The Pre-Greek Substrate

A nice Facebook reel discusses the pre-Greek substrate of the Indo-European Greek language for which we have about 1000 Greek words that don't appear to have Indo-European origins as evidence.

The geographic extent of the pre-Greek substrate

It notes the geographic extent of the substrate (which is similar to that of modern Greece plus the west coast of Turkey), and the subject matter of the substrate words including animals, plants, toponyms, terrain types, large sea related words, other natural phenomena, proper names, and particularly notably, most of the gods in the Greek pantheon. It also notes distinctively non-Indo-European phonemes found in many pre-Greek substrate words like "nth" and "ss" which were suffixes in the pre-Greek substrate.

My intuition is the the pre-Greek substrate had a larger than average impact on Greek compared to other Indo-European languages, but probably less than the Indo-Anatolian languages. The fact that many god names were borrowed into Greek also suggests that this may be a general feature also shared by Indo-Aryan (i.e. Sanskrit derived) and Indo-Iranian language, and perhaps by Germanic languages as well.

Some substrate source words:

Davidski At Eurogenes On The Indo-European Homeland

Davidski at Eurogenese has provided some thoughts on the Indo-European homeland in a teaser post with an updated large data set of ancient and modern DNA from Europe. He states:

(Interactive version here)

- Yamnaya is almost certainly derived from Serednii Stih (aka Sredny Stog). I've been talking about this for years and you can probably pick it up without too much trouble in the PCA above. Finally, even Iosif Lazaridis, David Reich, Nick Patterson and friends are now on board with this idea as per their latest paper on the topic (see Lazaridis et al. 2025).

- However, I'm not convinced by the Lazaridis et al. hypothesis that the Caucasus–lower Volga (CLV) cline is intimately linked to the Indo-Anatolian and proto-Anatolian expansions. That's because the CLV cline is an artifact of isolation-by-distance working for thousands of years across a vast and highly diverse landscape, and it includes a wide range of populations that usually have nothing to do with each other.

- The question of who actually spoke Indo-Anatolian first will, in all likelihood, never be solved to everyone's satisfaction. But the number of true candidate groups is actually quite small, and I reckon they're almost certainly all highlighted in my PCA above. Wink, wink, nudge, nudge.

My longstanding hypothesis is that Indo-Europeans established themselves in Anatolia close in time to the first historical attestation of their presence in the 18th century BCE, and that the Indo-Anatolian languages are more divergent than other Indo-European languages due to a stronger substrate effect from the Hattic language and related pre-Indo-European languages from Anatolia, because the substrate culture that they conquered was a vital and functioning Copper Age culture rather than the nearly collapsed Neolithic cultures that other Indo-Europeans encountered as a substrate. I believe that conventional wisdom in the field of historical linguistics attributes too much of the divergence between the Anatolian languages and other Indo-European language to the time depth from their common ancestor dialect.

New Combined Standard Model Constant Measurements

A new study tries to extract several Standard Model Constant measurements from the same data set and obtains results generally consistent with prior efforts to measure the same constants, but with greater uncertainty than the state of the art measurements of these quantities.

X17 Hypothesis Less Constrained Following Reanalysis of Data

The conclusion of a new reanalysis of X17 relevant experimental data loosens the constraints greatly. But, I remain deeply skeptical of its existence.

Also, why use units of 10^-3 GeV instead of MeV in your key chart?

[T]he revised exclusion limits no longer extend to the X17 mass of 16.88 MeV, leaving a sizeable region of parameter space for the vector-boson interpretation of the anomaly, bounded by the NA64 and Orsay constraints. Interestingly, the remaining allowed interval, 6.5 × 10^−5 ≲ εe ≲ 1.1 × 10^−4, is compatible with the recent preliminary measurement of the X17 lifetime. We further observe that, for these coupling values, the X17 decay length for a 100 GeV/c e− beam-dump experiment is of the order of few meters, resulting to an invisible signature for a missing-energy setup such as NA64-e [51]. The X17 parameters space not any longer constrained by E141 could thus be explored in the near future by NA64 through the invisible-mode dataset accumulated so far by the experiment.

Since its first observation by the ATOMKI experiment in 2018, the ∗Be anomaly has attracted considerable interest within the dark sector community as it may indicate the existence of a new fundamental particle with a mass of about 16.9 MeV, the X17. However, the minimal model describing X17 as a new vector boson is severely constrained by null results from legacy beam-dump experiments. Among these, the E141 experiment at SLAC places stringent limits on the X17 coupling to electrons εe in the 5.1 × 10^−5 ≲ εe ≲ 1.7 × 10^−4 region. 

This excludes the possibility of a long-lived X17, potentially in contrast with the preliminary estimate of the particle lifetime recently reported by the ATOMKI collaboration. The E141 limits commonly adopted in the literature rely on reinterpretations of the original analysis under solid but simplifying assumptions. While these studies provide a reliable estimate of the experiment's reach, they rely on approximations that were well justified when the boson mass was largely unconstrained. With the X17 mass now confined to a narrow region by recent experimental observations, a more refined treatment of the E141 sensitivity becomes necessary. 

In this work, we revisit the E141 exclusion limits in the X17 scenario by performing a dedicated reanalysis that incorporates a more accurate treatment of the experimental setup and signal prediction. We quantify the impact of these refinements on the excluded parameter space and discuss their implications for the compatibility between the E141 constraints and the vector boson interpretation of the ATOMKI anomalies.

A. Celentano, A. Marini, L. Marsicano, "Updated E141 constraints on a long-lived X17 vector boson" arXiv:2607.22102 (July 24, 2026).

Another recent X17 paper highlighted by @neo is as follows:

The X17 particle has been proposed to explain the invariant mass anomalies observed in electron-positron pairs during nuclear transitions at the Atomki experiment. Motivated by recent observations of 8B solar neutrinos induced coherent elastic neutrino-nucleus scattering (CEνNS), we present the first comprehensive analysis of the hypothetical boson using data from multi-ton dark matter direct detection facilities. 

We consider the new particle as a light Z′ mediator arising from a spontaneously broken U(1)′ symmetry, featuring both vector and axial-vector couplings to leptons. By evaluating the latest datasets from XENONnT, PandaX-4T, and LUX-ZEPLIN, we derive stringent limits on the effective vector coupling utilizing marginalization procedures. Our global analysis provides competitive constraints that meaningfully narrow the allowed parameter space of the model, while exhibiting a clear sensitivity to the tau-flavor coupling.

M. F. Mustamin, M. Demirci, M. Deniz, "Signatures of X17 through Coherent Elastic Solar Neutrino-Nucleus Scattering in Direct Detection Searches"arXiv:2607.12691 (July 14, 2026).

The conclusion of this article states:

Motivated by the first observation of coherent elastic neutrino-nucleus scattering induced by 8B solar neutrinos, we have derived robust constraints on the effective couplings of a light Z′ gauge boson, interpreted here as the X17 particle. Initially conjectured to explain the invariant mass anomalies observed by the Atomki experiment, this hypothetical mediator can be handled within a U(1)′ gauge symmetry framework. Crucially, we have explicitly accounted for the flavor-dependent nature of the couplings, which naturally arise from solar neutrino flavor transitions during their propagation to Earth. 

Our analysis utilized the latest datasets from direct detection searches at XENONnT, PandaX-4T, and LUX-ZEPLIN experiments. While these multi-ton direct detection facilities were fundamentally designed to search for weakly interacting massive dark matter particles, their recent milestone in detecting solar neutrino-induced nuclear recoils offers a novel and powerful avenue for probing BSM physics. We systematically evaluated the flavor-dependent effective couplings—Cνe eff, Cνµ eff, and Cντ eff—that quantify the X17 interactions with the xenon target. By rigorously marginalizing over the relevant effective neutrino couplings, we have derived comprehensive 1 dof and 2 dof limits of the effective vector couplings using each dataset released by the experiments. Our global analysis reveals that PandaX-4T and LUXZEPLIN provide relatively similar behavior, while the combined datasets effectively break individual experimental degeneracies. Most importantly, we have found that the SM hypothesis remains completely protected and consistent within the 90% CL allowed regions across all flavor combinations. Overall, our derived bounds are highly competitive with the allowed parameter spaces previously mapped by IceCube and COHERENT+reactor studies. We also highlight the sensitivity of these detectors to the tau-flavor coupling, a direct consequence of the oscillated solar neutrino flux.

A non-lepton universal coupling seems particularly dubious.

The Pipeline

I scan about 45,000 physics articles a year. I bookmark and think carefully about around 4,500 of them a year. I read the underlying article's body text for about 450 of them a year. I blog about 150 of them a year.

This is post 3,001 at this blog.