Homo Longi Were Denisovans

The archaic hominin skull from China provisionally classified as a member of the species Homo Longi has been linked to Denisovan DNA and proteins. This also makes it possible to know what a Denisovan looked like as shown in the image below.

The connection has been suspected, but not proven, for some time.

Population Replacement In The Columbian Highlands

In Europe, the first farmers of Europe, derived from Western Anatolian farmers, largely replaced Europe's original hunter-gatherers (who actually show continuity between the periods before and immediately after the Last Glacial Maximum), and in turn, received very substantial genetic admixture from late Copper Age/early Bronze Age Indo-Europeans from more or less where Ukraine is today. This diluted both first farmer ancestry, and the already highly diluted European hunter-gather ancestry that was admixed into those first farmer populations. In some places, like Britain, the population replacement of first farmers by Indo-Europeans was nearly complete.

Something similar apparently happened in East and Southeast Asia.

A new study established that the Americas did not break from this pattern, with some of its early agriculturists replacing pre-existing hunter-gatherer populations in a similarly genocidal pattern. If anything, this replacement was even more complete.

Sometime between 4000 BCE and 0 CE, in the Columbian highlands, probably coinciding with a new archaeological culture whose artifacts appear around 1000 BCE to 800 BCE, a millennium after maize cultivation began around 1800 BCE (but possibly before the full blown ceramic culture emerged), a clade of indigenous South American hunter-gatherers (with ancestry dating back to the initial wave of human settlement of South America) were replaced by a different group of indigenous South Americans.

The 1800 BCE date is from A. Gómez, et al., "A Holocene pollen record of vegetation change and human impact from Pantano de Vargas, an intra-Andean basin of Duitama, Colombia." 145 Rev. Palaeobot. Palynol. 143–157 (2007) (full paper available here), and really only definitively points to deforestation and Amaranth cultivation at that point in the highlands of Columbia.

From Wikipedia.

The population that replaced them, which is genetically linked to the speakers of Chibchan languages and probably originated in Central America, has remained the dominant population of the region in genetic continuity with their ancestors since this population replacement occurred, although later populations admixed with them and brought new languages in some parts of the region. 

There is no evidence that anyone from the pre-agricultural, pre-ceramic culture that was replaced in the Columbian highlands survived, or even significantly admixed with surviving populations.

The new agriculturalist culture did not really come into its own archaeologically until 1000 BCE to 800 BCE, so we can't know for sure if the replacement took place suddenly (although the lack of admixture between the new and old populations suggests that it did) or more gradually, or how long after maize cultivation, a thousand years earlier than this culture's pots appeared, the population replacement happened. 

Conservatively, it happened in some short time period between 1800 BCE and 800 BCE (about 3,000 to 4,000 years after it happened in Europe). Realistically, it probably happened on the later side of that time range when other components of the emerging farmer culture, like pottery and possibly other key domesticated plants and/or animals, joined with improved maize cultivation to give rise to a technologically dominant new culture.

The introduction and discussion sections of a new study released May 28, 2025 in the journal Scientific Advances by Kim-Louise Krettek, et al., explain that:

Genetic studies on ancient and present-day Indigenous populations have substantially contributed to the understanding of the settlement of the Americas. Those studies revealed that the population ancestral to non-Arctic Native Americans derives from a genetic admixture between ancient East Asian and Siberian groups somewhere in North-East Asia before 20,000 years before the present (yr B.P.). Around 16,000 yr B.P., after its arrival in North America, this genetic ancestry split into two lineages known as northern Native American and southern Native American. While northern Native American ancestry is largely confined to ancient and current populations of North America, the southern Native American lineage expanded further south and constitutes the main ancestry component of ancient and present-day Indigenous South Americans. 

Southern Native American ancestry diversified within North America into at least three sublineages, i.e., one related to the Clovis-associated Anzick-1 individual from western Montana (USA), one found in ancient California Channel Islands individuals and the last one representing the main ancestry source of modern-day Central and South Americans.  

Each of these sublineages provided a wave of ancestry into the gene pool of ancient South Americans. Individuals from Chile and Brazil dating back to around 12,000 and 10,000 yr B.P., respectively, were more genetically related to the Anzick-1 genome than individuals from the eastern Southern American coast, Southern Cone and the Andes from 10,000 yr B.P. onward. In addition, the California Channel Islands ancestry was found in the Central Andes by 4200 yr B.P. and became widespread in the region thereafter. However, the exact timing of these population movements into the southern subcontinent remains largely unsolved to date. 

The Isthmo-Colombian area, stretching from the coast of Honduras to the northern Colombian Andes, is critical to understanding the peopling of the Americas. Besides being the land bridge between North and South America, it is at the center of the three major cultural regions of Mesoamerica, Amazonia, and the Andes. At the time of European contact, the region was inhabited by a complex mosaic of human populations, mainly speakers of Chibchan, Chocoan, Carib, and Arawakan languages. 

Among those populations, those who were speakers of Chibchan languages were the most widespread in the region in terms of demography, cultural diversity, and territorial distribution. Chibchan is a language family with multiple, highly distinct branches, many of which are still spoken today in different regions of the Isthmo-Colombian area. The homeland and antiquity of the Proto-Chibchan language and the ancestor of all Chibchan languages remain subjects of debate. High intrafamily variation in terms of lexicon and grammar suggests that the language family is ancient and began diversifying several thousand years ago. The locus of that incipient diversification, however, is still uncertain. Most scholars believe that this protolanguage began to diversify in Lower Central America, where the largest number of these languages is spoken today. However, some evidence suggests that Proto-Chibchan might have originated in South America and then diversified in Central America at a much later date. 

Genetic studies of ancient and present-day Isthmo-Colombian Indigenous populations revealed a distinctive ancestry component primarily associated with speakers of Chibchan languages. However, whereas mitochondrial DNA (mtDNA) studies suggested a migration of Chibchan-related ancestry from Central America into Colombia and Venezuela, genome-wide studies favored an opposite, south-to-north population movement. According to the latter model, speakers of Chibchan languages from Central America are not direct descendants of the first settlers in the region but, instead, derive from a more recent back migration from South to Central America. 

The southernmost region of the Isthmo-Colombian area is the Altiplano Cundiboyacense (hereafter Altiplano). This plateau with an average altitude of 2600 m in the Eastern Cordillera of the Colombian Andes was inhabited by ancient hunter-gatherer groups from the Late Pleistocene. During the Early and Middle Holocene phases of the Preceramic period (~11,500 to 4000 yr B.P.), populations on the Altiplano underwent multiple cultural transformations, most notably increased sedentism and a transition from a hunter-gatherer subsistence to the introduction of horticultural practices and forest management. However, it was not until the early Late Holocene, ~3800 yr B.P., that the first clear evidence of maize cultivation appeared. 

During the subsequent Formative period (~3000 to 1000 yr B.P.), a distinct type of pottery emerged on the Altiplano that is referred to as the Herrera ceramic complex, also known in the literature as the Herrera period (2800 to 1200 yr B.P.). It is still highly debated whether Herrera-associated groups on the Altiplano derived from an in situ development of local hunter-gatherers or were a consequence of population dispersals into the region. 

Around 1200 yr B.P., a cultural phase, known as the Muisca period, began on the Altiplano and lasted until the imposition of the Hispanic Colonial regime in the mid-16th century. Most available evidence is suggestive of population continuity with the preceding Herrera period. The Muisca period is characterized by a relatively continuous process of demographic growth, development of agriculture and trade, and social and political complexification. These factors played a considerable role in shaping the Muisca culture and gave rise to the Chibchan-speaking population that dominated the Altiplano until European colonization. 

While several studies have reported mtDNA data from ancient Colombian individuals, genome-wide data from this region are still entirely lacking to date. In this study, we generated mtDNA and genome-wide data of 21 ancient individuals from two areas of the Altiplano (Bogotá plateau and Los Curos). Our data, spanning a time transect between around 6000 and 500 yr B.P., provide an opportunity to explore several key questions: 

(i) Which southern Native American genetic ancestry do Preceramic individuals from the Altiplano derive from? 

(ii) Were the cultural transformations associated with the Herrera and Muisca periods accompanied by migrations and demographic changes? 

(iii) How is the genetic ancestry observed in speakers of Chibchan languages related to that of ancient individuals from the Altiplano? 

(iv) What are the genetic relationships between the generated ancient genomes and the existing genomic data of present-day Indigenous communities from Colombia and neighboring regions?

In this study, we generated genome-wide data from 21 individuals spanning a time transect of almost 6000 years from the Altiplano, which represents the southern edge of the Isthmo-Colombian area. Our findings contribute to a better understanding of the population history of this area, a key region in the peopling process of South America. We show that the hunter-gatherer population from the Altiplano dated to around 6000 yr B.P. lack the genetic ancestry related to the Clovis-associated Anzick-1 genome and to ancient California Channel Island individuals, suggesting their affiliation to the southern Native American lineage that became the primary source of ancestry of South Americans by 9000 yr B.P. 

However, unlike ancient genomes from the Andes and the Southern Cone that are associated with the same wave of ancestry, the analyzed Preceramic individuals from Colombia do not share distinct affinity with any ancient or modern-day population from Central and South America studied to date. Colombia_Checua_6000BP can thus be modeled as a previously undescribed distinct lineage deriving from the radiation event that gave rise to multiple populations across South America during its initial settlement. 

The cultural transition between the Preceramic and Herrera periods is associated with a seemingly complete replacement of the local genetic profile. This challenges the model where local hunter-gatherers developed in situ as suggested by morphometric studies and an ancient mtDNA time transect. Instead, our study provides evidence for a major genetic turnover on the Altiplano occurring after 6000 yr B.P. but before 2000 yr B.P. Since the mechanisms and precise temporal scale of this replacement event remain uncertain, we cannot directly associate it with the emergence of maize cultivation ~3800 yr B.P. However, our data do support the archaeological hypothesis that the introduction of pottery associated with the Herrera ceramic complex was mediated through population dispersals. 

Our results show that the incoming genetic ancestry on the Altiplano is related to ancient and present-day populations speaking Chibchan languages from Central America. This can be explained most parsimoniously by Chibchan-related migrations from Lower Central America to South America, rather than back-migration to the isthmus. 

A separate study found evidence for a previously unknown south-to-north expansion of Chibchan-related ancestry from Lower Central America into the Mayan territories of Belize by 5600 yr B.P. Therefore, rather than modeling Central American populations associated with Chibchan languages as deriving from a mixture between North and South American ancestries, these results are consistent with an origin of Chibchan-related ancestries in Lower Central America, followed by bidirectional gene flow toward both Meso- and South America. This model of an original “Chibchan homeland” in Central America is supported not only by mtDNA studies on present-day populations who speak Chibchan languages but also from linguistic observations, indicating that the isthmus region exhibits the highest diversity within this language family. 

From an archaeological perspective, the Chibchan-related ancestry is first identified in 2000-year-old individuals associated with Herrera ceramics. In addition, previously sequenced Ceramic-associated individuals from Venezuela dated to 2400 yr B.P. also showed a high affinity to Central American populations speaking Chibchan languages. Despite the similar ancestry pattern and temporal frame, the two populations do not appear to form a simple sister group. This could be in line with linguistic evidence that suggests multiple, distinct Chibchan language expansions into South America, but additional studies will be necessary to further clarify this issue. 

After the arrival of the Chibchan-related ancestry, which completely reshaped the genetic landscape of the region, we find evidence of a long period of genetic continuity in the genetic profile of the local populations for over 1500 years (from at least 2000 to 500 yr B.P.). The stability in genetic ancestry encompasses the end of the Herrera period and the beginning of the Muisca period. This points to a scenario in which populations speaking languages from the Chibchan lineage would have settled the Altiplano before the emergence of traits normally associated with the Muisca culture, and it shows that this cultural transition took place without a substantial migration from regions with a distinct genetic ancestry composition. In addition, such a genetic continuity extends through different cultural phases within the Muisca period and persists until the Spanish colonization. Colonial linguistic documentation established that Muisca people spoke a now extinct Chibchan language. Our findings not only confirm their genetic link with speakers of Chibchan languages from Central America but also suggest that ancestral Chibchan languages, possibly basal to the Magdalenic branch that gave rise to the documented Muisca language, might have already been spoken on the Altiplano during the pre-Muisca Herrera period. 

While the representation of Indigenous populations in our dataset is certainly not exhaustive, the observed spatial pattern in the genetic affinity of post-2000 yr B.P. ancient Colombians with present-day Indigenous populations raises questions regarding the uneven distribution of populations speaking Chibchan languages across the Isthmo-Colombian area at the time of the Hispanic colonization, also referred to as a Chibchan “archipelago”. 

One possible explanation is that this distribution resulted from separate dispersals from Central America to different locations of northern South America rather than a single expansion wave, as suggested by the internal branching pattern of the Chibchan language family. However, it is also possible that the initial spread was more widespread and got later fragmented by post-Chibchan migration and admixture events. The observation that Chibchan-affiliated populations from northern Colombia have a significantly reduced genetic affinity to post-2000–yr B.P. ancient Colombians than to Lower Central Americans supports the role of population admixture in shaping the genetic diversity of northern South America.

Also, while the earlier South American hunter-gatherer clade that went extinct probably dated to the founding wave of the modern humans in South America, they did not have notable Australasian or Melanesian ancestry, disfavoring the existence of a dramatically genetically distinct founding population of the Americas that preceded the main founding wave of modern humans and has Australasian or Melanesian genetic affinities that ancient.

Chinese Script v. English Statistics

The average number of strokes in a Chinese character is roughly 12.

The average number of strokes in a letter of the English alphabet is 1.9.

The average number of syllables in an English word is 1.66 (and 5 letters).

The average number of syllables in a Chinese word is roughly 2 (and 24 strokes).

The average number of words in an English sentence is 15-20.

The average number of words in a Chinese sentence is 25 (ballpark figure; see here)

Chinese has more than 100,000 characters.

English has 26 letters.

Total number of English words; over 600,000 (Oxford English Dictionary)

Total number of Chinese words: a little over 370,000 (Hànyǔ dà cídiǎn 漢語大詞典 [Unabridged dictionary of Sinitic])

From Language Log.

Quantum Gravity Can't Violate CPT

The reasoning in this article is sound and means that quantum gravity should preserve Charge-Parity-Time (CPT) symmetry, not just in an emergent low energy approximation, but at all energy scales.

CPT symmetry is at the heart of the Standard Model of particle physics and experimentally very well tested, but expected to be broken in some approaches to quantum gravity. It thus becomes pertinent to explore which of the two alternatives is realized: (i) CPT symmetry is emergent, so that it is restored in the low-energy theory, even if it is broken beyond the Planck scale, (ii) CPT symmetry cannot be emergent and must be fundamental, so that any approach to quantum gravity, in which CPT is broken, is ruled out. 

We explore this by calculating the Renormalization Group flow of CPT violating interactions under the impact of quantum fluctuations of the metric. We find that CPT symmetry cannot be emergent and conclude that quantum-gravity approaches must avoid the breaking of CPT symmetry. 

As a specific example, we discover that in asymptotically safe quantum gravity CPT symmetry remains intact, if it is imposed as a fundamental symmetry, but it is badly broken at low energies if a tiny amount of CPT violation is present in the transplanckian regime.

Astrid Eichhorn, Marc Schiffer, "No dynamical CPT symmetry restoration in quantum gravity" arXiv:2506.12001 (June 13, 2025).

Ancient UP Agriculture

Drone based LIDAR has made a major new find in North America:

A new study has found that a thickly forested sliver of Michigan’s Upper Peninsula is the most complete ancient agricultural location in the eastern United States. The Sixty Islands archaeological site is recognized as the ancestral home of the Menominee Nation. Known to the members of the tribe as Anaem Omot (Dog’s Belly), the area is a destination of pilgrimage, where remains of the settlement date to as far back as 8,000 B.C.

Located along a two-mile stretch of the Menominee River, Sixty Islands is defined by its cold temperatures, poor soil quality and short growing season. Although the land has long been considered unsuitable for farming, an academic paper published on Thursday in the journal Science revealed that the Menominee’s forbears cultivated vast fields of corn and potentially other crops there.

From the New York Times.

I'll update if time permits after reading the full paper.

The Latest Neutrino Mixing Data

The work to measure the mixing properties of neutrinos continues. A normal mass ordering and near maximal CP violation continues to be preferred.

T2K has made improved measurements of three-flavor neutrino mixing with 19.7(16.3) × 10^20 protons on target in (anti-)neutrino-enhanced beam modes. A new sample of muon-neutrino events with tagged pions has been added at the far detector, increasing the neutrino-enhanced muon-neutrino sample size by 42.5%. In addition, new samples have been added at the near detector, and significant improvements have been made to the flux and neutrino interaction modeling. T2K data continues to prefer the normal mass ordering and upper octant of sin^2θ(23) with a near-maximal value of the charge-parity violating phase with best-fit values in the normal ordering of δCP=−2.18+1.22−0.47, sin^2θ(23)=0.559+0.018−0.078 and Δm(23)^2=(+2.506+0.039−0.052)×10^−3 eV^2.

The T2K Collaboration, "Results from the T2K experiment on neutrino mixing including a new far detector μ-like sample" arXiv:2506.05889 (June 6, 2025).

The preference for the upper quadrant was about 2.3 sigma, and the preference for a normal ordering was about 2.7 sigma. With regard to CP-violation:

The data preferred values of δCP close to −π/2 radians, excluding values around +π/2 radians at >3σ, and excluding the CP-conserving values of 0 and π at 90% confidence. However [with further analysis] . . . the result to no longer exclude δCP = π at 90% confidence. The result was statistically limited and can be expected to improve as more data is accumulated.

New World Y1K Demographic Trends

Viewing event 350 years apart as part of the same trend is further in the direction of lumping than I'm comfortable with, but it is good to have a perspective on the pre-Columbian Americas that isn't static, with the implicit assumption that it was always the way it was when Europeans first encountered it.

[A] team led by archaeologist Robert Kelly of the University of Wyoming has studied this period using a previously assembled database of some 100,000 radiocarbon dates from across the United States. (See “Save the Dates.”) They used the dates to track population movements and demographic decline during this turbulent era, which was marked by drought, warfare, and disease. “We knew in a piecemeal fashion that these conditions drove demographic changes in different regions,” says Kelly. “But the radiocarbon data gives us a powerful new tool to understand population decline across the continent.”

After dividing the United States into 18 watersheds, the team analyzed the frequency of radiocarbon dates in each region and demonstrated that a cascading demographic collapse began in the central Rockies around a.d. 800 and later accelerated in multiple regions of central North America after 1150. The team’s analysis shows that the population of watersheds in California, the Pacific Northwest, the Great Lakes, and New England actually grew during the same period. This was likely because groups made their way from regions stricken by drought and warfare toward the coasts. Nonetheless, the radiocarbon data suggests that the overall Native American population declined by at least 30 percent from its peak before 1150.

From Archaeology Magazine.

The Latest Wide Binary Paper Shows Newtonian Behavior

The Wide Binary analysis debate continues. This paper doesn't see MOND-like behavior in wide binaries.

Of the 44 pairs observed with HARPS, 27% show sign of multiplicity or are not suitable for the test, and 32 bona-fide WBs survive our selection. Their projected separation s is up to 14 kAU, or 0.06 parsec. We determine distances, eccentricities and position angles to reproduce the velocity differences according to Newton's law, finding reasonable solutions for all WBs but one, and with some systems possibly too near pericenter and/or at too high inclination. Our (limited) number of WBs does not show obvious trends with separation or acceleration and is consistent with Newtonian dynamics. We are collecting a larger sample of this kind to robustly assess these results.

From R. Saglia (2025).

Conformal Gravity As A Dark Matter Alternative

One proposed modification of General Relativity that has been proposed to explain dark matter phenomena is Conformal Gravity, which basically preserves angles in transformations adding an additional symmetry to GR.

A new paper suggests that Conformal Gravity fails in elliptical galaxies.

As an alternative gravitational theory to General Relativity (GR), the Conformal Gravity (CG) has recently been successfully verified by observations of Type Ia supernovae (SN Ia) and the rotation curves of spiral galaxies. 

The observations of galaxies only pertain to the non-relativistic form of gravity. In this context, within the framework of the Newtonian theory of gravity (the non-relativistic form of GR), dark matter is postulated to account for the observations. On the other hand, the non-relativistic form of CG predicts an additional potential: besides the Newtonian potential, there is a so-called linear potential term, characterized by the parameter γ∗, as an alternative to dark matter in Newtonian gravity. 

To test CG in its non-relativistic form, much work has been done by fitting the predictions to the observations of circular velocity (rotation curves) for spiral galaxies. 

In this paper, we test CG with the observations from elliptical galaxies. Instead of the circular velocities for spiral galaxies, we use the velocity dispersion for elliptical galaxies. By replacing the Newtonian potential with that predicted by non-relativistic form of CG in Hamiltonian, we directly extend the Jeans equation derived in Newtonian theory to that for CG. By comparing the results derived from the ellipticals with that from spirals, we find that the extra potential predicted by CG is not sufficient to account for the observations of ellipticals. Furthermore, we discover a strong correlation between γ∗ and the stellar mass M∗ in dwarf spheroidal galaxies. This finding implies that the variation in γ∗ violates a fundamental prediction of Conformal Gravity (CG), which posits that γ∗ should be a universal constant.

Li-Xue Yue, Da-Ming Chen, "Test of conformal gravity as an alternative to dark matter from the observations of elliptical galaxies" arXiv:2506.03955 (June 4, 2025).

The Missing Baryons Are Probably In Deep Space

The missing baryon problem is that we can't find where all of the ordinary matter that should exist is located. New studies such as this one strongly suggest that it is mostly spread diffusely between galaxies.

Fast radio bursts (FRBs) are emerging as powerful cosmological probes for constraining the baryon fraction in the intergalactic medium (IGM), offering a promising avenue to address the missing baryon problem. In this paper, we analyze constraints on the IGM baryon fraction (fIGM) using 92 localized FRBs, incorporating a corrected probability distribution function for the IGM dispersion measure within three different cosmological models. We find that variations in the underlying cosmological model have a negligible impact on the inferred values of fIGM. While the NE2001 Galactic electron density model yields slightly higher fIGM values compared to the YMW16 model, the results are consistent within the 1σ confidence level. Additionally, there is no statistically significant evidence for redshift evolution in fIGM. Our analysis constrains fIGM to the range 0.8∼0.9, providing strong support for the idea in which the majority of the missing baryons reside in the diffuse IGM.

Yang Liu, Yuchen Zhang, Hongwei Yu, Puxun Wu, "Constraining the Baryon Fraction in the Intergalactic Medium with 92 localized Fast Radio Bursts" arXiv:2506.03536 (June 4, 2025).

The Final Fermilab Muon g-2 Measurement

From this morning's seminar: The new experimental result from Fermilab Runs 1-6 combined is:

0.01165920705(148) which is 127 parts per billion. This exceeded their goal of 140 ppb.

Including the Brookhaven result in the global experimental average only slightly tweaks this result (by 10 * 10^-12 higher) because the average is inverse error weighted and the Brookhaven result has four times more uncertainty and is only modestly higher itself. Runs 4-6 whose results were announced today, slightly pulled up the total value. It's result was 5 * 10^-12 higher than the overall average.

A crude breakdown of the sources of the uncertainty in the final results was as follows (the 125 ppb uncertainty total differs from everything else that puts it at 127 ppb).

The 127 ppb uncertainty in the experimental result (i.e. 0.01165920705(148)) compares to a 530 ppb uncertainty in the 2025 White Paper predicted value of muon g-2 which is a(SM)(μ) = 116592033(62) × 10^−11 (530 ppb).

The experimental value minus the SM prediction is (375 ± 637) × 10^−12 which is a difference of about 0.6 sigma, which is a very strong global confirmation of the Standard Model of Particle Physics at low to moderate energies.

The world average value minus the SM prediction is (385 ± 637) × 10^−12 which is also a difference of about 0.6 sigma, which is a very strong global confirmation of the Standard Model of Particle Physics at low to moderate energies.

Most likely, the discrepancy is mostly due to the leading order hadronic vacuum polarization (LO HVP) calculation in the Standard Model prediction being about 0.5% low in a calculation with a ± 0.9% uncertainty.

This result disfavors the hypothetical X17 particle, since a 16.9 MeV fundamental boson would very likely have a significant effect on the anomalous magnetic moment of the 105.7 MeV muon.

The link to the Fermilab paper reporting this is here. It's abstract states:

A new measurement of the magnetic anomaly aµ of the positive muon is presented based on data taken from 2020 to 2023 by the Muon g−2 Experiment at Fermi National Accelerator Laboratory (FNAL). This dataset contains over 2.5 times the total statistics of our previous results. From the ratio of the precession frequencies for muons and protons in our storage ring magnetic field, together with precisely known ratios of fundamental constants, we determine aµ = 1165920710(162) × 10^−12 (139ppb) for the new datasets, and aµ = 1165920705(148) × 10^−12 (127ppb) when combined with our previous results. The new experimental world average, dominated by the measurements at FNAL, is aµ(exp) = 1165920715(145) × 10^−12 (124ppb). The measurements at FNAL have improved the precision on the world average by over a factor of four.

More On 22,000 Year Old Footprints In New Mexico

According to a new study, ancient footprints and drag marks at White Sands National Park in New Mexico suggest the earliest known North Americans used wooden travois-like "vehicles" to transport goods, and possibly even people, 22,000 years ago.

This account is based upon:

A travois is crafted from one or more wooden poles and is one of the simplest prehistoric vehicles. Although these devices likely played vital roles in the lives of ancient peoples, they have low preservation potential in the archaeological record. Here we report linear features associated with human footprints, some of which are dated to ∼22,000 years old, preserved in fine-grained sediments at White Sands National Park (New Mexico, USA). Using a range of examples, we identify three morphological types of trace in late Pleistocene sediments. Type I features occur as single, or bifurcating, narrow (depth > width) grooves which extend in planform from 2 to 50 m in length and trace either straight, gently curved or more irregular lines. They are associated with human footprints, which are truncated longitudinally by the groove and are not associated with other animal tracks. Type II examples are broader (width > depth) and form shallow runnels that typically have straight planforms and may truncate human footprints to one side. Type III examples consist of two parallel, equidistant grooves between 250 and 350 mm apart. They trace gently curving lines that can extend for 30+ m. Human footprints are associated with these features and may occur between, and to the side of, the parallel grooves. We review a range of possible interpretations including both human and non-human explanations and conclude that the most parsimonious explanation is that they represent drag marks formed by travois consisting of a single pole or crossed poles pulled by humans, presumably during the transport of resources. As such this unique footprint record may represent one of the earliest pieces of evidence for the use of transport technology.

Bennett, M. R., et al., "The ichnology of White Sands (New Mexico): Linear traces and human footprints, evidence of transport technology?" Quaternary Science Advances, 17(100274), 100274 (2025) (open access) doi:10.1016/j.qsa.2025.100274

The dating was confirmed in this 2023 paper:

Editor’s summary 

Traditionally, researchers believed that humans arrived in North America around 16,000 to 13,000 years ago. Recently, however, evidence has accumulated supporting a much earlier date. In 2021, fossilized footprints from White Sands National Park in New Mexico were dated to between 20,000 and 23,000 years ago, providing key evidence for earlier occupation, although this finding was controversial. Pigati et al. returned to the White Sands footprints and obtained new dates from multiple, highly reliable sources (see the Perspective by Philippsen). They, too, resolved dates of 20,000 to 23,000 years ago, reconfirming that humans were present far south of the ice sheets during the Last Glacial Maximum. 

—Sacha Vignieri 

Abstract 

Human footprints at White Sands National Park, New Mexico, USA, reportedly date to between ~23,000 and 21,000 years ago according to radiocarbon dating of seeds from the aquatic plant Ruppia cirrhosa. These ages remain controversial because of potential old carbon reservoir effects that could compromise their accuracy. We present new calibrated 14C ages of terrestrial pollen collected from the same stratigraphic horizons as those of the Ruppia seeds, along with optically stimulated luminescence ages of sediments from within the human footprint–bearing sequence, to evaluate the veracity of the seed ages. The results show that the chronologic framework originally established for the White Sands footprints is robust and reaffirm that humans were present in North America during the Last Glacial Maximum.

Jeffrey S. Pigati, et al., "Independent age estimates resolve the controversy of ancient human footprints at White Sands" 382 (6666) Science 73-75 (October 5, 2023).

A Belated 14th Birthday For This Blog

The first post on this blog was made on May 22, 2011. In the first 14 years of this blog, which ended on May 21, 2025, I made 2805 posts, which is just slightly more than 200 posts per year. 

Unlike its sister blog, Wash Park Prophet, the number of posts per year has been fairly consistent for this entire time period.

I have made minor updates to my two conjectures pages to reflect new developments and correct errors of spelling, grammar, and style, and to enhance clarity.

Human Migration To South America

A new, rather mediocre, study that emphasizes genetic diversity in South America tends to track the New World settlement paradigm rather closely. Honestly, for a major new paper in a major scientific journal, it adds surprisingly little to existing knowledge. 

Uncontacted or recently contacted populations in Amazonia and Papuans are the least genetically diverse.  This study, by not mentioning it at all, seems to disfavor the hypothesis of ancient Papuan/Australasian ancestry in Amazonian populations in South America, although this is a key issue in South American population history that really should have been at least discussed in this paper, even if it couldn't reach a definitive conclusion regarding this point with its own data.

The paper also, implicitly suggests (consistent with prior research), that progenitor modern human populations that left foot prints in New Mexico about 23,000 years ago made only an indiscernible impact, if any, on the primary founding population of the Americas starting around 14,000 years ago. A better discussion of how the genetic profiles of Native American in North America differs from those in South America would also have been welcome. It seems to suggest a somewhat older than conventional population history for the founding population of North America, but does so with little meaningful discussion of North American population genetics.

The lack of data from the Atlantic coast of South America and the very thin data from the Amazon, even compared to prior studies of South American genetics, also suggests to me that it is possible that there could be five rather than four main branches of South American settlement. Even if one can't find "pure" indigenous South American ancestry in this region, it should be possible from large databases of modern populations in this region from prior studies, which is home to a large share of all South Americans, to make strong inferences about it from individuals modern populations in the region with indigenous admixture.

There is also too little discussion of the population genetic impact of the Columbian Exchange on either the main different population groups it infers in South America or on the strength of the inferences it is making. We would expect this event in the last 500 years to cause strong fitness based selection, and possibly hard selective sweeps on HLA genetic diversity, an rate unprecedented in the previous 13,500 years, and HLA genetic diversity is one of the important pieces of data that the study examines. But this question isn't elevated or focused upon by the authors.

Editor’s summary

From our origins in Africa, humans have migrated and settled across the world. Perhaps none of these migrations has been the subject of as much debate as the expansion into and throughout the Americas. Gusareva et al. used 1537 whole-genome sequenced samples from 139 populations in South America and Northeast Eurasia to shed light on the population history of Native Americans. Collected as a part of the GenomeAsia 100K consortium, analysis of these data showed that there are four main ancestral lineages that contributed to modern South Americans. These lineages diverged from each other between 10,000 and 14,000 years ago, and this analysis reveals more details of the population history dynamics in these groups. —Corinne Simonti

Abstract

Genome sequencing of 1537 individuals from 139 ethnic groups reveals the genetic characteristics of understudied populations in North Asia and South America. Our analysis demonstrates that West Siberian ancestry, represented by the Kets and Nenets, contributed to the genetic ancestry of most Siberian populations. West Beringians, including the Koryaks, Inuit, and Luoravetlans, exhibit genetic adaptation to Arctic climate, including medically relevant variants. 

In South America, early migrants split into four groups—Amazonians, Andeans, Chaco Amerindians, and Patagonians—~13,900 years ago. Their longest migration led to population decline, whereas settlement in South America’s diverse environments caused instant spatial isolation, reducing genetic and immunogenic diversity. These findings highlight how population history and environmental pressures shaped the genetic architecture of human populations across North Asia and South America.

Abstract

INTRODUCTION

During the late Pleistocene, humans expanded across Eurasia and eventually migrated to the Americas. Those who reached Patagonia, at the southern tip of South America, completed the longest migration out of Africa.

RATIONALE

The extent of basal divergences, admixture, and degrees of isolation among Indigenous North Eurasian and Native South American populations remain debated, with most insights derived from genome-wide genotyping data. This study aims to deepen our understanding of the ancient dynamics that shaped contemporary populations in North Eurasia and the Americas. By using large-scale whole-genome sequencing of 1537 individuals from 139 ethnic groups in these regions, we examined population structures, elucidated prehistoric migrations, and explored the influence of past environmental factors on the diversification of human populations.

RESULTS

Advances in large-scale genomic sequencing have considerably enhanced our understanding of the genetic ancestry of human populations across North Eurasia and South America. Our analysis reveals that all contemporary Siberians, as well as some Northeast Europeans and Central Asians, share ancestry with the West Siberian groups, represented by the Kets and Nenets. Their ancestors were widespread across Siberia 10,000 years ago (ya), but now these groups face population decline by 73.6% and are becoming a minority.

The populations of west Beringia, including the Koryaks, Inuit, and Luoravetlans, are the most genetically distinct from other Siberians. These groups have adapted to Arctic conditions with genetic variations related to lipid metabolism, thermogenesis, sensory perception, and the regulation of reproductive and immune functions. 

We were not able to identify a specific Siberian group as the direct ancestors of Native Americans owing to deep divergence and limited genetic continuity. However, west Beringian populations remain closely related to Native Americans. Koryaks and Inuit show 5 and 28% Native American ancestry, respectively, owing to gene flow between 700 and 5100 ya.

We estimated the split time of Native South Americas into Amazonians, Andeans, Chaco Amerindians, and Patagonians to have occurred 13,900 to 10,000 ya. Migration and settlement across the continent led to population isolations due to geographic boundaries and a reduction in their genetic diversity, particularly affecting immune genes, such as the human leukocyte antigen (HLA) genes. Over the past 10,000 years, all four Native South American lineages have experienced population declines ranging from 38 to 80%. This dramatic decline, combined with the loss of traditional lifestyles, cultural practices, and languages, has pushed some Indigenous communities, such as the Kawésqar, to the brink of extinction.

CONCLUSION

The migration to an uninhabited continent of South America through the narrow Isthmus of Panama resulted in a founder effect among Native South Americans, leading to reduced genetic diversity compared with that of Indigenous populations of North Eurasia. Over 13,900 years, geographic barriers within the continent further isolated Indigenous groups, subsequently reducing genetic diversity. These groups faced a profound challenge with the arrival of European colonists in the 1600s, who introduced new adversities that threatened their long-standing endurance. 

Genetic ancestry and nucleotide diversity. 

Colors represent genetic ancestries estimated by whole-genome sequencing data of contemporary human populations. Countries having no data remained empty. Circle size indicates the average nucleotide diversity of each population.

Elena S. Gusareva, et al., "From North Asia to South America: Tracing the longest human migration through genomic sequencing" 388 (6748) Science (May 15, 2025) DOI: 10.1126/science.adk5081

The introduction in the body text puts the findings in context:

The late Pleistocene saw the expansion of humans into the frigid lands of Eurasia. The earliest known presence of modern humans in northern Eurasia at latitudes greater than 50°N was around 45,000 years ago (ya) in West Siberia, and by 31,600 ya, humans had migrated far east toward Beringia, north of the Arctic Circle at 71° N. The earliest human remains identified in this region are two Yana Rhinoceros Horn Site individuals that, despite their extreme Northeast Siberian geographical location, show substantial genetic relatedness to early West Eurasian hunter-gatherers. 

The Upper Palaeolithic people who initially populated Northeast Siberia were then replaced by arrivals from East Asia. The Kolyma1 remains, excavated near the Chukotka region and dated as being from 9800 ya, demonstrate greater affinity to East Asians and present-day west Beringian populations, such as Koryaks and Luoravetlans (also known as Chukchi), as well as to Native Americans. The linguistic and cultural diversity of present-day Indigenous Siberian populations is mirrored by the complex patterns of admixture, as shown by genome-wide genotype data analysis. This genetic structure in Siberians, comprising several ancestral components, is estimated to have emerged within the past 10,000 to ~3400 years. The Western Eurasian ancestry component presented in a majority of Indigenous Siberian populations is not the result of postcolonial Russian admixture but one of the ancient components dating back to 12,500 to 25,000 ya in different Siberian populations. Among the present-day populations of Northeast Eurasia, the Koryaks from the Kamchatka Peninsula and the Inuit from Chukotka show the closest genetic relatedness to Native North Americans. 

The migration of humans to the Americas occurred when the Bering Land Bridge was still open, with the earliest human remains in North America found in the Clovis burial site in western Montana dating back to around 12,700 ya. However, recent evidence suggests human presence in North America from at least 23,000 ya. By the time the Ice-Free Corridor opened up and became suitable for travel around 13,300 ya, humans were already widely dispersed in North America, likely owing to Pacific coastal migration routes. The divergence between northern and southern Native American populations is estimated to have occurred between 17,500 and 14,600 ya south of the North American ice sheets, according to modern and ancient genomic analyses. The rapid dispersal of humans in South America is suggested by archaeological records, which date the earliest human presence in North Patagonia, the southernmost tip of the Americas, to 14,500 ya. However, the number of basal divergences, founding populations, admixture, and the degrees of isolation among Native South American populations remain a subject of debate, with most of the current understanding coming from analyses of genome-wide genotyping or ancient DNA data. Additionally, fine-scale population genetic studies based on high-coverage whole-genome sequencing datasets for contemporary populations of North Eurasia and South America have not been performed to date.

The body text's discussion of population decline in South America (which has been continuous and not just entirely due to the Columbian exchange) is notable since rare haplotypes and ancestrally informative genes are strongly prone to being purged in periods of declining population (while happens only rarely in expanding populations). Consistent with this these populations have low genetic diversity.

The population split time estimates also suggest that the divergence of the four Native South American lineages occurred over a short period, from 13,900 to 10,000 ya. All four lineages show a continuous population decline. However, the Andean highlanders managed to maintain their population size during the rise of maize horticulture around 5200 to 3700 ya. It has declined by 45.1% since then (Ne from 1771 to 972), whereas Chaco Amerindians have declined by 46.89% (Ne from 1448 to 769) since 10,000 ya. Amazonians and especially Patagonians have seen a dramatic decrease in population size over the past 10,000 years, with declines of 66.59% (Ne from 1368 to 457) and 79.68% (Ne from 1171 to 238), respectively.

To assess the impact of population decline on genetic diversity, we estimated genome-wide runs of homozygosity (ROHs) segments. In Native South Americans, the average number and length of ROHs segments estimated across all populations were 10.5 and 1.3 times higher than those in Africans (Yoruba) and 3.75 and 1.2 times higher than those in Northeast Europeans, respectively. The highest abundance of extended ROHs was observed in Amazonians, Patagonian Kawésqar, and Chaco Amerindians and was similar to that seen in isolated island populations, such as the Andamanese and Baining. This high homozygosity is likely the result of the founder effect due to long-distance migration and/or population isolation. The strong correlation between the average total number of ROHs and the average nucleotide diversity (Pearson correlation coefficient r = –0.78) supports the idea that the extended homozygosity is a result of population history.

The body text of the discussion section notes that:

Our analysis of whole-genome datasets also allowed us to infer the split time between North Eurasians and Native Americans, which occurred between 26,800 and 19,300 ya. This finding is consistent with estimates based on the recently published paleontological discovery of human footprints in North America (south-central New Mexico) dating back to 23,000 and 21,000 ya, as well as with other genetic studies, despite differences in the cohorts that were investigated. 

A previous study of ancient genomes suggests limited genetic continuity in Beringia, as the most recent Arctic colonization occurred 6000 ya. Therefore, it is likely that the first ancestors of the Native Americans in this region were replaced by the most recent wave of migration. We could not identify a specific Siberian group as direct Native American ancestors among the contemporary Indigenous populations in our dataset. However, we show that west Beringian populations, such as Inuit, Luoravetlans, and Koryaks, are genetically the closest to Native Americans. Moreover, we revealed the gene flow from Native Americans back to Inuit and Koryaks in Chukotka and the Kamchatka Peninsula between 700 to 5100 ya. Our analyses also demonstrated the shared ancestry between the west Beringian populations and contemporary Native North Americans, particularly the Chipewyan from Canada. This genetic relatedness is consistent with the PCA results. These findings are in line with previous reports that describe multiple waves of Northeast Asian gene flow into North Americans, including Neo-Inuit lineages. 

By using our genome sequencing data from diverse Native South Americans, we have discovered that the simultaneous split of the four Native South American ancestral lineages occurred between 13,900 and 10,000 ya from a common ancestral population in Mesoamerica. This rapid radial dispersal and the establishment of sedentary settlements across South America are supported by previous genetic studies and the archaeological findings of early technologies (such as stone tools) that indicate regional cultural diversification in South America from at least 13,000 ya. This divergence occurred shortly after the split of the ancestral Native American lineages into northern and southern branches, which happened between 17,500 and 14,600 ya south of the North American ice sheets. By the time the Ice-Free Corridor was fully opened 14,300 to 13,300 ya during the abrupt warming, humans were already widely dispersed in North America. 

Our study shows that the human migration across South America resulted in population splits with a loss of genetic diversity due to founder effects. Geographical and environmental boundaries caused population isolation and further enhanced the genetic homogenization, similar to islander populations. The demographic history has greatly influenced the Patagonian Kawésqar, whose ancestors migrated the farthest distance out of Africa. They have the smallest effective population size and one of the smallest genetic distances between community members. It has been reported that contemporary Native Patagonians (including the Kawésqar) show the highest genetic affinity to ancient Patagonian maritime individuals that lived 1000 ya, indicating genetic continuity in the region. Our study cannot provide evidence for the reported back migration from the Southern Cone along South America's Atlantic coast owing to a lack of data on east coastal Native South American populations. 

Our study also suggests that close genetic relatedness in Indigenous populations, along with reduced heterozygosity in HLA genes, may impact antigen recognition ability to new unexposed pathogens. In combination with socioeconomic factors and limited access to medical care, this could pose a potential health risk. High–pathogen load regions, such as Southeast Asia, tend to have a higher diversity of promiscuous HLA-DRB1 alleles, which allows them to respond to a wider range of extracellular pathogens. However, emerging evidence that divergent allele advantage (a mechanism where the HLA genotypes present a broader set of epitopes) and increase in HLA alleles promiscuity level may counterplay the effect of loss of heterozygosity in HLA genes. Our work highlights a noteworthy implication for future research in population-based disease cohorts: Epitope-binding repertoire studies are essential for identifying the dynamic effects of limited HLA diversity on disease susceptibility. 

Access to the vastness of the South American continent was constrained by the relatively small landmass of the Isthmus of Panama. Consequently, migrating groups could only inhabit the continent from a singular direction, limiting the genetic diversity of human individuals. This ultimately led to the emergence of the four ancestries described in our analysis. Although Indigenous groups managed to maintain their populations for over 13 millennia with minimal interaction with other groups, their endurance faced a critical challenge with the arrival of the initial colonists in the 1600s.

The Pros And Cons Of MOND

In my view, this analysis is too critical and misses key achievements of MOND-derived theories in the cosmology realm (while doing to little to compare MOND to the competition). But it is still a notable article.

Modified Newtonian Dynamics (MOND) is an alternative to the dark matter hypothesis that attempts to explain the "missing gravity" problem in astrophysics and cosmology through a modification to objects' dynamics. Since its conception in 1983, MOND has had a chequered history. Some phenomena difficult to understand in standard cosmology MOND explains remarkably well, most notably galaxies' radial dynamics encapsulated in the Radial Acceleration Relation. But for others it falls flat -- mass discrepancies in clusters are not fully accounted for, the Solar System imposes a constraint on the shape of the MOND modification seemingly incompatible with that from galaxies, and non-radial motions are poorly predicted. An experiment that promised to be decisive -- the wide binary test -- has produced mainly confusion. This article summarises the good, the bad and the ugly of MOND's observational existence. I argue that despite its imperfections it does possess ongoing relevance: there may yet be crucial insight to be gleaned from it.

Harry Desmond, "Modified Newtonian Dynamics: Observational Successes and Failures" arXiv:2505.21638 (May 27, 2025) (8 pages) (invited contribution to the 2025 Gravitation session of the 59th Rencontres de Moriond).

About Chirality Oscillation In Neutrinos

The weak force, and neutrinos which only interact via the weak force, are the most chiral parts of the Standard Model of Particle Physics. I am deeply skeptical of any beyond the Standard Model physics proposal which contains right handed neutrinos.

It has been claimed in a number of publications that neutrinos can exhibit chirality oscillations. In this note we discuss the notion of chirality and show that chiral neutrino oscillations in vacuum do not occur. We argue that the incorrect claims to the contrary resulted from a failure to clearly discriminate between quantum fields, states and wave functions. We also emphasize the role played in the erroneous claims on the possibility of chirality oscillations by the widely spread misconceptions about negative energies.

Evgeny Akhmedov, "On chirality and chiral neutrino oscillations" arXiv:2505.20982 (May 27, 2025).

Muon g-2 White Paper Updated

Next week, on June 2, 2025, the final round of experimental results for muon g-2 will be announced. Ahead of that there is an update of the Muon g-2 White paper that got the Standard Model predicted value for muon g-2 badly wrong. The revised version acknowledges this mistake and remarks that the revised prediction is spot on with the experimental value of muon g-2. 

The revised state of the art Standard Model prediction will still be about four times less precise than the experimentally measured value after June 3, 2025, however. The predicted value's uncertainty is greater than the experimentally measured uncertainty almost entirely due to the uncertainties in the QCD (quantum chromodynamics a.ka. strong force) calculation of the leading order hadronic vacuum polarization contribution to muon g-2. 

These uncertainties are hard to reduce, since the values of the fundamental physical constants relevant to the calculation, like the value of the strong force coupling constant's value and the light quark masses, have uncertainties of the same magnitude as the total HVP calculation.

The consistency of the experimental value of muon g-2 and the value for it predicted in the Standard Model, is a broad global high precision measurement of the consistency of all parts of the low to medium energy scale Standard Model of Particle Physics with the real world.

The consistency which exists strongly disfavors the discovery of any beyond the Standard Model physics at a next generation particle collider (even though there one could cherry pick potential modifications of the Standard Model that haven't already been ruled out by other high energy physics data, that could have no impact on muon g-2, or would have an impact that is too negligible to discern).

This summary chart appears in the introduction to the paper:

A chart from the conclusion shows how the old White Paper Standard Model prediction for muon g-2 and the new one differ.

We present the current Standard Model (SM) prediction for the muon anomalous magnetic moment, aμ, updating the first White Paper (WP20) [1]. 

The pure QED and electroweak contributions have been further consolidated, while hadronic contributions continue to be responsible for the bulk of the uncertainty of the SM prediction. Significant progress has been achieved in the hadronic light-by-light scattering contribution using both the data-driven dispersive approach as well as lattice-QCD calculations, leading to a reduction of the uncertainty by almost a factor of two. 

The most important development since WP20 is the change in the estimate of the leading-order hadronic-vacuum-polarization (LO HVP) contribution. A new measurement of the e+e−→π+π− cross section by CMD-3 has increased the tensions among data-driven dispersive evaluations of the LO HVP contribution to a level that makes it impossible to combine the results in a meaningful way. At the same time, the attainable precision of lattice-QCD calculations has increased substantially and allows for a consolidated lattice-QCD average of the LO HVP contribution with a precision of about 0.9%. 

Adopting the latter in this update has resulted in a major upward shift of the total SM prediction, which now reads a(SM)(μ) = 116592033(62) × 10^−11 (530 ppb). When compared against the current experimental average based on the E821 experiment and runs 1-3 of E989 at Fermilab, one finds a(exp)(μ)−a(SM)(μ) = 26(66) × 10^−11, which implies that there is no tension between the SM and experiment at the current level of precision. The final precision of E989 is expected to be around 140 ppb, which is the target of future efforts by the Theory Initiative. The resolution of the tensions among data-driven dispersive evaluations of the LO HVP contribution will be a key element in this endeavor.

R. Aliberti, et al., "The anomalous magnetic moment of the muon in the Standard Model: an update" arXiv:2505.21476 (May 27, 2025) (188 pages).

The conclusion explains that:

By comparing the uncertainties of Eq. (9.5) and Eq. (9.4) it is apparent that the precision of the SM prediction must be improved by at least a factor of two to match the precision of the current experimental average, which will soon be augmented by the imminent release of the result based on the final statistics of the E989 experiment at Fermilab. We expect progress on both data-driven and lattice methods applied to the hadronic contributions in the next few years. Resolving the tensions in the data-driven estimations of the HVP contribution is particularly important, and additional experimental results combined with further scrutiny of theory input such as from event generators should provide a path towards this goal. Further progress in the calculation of isospin-breaking corrections, from both data-driven and lattice-QCD methods, should enable a robust SM prediction from τ data as well. For lattice-QCD calculations of HVP continuing efforts by the world-wide lattice community are expected to yield further significant improvements in precision and, hopefully, even better consolidation thanks to a diversity of methods. The future focus will be, in particular, on more precise evaluations of isospin-breaking effects and the noisy contributions at long distances. 

The role of aµ as a sensitive probe of the SM continues to evolve. We stress that, even though a consistent picture has emerged regarding lattice calculations of HVP, the case for a continued assessment of the situation remains very strong in view of the observed tensions among data-driven evaluations. New and existing data on e+e− hadronic cross sections from the main collaborations in the field, as well as new measurements of hadronic τ decays that will be performed at Belle II, will be crucial not only for resolving the situation but also for pushing the precision of the SM prediction for aµ to that of the direct measurement. This must be complemented by new experimental efforts with completely different systematics, such as the MUonE experiment, aimed at measuring the LO HVP contribution, as well as an independent direct measurement of aµ, which is the goal of the E34 experiment at J-PARC. The interplay of all these approaches, various experimental techniques and theoretical methods, may yield profound insights in the future, both regarding improved precision in the SM prediction and the potential role of physics beyond the SM. Finally, the subtleties in the evaluation of the SM prediction for aµ will also become relevant for the anomalous magnetic moment of the electron, once the experimental tensions in the determination of the fine-structure constant are resolved.

Basically, the conclusion calls for scientists to get to the bottom of why the experiments that were used as a basis for the first White Paper prediction were wrong, and hopes against all reasonable expectations that the process of doing that will reveal new physics.

The paper's claim that the uncertainty in the Standard Model prediction can be cut dramatically "in the next few years" is pretty much wishful thinking.

This paper doesn't address in detail how completely this result ruled out new physics, but further papers by unaffiliated scientists will no doubt do just that not long after the new experimental results are released next week. 

A Renormalizable Tweak To General Relativity Proposed

A new proposal to tweak general relativity, if it is correct (and it is consistent with observations), would break down the main barrier to developing a working quantum gravity theory.

Asymptotically Weyl-invariant gravity (AWIG) is further developed within the Palatini formalism as a power-counting renormalizable alternative to general relativity (GR). An expression for the dimensionless exponent n(R) is derived based on dynamical dimensional reduction. We show that this version of AWIG naturally resolves several theoretical issues normally associated with the Palatini formalism. 

A falsifiable prediction regarding the frequency of gravitational waves from binary black hole mergers is made. A preliminary analysis of gravitational wave GW150914 yields a maximum tension of 0.9 sigma with GR and marginally favours AWIG. A similar analysis of gravitational wave GW151226 yields a maximum tension of 2.7 sigma with GR and favours AWIG more significantly.

Daniel Coumbe, Aria Rahmaty, "A Falsifiable Alternative to General Relativity" arXiv:2505.15399 (May 21, 2025).

A New Z Boson Mass Measurement At The LHC

The Large Hadron Collider has measured the Z boson mass of 91.18842 ± 0.00093 GeV, which is about twice as precise as the previous world average, and slightly higher (by about one part per  217,114).

This compares to the LEP value from the year 2006 of 91.1876 ± 0.0021 GeV, the CDF value from Tevatron from the year 2022 of 91.1923 ± 0.0071 GeV, and the PDF world average of those two values of 91.1880 ± 0.0020 GeV. The new LHC measurement is consistent with the previous world average and with the two measurements that went into forming that world average.

The new inverse error weighted global average Z boson mass should be about 91.18829 ± 0.0008 GeV.

The first dedicated Z-boson mass measurement at the LHC with Z→μ+μ− decays is reported. The dataset uses proton-proton collisions at a centre-of-mass energy of 13 TeV, recorded in 2016 by the LHCb experiment, and corresponds to an integrated luminosity of 1.7 fb−1. A template fit to the μ+μ− mass distribution yields the following result for the Z-boson mass, m(Z) = 91184.2 ± 8.5 ± 3.8 MeV, where the first uncertainty is statistical and the second systematic. This result is consistent with previous measurements and predictions from global electroweak fits.

LHCb Collaboration, "Measurement of the Z-boson mass" arXiv:2505.15582 (May 21, 2025).

BBN Tensions And The LambdaCDM Model

Stacy McGaugh's latest post at his Triton Station blog explains why Big Bang Nucleosynthesis (BBN) poses a challenge to the LambdaCDM Standard Model of Cosmology. 

Basically, BBN favors a lower primordial baryon density as of the time of nucleosynthesis, while the cosmic microwave background (CMB) astronomy data when interpreted in light of the LambdaCDM model in a model-dependent way, favors a primordial baryon density as of the time of nucleosynthesis that is two times higher.

But, there are lots of technical issues that make the 4-5 sigma discrepancy less obviously an irreconcilable conflict than it might otherwise seem to be.