Austronesian-Papuan People Replaced The First Modern Humans In Wallacea

Wallacea is the ecological region between the Wallace Line and the Lydekker Line (image via Wikipedia at the link). The plants and animals there differ greatly from those to the west (which were connected by land to mainland Asia when sea levels were lower) because neither animals nor 46,000 years of settlers after the first modern humans to cross into it, could cross the roughly 30 miles of deep sea between the regions.

The most basal modern human populations outside Africa, which also have the greatest Denisovan admixture, are the indigenous people of Papua New Guinea and Australia. People from this wave were also present on the islands of the Wallacean Archipelago in Indonesia and lived there undisturbed for about 46,000 years. 

But, when Papuans made contact with and fused with Austronesian sea farers (who originated on the island that is now called Taiwan) around 3500 years ago, contemporaneously with the late Bronze Age in Europe, the resulting fused population replaced the descendants of the first wave of modern humans in the Wallacean Achipelago.

Significance

We present a comprehensive study of the human genetic history of the Wallacean Archipelago and West Papuan regions of Indonesia, including 254 newly sequenced genomes, mostly from previously undocumented populations. In combination with linguistic and archaeological evidence, we show that Wallacean societies were transformed by the spread of genes and languages from West Papua in the past 3,500 y—the same period that Austronesian seafarers were actively mixing with Wallacean and Papuan groups. These migrant groups have largely replaced local Wallacean ancestry sources, challenging common assumptions that Papuan-related ancestry in Wallacea descends from first human migrants enroute to Sahul >50,000 y ago, and suggesting that these ancient movements may not be readily recoverable from modern genetic data alone.

Abstract

The tropical archipelago of Wallacea was first settled by anatomically modern humans (AMH) by 50 thousand years ago (kya), with descendent populations thought to have remained genetically isolated prior to the arrival of Austronesian seafarers around 3.5 kya. 

Modern Wallaceans exhibit a longitudinal countergradient of Papuan- and Asian-related ancestries widely considered as evidence for mixing between local populations and Austronesian seafarers, though converging multidisciplinary evidence suggests that the Papuan-related component instead comes primarily from back-migrations from New Guinea. 

Here, we reconstruct Wallacean population genetic history using more than 250 newly reported genomes from 12 Wallacean and three West Papuan populations and confirm that the vast majority of Papuan-related ancestry in Wallacea (~75 to 100%) comes from prehistoric migrations originating in New Guinea and only a minor fraction is attributable to the founding AMH settlers. 

Mixing between Papuan and local Wallacean lineages appears to have been confined to the western and central parts of the archipelago and likely occurred contemporaneously with the widespread introduction of genes from Austronesian seafarers—which now comprise between ~40 and 85% of modern Wallacean ancestry—though dating historical admixture events remains challenging due to mixing continuing into the Historical Period. In conjunction with archaeological and linguistic records, our findings point to a dynamic Wallacean population history that was profoundly reshaped by the spread of Papuan genes, languages, and culture in the past 3,500 y.

Gludhug A. Purnomo , Shimona Kealy, Sue O’Connor, Raymond Tobler, et al., "The genetic origins and impacts of historical Papuan migrations into Wallacea" 121 (52) PNAS e2412355121 (December 17, 2024). Hat tip to DDeden.

Archaic Hominins That Were Contemporaneous With Modern Humans

There were at least eight named non-H. sapiens archaic hominin species that existed in time periods overlapping those of  modern humans, H. sapiens, who evolved around 300,000 years ago. All were in the "Old World". There is no credible evidence that archaic hominin ever made it to the Americas, Australia, New Zealand, or most of the other islands of Oceania beyond island southeast Asia.

One was H. erectus that went extinct around 100,000 years ago after more than two million years roaming the Old World, first in Africa and later in Asia. There were also two hobbit-like species in island Southeast Asia, three East Eurasian sister clades to modern humans, the small but not hobbit-like H. naledi in Southern Africa, and Neanderthals in West Eurasia, although some of these species may actually be regional variants of the same species. 

All of these archaic hominin species had gone extinct (with the possible extended duration of a small isolated relict population or two, perhaps H. floresiensis) by about 29,000 years ago, leaving modern humans as the sole survivors (although some modern humans have Neanderthal ancestry (up to about 2%) from admixture events starting around 100,000 years ago, and some modern humans have both Neanderthal and also up to about 6% Denisovan ancestry, although absolute percentages are harder to estimate than percentages relative to other individuals with the same kind of introgression) from admixture events around the time that modern humans reached Southeast Asia. Incidentally, the introgression went both ways, with Neanderthals having up to 6% modern human introgressed ancestry, possibly due to events as much as 250,000 years ago. These sister clades capable of producing hybrid offspring may have been regionally specialized into climate niches.

Notably the remains of the Red Deer Cave People of China from 14,000 years ago (a few thousand years before the start of the Holocene era) are genetically modern humans and are not archaic hominins despite some of their seemingly archaic features. See also here.

I am also inclined to think that they may yet be a small relict population of small archaic hominins in a remote Indonesian jungle on the island of Sumatra and perhaps Flores as well, where these cryptids, called Orang Pendek, locally, have been attested but not definitively confirmed to still exist. I discuss this further at this post.

Homo floresiensis (discovered in 2003) are commonly known as "hobbits" and have been found on the island of Flores. Their phylogeny is disputed, but I find the theory that they are an asian branch of H. habilis to be most convincing. H. luzonesis (discovered in 2007) is similar and contemporaneous, but found further east in the Philippines and is supported by a less complete archaeological record. Both of these diminutive species are found in association with late Pleistocene tools and "oriental fauna".

Personally, being more of a lumper than a splitter, I'm inclined to see H. floresiensis and H. luzonesis as sub-species variations of the same species ("race" within that species to use some outdated terminology), and likewise to see H. longi, H. juluensis, and Denisovans as sub-species variations of the Denisovan species. The Hualongdong archaic hominin fossils, might be another hybrid individual or could be a hybrid individual, perhaps a Neanderthal-Denisovan hybrid individual (something that has precedent in a Denisovan cave DNA sample). 

Academic anthropologists, in contrast, tend to be splitters, in part, because it is cool and career advancing to discover and name your own archaic species, in part because the data is so fragmentary that grouping different fragmentary remains in a clade presumes relationships between the remains that aren't solidly proven, and in part, because it is easy to underestimate how much morphological diversity is possible within a single species if populations of it exposed to different environmental conditions.

H. longi a.ka. "dragon man" dates to an earlier time period (still contemporaneous with modern humans in Africa) in China and Manchuria, was discovered in 1933, and has been hypothesized to be a sister clade to Neanderthals, Denisovans, and modern humans, and a descendant of the pre-modern human hominin species H. antecessor due in part to basal archaic features in the skull. 

H. juluensis (literally "big heads") is contemporaneous H. longi, and beyond that time frame into the time frame of H. floresiensis and was discovered from 1976-1979 in China and Tibet. The authors assign this specimen along with Xiahe and Penghu fossils, to the Denisovan species (a sister clade to Neanderthals and modern humans) based upon comparisons of their fossil teeth and rough geographic proximity. H. juluensis is found in association with early Paleolithic tools and remains of Paleoarctic fauna. But they have larger brain cases than H. longi. A previous suggestions of the link between H. longi and the Denisovan species are discussed here and here at this blog. At least one Denisovan tooth has been found in Laos dated to 131,000 years ago.

The article also discusses the Hualongdong archaic hominin fossils that "date to the late Middle Pleistocene (~300,000 years BP) and display a mosaic of characteristics that cannot be easily fitted into any one lineage," although they are closer to H. longi and H. juluensis. This individual could be a hybrid between these two subspecies, with H. erectus, or with a Neanderthal who was far east of his usual range.

Prior to 2021, H. longi and H. juluensis tended to be classified as H. erectus (remains of which start to appear at a much greater time depth in Asia) or as archaic modern humans.

The Narmada and Maba partial skulls, especially the latter, are suggestively associated with Neanderthals by the article.

These Asian archaic species also overlap in time with the Southern African archaic hominin clade H. naledi which is a sister clade to the modern human ancestors and to the common ancestor of modern humans, Neanderthals, and Denisovans, but is not actually among our ancestors. As I explained at the link, this species "is basically a story from The Silmarillion of hominin evolution. It is entertaining, especially for hard core human evolution fans, but it doesn't really advance the plot."

A small number of papers reported genetic evidence in modern Africans of admixture with an archaic hominin "ghost species" in Africa, but subsequent papers have explained this "ghost species" signal as a methodological artifact that merely arises from population structure in early modern human Africans (see also here). But there may have been relict archaic hominins that did not admix with modern humans in Africa that were also contemporaneous with modern humans, at least, early on.

The question of whether behaviorally modern humans started showing advanced behavior around 70,000-50,000 years ago (at the dawn of the Upper Paleolithic era and close in time to the Out of Africa event for modern humans), was associated with an evolutionary leap in their brains is an open and unresolved question. See also here (addressing the question of what made modern humans genetically distinct from archaic hominins).

A greater degree of Late Quaternary hominin morphological variability is present in eastern Asia than previously assumed. Indeed, a number of distinct populations are present, some that now have new specific names: Homo floresiensis; H. luzonensis; H. longi; H. juluensis. With this piece, we describe the various groupings based on the current hominin fossil record of eastern Asia.

Christopher J. Bae & Xiujie Wu, "Making sense of eastern Asian Late Quaternary hominin variability" 15 Nature Communications 9479 (November 2, 2024) (opoen access) (hat tip to neo).

Papuan Demographic History From Modern Genomes

A new pre-print at bioRxiv disputes the status of Papuans (presumably together with aboriginal Australians) as an outgroup to both European and Asian populations. Instead, it positions them as a sister population of other Asian populations.

The demographic history of the Papua New Guinean population is a subject of significant interest due to its early settlement in New Guinea, at least 50 thousand years ago, and its relative isolation compared to other out of Africa populations. This isolation, combined with substantial Denisovan ancestry, contributes to the unique genetic makeup of the Papua New Guinean population. Previous research suggested the possibility of admixture with an early diverged modern human population, but the extent of this contribution remains debated. 

This study re-examines the demographic history of the Papua New Guinean population using newly published samples and advanced analytical methods. Our findings demonstrate that the observed shifts in relative cross coalescent rate curves are unlikely to result from technical artefacts or contributions from an earlier out of Africa population. Instead, they are likely due to a significant bottleneck and slower population growth rate within the Papua New Guinean population. Our analysis positions the Papua New Guinean population as a sister group to other Asian populations, challenging the notion of Papua New Guinean as an outgroup to both European and Asian populations. 

This study provides new insights into the complex demographic history of the Papua New Guinean population and underscores the importance of considering population-specific demographic events in interpreting relative cross coalescent rate curves.

Mayukh Mondal, et al., "Resolving out of Africa event for Papua New Guinean population using neural network" bioRxiv (September 23, 2024) https://doi.org/10.1101/2024.09.19.613861

The introduction to the paper explains that:

The Papua New Guinean (PNG) population is among the most fascinating in the world, owing to its unique demographic history. Following the Out Of Africa (OOA) event, modern humans populated New Guinea at a remarkably early date-at least 50 thousand years ago. Since then, the population has remained relatively isolated compared to other OOA populations (such as European and Asian populations) and has gone through a strong bottleneck. The substantial Denisovan ancestry within the PNG population and the strong correlation between Denisovan and Papuan ancestries, contribute to the genetic distinctiveness of the PNG population. 

Researchers have suggested that the genomes of PNG populations contain evidence of admixture with a modern human population that might have diverged from African populations- around 120 thousand years ago- much earlier than the proclaimed primary divergence between African and OOA populations. However, the extent to which this early diverged population contributed to the genome of PNG populations remains a subject of ongoing debate. Interestingly, this early migration hypothesis is more widely accepted by archeologists. 

Pagani et al supports this hypothesis, notably through Relative Cross-Coalescent Rate (RCCR) analysis. This RCCR analysis suggests that the PNG population diverged from African populations significantly earlier than other OOA populations. They argued that this earlier divergence indicated by the RCCR curve might reflect a contribution from an earlier OOA population specific to PNG. While this shift in the RCCR curve is well-documented, some researchers attribute it to technical artefacts such as low sample sizes and phasing errors rather than genuine demographic events. 

The origins of the primary lineage of the PNG population have also been contested. Some researchers propose that the PNG population is closely related to the Asia-Pacific populations and serves as a sister group to other Asian populations. Conversely, other researchers argue that the PNG population is an outgroup to both European and Asian populations. 

Recent advancements in analytical methods may provide new insights into these debates. For example, Approximate Bayesian Computation with Deep learning and sequential Monte Carlo (ABC-DLS) allows for the use of any summary statistics derived from simulations to train neural networks, which can then predict the most likely demographic models and parameters based on empirical data. Additionally, the Relate software enhances RCCR analysis by employing a modified version of the hidden Markov model, initially used in the Multiple Sequentially Markovian Coalescent (MSMC) method, allowing for the analysis of thousands of individuals with greater robustness. 

In this paper, we re-examine the demographic history of the PNG population using newly published samples combined with data from the 1000 Genome Project and cutting edge methods. This approach has enabled us to address these longstanding questions with greater precision. We first generate new empirical RCCR curves and demonstrate that the previously observed shift is unlikely to be the result of low sample size or phasing errors. Through simulations, we further show that the PNG population is indeed a sister group to other Asian populations and this shift is probably not due to contributions from an earlier OOA population. Instead, it is likely a consequence of a significant bottleneck and slower population growth in the PNG population.

The paper then defines the demographic models that the paper analyzed at a broad brush level:

To explore the demographic processes causing the observed RCCR shift, we tested five plausible demographic scenarios labelled A, O, M, AX and OX. In Model A, the PNG and East Asian populations are sister groups. Model O positions the PNG population as an outgroup to both European and East Asian populations. Model M combines elements of both A and O, suggesting that the PNG population arose from admixture between a sister group of the Asian population and an outgroup of European and Asian populations. Model AX postulates that the PNG population is a sister group to the Asian population but received input from an earlier OOA population. Finally, in Model OX, the PNG population receives a contribution from an earlier OOA population, while remaining ancestry came from an out group to the European and East Asian populations. . . .  

The best-fitting parameters for Model A largely correspond with the previously established OOA model, with some deviations specific to the inclusion of the PNG population. 

Our model suggests that all OOA populations, including PNG, diverged from African populations (represented by Yoruba) around 62.4 (62- 62.8) thousand years ago, experiencing a significant bottleneck. Approximately 52 (51.6- 52.8) thousand years ago, Neanderthals contributed around 3.7% (3.59- 3.85%) of the genome to these OOA populations. Shortly thereafter, Europeans and East Asians diverged from the PNG populations around 51.2 (50.8- 51.6) and 46.2 (45.9- 46.5) thousand years ago, respectively. The PNG population then mixed with Denisovans around 31.2 (31.1- 31.5) thousand years ago, contributing approximately 3.16% (3.05- 3.21%) to the genome of PNG. 

Our analysis also shows that the PNG population experienced a more severe bottleneck (674 [663- 689] of effective population size) than other OOA populations (i.e. Europeans 3512 [3423- 3589] and East Asians 1771 [1730- 1799] of effective population size), with growth rates significantly lower than those of other OOA populations, consistent with previously published data. 

While our parameter inference is generally robust within the individual model, substantial changes occur when the underlying model is altered. Given that determining the precise demographic model for human populations is an ongoing effort, parameter estimates should be considered supplementary to the model rather than independent results. 

The concluding discussion of the results notes that:

We successfully replicated the shift observed by Pagani et al., confirming its presence in both physically mapped and statistically phased sequences, which involved over 100 PNG samples. This consistency suggests that the shift is reproducible, though its underlying cause may differ from the original interpretation of Pagani et al.. 

Our analysis using ABC-DLS supports a simpler demographic model for PNG populations, proposing them as a sister group to Asians with no substantial detectable contribution from an earlier OOA population. Interestingly, our simulated models reveal that a stronger bottleneck with a lower growth rate could produce a similar shift in RCCR analysis and potentially be misinterpreted as a signal of an earlier population separation. While RCCR is a valuable proxy for estimating the separation time between populations, it is not without biases. The shift could result from various factors, including earlier divergence times, admixture with earlier diverged populations, or even a bottleneck in one of the populations, as demonstrated in our study. Interestingly this demographic history of stronger bottleneck with slower growth rate was also experienced by the Andamanese population, which explains the shift found in the Andamanese population as well. Thus, using RCCR analysis to rebuild the tree of divergence might need to be revised.

The observed shift in the RCCR curve suggests that a recent bottleneck can impact estimates of effective population size in the distant past. Notably, in our simulations, the Papua New Guinean bottleneck occurred much later (around 46.2 thousand years ago) than the observed shift (peaking around 100 thousand years ago) with a population (Yoruba) that separated a long time ago. This finding implies that the estimation of effective population size and cross-coalescent rates may not be entirely independent, potentially affecting RCCR analysis in its current form. Further analysis suggests that the estimation of coalescent rate was affected earlier than true changes of effective population size, which shifts the RCCR curve as RCCR is a ratio of coalescent rates. Additionally, this shift was absent in simulations involving populations that separated 300 thousand years ago, akin to the San population, indicating that the bottleneck effect diminishes over longer separation times.

Our results also reveal that when the contribution from an earlier OOA population is between 1-5%, our neural analysis misclassifies the Model AX to be Model A at a higher rate. We found that when the contribution from an earlier OOA population is set between 1-5%, our ABC-DLS analysis tends to misclassify the Model AX as Model A at a higher rate. A similar issue arises with Model M, where a low contribution (less than 5%) from an outgroup Eurasian population can still be misclassified as Model A. Thus our analysis does not work for less than 5% contribution from these unknown ghost populations, though Model OX does not show a similar phenomenon with Model A misclassification. While we cannot completely rule out the possibility of a small contribution from these populations, our analysis suggests that such models are not necessary to explain the RCCR shift as previously proposed.

Interestingly, our results position PNG as a sister group to Asian populations rather than an outgroup of European and Asian. The primary difference between those models and ours lies in the migration rates between populations. Previous models that incorporated significant migration rates between populations were found to have confounded results, leading us to avoid including migration rates in our models. Without migration, our Model O closely resembles the previous models of PNG. Given that those models used substantial migration rates, they are not directly comparable to our models without migration rate. Indeed with high migration rates, our approach failed to distinguish between Model A and O with high certainty. Still our work suggests that the main lineage of PNG is coming from a sister group of Asia, which was not confounded by a convoluted migration rate patterns between populations.

Our parameter estimation suggests that the PNG population separated from other populations around 46.2 (45.9 - 46.5) thousand years ago, a timeline that aligns with archaeological estimates of when the ancestors of PNG reached the ancient continent of Sahul, the landmass that once connected New Guinea and Australia. 

Additionally, our Relate analysis indicates that the separation time between PNG and European populations was the longest observed among OOA populations. However, as our model suggests, this is likely a bias caused by the bottleneck of PNG. This bottleneck may lead to an overestimation of the separation time, particularly in RCCR analysis. In reality, it is more likely that PNG and East Asian populations separated later than the divergence between PNG and European populations. 

In conclusion, our study provides compelling evidence that the unique demographic events—specifically, a significant bottleneck and slower population growth—within the PNG population are key factors influencing the observed shifts in RCCR curves. These findings not only refine our understanding of PNG's demographic history but also emphasise the necessity of accounting for population-specific demographic events when interpreting RCCR curves. 

Pre-Colombian New World Admixture In Ancient Easter Island Genomes

Polynesian people reached Easter Island around 1250 CE and were the first humans there. Europeans first reached the island in 1722 CE, at which time there were 1,500 to 3,000 people living there. European diseases, Europeans killing them, and Portuguese slave traders brought the Polynesian population down to a low point of 110 people some time after the 1860s. This paper's introduction suggested that as many as 15,000 people were living on the island on its pre-European peak, but later studies and this paper suggest that this peak population was greatly overestimated. The best fit to the genetic data shows a steady but slow population increase on the island after it was settled until European first contact, and the ecological collapse theory is rejected.

About 10% of Easter Island ancestry comes from pre-Columbian admixture with the indigenous peoples of the Americas as a result of admixture events in the time period from 1250-1430 CE, with a best fit timing in the late 1300s. This date also strongly favors admixture with indigenous Americans after, and not before the ancestors for the sampled individuals arrived on Easter Island. In particular, "the Native American component in Ancient Rapanui to be most closely related to Pacific Coast South Americans and not North Americans or populations east of the Andes further substantiates trans-Pacific contacts between Polynesians and Native Americans."

This further corroborates prior evidence of pre-Columbian contact between Polynesians and the pre-Columbian peoples of the Americas, and is also consistent the with expected time frame of these contacts from prior data.

we reconstructed the genomic history of the Rapanui on the basis of 15 ancient Rapanui individuals that we radiocarbon dated (1670–1950 CE) and whole-genome sequenced (0.4–25.6×). We find that these individuals are Polynesian in origin and most closely related to present-day Rapanui, a finding that will contribute to repatriation efforts. Through effective population size reconstructions and extensive population genetics simulations, we reject a scenario involving a severe population bottleneck during the 1600s, as proposed by the ecocide theory. Furthermore, the ancient and present-day Rapanui carry similar proportions of Native American admixture (about 10%). Using a Bayesian approach integrating genetic and radiocarbon dates, we estimate that this admixture event occurred about 1250–1430 CE.

From here. The body text of the article provides some background:

several pieces of evidence suggest that Rapa Nui did not constitute the easternmost point of long sea voyages and that Polynesian peoples eventually reached the Americas before Columbus. 

Genetic studies on present-day individuals have supported such contact. Present-day Rapanui were found to harbour Native American and European admixture in their genomes. Notably, in that work, Native American admixture (dated 1280–1495 CE) was estimated to pre-date European admixture (dated 1850–1895 CE). 

More recently, Native American admixture was detected not only in present-day individuals from Rapa Nui, but also from Rapa Iti, Tahiti, Palliser, Nuku Hiva (North Marquesas), Fatu Hiva (South Marquesas) and Mangareva. In that study, the Native American gene flow in the different islanders was dated between 1150 (South Marquesas) and 1380 CE (Rapa Nui), in line with the date estimated in ref. 5. 

However, the only two ancient DNA studies of ancient Rapanui so far did not find evidence for Native American admixture. The first study focused on mitochondrial DNA from 12 individuals, whereas the second analysed low-depth (0.0004–0.0041×) whole-genome data from 5 individuals dating before and after European contact. In the latter, downstream population genetic analyses confirmed that the five ancient individuals were Polynesian. However, even though the analysed human remains were post-dating the inferred Native American admixture time, no Native American ancestry was reported in these ancient genomes, casting doubt on the findings based on data from present-day populations.

The admixture and Native American contract dates cited above are also just in the right time frame to explain the geographic distribution and lack of fixation of "Paleo-Asian" ancestry in modern South American populations, although that scarce Paleo-Asian component is very small and is seemingly not a very close match to Polynesian ancestry. 

The geographic spread and lack of fixation of the Paleo-Asian component in South America is inconsistent and irreconcilable with a time depth greater than that of the primary founding population of the Americas for that genetic ancestry component.

Easter Island May Have Independently Developed A Written Script

The people of Easter Island may have independently developed their own written script in a language that is now lost. The script is undeciphered.

A tablet of wood inscribed with the undeciphered "rongorongo" script from the Eastern Pacific island Rapa Nui, also called Easter Island, predates the arrival of Europeans there, strengthening the likelihood that the script is one of the few independently invented writing systems. The wood from one of four rongorongo tablets preserved in a collection in Rome dates to between 1493 and 1509 — more than 200 years before the first recorded arrival of Europeans on the island in the 1720s[.] . . . the results support the idea that rongorongo was an original invention by the Rapa Nui islanders rather than being influenced by the writing they'd seen used by Europeans.

Rapa Nui, which sits nearly 2,400 miles (3,800 kilometers) off the coast of Chile, was settled by humans between 1150 and 1280. Although Europeans arrived in the 18th century, they didn't notice the local glyph-based script until 1864, which now exists on only 27 wooden objects, none of which are still on the island. Catholic missionaries took four of these tablets in 1869 and sent them to the bishop of Tahiti, who later sent them to Europe.

Ferrara and her colleagues conducted radiocarbon dating on tiny samples of the four rongorongo tablets held by a congregation of Catholic nuns based in Rome. The radiocarbon dates suggested that three of the tablets were made from trees felled in the 18th or 19th centuries, but the radiocarbon date of a fourth indicated it came from a tree felled in the 15th century, Ferrara said. That predates the arrival of Europeans on Rapa Nui and suggests that the rongorongo script was in use before then, she said.

(Image credit: INSCRIBE and RESOLUTION ERC Teams) 

In this case, however, the inscription was probably made about the time the wood was obtained, because the alternative explanation — that the wood had been stored for more than 200 years before it was used — seems unlikely, she said. The new analysis also suggested the wood from the oldest tablet came from a tree species not native to Rapa Nui, and the researchers think it was probably a piece of driftwood.

Rapa Nui is famous for its many archaeological mysteries, including the giant stone heads known as moai, and many people have tried — without success — to decipher the rongorongo script.

Ferrara said more than 400 different rongorongo glyphs have been recognized among the roughly 15,000 surviving characters, and none correspond to any other known system of writing.

Rafal Wieczorek, a chemist at the University of Warsaw who was not involved in the latest study but has investigated other rongorongo tablets, said that while the new research isn't conclusive, it is a strong indication that the script was an independent invention — perhaps one of only a handful of times when a writing system had been invented from scratch, without knowledge of other writing systems. . . . "I actually believe that rongorongo is one of the very few independent inventions of writing in human history, like the writing of the Sumerians, the Egyptians and the Chinese," he said. "But belief is a different thing than hard data … so ideally, we would like to test all the tablets."

From Live Science.

Given that only sample on "old wood" was driftwood anyway, the possibility that the script is not as ancient as the date of the wood suggests is less of a stretch than it might seem. It wouldn't have to have been stored for 200 years. It would be enough for it to have lingered where it originally fell for decades and then for it to have drifted to Easter Island much later.

The fact that the script didn't spread elsewhere in Polynesia when it was known to have some level of trade with it is also a challenge to the notion that the script was developed independently in the late 15th or early 16th centuries.

But, the age of the wood makes it at least possible that the script predates European contact, and the lack of any connection to other known scripts is also an important factor favoring its status as an independent script.

Wikipedia covers it at length here. It notes that: "some calendrical and what might prove to be genealogical information has been identified, none of these glyphs can actually be read. . . . Oral history suggests that only a small elite was ever literate and that the tablets were sacred." It states that the conventional view is that this is a proto-language mnemonic device, which students wrote on fragile banana leaves, rather than a true language. Unlike other proto-linguistic scripts, like the Harappan script (of the Indus River Valley) and Vinca script (of the Balkans), and early hieroglyphs, however, this one does not appear to have had a primarily economic purpose.

The paper and its abstract are as follows:

Placing the origin of an undeciphered script in time is crucial to understanding the invention of writing in human history. Rapa Nui, also known as Easter Island, developed a script, now engraved on fewer than 30 wooden objects, which is still undeciphered. Its origins are also obscure. Central to this issue is whether the script was invented before European travelers reached the island in the eighteenth century AD. Hence direct radiocarbon dating of the wood plays a fundamental role. Until now, only two tablets were directly dated, placing them in the nineteenth c. AD, which does not solve the question of independent invention. Here we radiocarbon-dated four Rongorongo tablets preserved in Rome, Italy. One specimen yielded a unique and secure mid-fifteenth c. date, while the others fall within the nineteenth c. AD. Our results suggest that the use of the script could be placed to a horizon that predates the arrival of external influence.

Ferrara, S., Tassoni, L., Kromer, B. et al. "The invention of writing on Rapa Nui (Easter Island). New radiocarbon dates on the Rongorongo script." 14 Sci Rep 2794 (Feb. 2, 2024) (open access) https://doi.org/10.1038/s41598-024-53063-7

The Easter Island Statues Have Bodies

Via this news story (which has many more photos of Easter Island statue bodies).

The fact that the Easter Island (a.k.a. Rapa Nui) statues (which are known as "moai" from the Spanish word for statue) have bodies is old news. 

But the statues shown with their full bodies are still striking to actually see, and are a nice image to brighten your day. Why these statutes ended up getting so deeply buried also appears to be a still open question in anthropology.

What are they?

Moai or moʻai (/ˈmoʊ.aɪ/ (listen) MOH-eye; Spanish: moái; Rapa Nui: moʻai, lit. 'statue') are monolithic human figures carved by the Rapa Nui people on Rapa Nui (Easter Island) in eastern Polynesia between the years 1250 and 1500. Nearly half are still at Rano Raraku, the main moai quarry, but hundreds were transported from there and set on stone platforms called ahu around the island's perimeter. 

Almost all moai have overly large heads, which comprise three-eighths the size of the whole statue and they have no legs. The moai are chiefly the living faces (aringa ora) of deified ancestors (aringa ora ata tepuna). The statues still gazed inland across their clan lands when Europeans first visited the island in 1722, but all of them had fallen by the latter part of the 19th century. The moai were toppled in the late 18th and early 19th centuries, possibly as a result of European contact or internecine tribal wars. . . .

Though moai are whole-body statues, they are often referred to as "Easter Island heads" in some popular literature. This is partly because of the disproportionate size of most moai heads, and partly because many of the iconic images for the island showing upright moai are the statues on the slopes of Rano Raraku, many of which are buried to their shoulders. Some of the "heads" at Rano Raraku have been excavated and their bodies seen, and observed to have markings that had been protected from erosion by their burial.

The average height of the moai is about 4 m (13 ft), with the average width at the base around 1.6 m (5.2 ft). These massive creations usually weigh around 12.5 tonnes (13.8 tons) each. . . . 

It is thought that the moai with carved eye sockets were probably allocated to the ahu and ceremonial sites, suggesting that a selective Rapa Nui hierarchy was attributed to the moai design until its demise with the advent of the religion revolving around the tangata manu. 

. . .

Archaeologists believe that the statues were a representation of the ancient Polynesians' ancestors. The moai statues face away from the ocean and towards the villages as if to watch over the people. The exception is the seven Ahu Akivi which face out to sea to help travelers find the island. There is a legend that says there were seven men who waited for their king to arrive. A study in 2019 concluded that ancient people believed that quarrying of the moai might be related to improving soil fertility and thereby critical food supplies.

. . .

Those moai that are less eroded typically have designs carved on their backs and posteriors. The Routledge expedition of 1914 established a cultural link between these designs and the island's traditional tattooing, which had been repressed by missionaries a half-century earlier. . . .

The statues were carved by the Polynesian colonizers of the island, mostly between 1250 and 1500 [CE]. In addition to representing deceased ancestors, the moai, once they were erected on ahu, may also have been regarded as the embodiment of powerful living or former chiefs and important lineage status symbols. Each moai presented a status: "The larger the statue placed upon an ahu, the more mana the chief who commissioned it had." The competition for grandest statue was ever prevalent in the culture of the Easter Islanders. The proof stems from the varying sizes of moai.

Completed statues were moved to ahu mostly on the coast, then erected, sometimes with pukao, red stone cylinders, on their heads. Moai must have been extremely expensive to craft and transport; not only would the actual carving of each statue require effort and resources, but the finished product was then hauled to its final location and erected.

The quarries in Rano Raraku appear to have been abandoned abruptly, with a litter of stone tools and many completed moai outside the quarry awaiting transport and almost as many incomplete statues still in situ as were installed on ahu. In the nineteenth century, this led to conjecture that the island was the remnant of a sunken continent and that most completed moai were under the sea. That idea has long been debunked, and now it is understood that: 

• Some statues were rock carvings and never intended to be completed. 
• Some were incomplete because, when inclusions were encountered, the carvers would abandon a partial statue and start a new one. Tuff is a soft rock with occasional lumps of much harder rock included in it.
• Some completed statues at Rano Raraku were placed there permanently and not parked temporarily awaiting removal.
• Some were indeed incomplete when the statue-building era came to an end.

. . .

Since the island was largely treeless by the time the Europeans first visited, the movement of the statues was a mystery for a long time; pollen analysis has now established that the island was almost totally forested until 1200 CE. The tree pollen disappeared from the record by 1650. 

. . . 

Originally, Easter Islanders had a paramount chief or single leader. Through the years the power levels veered from sole chiefs to a warrior class known as matatoʻa. The therianthropic figure of a half bird and half-man was the symbol of the matatoʻa; the distinct character connected the sacred site of Orongo. The new cult prompted battles of tribes over worship of ancestry. Creating the moai was one way the islanders would honor their ancestors; during the height of the birdman cult there is evidence which suggests that the construction of moai stopped.

A Detailed Prehistory Of Micronesia

A new study provides a maximally detailed five wave model of the prehistoric human settlement of Micronesia, relying on ancient and modern DNA, linguistics and archaeology.

Notably, it determines that the Mariana Islands lack Papuan ancestry, and that Micronesians were strictly matrilocal.

Micronesia began to be peopled earlier than other parts of Remote Oceania, but the origins of its inhabitants remain unclear. We generated genome-wide data from 164 ancient and 112 modern individuals. 

Analysis reveals five migratory streams into Micronesia. Three are East Asian related, one is Polynesian, and a fifth is a Papuan source related to mainland New Guineans that is different from the New Britain–related Papuan source for southwest Pacific populations but is similarly derived from male migrants ~2500 to 2000 years ago. 

People of the Mariana Archipelago may derive all of their precolonial ancestry from East Asian sources, making them the only Remote Oceanians without Papuan ancestry. 

Female-inherited mitochondrial DNA was highly differentiated across early Remote Oceanian communities but homogeneous within, implying matrilocal practices whereby women almost never raised their children in communities different from the ones in which they grew up.

Yue-Chen Liu, et al., "Ancient DNA reveals five streams of migration into Micronesia and matrilocality in early Pacific seafarers" 377 (6601) Science 72-79 (June 30, 2022).

The Origins Of Domesticated Chickens

Chickens were domesticated much later than I expected and spread to various places outside Southeast Asia much later than I would have expected (particularly given that a leading Harappan city in the Indus River basin was called "Chicken City" and the fact that they seemed to be part of the Austronesian domesticates package at some point).

For what it is worth, while the positive evidence they cite for the presence of domesticated chickens in various places is solid, the case that they make that earlier evidence, particularly from South Asia and island Southeast Asia, is not credible, is quite conservative and should be taken with a grain of salt.

Though chickens are the most numerous and ubiquitous domestic bird, their origins, the circumstances of their initial association with people, and the routes along which they dispersed across the world remain controversial. In order to establish a robust spatial and temporal framework for their origins and dispersal, we assessed archaeological occurrences and the domestic status of chickens from ∼600 sites in 89 countries by combining zoogeographic, morphological, osteometric, stratigraphic, contextual, iconographic, and textual data. 

Our results suggest that the first unambiguous domestic chicken bones are found at Neolithic Ban Non Wat in central Thailand dated to ∼1650 to 1250 BCE, and that chickens were not domesticated in the Indian Subcontinent. 

Chickens did not arrive in Central China, South Asia, or Mesopotamia until the late second millennium BCE, and in Ethiopia and Mediterranean Europe by ∼800 BCE. 

To investigate the circumstances of their initial domestication, we correlated the temporal spread of rice and millet cultivation with the first appearance of chickens within the range of red junglefowl species. Our results suggest that agricultural practices focused on the production and storage of cereal staples served to draw arboreal red junglefowl into the human niche. Thus, the arrival of rice agriculture may have first facilitated the initiation of the chicken domestication process, and then, following their integration within human communities, allowed for their dispersal across the globe.

Joris Peters, et al., "The biocultural origins and dispersal of domestic chickens" 119 (24) PNAS e2121978119 (June 6, 2022) (open access).

The Precursors In America Failed To Thrive

There is pretty strong evidence (especially, well dated footprints from 22,000 to 30,000 years ago) of modern humans in North America, at least prior to and during the Last Glacial Maximum ca. 20,000 years ago, long before the Founding population of the Americas should have arrived around 15,000 years ago.

West Hunter considers conditions that would fit their "failure to thrive" in the New World, as evidenced by a complete lack of human remains, few and marginal possibly human made tools, and a lack of mass extinctions, in "virgin territory" without competition from other hominins. He notes:

The problem with the idea of an early, pre-Amerindian settlement of the Americas is that (by hypothesis, and some evidence) it succeeded, but (from known evidence) it just barely succeeded, at best. Think like an epidemiologist (they’re not all stupid) – once humans managed to get past the ice, they must have had a growth factor greater than 1.0 per generation – but it seems that it can’t have been a lot larger than that . . . .

A saturated hunter-gatherer population inhabiting millions of square miles leaves a fair number of artifacts and skeletons per millennium – but we haven’t found much. We have, so far, found no skeletons that old. I don’t think we have a lot of totally convincing artifacts, although I’m no expert at distinguishing artifacts from geofacts. (But these were modern humans – how crude do we expect their artifacts to be?)

For-sure footprints we’ve got, and intriguing genetic data.

A priori, I would expect hunter-gatherers entering uninhabited America to have done pretty well, and have high population growth rates, especially after they become more familiar with the local ecology. There is good reason to think that early Amerindians did: Bayesian skyline analysis of their mtDNA indicates fast population growth. They were expert hunters before they ever arrived, and once they got rolling, they seem to have wiped out the megafauna quite rapidly.

But the Precursors do not seem to have become numerous, and did not cause a wave of extinctions (as far as I know. check giant turtles.).

I've underlined some thoughts that I don't agree with fully. It looks like the Younger Dryas was a much bigger factor in mass extinctions relative to the overkill hypothesis than we previously expected. 

And then there is the genetic evidence. Unlike Cochran, I am quite convinced that it is basically mathematically impossible for this pre-Founding population to have been the source of "Paleo-asian" autosomal DNA in South America, which is much more likely to have arrived ca. 1200 CE via Oceanians (although other possibilities in that time frame could work as well). The frequency of the Paleo-Asian component is just too variable. And, any population that stayed isolated population genetically for more than 14,000 years to finally burst out into South America would be incredibly genetically distinctive (much like the Kalash people who are incredibly genetically distinctive after their small population was isolated for much less long a time period than that).

Statistical artifacts of the methods used and/or selective pressure against some Oceanian distinctive genes that make the remaining component look Onge rather than Papuan-like, could explain the closer f-test statistical matches to these populations. A relict non-Oceanian Paleo-asian population from Northeast Asia arriving in that time frame could work also but seems less plausible. Loss of distinctive Oceanian autosomal DNA during periods of stable population with low effective population size or during periods of shrinking populations during times of adverse conditions could also purge so statistically important genetic identifiers in what is already a small share of the total genome in the people who have it.

Further, some of the more convincing earlier pre-14,000 year ago finds of arguable stone tool making and fire use in the Americas were in North America (including Mesoamerica) or northeastern South America, not in the greater Amazon jungle basin where Paleo-asian ancestry has been found. 

But the points he makes about a "Precursor" (I like Cochran's choice of words here) population's lack of success are still valid. There shouldn't have been Malthusian limits to their population in the New World that allowed them to sustain their population, but population growth would have had to be exceedingly slight in the long run to be consistent with the available evidence. He considers some possibilities and I underline the ones that I think are too implausible to take seriously:

What might have limited their biological success?

Maybe they didn’t have atlatls. The Amerindians certainly did.

Maybe they arrived as fishermen and didn’t have many hunting skills. Those could have been developed, but not instantaneously. An analogy: early Amerindians visited some West Coast islands and must have had boats. But after they crossed the continent and reached the Gulf of Mexico, they had lost that technology and took several thousand years to re-develop it and settle the Caribbean. Along this line, coastal fishing settlements back near the Glacial Maximum would all be under water today.

Maybe they fought among themselves to an unusual degree. I don’t really believe in this, am just throwing out notions.

Maybe their technology and skills set only worked in a limited set of situations, so that they could only successfully colonize certain niches. Neanderthals, for example, don’t seem to have flourished in plains, but instead in hilly country. On the other hand, we don’t tend to think of modern human having such limitations.

One can imagine some kind of infectious disease that made large areas uninhabitable. With the low human population density, most likely a zoonosis, perhaps carried by some component of the megafauna – which would also explain why it disappeared.

What do I think?

In a nutshell, the Precursor population was probably just slightly below the tipping point that they needed to thrive, in terms of population size, knowledge, and the resources they brought with them, but just large enough to establish a community that was marginally sustainable in the long run with inbreeding depression and degraded technology.

I think the that Precursors were probably derived from one or more small expeditions from a population close to the ultimate Founding population of the Americas rooted in Northeast Asia that survived where many who left no trace at all died, as something of a fluke. 

A Kon-Tiki style transpacific route,  or trans-Atlantic Solutrean hypothesis route would be anachronistic technologically at 22,000 years ago or more and is disfavored by other evidence, including genetic evidence, as well. Claims of hominins in the Americas 130,000 years ago, are likewise not credible.

The Precursors probably had no dogs or other domesticated animals on their boat(s). But dogs were, in my opinion, probably a major fitness enhancing technology for the post-Papuan/Australian aborigine wave of modern humans in mainland Asia (the Papuan/Australian wave didn't have dogs), and for the Founding population of the Americas.

They probably had  a small founding population that suffered technological degradation similar to what Tasmania experienced when it separated from Australia for 8,000 years, including the loss of maritime travel technology needed to reunite with kin left behind in Asia or Beringia. See Joseph Henrich, "Demography and Cultural Evolution", 69(2) American Antiquity 197-214 (April 2004) but see Krist Vaesen, "Population size does not explain past changes in technological complexity" PNAS (April 4, 2016) (disputing this conclusion, unconvincingly IMHO).

For example, as Cochran notes, they may have known how to fish and hunt from boats, but not how to make boats, or how to hunt terrestrially, at first. 

The effective population size of the Founding population of the Americas was ca. 200-300 people; Henrich's hypothesis sees major degradations in technology as the population size falls significantly below 100, which would have been a typical size for a one-off exploratory expedition that was stranded and unable to return.  Once technology is lost, it can be recovered or rebuilt over time, but it takes much longer to innovate than to preserve culture transmitted from previous generations or to imitate neighboring civilizations. 

The loss of technology may not simply have been a matter of raw numbers either. Vaesen's counter-examples are very small, stable, complete hunter-gather communities. But an exploratory expedition may have consisted of bold young people not fully trained in reproducing their culture's technologies, even if they had enough raw numbers of people to do so, rather than the tribe or band's skill craftspeople.

They probably suffered inbreeding depression greater than the main founding population of the Americas due to a smaller founding population size. A scientific report in Nature (March 5, 2019) notes that:

Franklin has proposed the famous 50/500 rule for minimum effective population size, which has become the threshold to prevent inbreeding depression. This rule specifies that the genetic effective population size (N(e)) should not be less than 50 in a short term and 500 in a long term.

The possibility that the Precursors derived from one or more expeditions with an effective population size less than 50 in the short term, regardless of its long term size, seems plausible. Even if there were several dozen men on the expedition, it is very plausible that there could have been fewer than twenty-five reproductive age women on the expedition at the outset needed to avoid short run inbreeding depression, and many of them were probably cousin and/or siblings. 

These inbreeding depression effects could have lasted many, many generations without input from an outside population source, leaving a much less smart, much less fit group in the next few generations than in their first generation.

They probably faced challenges to thriving at hunting and gathering due to the ice age that caused the Last Glacial Maximum that their degraded technology didn't help them to overcome. They may have landed in North American fairly near to the glacial area that was particularly impaired.

They probably did go extinct in all, or almost all, of their range, after not too many generations. They may not have reached South America until after the Last Glacial Maximum at all, and if they did, may not have penetrated very far into it, sticking to the Gulf Coast.

To the extent that they didn't go extinct, they probably lost many of their uniparental genetic markers during sustained periods of stable low populations or population busts, as opposed to the preservation of the markers usually found in expanding populations. 

They also probably weren't all that genetically distinct from the Founding population of the Americas from which they were only separated for a few thousand years. A small effective population takes many generations to generate distinct mutations and both the Founding population of the Americas and the Precursors would have had small effective populations for most of the Last Glacial Maximum ice age.

The Founding population, due to a larger founding population, better technology retention, less inbreeding, dogs, and better climate conditions, expanded rapidly.  When the much more advanced Founding population arrived, the remnants of the Precursors that remained, if any, would have been diluted almost invisibly into the very genetically similar Founding population and may have died out from competition, or at least, shed any of its distinctive uniparental markers, with it as well.

Footnote

"Failure to thrive" is a phrase most commonly used in medicine to describe phenomena without a specific and well-determined cause of a child's lack of development at the pace of normal children in health environments. Usually, it is attributed to poor nutrition either in quality or quantity.

New World Hepatitis B Virus Strain Diverged 17Kya to 20Kya

A new study has examined ancient hepatitis B virus DNA. As Bernard's blog explains (in a translation from the original French by Google), because this virus is solely transmitted from humans to other humans (with some slight overlap with great apes), its evolution over time can be used as a proxy for ancestrally informative genetic information about people.

The hepatitis B virus affected in 2015, 257 million people around the world according to the WHO, of whom about a million died. It is transmitted through contact with body fluids mainly during sexual relations or in perinatal contexts. There is no environmental or animal reservoir. Therefore, this virus spreads with the dispersal of human beings. The latest paleogenetic studies have made it possible to find the hepatitis B virus in skeletons belonging to different periods, in particular in the Neolithic of Europe.

The Phylogeny Of Hepatitis B Virus Strains:

The figure below shows in A and B the position of the various old samples and in C the current distribution of the various genotypes of the virus:

The New World Strains And Their Implications

Particularly notable is the estimated genetic mutation rate divergence time of the Hep B virus strains found in the Americas (related to modern strains F and H) from the strains found in Eurasia (related to modern human strains A, B, C, D, E, G, and I, and to the modern great ape strain J), a split of 17,000 to 20,000 years, which is around the time of the Last Glacial Maximum.

Notably, the predominantly American strains of Hep B with this deep ancestral split are now largely confined to Western South America and Meso-america. Presumably American strains of the Hep B virus were replaced by Old World strains of Hep B, first by Paleo-Eskimo and Thule waves of migration in Arctic and Sub-Arctic North America (which were probably one source of strain B), and then by strains brought by post-Columbian migrants to the Americas, who probably initially brought strains A and D, with later immigration to North America bringing strains B and C from Asia.

The estimated timing of the genetic divergence of private American Hep B strains in modern and ancient DNA  is more recent that newly announced well-dated archaeological evidence (from footprints in New Mexico) of a modern human presence in the Americas back to at least 23,000 years ago. Thus, this adds to other evidence that suggests that the first wave of modern humans in the Americas had little ecological impact and made little, if any, genetic contribution to subsequent waves of modern humans on the two continents. 

The high levels of intra-population variation in "Paleo-Asian" ancestry in South American populations also suggests strongly that this Paleo-Asian ancestry cannot have origins in these earliest modern humans in the Americas. Contact between indigenous South Americans and Polynesian mariners ca. 1200 CE not far from where the first traces of Paleo-Asian ancestry were observed in indigenous American populations is a much more plausible explanation for the observed Paleo-Asian ancestry that is seen in low frequencies in South American tribes. 

The date of the Old World v. New World Hep B strain split also indicates that ancient strains of Hep B that were circulating in Asia in the Upper Paleolithic era before entering the Americas were entirely replaced in Asia in the Neolithic era or later. And, the timing of the split suggests that the private American strains of Hep B are more likely to have a source in the Northeast Asian/Siberian component of the founding population of the Americas (which has more recent genetic connections with West Eurasia) than from the more East Asian component of the founding population of the Americas (which may have been free of Hep B in the Upper Paleolithic era, although there is no way to confirm that earlier strains of Hep B there weren't merely replaced by later more virulent ones and the small founding population from each component means that strains of Hep B that were circulating in Asia at the time could have simply not been brought to the Americas due to random chance). 

The Phylogeny Of Old World Hep B Strains

The split between East and Southeast Asian (and Arctic North American) strains of the Hep B virus (B, C and I) and one found in Europe and Africa (A) dates to about 5500 BCE (which predates Austronesian maritime expansion in Oceania and island Southeast Asia), in the Middle Neolithic era but with the expansion of the current strains mostly dating to after 1000 BCE. 

The split between both of these strains and the strain with the most global distribution (D) as well as ancestor to a predominantly African strain (E) is to about 6500 BCE, which is early to middle Neolithic (again, with a mostly post-Bronze Age expansion).

The Hep B virus strains related to modern humans strain G and modern great ape strain J were predominant in the time period from the Mesolithic to the Bronze Age in Europe and Anatolia, but are now only a tiny share of the total mix, and might have been missed entirely but for the intensity of medical genetic research using European samples.

The fact that the non-human great ape strains of the Hep B virus (J) has a more recent mutation dated split in the Mesolithic era (ca. 13,000 BCE to 10,000 BCE) than the split between the New World and Old World strains is also notable. Given the predominance of human strains of modern Hep B and the timing, a human to great ape transmission in this time frame somewhere in tropical or subtropical sub-Saharan Africa on at least two separate instances in the Mesolithic era seems far more likely than the reverse scenario. These transmissions probably involved great ape exposure to the blood of an infected human rather than intercourse, although there is no way to tell definitively.

Wallacea and Sahul

We can't tell from the available data if Hep B was present and replaced by later strains in Wallacea or the Sahul region in the Upper Paleolithic era as it was in Asia and North America, or if it arrived later (at the time of the arrival of the dingo in a time period ca. 3000 BCE to 8000 BCE, via later Asian maritime travelers, or with later maritime contact with Europeans). 

Given the small founding populations of Wallacea and the Sahul region in the Upper Paleolithic era (ca. 50,000 to 70,000 years ago), which was probably in the low hundreds, it is quite possible that Hep B was absent at that time (although it was present in the Americas which has a similarly small founding population).

But it is also possible that the absence of evidence simply reflects a limited supply of ancient viral DNA from the region and limited whole genome sampling of Hep B cases among aboriginal Australians and indigenous peoples to the east of the Wallace line.

Austronesians In Antarctica

Oral histories that are likely to be accurate indicate that Austronesian Maori mariners from New Zealand made regular trips to Antarctica starting ca. 600s CE. 

The paper is:

Priscilla M. Wehi, et al., "A short scan of Māori journeys to Antarctica." Journal of the Royal Society of New Zealand 1 (2021) DOI: 10.1080/03036758.2021.1917633 (open access).

For what it is worth, the abstract is poorly written, but the body text has some decent nuggets of insight.

An Overview Of East Asian and Southeast Asian Historical Linguistics

Overview

There are nine main language families in Southeast Asia and East Asia: Japonic (Japanese and a couple of related languages spoken on remote Japanese languages), Korean, Ainu (a language isolate spoken by indigenous people of Northern Japan), Sino-Tibetan (including Chinese, the Tibetan languages and Burmese), Austronesian (also spoken in Polynesia), Thai-Kadai a.k.a. Kra-Dai (of which the language of Thailand is best known), Austroasiatic a.k.a. Mon-Khmer (the most famous of which are Vietnamese and the Munda languages of India and also including the Khmer languages of Cambodia) and Hmong-Mien (a language family of an important minority population in Southeast Asia and South China). 

Genetic and linguistic evidence, however, shows that the Hmong-Mien language family is an offshoot of the Austroasiatic language family. There is strong but not universally accepted evidence that Austroasiatic languages and Thai-Kadai languages are part of a larger macro-language family. There is strong but not universally accepted evidence that the Japonic and Korean languages are part of the same language family.

Sino-Tibetan languages have their roots in the North Chinese millet farming Neolithic revolution on the Yellow River. 

The other four language families have their roots in the Southern Chinese rice farming Neolithic revolution on the Yangtze River. The Austronesian and possibly the Thai-Kadai language families originate in the lower Yangtze River basin. The Austroasiatic, Hmong-Mien and possibly the Thai-Kadai language families originate in the middle Yangtze River basin.

It is likely that none of the major languages of Southeast Asia were spoken there prior to about 2200 BCE. Prior to that point, Southeast Asia was largely populated by Hoabinhian hunter-gatherer populations whose languages are largely lost.

Y-DNA evidence suggests that Austronesian language family speakers are an out group to the other four major Southeast Asian and East Asian language families (Sino-Tibetan, Austroasiatic, Hmong-Mien, Thai-Kadai), with people speaking those languages linked to Austronesians only at a greater time depth.[1] This could be a misleading signal driven by the admixture of Austronesians with Austro-Melanesian populations, however.

The World In 4100 BCE

In 4100 BCE, domesticated rice was not available anywhere in the world except (1) the Yangtze River basin and (2) in the Ganges River basin in India (where it was just a few hundred years old as a domesticated crop). It would be domesticated in South American about a century after that. 

At that time, domesticated millet was not available anywhere in South Asia, Southeast Asia or East Asia except in the Yellow River basin and its near vicinity.

The World In 3100 BCE 

In 3100 BCE, farming was absent, and Paleolithic hunter-gatherers were the sole inhabitants of Japan, Taiwan, mainland Southeast Asia, island Southeast Asia, Papuan New Guinea and the immediately adjacent islands, the Philippines, Australia, and all of South Asia to the east of the Indus river Valley, the now barren Sarasvati river basin and the Ganges river basin. 

None of the languages spoken in Southeast Asia (other than the Papuan languages) or Taiwan or the Philippines today were spoken there. The only language now spoken in in the Japanese islands that existed then was Ainu.

None of the languages now spoken in South Asia or Iran today were spoken there, with the possible exception of the Dravidian languages. The Dravidian languages, if spoken at all, were confined to the small tribes of hunter-gatherers who would adopt farming for the first time in Southern India in the South Indian Neolithic Revolution. 

Oceania from Hawaii and Easter Island to Guam and the Mariana Islands to Fiji and Tonga and the Cook Islands and New Zealand, and also Antarctica, were places where no primate, let alone a modern human, had ever set foot.

In Africa, Bantu expansion had not yet begun, so pretty much all of Africa to the South of the Congo River basin and the jungles of the Congo, and much of East Africa, was inhabited only by hunter-gatherers, and racial and linguistic diversity in Africa was much greater. Likewise, the ethnogenesis of the Berber people had not yet occurred.

In Europe, people with the new predominant Northern European phenotypes (e.g. people with blond hair and blue eyes) did not exist and Indo-European languages were confined to Eastern Europe. The percentage of ancestry of modern Irish people traceable to 3100 BCE is close to negligible as it underwent near total population replacement.

The Ainu Language

The Ainu language is derived from one of the languages of the Jomon hunter-gathers of Japan who inhabited the area from the paleolithic era. It was probably influenced by or related to Paleo-Siberian languages. All of these languages are now nearly moribund.

The Japonic and Korean Languages

The Japanese languages arose when the Yayoi people migrated to Japan from Korea ca. 400 BCE to 300 BCE, derived from the pre-existing language, probably a sister language to Korean, spoken by these people. The deep origins of the Korean language in pre-history aren't well understood.

The Austronesian Languages

The Austronesian expansion from Taiwan began about 3000 BCE, and this expansion of one of the indigenous languages of Formosa is arguably really what defines this language family.[2] The indigenous Formosan languages are probably all derived from the Neolithic Dapenkeng culture that abruptly appeared and quickly spread around the coast of the island around 4000 BCE to 3000 BCE (displacing prior Negrito hunter-gatherer populations), only preceding the migration of one of those cultures to other islands by within the margin of error of available dating methods.[3] The particular archeological culture of mainland South China from which this culture was derived is unresolved, in part because archaeological data from that time period is sparse and undeveloped.[4] 

The Sino-Tibetan Languages

[T]he main ancestry of high-altitude Tibeto-Burman speakers originated from the ancestors of Houli/Yangshao/Longshan ancients in the middle and lower Yellow River basin, consistent with the common North-China origin of Sino-Tibetan language and dispersal pattern of millet farmers.[5]

This conclusion is contrary to many 20th century and early 21st century proposals (putting a homeland in Northeast India or Southern China) but now probably represents conventional wisdom in the field.[5]

So, the Sino-Tibetan languages date the North Chinese Neolithic Revolution which was millet farming and independent in origin from South Chinese and Southeast Asian rice farming. The earliest archaeological culture in this region is the Nanzhuangtou culture which started around 8500 BCE, but it isn't clear that that culture was in linguistic continuity with the cultures that gave rise to the Sino-Tibetan language family. Two major studies in 2019 favor this model but assign a more recent origin to the language family than the first Neolithic culture of the region:

Zhang et al. (2019) performed a computational phylogenetic analysis of 109 Sino-Tibetan languages to suggest a Sino-Tibetan homeland in northern China near the Yellow River basin. The study further suggests that there was an initial major split between the Sinitic languages and the Tibeto-Burman languages approximately 4,200 to 7,800 years ago [2200 BCE to 5800 BCE] (with an average of 5,900 years ago [3900 BCE]), associating this expansion with the Yangshao culture and/or the later Majiayao culture. Sagart et al. (2019) also performed another phylogenetic analysis based on different data and methods to arrive at the same conclusions with respect to the homeland and divergence model, but proposed an earlier root age of approximately 7,200 years ago [5200 BCE], associating its origin with the late Cishan and early Yangshao culture.[6]

The Northern millet farmers and Southern Rice farmers started to integrate into a common culture in which the Han Chinese component eventually became dominant around 3500 BCE.[7]

Other Southeast And East Asian Language Families

Rice was domesticated in Southern China around 7400 BCE.[8] But that doesn't mean that the initial rice domesticating culture was in linguistic continuity with the first Austro-Asiatic populations. And the time depth of the various language of the region is muddy. 

There are two most likely centers of domestication for rice as well as the development of the wetland agriculture technology. 

The first, and most likely, is in the lower Yangtze River, believed to be the homelands of the pre-Austronesians and possibly also the Kra-Dai, and associated with the Kauhuqiao, Hemudu, Majiabang, Songze, Liangzhu, and Maqiao cultures. It is characterized by pre-Austronesian features, including stilt houses, jade carving, and boat technologies. Their diet were also supplemented by acorns, water chestnuts, foxnuts, and pig domestication.

The second is in the middle Yangtze River, believed to be the homelands of the early Hmong-Mien-speakers and associated with the Pengtoushan, Nanmuyuan, Liulinxi, Daxi, Qujialing, and Shijiahe cultures. Both of these regions were heavily populated and had regular trade contacts with each other, as well as with early Austroasiatic speakers to the west, and early Kra-Dai speakers to the south, facilitating the spread of rice cultivation throughout southern China.

By the late Neolithic (3500 to 2500 BC), population in the rice cultivating centers had increased rapidly, centered around the Qujialing-Shijiahe culture and the Liangzhu culture. Liangzhu and Shijiahe declined abruptly in the terminal Neolithic (2500 to 2000 BC). With Shijiahe shrinking in size, and Liangzhu disappearing altogether. This is largely believed to be the result of the southward expansion of the early Sino-Tibetan Longshan culture. ... This period also coincides with the southward movement of rice-farming cultures to the Lingnan and Fujian regions, as well as the southward migrations of the Austronesian, Kra-Dai, and Austroasiatic-speaking peoples to Mainland Southeast Asia and Island Southeast Asia. A genomic study also indicates that at around this time, a global cooling event (the 4.2 k event) led to tropical japonica rice being pushed southwards, as well as the evolution of temperate japonica rice that could grow in more northern latitudes.[7]  

The Tai-Kadai Languages

The Tai-Kadai languages are now most widely spoken in the mainland Southeast Asian country of Thailand, but, this is actually the most recent language family to arrive in Southeast Asia from Southern China.

The high diversity of Kra–Dai languages in Southern China points to the origin of the Kra–Dai language family in Southern China. The Tai branch moved south into Southeast Asia only around 1000 CE.[9]

Genetically, the biggest difference between the Tai-Kadai people within Southeast Asia, and the Austroasiatic populations of Southeast Asia, both of whom have origins in the early Neolithic rice farmers of the Yangtze River basin of Southern China, is that Austroasiatic people, having arrived earlier, have more Hoabinhian hunter-gatherer admixture.[10]

There is strong, but not universally accepted evidence that the Thai-Kadai language family and the Austronesian language family are part of a larger macro-language family.[11]

The Austro-Asiatic and Hmong-Mien Languages

The Austroasiatic language family is probably derived from Southern Chinas Neolithic Rice farmers who trace their culture origins to the domestication of Chinese rice in an independent domestication event. Ancient DNA suggests that this is was the first of the language families of modern Southeast Asia to be spoken there by people who resided there.

The expansion from South China to Southeast Asia took place around 4,000 years ago and close in time to the spread of the Austronesians in Southeast Asia. They displaced Hoabinhian hunter-gatherer populations in Southeast Asia.[12] 

Ancient DNA shows populations genetically similar to modern Austro-Asiatic populations in Vietnam, Laos, and mainland Malaysia by 2200 BCE. [13] But the archaeological record is thin in the relevant time period from the South Chinese Neolithic revolution to 2200 BCE, so dating it is tricky. Still, the oldest ancient DNA may have been from close to the time that the language family arrived there since:

The spread of japonica rice cultivation to Southeast Asia started with the migrations of the Austronesian Dapenkeng culture into Taiwan between 3500 and 2000 BC (5,500 BP to 4,000 BP). The Nanguanli site in Taiwan, dated to ca. 2800 BC, has yielded numerous carbonized remains of both rice and millet in waterlogged conditions, indicating intensive wetland rice cultivation and dryland millet cultivation. A multidisciplinary study using rice genome sequences indicate that tropical japonica rice was pushed southwards from China after a global cooling event (the 4.2k event) that occurred approximately 4,200 years ago.[13] 

A genetically based conclusion that the Hmong-Mien peoples are a comparatively recent offshoot of the Mon-Khmer peoples, something that linguistic analysis has not reached consensus upon, is a finding of considerable importance in parsing out the prehistory of Southeast Asia, even though the hypothesis that Mon-Khmer and Hmong-Mien both belong to a macrolinguistic family (sometimes called Yangtzean) has existed for some time as one of several efforts to link the languages of South China and Southeast Asia into linguistic macrofamilies. An expanded study of Y-DNA population genetics in Southeast Asia by Chinese researchers, confirms that close genetic ties of Mon-Khmer (a.k.a. Austro-Asiatic when the Munda of India are also included) and Hmong-Mien peoples, at least in the patriline, focusing on the O3a3b-M7 Y-DNA haplogroup where the Mon-Khmer appearing at a basal position while Hmong-Mien and Tibeto-Burmese individuals with this hapologroup have subhaplogroups more on the fringes of this patriline tree. O3a3c1-M117, the dominant East Asian haplogroup shows a similar pattern.[1] 

References 

[1] Cai X, et al. "Human Migration through Bottlenecks from Southeast Asia into East Asia during Last Glacial Maximum Revealed by Y Chromosomes." PLoS ONE 6(8): e24282 (2011). doi:10.1371/journal.pone.0024282 

[2] Irina Pugach, "Ancient DNA from Guam and the Peopling of the Pacific" (2021) PNAS

[3] Wikipedia article on History of Taiwan: Early settlement. 

[4] Wikipedia article on Dapenkeng culture: Proposed mainland antecedents.

[5] Mengge Wang, "Peopling of Tibet Plateau and multiple waves of admixture of Tibetans inferred from both modern and ancient genome-wide data" (2020) bioRxiv

[6] Wikipedia article on Sino-Tibetan languages: Homeland citing Zhang, Menghan; Yan, Shi; Pan, Wuyun; Jin, Li (2019), "Phylogenetic evidence for Sino-Tibetan origin in northern China in the Late Neolithic", Nature, 569 (7754): 112–115, and Sagart, Laurent; Jacques, Guillaume; Lai, Yunfan; Ryder, Robin; Thouzeau, Valentin; Greenhill, Simon J.; List, Johann-Mattis (2019), "Dated language phylogenies shed light on the history of Sino-Tibetan", Proceedings of the National Academy of Sciences of the United States of America, 116 (21): 10317–10322.

[7] Wikipedia article on Rice: Origins in China

[8] Domestic rice grown in China 9400 years ago (the Smithsonian) 

[9] Wikipedia article on Kra-Dai languages

[10] Razib Khan, "Indian Ancestry In Southeast Asia Is Older Than Statistical Genetic Tests Suggest" (2020) citing Wibhu Kutanan, et al., "Reconstructing the human genetic history of mainland Southeast Asia: insights from genome-wide data from Thailand and Laos" (2020) bioRxiv

[11] Wikipedia article on Austro-Tai languages.

[12] McCall et al., "Ancient Genomics Reveals Four Prehistoric Migration Waves into Southeast Asia" (2018) bioRxiv.

[13] Wikipedia article on Rice: Southeast Asia