Wednesday, February 21, 2024

The Population Genetics Of India

A new preprint has no really shocking results, but provides many refinements to our previous understanding of historical genetics in India. Credit where credit is due for acknowledging the existing of early waves of modern humans in India even though they haven't left much of a genetic trace in modern populations. It also seems that there was secondary Neanderthal admixture in South Asia in addition to the admixture that took place in the Middle East.
India has been underrepresented in whole genome sequencing studies. We generated 2,762 high coverage genomes from India––including individuals from most geographic regions, speakers of all major languages, and tribal and caste groups––providing a comprehensive survey of genetic variation in India. With these data, we reconstruct the evolutionary history of India through space and time at fine scales. 
We show that most Indians derive ancestry from three ancestral groups related to ancient Iranian farmers, Eurasian Steppe pastoralists and South Asian hunter-gatherers. 
We uncover a common source of Iranian-related ancestry from early Neolithic cultures of Central Asia into the ancestors of Ancestral South Indians (ASI), Ancestral North Indians (ANI), Austro-asiatic-related and East Asian-related groups in India. 
Following these admixtures, India experienced a major demographic shift towards endogamy, resulting in extensive homozygosity and identity-by-descent sharing among individuals. 
At deep time scales, Indians derive around 1-2% of their ancestry from gene flow from archaic hominins, Neanderthals and Denisovans. By assembling the surviving fragments of archaic ancestry in modern Indians, we recover ∼1.5 Gb (or 50%) of the introgressing Neanderthal and ∼0.6 Gb (or 20%) of the introgressing Denisovan genomes, more than any other previous archaic ancestry study. Moreover, Indians have the largest variation in Neanderthal ancestry, as well as the highest amount of population-specific Neanderthal segments among worldwide groups. 
Finally, we demonstrate that most of the genetic variation in Indians stems from a single major migration out of Africa that occurred around 50,000 years ago, with minimal contribution from earlier migration waves
Together, these analyses provide a detailed view of the population history of India and underscore the value of expanding genomic surveys to diverse groups outside Europe.
Elise Kerdoncuff, et al., "50,000 years of Evolutionary History of India: Insights from ∼2,700 Whole Genome Sequences"  (February 17, 2024).

Aztec Human Sacrifice

"For the re-consecration of the Great Pyramid of Tenochtitlan in 1487, the Aztecs reported that they killed about 80,400 prisoners over the course of four days. According to Ross Hassig, author of Aztec Warfare, "between 10,000 and 80,400 persons" were sacrificed in the ceremony."
From Wikipedia.

Recall that this city had a population of 200,000 non-prisoner residents, which while huge for the time, is only about three times greater than the number of people sacrificed.

Monday, February 19, 2024

The XENONnT Dark Matter Experiment

The XENONnT dark matter experiment will have about ten times more sensitivity to WIMPS (a type of dark matter candidate) than the previous XENON1T. 

I fully expect that it will produce a null result without detecting any traces of dark matter that don't turn out to be false positives in the end.

The Black Hole - Galaxy Mass Correlation

The mass of the central supermassive black hole of a galaxy and the inferred mass of its dark matter halo (and the total mass of a galaxy) are correlated, although not terribly tightly. 

Some of the scatter in the relationship may be due to measurement error as central supermassive black hole mass, inferred dark matter halo mass, and galaxy total mass are all challenging to measure.


Archaeologists have finally found examples of and deciphered a Bronze Age alloy associated with the lost city of Atlantis called "Orichalcum."

This insight, in my view, this is quite consistent with my leading candidate for Atlantis which is the capital city of Tartessos. Their Paleo-Hispanic language is by default an isolate but seems closer to Basque than to any Indo-European language, despite some Celtic borrowings and the use of a Phoenician derived script and their culture's adoption of Phoenician religious practices.

A group of naval archeologists has uncovered two hundred ingots spread over the sandy seafloor near a 2,600-year-old shipwreck off the coast of Sicily. The ingots were made from orichalcum, a rare cast metal that ancient Greek philosopher Plato wrote was from the legendary city of Atlantis.

A total of 39 ingots (metal set into rectangular blocks) were, according to Inquisitr, discovered near a shipwreck. BBC reported that another same metal cache was found. 47 more ingots were found, with a total of 86 metal pieces found to date.

The wreck was discovered in 1988, floating about 300 meters (1,000 ft) off the coast of Gela in Sicily in shallow waters. At the time of the shipwreck Gela was a rich city and had many factories that produced fine objects. Scientists believe that the pieces of orichalcum were destined for those laboratories when the ship sank.

Sebastiano Tusa, Sicily’s superintendent of the Sea Office, told Discovery News that the precious ingots were probably being brought to Sicily from Greece or Asia Minor.

Tusa said that the discovery of orichalcum ingots, long considered a mysterious metal, is significant as “nothing similar has ever been found.” He added, “We knew orichalcum from ancient texts and a few ornamental objects.”

According to a Daily Telegraph report, the ingots have been analyzed and found to be made of about 75-80 percent copper, 14-20 percent zinc and a scattering of nickel, lead, and iron.

The name orichalucum derives from the Greek word oreikhalkos, meaning literally “mountain copper” or “copper mountain”. According to Plato’s 5th century BC Critias dialogue, orichalucum was considered second only to gold in value, and was found and mined in many parts of the legendary Atlantis in ancient times.

Plato wrote that the three outer walls of the Temple to Poseidon and Cleito on Atlantis were clad respectively with brass, tin, and the third, which encompassed the whole citadel, “flashed with the red light of orichalcum”.

The interior walls, pillars, and floors of the temple were completely covered in orichalcum, and the roof was variegated with gold, silver, and orichalcum. In the center of the temple stood a pillar of orichalcum, on which the laws of Poseidon and records of the first son princes of Poseidon were inscribed.

For centuries, experts have hotly debated the metal’s composition and origin.

According to the ancient Greeks, orichalcum was invented by Cadmus, a Greek-Phoenician mythological character. Cadmus was the founder and first king of Thebes, the acropolis of which was originally named Cadmeia in his honor.

Orichalcum has variously been held to be a gold-copper alloy, a copper-tin, or copper-zinc brass, or a metal no longer known. However, in Vergil’s Aeneid, it was mentioned that the breastplate of Turnus was “stiff with gold and white orachalc” and it has been theorized that it is an alloy of gold and silver, though it is not known for certain what orichalcum was.

Orichalcum is also mentioned in the ‘Antiquities of the Jews’ (1 st century AD) – Book VIII, sect. 88 by Josephus, who stated that the vessels in the Temple of Solomon were made of orichalcum (or a bronze that was like gold in beauty).

Today, some scholars suggest that orichalcum is a brass-like alloy, which was made in antiquity the process of cementation, which was achieved through the reaction of zinc ore, charcoal and copper metal in a crucible.

The latest discovery of the orichalcum ingots that had laid for nearly three millennia on the seafloor may finally unravel the mystery of the origin and composition of this enigmatic metal.

From Archaeology World

Thursday, February 15, 2024

A Combined LHC Top Quark Mass Measurement

A new combined LHC top quark mass measurement, the excludes the latest highest energy LHC runs, however, is available. The two sigma range for the top quark pole mass in this combination is 171.86-173.18 GeV with a best fit value of 172.52 GeV. This result is essentially the same as the Particle Data Group value, but cuts the uncertainty in half.
A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The data sets used correspond to an integrated luminosity of up to 5 and 20^−1 of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak t-channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is m(t) = 172.52 ± 0.14 (stat) ± 0.30 (syst) GeV, with a total uncertainty of 0.33 GeV.
CMS and ATLAS Collaborations, "Combination of measurements of the top quark mass from data collected by the ATLAS and CMS experiments at s√=7 and 8 TeV" arXiv:2402.08713 (February 13, 2024).

Mach's Principle Considered

The possibility that inertia could be an emergent phenomena derived from gravity, and that gravity itself might even be an emergent phenomena from quantum physics and thermodynamics, is seductive but elusive.
The question of where the inertial properties of matter come from has been open for a long time. Isaac Newton considered inertia an intrinsic property of matter. Ernst Mach held a different view whereby the inertia of a body comes from its interaction with the rest of the universe. This idea is known today as Mach's principle. We discuss Mach's principle based on transactional gravity, the recently developed completion of the entropic gravity program by the physics of quantum events induced by transactions. A consequence of the analysis is a fundamental relation between the gravitational constant G and the total mass in the causal universe, derived by means of entropic principles. 
A. Schlatter, R. E. Kastner, "A Note on the Origin of Inertia" arXiv:2402.09365 (February 14, 2024).

Galaxy Formation Was Underway 600 Million Years After The Big Bang

The James Webb Space Telescope (JWST) has seen proto-galaxy formation about 600 million years after the Big Bang (about 13.2 billion years ago), which is shortly after galaxy formation should be possible.
The most distant galaxies detected by JWST are assembling in a Universe that is less than 5% of its present age. At these times, the progenitors of galaxies like the Milky Way are expected to be about 10,000 times less massive than they are now, with masses quite comparable to that of massive globular clusters seen in the local Universe. Composed today primarily of old stars and correlating with the properties of their parent dark matter halos, the first globular clusters are thought to have formed during the earliest stages of galaxy assembly. 
In this article we explore the connection between star clusters and galaxy assembly by showing JWST observations of a strongly lensed galaxy at zspec = 8.304, exhibiting a network of massive star clusters (the 'Firefly Sparkle') cocooned in a diffuse arc. 
The Firefly Sparkle exhibits the hallmarks expected of a future Milky Way-type galaxy captured during its earliest and most gas-rich stage of formation. The mass distribution of the galaxy seems to be concentrated in ten distinct clusters, with individual cluster masses that straddle the boundary between low-mass galaxies and high-mass globular clusters. The cluster ages suggest that they are gravitationally bound with star formation histories showing a recent starburst possibly triggered by the interaction with a companion galaxy at the same redshift at a projected distance of ∼2 kpc away from the Firefly Sparkle. The central star cluster shows nebular-dominated spectra consistent with high temperatures and a top-heavy initial mass function, the product of formation in a very metal poor environment. Combined with abundance matching that suggests that this is likely to be a progenitor of galaxies like our own, the Firefly Sparkle provides an unprecedented case study of a Milky Way-like galaxy in the earliest stages of its assembly in only a 600 million year old Universe.
Lamiya Mowla, et al., "The Firefly Sparkle: The Earliest Stages of the Assembly of A Milky Way-type Galaxy in a 600 Myr Old Universe" arXiv:2402.08696 (February 12, 2024).

Wednesday, February 14, 2024

New Cosmology Bounds On Neutrino Mass

In V. Ghirardini, et al., "The SRG/eROSITA All-Sky Survey: Cosmology Constraints from Cluster Abundances in the Western Galactic Hemisphere" (Feb. 13, 2023), a major new dataset constrains the possible range of the sum of the three neutrino masses. 

The best fit value of the lightest neutrino mass eigenstate (considering both cosmology and oscillation data) is 1 meV, with a range of 0-5 meV at the 95% confidence level.

7.3. Constraints on the νCDM Cosmology 

Albeit their small size and mass, the left-handed neutrinos influence the formation of large-scale structure by hindering the formation of small-scale haloes and leaving their imprints on the gravitational collapse process. The relative number of low-mass haloes in cluster abundance measurements can shed light on the summed masses of three left-handed neutrino species. With the discovery of neutrino oscillations between different flavors, electron, muon, and tau neutrinos, it has become clear that neutrino eigenstates must have non-zero mass (Fukuda et al. 1998; Ahmad et al. 2002). The theoretical predictions indicate a hierarchical relation between the mass eigenstates of the three species of neutrinos; however, their ordering in mass remains elusive. Based on the normal neutrino mass hierarchy model, the third neutrino mass eigenstate, associated with the tau neutrino, is the heaviest among the three. This is followed by the eigenstate of the muon neutrino, which has an intermediate-mass, and that of the electron neutrino, i.e., mτ >mµ >me. The ordering is swapped in the inverted mass hierarchy model such that mτ < mµ<me. Recent constraints of their summed mass show that the lower limit provided by the oscillation experiments depends on the assumed underlying hierarchy model (Qian &Vogel 2015; Esteban et al. 2020), with a lower limit of mν >0.059eV for normal mass hierarchy and mν>0.101eV for the inverted hierarchy models (Tanabashi et al. 2018; Athar et al. 2022). Constraining the summed mass to <0.1eV implies that the inverted model is excluded. The ground-based experiments through beta decay of tritium imply the sum to be mν <1.1eV at 90% confidence level, a narrow range for the allowed summed mass (Aker et al. 2019). The space-based Planck CMB measurements provide a similar upper limit of mν<0.26 eV at 95% confidence level (Planck Collaboration et al. 2020a). As we probe the largest collapsed objects in the Universe, galaxy clusters, the cluster number counts can be used to constrain the summed masses of the neutrinos. To do so, we allow the sum of neutrino masses to be free in the cosmology pipeline, with a uniform prior of U(0eV,1eV). We stress that our lower limit is set to 0eV instead of a value of 0.059eV (Tanabashi et al. 2018) adopted by the PlanckCMB 2020 analysis. As the lower limit on the neutrino mass depends on the assumptions of the neutrino mass model, we do not make any prior assumptions about its value and adopt uniform priors on its value to avoid this parameter from affecting our posterior distributions. The cosmological constraints with free neutrino mass components are; 

Ωm=0.29+0.01 −0.02 



mν<0.22eV (95% CL) (36) 

These results are visualized in Fig.11. The upper limit to the sum of neutrino masses is mν <0.22eV. Our results represent the tightest limits on the sum of neutrino masses from cluster abundance experiments; for instance, the SPT-SZ sample results in an upper limit of <0.74eV(95% confidence interval) (Bocquet et al. 2019). The eROSITA upper limits on the neutrino masses are competitive and informative at a similar precision with thePlanckCMB2020 measurements, mν < 0.26eV (95%CL) (Planck Collaboration et al. 2020a). We verify that the values of the Ωm and σ8 remain statistically consistent when mν is allowed to be non-zero, see Fig.B.4. We find that eRASS1 and PlanckCMBνCDM parameters are consistent at the 2.0σ level.

Given the excellent agreement with PlanckCMB measurements, the resulting cosmological parameters of two probes can be combined in a statistically meaningful way, enabling a much tighter measurement of the impact of massive neutrinos on both the formation and evolution of the large-scale structure and on the primordial density field. As performed in the ΛCDM analysis, we combine our results with the PlanckCMB constraints to break the degeneracy between Ωm and σ8. We obtain;




mν<0.11eV (95% CL) (37) 

Simultaneously fitting our measurements with Planck CMB 2020 likelihood chains yield an upper limit of mν < 0.11eV, consistent with the results in the literature results with marginally consistent with the inverted mass hierarchy model, which requires mν > 0.101eV. 

As a final step, we combine eRASS1 cluster abundance measurements through importance sampling with PlanckCMB and with the lower limits from ground-based oscillation experiments (Tanabashi et al. 2018). In the case of a normal mass hierarchy scenario, the summed masses of mν=0.08 +0.03 −0.02eV, while assuming the inverted mass hierarchy model, we obtain summed masses of mν =0.12 +0.03 −0.01eV. 

It is interesting to point out, from Fig.C.1, that the constraints on the mass of the lightest neutrino eigenstates are similar: for both mass hierarchy we obtain m(light) = 0.01 +0.020 −0.005 eV (68% confidence intervals) or with an upper limit of 0.04 eV.

Tuesday, February 13, 2024

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."

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)

Monday, February 12, 2024

Cultural Diversity In The European Upper Paleolithic

The earliest modern humans in Europe were not monolithic culturally. Similar studies examined Neolithic Europe.
Mechanisms governing the relationship between genetic and cultural evolution are the subject of debate, data analysis and modelling efforts. Here we present a new georeferenced dataset of personal ornaments worn by European hunter-gatherers during the so-called Gravettian technocomplex (34,000–24,000 years ago), analyse it with multivariate and geospatial statistics, model the impact of distance on cultural diversity and contrast the outcome of our analyses with up-to-date palaeogenetic data. We demonstrate that Gravettian ornament variability cannot be explained solely by isolation-by-distance. Analysis of Gravettian ornaments identified nine geographically discrete cultural entities across Europe. While broadly in agreement with palaeogenetic data, our results highlight a more complex pattern, with cultural entities located in areas not yet sampled by palaeogenetics and distinctive entities in regions inhabited by populations of similar genetic ancestry. Integrating personal ornament and biological data from other Palaeolithic cultures will elucidate the complex narrative of population dynamics of Upper Palaeolithic Europe.
Jack Baker, Solange Rigaud, Daniel Pereira, Lloyd A. Courtenay & Francesco d’Errico, "Evidence from personal ornaments suggest nine distinct cultural groups between 34,000 and 24,000 years ago in Europe", Nature Human Behaviour (January 29, 2024).

Science magazine discusses the paper:
For ice age hunters in Europe some 30,000 years ago, styles of ornaments including amber pendants, ivory bangles, and fox tooth beads may have also signaled membership in a particular culture, researchers report today in Nature Human Behaviour. The study, which compared thousands of handcrafted beads and adornments from dozens of widespread sites, suggests at least nine distinct cultures existed across Europe at this time.

“It’s a landmark paper,” says archaeologist Peter Jordan, a professor at Lund University and Hokkaido University who was not involved with the study. For centuries, archaeologists have tried to distinguish ancient peoples based on similarities in their artifacts. In recent years, however, sorting populations by ancient genetic group has at times overshadowed the archaeology. Here, “The archaeology strikes back,” Jordan says. “[It’s] showing that we can generate new narratives that also use a very rigorous, quantitative approach to the study of material traditions.”

The earliest known ornamental beads—seashells punched for stringing—come from early Homo sapiens sites dated to between 150,000 to 70,000 years ago in Africa and the eastern Mediterranean coast. Unlike knives or awls, ornaments offer no obvious survival functions. Instead, anthropologists think they likely communicated one’s traits and achievements, such as reaching adulthood, hunts completed, or family lines. “It’s a kind of common language or common discourse with other individuals in that group,” Jordan says. Many scholars think the invention of beads indicates that our ancestors had also evolved the capacity for symbolism and language.

Between 34,000 and 24,000 years ago, foragers in Europe fashioned beads from a diverse array of materials including ivory, bone, human and animal teeth, and flashy stones. These communities also painted caves and crafted so-called Venus figurines resembling voluptuous women, while coping with the glaciers and frigid temperatures of the last ice age. Despite the “horrendous” conditions, their artistic expressions suggest these people “weren’t just surviving—they were thriving,” says University of Bordeaux archaeologist and doctoral student Jack Baker.

As part of his dissertation, Baker aimed to find out. In 2020, he began to comb the literature for every ornament reported from 112 Gravettian burial and habitation sites excavated between the mid-1800s to 2010s. He classified thousands of beads into 134 types based on their raw materials and other design elements.

Next, he compared bead types between sites and found that places with similar accoutrements clustered geographically. Nine distinct groups emerged. People at the easternmost sites, such as Kostenki along the Don River in Russia, seemed to prefer ornaments made of stone and red deer canines, whereas those in northwest Europe wore tube-shaped shells of Dentalium mollusks.

Because of the widespread locations of figurines and similarly fashioned spearpoints, archaeologists traditionally clumped all these people into a single culture known as the Gravettian, spread from what is now Portugal to Russia. More recently, though, analyses of subtle differences in stone toolmaking, funerary practices, and ancient DNA have suggested more than one group roamed the continent at this time. Could the diverse beads found from this period result from different cultures?

The Gravettian was not “one monolithic thing,” Baker says, but instead included several culturally distinct groups, each hewing to their own ornamental traditions. His team thinks these groups crossed paths: The team’s computer simulations suggest the patterns of bead differences most resemble a scenario in which neighboring groups occasionally swapped styles or territories. Perhaps ivory-adorned people gazed across a river and spotted a band decked in vibrant seashells: “They would have been like, ‘Oh my God! Someone completely different!’” Baker imagines. Despite those differences, some cultural and genetic exchange seems to have occurred.

DNA from human remains excavated from Gravettian sites identified two major genetic lineages in Europe at the time: one situated around the Pyrenees Mountains, and another in central and Eastern Europe. The bead-based groups mostly accorded with these populations, but added more subdivisions and a few twists, including data for places that have yet to yield ancient DNA, such as Moldova and southern Spain.

For groups for which genetic data are available, being closely related didn’t necessarily mean they wore matching jewelry. Ancient groups living in modern-day Italy, for example, shared ancestry but some buried their dead with cowrie shells and others put fish vertebrae and ivory beads into graves. In contrast, in what’s now France and Belgium, individuals with different ancestry sported similar ornaments. These results imply somewhat porous, shifting cultural boundaries, and perhaps some adornment differences for people with special social roles.

It makes sense that some peoples with shared ancestry may develop different cultural identities, reflected by their fashions and other behaviors—and conversely, that distinct genetic groups can blend culturally, says Cosimo Posth, a paleogeneticist at the University of Tübingen who was not involved with the new study. “It’s expected that genes don’t always match the culture that you’re carrying.”

Tuesday, February 6, 2024

A Higgs Boson Anomaly?

Scientists analyzing all available Higgs boson data from the Large Hadron Collider (LHC) observe a 2 sigma tension between the Standard Model prediction for the coupling of quarks and leptons to the Higgs boson and the observed values of those couplings, but see no tension between the predicted and observed couplings of W and Z bosons to the Higgs boson.

This isn't all that significant. Two sigma tensions disappear all the time with later more precise measurements. But it is something to be on the lookout for in future measurements of Higgs boson properties.
We perform global fits of the Higgs boson couplings to the full Higgs datasets collected at the LHC with the integrated luminosities per experiment of approximately 5/fb at 7 TeV, 20/fb at 8 TeV, and up to 139/fb at 13 TeV. Our combined analysis based on the experimental signal strengths used in this work and the theoretical ones elaborated for our analysis reliably reproduce the results in the literature. 
We reveal that the LHC Higgs precision data are no longer best described by the SM Higgs boson taking account of extensive and comprehensive CP-conserving and CP-violating scenarios found in several well-motivated models beyond the SM. Especially, in most of the fits considered in this work, we observe that the best-fitted values of the normalized Yukawa couplings are about 2σ below the corresponding SM ones with the 1σ errors of 3-5%. On the other hand, the gauge-Higgs couplings are consistent with the SM with the 1σ errors of 2-3%. Incidentally, the reduced Yukawa couplings help to explain the excess of the H→Zγ signal strength of 2.2±0.7 recently reported by the ATLAS and CMS collaborations.
Yongtae Heo, Dong-Won Jung, Jae Sik Lee, "Higgs Precision Analysis of the Full LHC Run 1 and Run 2 Data" arXiv:2402.02822 (February 5, 2024).

Ratio Of Proton Mass To Electron Mass Unchanged For 11.5 Billion Years

A recent paper observed that the proton-electron mass ratio has been unchanged since at least z=3.025 (about 11.5 billion years ago). The observed ratio of the difference in this ratio to the ratio itself at that redshift is(0.120±0.144)× 108. This is consistent with null hypothesis of zero at the one sigma level. All previous efforts to determine changes in physical constants in the distant past using astronomy observations have likewise seen no statistically significant difference.

Here is a chart converting redshift z to look back time (i.e. how long ago that z occurred). Note the shift from z amount in the left body of the table, to look back time in billions of years in the right body of the table, starting at z=6.

How Many Atomic Isotopes Are Possible?

The chemical properties of and element classification of an atom, i.e. composite structures made out of protons and neutrons bound in a nucleus by the residual strong force, is determined by the number of protons it has, but its isotopes depend upon the total number of protons and neutrons in its nucleus.

There isn't an obvious maximum number of isotopes. But isotopes with more nucleons (i.e. protons plus neutrons) decay because the residual strong force has limited range and can only bind so many nucleons.

Theorists have now calculated, at least in the case of isotopes with an even number of protons (i.e. how many even-Z nuclei are possible), how many different possible bound isotopes there are and have found that there are 4829 possible bound even-Z nuclei with 8 to 120 protons, of which we have experimentally measured masses for about a quarter of them. The atomic element with the most protons ever observed as of 2018 was element 118, called Oganesson (which is in the noble gas column of the periodic table even though it is a solid at room temperature), with a mass in atomic mass units of about 300. It has a half-life of 0.7 ms. This study didn't examine the number of possible isotopes with more than 120 protons.

Assuming that there are an order of magnitude similar number of odd-Z nuclei that are possible, and adding in the isotopes with Z=1 to Z=7, there are about 10,000 possible atomic isotopes with bound nuclei and 120 or fewer protons.

The model used also predicts the mass of each isotope, and for the 1244 isotopes for even-Z atoms for which experimental data is available, the root mean square difference between the experimental data and the predicted values is 1.477 MeV which is very good considering that the mass of a proton is about 938.3 MeV, the mass of a neutron is 940.6 MeV, the mass of an electron is 0.511 MeV (atoms are a bit heavier than the sum of the masses of their protons, neutrons, and electrons due to their binding energy). An atomic mass unit has a mass of about 931.5 MeV.

For example, Gadolinium with Z=64 in the middle of the range studied has an average mass of 157.25 amu which is about 146,478.4 MeV. So the model is predicting the masses of nuclear isotopes to a precision of about ten parts per million.

In all, about 3300 atomic isotopes (a.k.a. nucleotides) have been observed, of which 251 are stable (i.e. having no observed decays). Attempts to synthesize atomic elements 119 to 127 have so far been unsuccessful.
The mass table in the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the PC-PK1 density functional has been established for even-Z nuclei with 8≤Z≤120, extended from the previous work for even-even nuclei [Zhang et al. (DRHBc Mass Table Collaboration), At. Data Nucl. Data Tables 144, 101488 (2022)]. The calculated binding energies, two-nucleon and one-neutron separation energies, root-mean-square (rms) radii of neutron, proton, matter, and charge distributions, quadrupole deformations, and neutron and proton Fermi surfaces are tabulated and compared with available experimental data. A total of 4829 even-Z nuclei are predicted to be bound, with an rms deviation of 1.477 MeV from the 1244 mass data. Good agreement with the available experimental odd-even mass differences, α decay energies, and charge radii is also achieved. The description accuracy for nuclear masses and nucleon separation energies as well as the prediction for drip lines is compared with the results obtained from other relativistic and nonrelativistic density functional. The comparison shows that the DRHBc theory with PC-PK1 provides an excellent microscopic description for the masses of even-Z nuclei. The systematics of the nucleon separation energies, odd-even mass differences, pairing energies, two-nucleon gaps, α decay energies, rms radii, quadrupole deformations, potential energy curves, neutron density distributions, and neutron mean-field potentials are discussed.
DRHBc Mass Table Collaboration, "Nuclear mass table in deformed relativistic Hartree-Bogoliubov theory in continuum, II: Even-Z nuclei" arXiv:2402.02935 (February 5, 2024) (392 pages).

Another study (admittedly not a terribly credible one given that it is a pre-print on the Social Science Research Network by authors not affiliated with universities or chemical/physics research institutions) argues from a different perspective, that there can be no more than 137 possible chemical elements:
Using the particle-wave dualism of microparticles and the Bohr model of the atom, it is strictly shown that the maximum number of chemical elements in the periodic table cannot be more than 137. Since, starting from element 138, the speed of a 1S-electron when moving around the nucleus of an atom must be higher than the speed light in a vacuum. Therefore, Feynmanium (Z=137) is the last chemical element. It was also shown that a decrease in the half-life of chemical elements correlates with an increase in the 1S-electron relativism.
Volodymyr Bezverkhniy, Vitaliy Bezverkhniy, "The Speed of Light and the Number of Chemical Elements" SSRN (December 4, 2020). 

A 2022 paper has questioned the reasoning behind this calculation, however.

Another study has predicted properties of atomic nuclei with up to 174 nucleons plus one with 184 nucleons.

How Hot Is Quark Gluon Plasma?

Quarks and gluons are normally "confined", i.e. they can be observed only within hadrons and not "free" of a composite particle (except for top quarks with decay via the weak force before they have time to hadronize). But if you add enough energy, hadrons fall apart and their quarks and gluons from a quark gluon plasma (QGP).

At temperature does this happen? 

A recent measurement says (3.40 ± 0.55) × 1012 degrees Kelvin.

This is about 150 MeV in electron-volt units, and corresponds to 10-12 seconds after the Big Bang in the standard chronology of the universe.