Frontal sinuses and human evolution

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species? holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species. Variation in frontal sinus shape and dimensions has high potential for phylogenetic discussion when studying human evolution

Frontal sinuses and human evolution

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species’ holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species

Frontal sinuses and human evolution.

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species' holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of 'Homo erectus'. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species

Frontal sinuses and human evolution

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species’ holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species

Influence of tropho-climatic environment and reproduction on lipid composition of the euphausiid Meganyctiphanes norvegica in the Ligurian Sea, the Clyde Sea and the Kattegat

International audienceLipid content and lipid-class distribution in the northern krill Meganyctiphanes norvegica (M. Sars, 1857) was investigated in 3 contrasting (in terms of climatic and trophic conditions) areas: the Ligurian Sea, the Clyde Sea and the Kattegat. Seasonal differences in the lipid content of krill were closely related to food supply coupled with the krill reproductive state in both the Ligurian Sea and in the Clyde Sea. In the Kattegat, the lipid reserves of reproductive krill were low and probably used continuously over a longer reproduction period and successive spawning cycles. In the Ligurian and Clyde Seas, female krill lost 55 and 33% of their cephalothorax (CT) lipids through spawning. The content of triacylglycerol (TAG) and phosphatidylcholine (PC), both major lipids in the CT, were higher when food conditions were optimal at the 3 sites, and were correlated to chlorophyll a (chl a) concentration in the Ligurian and Clyde Seas. The influence of reproduction on lipid-class distribution in the Clyde and Ligurian Seas was expressed by a large decrease in PC and TAG throughout spawning, while in the Kattegat PC and TAG levels were low irrespective of the reproductive state. The relative influence of environmental and physiological factors on the lipid distribution of krill in the CT and abdomen (AB) among the 3 locations was evaluated using principal components analysis. In the CT, TAG and PC along with minor lipids were major discriminating factors and were strongly correlated to total lipid content and chl a concentrations. For reproducive krill, marked differences in the CT and AB indicated covariation between reproduction and trophic conditions. The influence of the physical environment on M. norvegica at sexual rest found expression in variation in the membrane lipids in the AB across the different temperature and salinity regimes at the 3 sites. The results are discussed in terms of adaptive mechanisms involving lipid distribution and metabolism developed by the species

Variation of lipid classes among organs of the Northern krill Meganyctiphanes norvegica, with respect to reproduction

Lipid content and class in the Northern krill Meganyctiphanes norvegica (digestive gland, stomach, gonad, fat body, abdomen) was investigated and correlated with sex and reproductive stage. Ready to spawn females, have high lipid content in ovaries, while in males and spent females, the major site of lipid deposits was the digestive gland, followed by the fat body. These differences among spawning and spent females are indicative of strong interactions between the ovary and digestive gland and the ovary and fat body during vitellogenesis. Triacylglycerols (TAG) were the major neutral lipid class with high levels in the digestive gland. The major phospholipid was phosphatidylcholine (PC) particularly in the muscular tissue of the abdomen. Phosphatidyl-ethanolamine (PE) and -serine-inositol (PS-PI), were present at intermediate levels. Reproductive males were depleted in TAG and diacylglycerols (DAG) in the digestive gland, gonad and fat body, and had 4 times lower cholesterol in the gonad than ready to spawn females. Furthermore, ready to spawn females had in the ovary higher amounts of TAG, DAG and phospholipids (PC, PE, PS-PI) than spent females. Linear relationships between lipid content and main lipid class (TAG, PC, PE, PS-PT) in different fractions of males and ready to spawn females showed that: (1). TAG was stored for both sexes in all cephalothorax fractions with highest values in the digestive gland and ovary fluid; (2). PC was accumulated for both sexes in the fat body and the gonad with a higher slope for females, with the highest values in the ovary fluid and in the abdomen of males and that (3). PS-PI was stored only in the ovary and abdomen of mature females. These results are discussed in terms of the strategy developed by Meganyctiphanes norvegica to allocate lipids to the next generation for optimised embryogenesis. (C) 2001 Elsevier Science Inc. All rights reserved

The scheduling of spawning with the moult cycle in Northern krill (Crustacea : Euphausiacea): a strategy for allocating lipids to reproduction

8th International Congress on Invertebrate Reproduction, AMSTERDAM, NETHERLANDS, AUG 10-14, 1998Euphausiids moult and grow throughout their life, which implies sharing of resources between growth and reproduction for adult krill. In the Northern krill, Meganyctiphanes norvegica (M. Sars), female krill produce eggs cyclically. Spawning moult cycles alternate with vitellogenic moult cycles for lipid yolk accumulation. Histology shows that lipids are associated with the R cells of the digestive gland in both sexes, with the yolk platelets of mature oocytes and with the fat body cell membranes and blood lacunae in reproducing females. Mature female krill can have a total lipid content twice as high as males, mostly due to accumulation in the ovary, the fat body and the haemolymph. In contrast, in males, as well as in non-reproducing females, the highest percentage of lipids is found in the digestive gland and the haemolymph. In Meganyctiphanes norvegica, the most abundant lipid fractions are polar lipids and triglycerides, the latter being relatively low in reproducing female gonad and fat body. Triglycerides are believed to be a pure energy source and polar lipids are essential for membrane development in embryos. The fatty acid content and composition of the triglyceride and polar lipid fractions in females are different from males, related to both reproductive and dietary processes. Higher levels of polyunsaturated fatty acids (PUFA) in the polar lipid fraction were found in reproductive females. During the non-reproductive season, the converse was found, indicating the specific role PUFA and other fatty acids play in growth and egg production. Adaptive processes linked to reproduction were studied comparatively in three populations of the Northern krill - Clyde Sea (W, Scotland), Kattegat (E, Denmark), Ligurian Sea (Mediterranean) - all differing considerably in climatic and trophic conditions. Such adjustments in lipid synthesis and storage are viewed as reproductive strategies developed by the Northern krill in response to different environmental conditions

Les sinus frontaux au cours de l’évolution humaine

International audienc

Frontal sinuses and human evolution

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species' holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species

Frontal sinuses and human evolution.

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species' holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species