the last 15 years New Guinea has gone from an interesting and curious Pacific outpost of the human species to being at the center of several deep and essential questions. How many distinct out-of-Africa migrations have humans actually undertaken? And how many admixture events with earlier human species? 2025’s Resolving out of Africa event for Papua New Guinean population using neural network leverages the data from ancient DNA, including 320 whole genomes, and the computational power of the 21st century in the form of neural networks, to extract greater analytic insight and finally tackle these evolutionary genetic questions.

When Nature published 2010’s Genetic history of an archaic hominin group from Denisova Cave in Siberia, paleogenomics was in its infancy, the total number of human whole-genome sequences was relatively small and analytic methods were still being developed to grapple with the welter of data. A total of 12 modern whole genomes were analyzed in that paper at 1 to 5-fold coverage, the number of times a region of the genome is resampled by the sequencing machine (for medical-grade diagnostic sequencing, we now usually require 20-30 fold coverage to ensure each genetic call’s accuracy). 2016’s Genomic analyses inform on migration events during the peopling of Eurasia, was a step forward, with “483 high-coverage human genomes from 148 populations worldwide.” That being said, population genomics was then arguably still establishing its footing, with analyses only recently having gone from inspecting a single precious whole genome to grappling with hundreds. This step change had just come within the space of five years. The most surprising result from the 2016 paper was that at least 2% of the Papuan genome originates from an early expansion, a largely false dawn of modern humans who left Africa long before that fateful little exodus 50,000 years ago. But it was greeted with some skepticism at the time given prior issues in the field with artifactual errors being introduced when the nuances of whole-genome analyses were still not wholly appreciated (a 2011 paper on Australian Aboriginals with a similar result seems to have suffered from this issue).