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prokaryotes can be fossilised, there are extremely limited direct examples in the fossil record [2]. Therefore, these findings could extend the record of Archaea fossils for the first time into the Archean, the eon when life first emerged on Earth.

These findings document the oldest direct evidence for subsurface methane-cycling microorganisms of primordial, most likely methanogens, consistent with their expected antiquity based on carbon isotope analysis of fluid inclusions [3] and molecular evidence [4].

PRINCIPAL PUBLICATION AND AUTHORS

Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment, B. Cavalazzi (a,b), L. Lemelle (c), A. Simionovici (d,e), S.L. Cady (f), M.J. Russel (g), E. Bailo (h), R. Canteri (i), E. Enrico (j), A. Manceau (d), A. Maris (k), M. Salomé (l), E. Thomassot (m), N. Bouden (m), R. Toucoulou (l), A. Hofmann (b), Sci. Adv. 7, 1-9 (2021); https:/doi.org/10.1126/sciadv.abf3963 (a) Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna (Italy) (b) Department of Geology, University of Johannesburg (South Africa) (c) 3LGL-TPE, ENS de Lyon, Université de Lyon, CNRS, Lyon (France) (d) ISTerre, University of Grenoble-Alpes, CNRS, Grenoble (France) (e) Institut Universitaire de France, Paris (France) (f) Pacific Northwest National Laboratory, EMSL, Richland (USA) (g) Dipartimento di Chimica, Università degli Studi di Torino (Italy) (h) WITec GmbH, Ulm, Germany. 9FBK Fondazione Bruno Kessler, Trento (Italy) (i) FBK Fondazione Bruno Kessler, Trento (Italy) (j) INRiM, Istituto Nazionale di Ricerca Metrologica, Torino (Italy) (k) Dipartimento di Chimica Giacomo Ciamician, Università di Bologna (Italy) (l) ESRF (m) Université de Lorraine, CNRS, CRPG, Nancy (France)

REFERENCES

[1] J.B. Glass et al., Geomicrobiol. J. 35, 81-89 (2018). [2] F. Sun et al., Geology 49, 13-18 (2021). [3] Y. Ueno et al., Nature 440, 516-519 (2006). [4] E.K. Moore et al., Nat. Geosci. 10, 629-636 (2017).

The secrets of ancient Egyptian inks unveiled by synchrotron-based microanalysis

The composition of red and black inks on ancient Egyptian papyri was studied with a variety of X-ray techniques. Different lead compounds detected in both red and black inks were precisely localised down to the sub-micrometric scale, revealing that lead was used as a dryer rather than as a pigment.

The earliest examples of preserving human thought by applying ink on a flexible and durable material (i.e., papyrus) are found in ancient Egypt at the dawn of recorded history (c. 3200 BCE). Egyptians used black ink for writing the

main body of text, while red ink was often used to highlight headings and keywords.

In this study, powerful synchrotron X-rays were used to investigate the composition of red and black inks inscribed on papyri from the only large-scale institutional library known to have survived from ancient Egypt the Tebtunis temple library (Figure 81). This research project was exceptional, not only due to the provenance of the samples, but also because the analysis included as many as 12 ancient Egyptian papyrus fragments (dating to c. 100 200 CE) all inscribed with both red and black inks (Figure 82a).

The experiments were mainly conducted at beamline ID21 and combined several synchrotron techniques (micro-

Fig. 81: Ruins of the town of Tebtunis, where the only temple library to survive from ancient Egypt was

discovered.