The 20 winning photos of La preuve par l'image (LPPI) 2023

There is no magic involved in the strange oscillations seen in this chain of metal balls. The movement is actually induced by a magnetic field produced by an electromagnet that completely encircles the pit where the chain of balls has been placed. By varying the intensity of the magnetic force applied, the researchers can counteract the effect of gravity. As a result, the metal ‘snake’ begins to undulate while moving slowly along, giving the impression that it is dancing to the rhythm of the…

Some twenty metres above the ground, this female bonobo (Pan paniscus) is sheltering from the rain under the canopy of the Manzano Forest, in the Democratic Republic of Congo. In the heart of this biotope, a combination of rainforest and savanna woodland, scientists are studying the vocal communications of our closest relatives in their natural environment. Most of the calls produced by bonobos serve to regulate their social interactions and movements, with the aim of making their identities…

This microscopic image of a sea urchin embryo after five hours of growth reveals the subtle process of cell division. Inside each cell (outlined in turquoise), the microtubules of the mitotic spindle (red) pull the chromosomes (green) in opposite directions, forming two new cells. The sea urchin embryo at an early stage is a biological model as original as it is useful: it helps to identify all the mechanisms that determine cell division orientation in human tissues and the consequences of…

Ces trois organismes échevelés et translucides, dont le plus grand mesure à peine 2 cm, sont des éponges d’un genre particulier. À la différence des autres spongiaires, qui filtrent l’eau pour se nourrir, "Lycopodina hypogeae", c’est son nom, utilise ses filaments garnis de crochets pour capturer de petits crustacés qu’elle digère ensuite lentement. Cette stratégie a permis à l’espèce de coloniser des milieux à la fois pauvres en nutriments et plongés constamment dans l’obscurité, comme le fond…

Surprising though it may seem, this bird’s eye view of the remains of the funerary complex of Queen Ankhnespepy II, near Cairo (Egypt), was captured at ground level. It is in fact the horizontal projection of a 3D model of this architectural complex covering an area of 2,800 m2 constructed during the Sixth Dynasty (2374-2140 BC). This comprehensive, ultra-realistic reconstruction of the site combines more than 2,000 photographs taken over the course of three successive excavation campaigns…

Culminant à plus de 2800 mètres d'altitude, le col d’Abano est un point de passage obligé pour les brigades pastorales touches. Dès le mois de mai, celles-ci escortent les troupeaux de moutons le long de cette piste sinueuse de l’est de la Géorgie. Le but de ce dangereux périple : atteindre au plus vite les terres d’estive de la Touchétie, région ancestrale de ce peuple de bergers. Véritable verrou naturel, le col d’Abano est aussi le point de convergence de trois géographies de la culture…

The howling winds that constantly batter France’s Kerguelen Islands aren’t making the job of these two scientists any easier. To pack up the samples they have just collected from the ancient glacial lake behind them, they have no choice but to shelter behind their rucksacks. Once back in the lab, the samples will be analysed in order to determine the chemical and microbiological composition of the lake water. This work forms part of a long-term research programme that seeks to understand how…

Although this burst of colour is reminiscent of the formation of a planetary nebula, the distances here are measured not in light years but in micrometres. This is in fact a cross-section of a root of "Arabidopsis thaliana", an iconic plant model for biologists. With the help of molecular marking techniques derived from bioorthogonal chemistry, scientists were able to use red, green and yellow fluorescence to distinguish the three components of lignin, a substance that gives plants their…

Malgré la finesse de leur tranchant, ces pointes de flèches en silex n’ont jamais servi à chasser du gibier ou repousser des assaillants. Provenant d’une sépulture de l’âge du Bronze ancien découverte près de Caen, elles témoignent du pouvoir dont jouissait le défunt. De récentes études ont montré que ces armatures de 3 à 4 cm de long aux ailerons disproportionnés étaient à l'origine emmanchées sur une hampe. Une pratique révélée ici par le traitement d’images. Sur les photos de pointes de…

Make no mistake: this might look like the caramelised crust of a crème brûlée, but it is actually a sample of plastic decomposing under the effect of heat. More precisely, the image shows the process of nucleation in which the gases produced by the combustion of a polymer collect in bubbles that then rise to the surface of the material, where they eventually burst. By modelling this phenomenon in underventilated environments such as high-energy performance buildings, scientists hope to develop…

In the centre of the island of Honshu, Japan, temperatures can fall to -20 °C in winter. To cope with this bitter cold, the Japanese macaques of Jigokudani have taken to bathing in the natural hot springs that have made the place famous. However, of the two hundred monkeys that make up this population, only about forty enjoy this privilege. When an individual not belonging to this dominant caste attempts to enter the pools, like this macaque here seen face-on, they are violently repelled. For…

Ce réseau de filaments vert électrique est l'œuvre de millions d’algues unicellulaires. Sous l’effet de sources de lumière intenses entourant la boîte de Petri où ont été déposés les micro-organismes, ces derniers convergent vers le centre de la boîte en se dissimulant derrière leurs congénères. Cherchant ainsi à se prémunir d’une exposition prolongée au flux de photons qui leur serait fatale, les algues finissent par dessiner un motif "tentaculaire". Les scientifiques qui étudient cette…

The visual appeal of this chromatic composition is deceptive. This is in fact a cluster of cancer cells from the peritoneal fluid of a patient with advanced ovarian cancer. This high-resolution image, which shows in detail the morphology of a cell cluster, reveals its metastatic potential. Under such circumstances, some nuclei, in blue, press up against the cell walls, in red. The yellow spots dotted around the interior of these same cells reveal the presence of a protein involved in the…

Contrary to appearances, this perfectly circular, iridescent membrane is not organic in nature. It is in fact a soap film stretched out by the action of centrifugal force. Illuminated by a laser beam that reveals its tiniest details, the film of soapy water is dotted with dark tearshaped spots that form at the edge of the film before migrating towards its centre. By studying their formation and the speed at which they move, the researchers can model the dynamics of the thinning of a soap bubble…

This mosaic of colours reveals the arrangement of stem cells inside a neural rosette. The image shows the interior of a brain organoid, a kind of miniature human brain created using stem cells from patients suffering from a form of hereditary epilepsy resistant to conventional antiepileptic drugs. The aim of this study model is to determine the role of a genetic mutation in the development of cortical malformations associated with the disease. Immunofluorescence makes it possible to distinguish…

Pour comprendre ce qui nous distingue de nos ancêtres, les paléoanthropologues s'appuient désormais sur la microtomographie de très haute résolution. Appliquée ici à un crâne de Néandertalien vieux de 40 000 ans, cette technique d’imagerie dévoile des structures anatomiques insoupçonnées. Sur ces reconstructions 3D, les empreintes du réseau veineux circulant près de la surface du crâne apparaissent en bleu. Les principales veines et artères qui acheminent le sang vers les différentes aires…

This is not a torture session but rather a totally painless experiment designed to reveal the subtle mechanisms involved in speech production. Sensors attached to the tongue and lips of this volunteer, who is placed in a low-intensity electromagnetic field, enable the movements of these articulatory organs to be recorded. This makes it possible to visualise how the tongue and lips work together to pronounce specific sounds and sequences of sounds. Through this experiment, researchers hope to…

This Weddell seal emerging from the pack ice is not a spy but a lactating female equipped with a miniature sonar. Attached to the animal’s fur, this device enables biologists to track its movements during its breath-hold dives in Antarctic coastal waters. The sonar also records the seal’s head and jaw movements as it hunts. Analysis of this data should help scientists to improve their understanding of the feeding behaviour of female Weddell seals during the critical lactation period.

These tentacles reminiscent of some terrifying deep-sea monster turn out to be completely harmless. This is in fact the tip of a stem of Arabidopsis thaliana, a species in the same family as mustard and used as a model plant by geneticists. The image, magnified 300 times with an electron microscope, reveals the flowering process in a specimen carrying a genetic mutation. As a result, instead of producing normal flowers at intervals of 137°, the plant generates these irregularly-arranged…

LPPI caption : Well into her nineties, Thérèse Josien-Poulain (1929-2022) still mastered to perfection the art of assembling the bones of prehistoric animals. A pioneer of French archaeozoology, which she developed in the mid-1950s, the scientist pursued most of her career from her house in Avallon, in the central eastern French region of Burgundy, which enabled her to reconcile family life and archaeology. In her home laboratory, she saw hundreds of thousands of fragments of fossilised…