Thursday, 30 October 2014

Parasite infections in German soldiers from the Kilianstollen First World War archaeological site.

The science of palaeoparasitology involves the study of parasite remains from palaeontological and archaeological sites. This rarely involves the recovery of whole parasite fossils; the presence of parasites being more commonly determined from eggs, biomarkers or pathological alteration of the remains (i.e. damage caused to the living host of the parasite that is visible in the preserved body). As such identifying specific parasites takes considerable skill, but is considered worthwhile for the insight it gives into the lives of both the parasite and the host.

In a paper published in the journal PLoS One on 15 October 2014, MatthieuLe Bailly of Chrono-Environment at the University of Franche-Comte, Michaël Landolt of Pôle d’Archéologie Interdépartemental Rhénan and Leslie Mauchamp and Benjamin Dufour, also of Chrono-Environment at the University of Franche-Comte, describe the presence of parasites in bodies from the Kilianstollen First World War archaeological site in the Alsace Region of France.

The Killianstollen was a gallery built by German soldiers for use as a refuge during enemy attacks during the winter of 1915/16. It was 125 m long and between 3.5 and 6 m beneath the surface. At about 1.30 pm on 18 March 1918 the southern part of the gallery collapsed following heavy shelling by French artillery, trapping 34 reservist soldiers from the German 94th Infantry Company. Thirteen of these soldiers were able to escape, but the remaining 21 were left for dead, eventually being excavated by archaeologists in 2011.

Le Bailly et al. took sediment samples from the abdomen regions of three bodies, a 20-year-old soldier, a 22-year-old corporal and a 35-year-old sergeant. These were solid samples, which were rehydrated, then crushed and sieved to extract parasite eggs.

The soldiers recovered during the excavations of ‘‘Kilianstollen’’ in Carspach. Michaël Landolt in Le Bailly et al. (2014).

No eggs were recovered from the body of the corporal. The body of the sergeant yielded two eggs of the Human Whipworm, Trichuris trichiura (a parasitic infection, the eggs of which have been recovered from a wide range of archaeological sites), and one egg of an unknown Capillariid (parasitic nematode).

Egg of Trichuris trichiura (53.19 by 27.45 mm) recovered in individual #1019 in Carspach Alsa‘‘Kilianstollen’’. Scale bar is 20 μm. Matthieu Le Bailly in Le Bailly et al. (2014).

The body of the soldier yielded 5 eggs considered to be from the same unknown Capillariid as the one from the sergeant. It also yielded one Tapeworm egg, Taenia sp. (there are three known species of Taenia that  infect humans, all of which could potentially be present at Kilianstollen), and 180 eggs from the Human Roundworm, Ascaris lumbricoides.
 Egg of Ascaris lumbricoides (66.57 by 53.04 mm) recovered in individual # 1018 in Carspach ‘‘Kilianstollen’’.Scale bar is 20 μm. Matthieu Le Bailly in Le Bailly et al. (2014).

A wide range of Capillariid Nematodes infect both human and animal hosts. Le Bailly et al. compared the specimens from Kilianstollen to a wide range of these, but were unable to make a positive identification. However they were most similar to the eggs of Eucoleus gastricus, a species which infects Rats rather than humans. This is quite plausible, as Rats are known to have been a problem at Kilianstollen and most similar First World War sites, with soldiers recording problems with Rat infestations, food being contaminated with Rat faeces and even instances of hungry soldiers eating Rats in both official records and private correspondence. If the eggs do come from Eucoleus gastricusor a similar Rat-infesting species then it cannot be determined that the soldiers were actually suffering from a Nematode infection or whether they had inadvertently consumed eggs from Rat faeces that were actually incapable of causing disease in a Human host.

Egg of Capillariid (65.036 by 28.38 μm) recovered in individual # 1018 in Carspach ‘‘Kilianstollen’’. Scale bar is 20 μm. Matthieu Le Bailly in Le Bailly et al. (2014).

Finally Le Bailly et al. note a considerable difference between the parasite load carried by the non-commissioned ranks and the common soldier at Kilianstollen, with no eggs recovered from the corporal, three belonging to two species from the sergeant and 186 eggs from three species from the common soldier. It is possible that this is simply an artefact of the small sample size, but it is also possible that it is the result of social stratification in the trenches, with non-commissioned ranks having access to better food, hygiene or information than common soldiers.

 Egg of Taenia sp. (34.95 by 32.25 mm) recovered in individual # 1018 in Carspach ‘‘Kilianstollen’’. Scale bar is 20 μm. Matthieu Le Bailly in Le Bailly et al. (2014).

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Parasite infections have been a fact of life for most humans throughout history, with the medical developments needed to fight them only becoming widely available since the Second World War. Studying the infections found in pre-modern populations is however difficult. Attempts to diagnose infections based upon historical records made by people who lacked the modern medical knowledge to record diagnostic symptoms accurately are an interesting parlour game, but not very...

 Tapeworms (Cestoda) are parasitic Flatworms that live in the digestive tracts of Vertebrate hosts, attaching themselves to the intestine wall and absorbing nutrients through their skins. Adult Tapeworms engage in sexual reproduction, producing eggs which are passed out of the host in its feces. Juvenile Tapeworms often inhabit...

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Magnitude 2.8 Earthquake in southwest Nottinghamshire.

The British Geological Survey recorded a Magnitude 2.8 Earthquake at a depth of 7 km between Nottingham and Mansfield in southwest Nottinghamhire, England, slightly after 7.15 pm GMT on Tuesday 28 October 2014. An event of this size is highly unlikely to have caused any damage or injuries, but people have reported feeling the event across southwest Nottinghamshire.

The epicenter of the 28 October 2014 Nottinghamshire Earthquake, and places where people reported feeling the event. BGS.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England.
The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.
Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process. 
(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

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Acheulian and Levallois technologies from a single Late Pleistocene site Armenia.

Stone tools associated with the Acheulian technology first appeared around 1.75 million years ago and spread across much of Eurasia from about 900 000 years ago onwards. The technology is typified by tools in which pieces are chipped away from a central core to leave a useable item such as a handaxe. The Levallois technology appeared in Africa around 300 000 years ago and spread across Eurasia by about 200 000 years ago. In Levallois technology the chips derived from a central core are themselves used as cutting tools, which the core is retained as a source of material rather than being used as a tool in itself, enabling a larger number of tools to be fashioned from a single piece of usable rock. This is thought to be a major conceptual shift, and is associated with the appearance of Early Modern Humans in Africa and Neanderthals in Europe. In technical terms the Archeulian technology is considered to be Early Palaeolithic while the Levallois is Middle Palaeolithic.

In a paper published in the journal Science on 26 September 2014, a team of scientists led by Daniel Adler of the Department of Anthropology at the University of Connecticut describe a site in Armenia at where obsidian tools belonging to both the Acheulian and Levallois technologies have been found.

The Nor Geghi site was discovered in 2008 in Hrazdan Gorge on the edge of the Armenian Volcanic Highlands. At the site obsidian (glassy volcanic rock) tools were found to be being eroded from a 135 m section on the west side the side of the gorge. The rocks here comprise sedimentary rocks interbedded with basalt lava flows derived from the Hatis, Gutanasar, and Mensakar volcanoes in the Gegham Range. These basalts are amenable to isotope dating methods, with the layer above the stone tools dated to 197 000 years ago, while the layer below is dated to 441 000 years ago, while an unconformity located below the stone tools produced sand grains dated to 308 000 years ago, suggesting the tools were deposited between 197 000 and 308 000 years ago (an unconformity represents a period when sediments were being eroded rather than deposited, sedimentary sequences associated with rivers typically contain many unconformities, as the river shifts is course and erodes where it had once deposited).

The Acheulian and Levallois tools at Nor Geghi appear to be eroded from a single plane, implying that they were made at the same time, and presumably by the same people (the alternative theory, that two different groups were living in the area and both visiting the site to make tools is rejected, since all human groups likely to have been in the area at the time are thought to have been intelligent enough to adopt a better technology if they saw it being used).  This implies that the tool-makers were in the process of switching from one technology to the other when occupying the site. This is significant, as it is currently widely believed that the Levallois technology was developed in Africa and then spread to Eurasia, replacing the earlier Acheulian technology. At Nor Geghi a transitional stage is for the first time recorded outside of Africa, suggesting that the development of a the new technology was not confined to a single place, but developed independently from the old technology across the Old World.

Obsidian artifacts from Nor Geghi.Levallois: (1 and 2) recurrent cores; (3, 11, 13 to 15 and 17) flakes; (4) point with retouched base; (5 to 8) blades; (9 and 10) preferential cores. Non-Levallois: (12) scraper with Quina retouch; (16)biface. Adler et al. (2014).

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Mammal remains from the Early Eocene of northern British Columbia.

The Early Eocene was a time of high species turnover among Mammals (and other groups), driven by two periods of extreme global warming, the Paleocene-Eocene Thermal Maximum about 55.8 million years ago and the Early Eocene Climatic Optimum, between about 53 and 50 million years ago. During the Early Eocene many of the Mammal groups which had survived the End Cretaceous Extinction disappeared, and were replaced by representatives of modern groups which persist to this day.

This makes Early Eocene Mammalian faunas of particular interest to palaeontologists, although examples of such faunas are somewhat rare, leading to a patchy understanding of Early Eocene Mammalian biogeography. In North America Mammal remains are known from Ellesmere Island in the Canadian High Arctic and the Western Interior of the United States, particularly Colorado and Wyoming, but are unknown from the rest of the continent.

In a paper published in the Journal ofVertebrate Palaeontology on 8 July 2014, Jaelyn Eberle of the University of Colorado Museum of Natural History and Department of Geological Sciences at the University of Colorado at Boulder, Natalia Rybczynski of Palaeobiology at the Canadian Museum of Nature and David Greenwood of the Department of Biology at Brandon University describe two Mammal specimens from the Driftwood Creek Beds (part of the Oota Lake Group) in Driftwood Canyon Provincial Park, east of Smithers in northern British Columbia.

The Driftwood Canyon Provincial Park was established in 1967 in order to protect the fossils there, after the landowner donated the site to the Province of British Columbia. The site has yielded extensive plant remains, predominantly Conifers (Redwoods, Cedars, Firs, Larches, Spruces, Pines and Golden Larches) with some broadleaved deciduous Angiosperms (Alders, Birches, Sassafrasses, Elms and members of the Oak Family) and other plants (Ginko and the Fern Azolla, which forms floating mats on still or slow moving waterways). The site has also yielded numerous Fish and Insect fossils, as well as some Bird remains, which have yet to be formally described. The site also has interbedded volcanic ashes, which allow for accurate isotopic dating, which currently dates the site at 51.77 million years old, within the Early Eocene Climatic Optimum. The site has been interpreted as a the bed of a small lake in an area surrounded by dense, conifer-dominated, woodland, with annual temperatures averaging 10-15˚C and seldom falling bellow freezing.

Driftwood Canyon fossil site. (A) map showing location of Driftwood Canyon Provincial Park and other key Eocene; (B) image of the north cliffface showing lake beds, and positions of radiometrically dated volcanic ash and the level at which the Erinaceid fossil was collected. Eberle et al. (2014).

The first specimen described is a right maxilla (upper jawbone) with some teeth, thought to have come from an Erinaceomorph Lipotyphlan (Hedgehog). It is named as Silvacola acares, where ‘Silvacola’ means ‘forest-dweller’ and ‘acares’ means ‘tiny’ as the specimen is very small for a Hedgehog. Hedgehogs have previously been described from the Late Palaeocene of Central Alberta and Southern Saskatchewan and the Eocene of Wyoming.

Right maxilla of Silvacola acares in labial view. Eberle et al. (2014).

The second specimen described is a partial right dentary (lower jawbone), again with some teeth intact, of a Tapir. This is referred to the Early to Middle Eocene genus Heptodon, though not confidently assigned due to the fragmentary nature of the material. Tapirs are thought to be good proxies for forested environments (modern Tapirs are strict forest dwellers and there are no known fossil Tapirs from deposits where forests can be ruled out), supporting the current palaeoenvironmental interpretation of the Driftwood Creek  deposits.

Right dentary assigned to cf. Heptodon in labial view. Eberle et al. (2014).

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Monday, 27 October 2014

Environmental factors influencing the Lionfish invasion of San Salvador Island in the Bahamas.

Lionfish, Pterois volitans, are large predatory Fish from the Indo-Pacific region that have become a serious invasive pest in the Caribbean and along the southeastern coast of North America. They were first recorded off the coast of Florida in 1985, and since then have spread across much of the region, rapidly coming to dominate the ecology of islands and reefs that they reach; a study of the waters around New Providence Island in the Bahamas showed that within six years of Lionfish reaching the island prey species which they targeted had declined by 65% and they had come to make up 40% of the biomass of all predatory fish around the island. Lionfish have also recently been recorded from the Mediterranean, and are currently considered one of the most threatening invasive species not just in reef environments, but in any ecosystem.

Two factors seem to have helped to facilitate Lionfish invasions. Firstly Lionfish are willing to take a wide range of prey and have a novel hunting technique, hovering over the prey fish then, disorientating the prey by flaring their large pectoral fins and sometimes blowing jets of water at the prey prior to striking. Secondly Lionfish are venomous, producing a potent toxin on spines on their dorsal, anal and pectoral fins. These adaptations are not seen in any Caribbean fish, and both prey and potential predators apparently lack any defences against them.

A Lionfish, Pterois volitans, in Prague Sea Aquarium. Karel Jakubec/Wikimedia Commons.

In a paper published in the journal PLoS One on 3 September 2014, Andrea Anton of the Curriculum for the Environment and Ecology at the University of North Carolina, and Michael Simpson and Ivana Vu of the Department of Biology at the University of North Carolina, describe the results of a study into Lionfish population density on San Salvador Island in the Bahamas. The study was carried out by divers in July-August 2009, four years after Lionfish were first recorded around the island (in 2005).

Anton et al. collected data on Lionfish densities from 18 sites around the island, along with data on small prey fish, medium prey fish, large predatory fish and large predatory Groupers (the only fish present that were large enough to be potentially able to predate Lionfish), as well as reef structure and complexity and wave exposure.

Map of study sites in the island of San Salvador (The Bahamas). Circles indicate the study sites. Numbers indicate study sites asfollows: (1) White Island, (2) Catto Cay, (3) Light House, (4) Baptism, (5) Crab Cay, (6) La Crevasse, (7) Danger Point, (8) Double Caves, (9) Grotto, (10) Great Cut, (11) Red House, (12) Gardness, (13) Sangrila, (14) Runway, (15) Club Med, (16) Yellow House, (17) Rocky Point, and (18) Green Cay. Anton et al. (2014). 

Anton et al. could find no correlation between the availability of prey, reef complexity or presence of Groupers and the population density of Lionfish; the Lionfish were apparently flexible enough to cope with any variation in reef habitat and prey availability found around the island, and seemed to be immune from predation by Groupers. Where other large predatory fish were present in higher numbers the population density of Lionfish rose, probably indicating an increased availability of prey; otherwise they seemed unperturbed by competition from other predators.

The one factor that did seem to inhibit the Lionfish was wave exposure, with the population density much lower in areas with higher exposure to waves. Anton et al. suspect that the presence of waves (experienced below the surface as energetic rotating vertical currents) disrupts the hunting strategy of Lionfish in these areas, making it impossible for them to hover over then strike at potential prey items. However they also note that these areas tend to have higher levels of seaweed density, and that this might also provide better cover for smaller fish attempting to avoid being eaten.

Anton et al. suggest that higher energy environments might serve as refuges for some reef fish species while efforts are made to control Lionfish invasions in the Caribbean (though not all reef fish can utilize such habitats; many tropical reef species have very tight environmental requirements). In the absence of any effective biological control of Lionfish in the Caribbean, control efforts have largely involved the removal of Lionfish by divers armed with spearguns, with organizations such as the Reef Environmental Education Foundation (REEF) holding Lionfish hunting derbies. However a recent study on Little Cayman Island found that two native Caribbean fish, the Nassau Grouper Epinephelus striatus, and Nurse Shark Ginglymosto macirratum, had learned to predate Lionfish, suggesting that Caribbean ecosystems may be able to adapt to the presence of this novel species given time.

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Interpretting turbidite deposits on the Eel Fan off the coast of Northern California.

Turbidites are sedimentary deposits formed by submarine landslides. They have a distinctive structure, typically course grained at the base with the sediment growing finer upwards within the deposit. Since the conditions for the formation of such deposits tend to persist for long periods of time, sequences made up of many repeated turbidite deposits are frequently encountered in the geological record. Such deposits are typically thought to arise from geologic events such as large Earthquakes or tsunamis.

In a paper published in the journal Geology on 15 August 2014, a team of scientists led by Charles Paull of the Monterey Bay Aquarium ResearchInstitute describe the results of a study of a sequence of turbidite deposits on the Eel Fan off the coast of Northern California. The Eel Fan is about 2.6 km beneath the sea surface and lays west the Eel Canyon. The Eel River is thought to have run directly into the Eel Canyon until the end of the Pleistocene, when sea levels were lower, but is now separated by about 20 km of shallow marine shelf.

Map showing location of high-resolution bathymetric surveys, with respect to Eel Canyon and Eel River, California, USA. Box in inset shows location of main figure with respect to California. Contours are at 50 m, and every 200 m interval. R.—River. Paull et al. (2014).

Paullet al. surveyed two areas of scouring, where subsequent landslips have exposed layered deposits, this the Monterey Bay Aquarium Research Institute’s remotely operated vehicle (ROV) Doc Ricketts, which was able to both photograph the deposits and drill cores up to 134 cm in length.

Video still images with an ~2.5 m field of view showing turbidite beds in scours on Eel Fan, California, USA. Horizontal push core being taken from the outcrop face is shown in (A). Note beds wrap around V-shaped ridge in (B). Paull et al. (2014).

Paul et al. first attempted to date the deposits using planktic Foraminifera from the fine grained sections of the sequences, but were unable to find sufficient material to do this. Next they attempted to obtain dates from reworked benthic Foraminifera (i.e. Formainiferans buried once then excavated and reburied by geological events) in the courser grained parts of the deposits. This resulted in dates of between 29 100 and 6100 before the present. Finally they obtained carbon isotope dates from wood samples within the deposits, producing dates of between 12 800 and 7100 years before the present.

By calculating the thinkness and age of the individual beds combined with their approximate ages, Paull et al. conclude that the turbidite flows occurred at a rate of about one every 36 years in the later part of the sequence, but about once every seven years during the Early Holocene (about 12 900 to 8000 years ago). This is far more frequent that can be accounted for by major Earthquake events, but fits well with the known frequency of flood events on the Eel River, which in the Early Holocene would have entered the sea much closer to the Eel Canyon.

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Assessing the lifestyles of Later Stone Age herders in the Orange River Valley of South Africa using their long-bone morphology.

The term Later Stone Age is used in South Africa to describe Holocene stone tool making cultures dating from about 10 000 years ago until the historical era. From the 1990s onwards efforts have been made to understand the lifestyle of Later Stone Age hunter-gatherers living in fynbos and temperate rainforest conditions by studying the morphology of long-bones (arm and leg bones) from archaeological sites. These bones are highly prone to modification during an individual’s lifetime, as they serve as supports and anchors for the limb muscles used in physical activity, and the body is capable of modifying the bone structure to provide support for repeated activity.

These studies have suggested that both male members of both populations had strong lower limbs, suggesting that they led very mobile lives - it was notable that the fynbos individuals were as robust in their lower limb strength despite the forest individuals living in much more hilly terrain. However lower limb bones were more developed in forest females than fynbos females, suggesting that terrain did play a role; both sexes had well developed lower limbs in forest populations, whereas the fynbos population was sexually dimorphic (i.e. the sexes were different), with males more robust than females.

The upper limbs were more developed in males in both populations, suggesting more physical activity was being undertaken by the males than the females. The males also showed asymmetry of the upper limb-bone development, this being slight in the fynbos males but quite pronounced in the forest males. It has been suggested that this asymmetry may reflect the different hunting methods of the two groups, with the forest hunters favouring spears (thrown with one hand) while those living on the fynbos preferred light bows (where both hands are used to hold the bow and draw the string). This has been supported by studying the limbs of modern athletes, tool assemblages from the two regions, and records of living San hunters living in the two areas.

The results of these studies have subsequently been used as a base to compare to other small-bodied Holocene hunter-gatherer populations in the Andaman Islands, Tierra Del Fuego and Australia. These studies found that the Andaman Islanders and Yahgan foragers of Tierra Del Fuego showed considerably higher upper limb-bone development that either South African population, consistent with a more aquatic lifestyle that involved frequent swimming and canoeing, while the Australian Aboriginal skeletons showed less development in both upper and lower limbs, which has been suggested to be indicative of a lifestyle involving considerably more foraging, at the expense of other activities.

In a paper published in the South African Journal of Science on 22 September 2014, Michelle Cameron of the Department of Archaeology andAnthropology at the University of Cambridge and the Department of Anthropology at the University of Toronto and Susan Pfeiffer of the Department of Anthropology at the University of Toronto and the Department of Archaeology at the University of Cape Town describe the results of a study of the limb bones of a new group, Later Stone Age herders from the Orange River Valley of South Africa.

Map of southern Africa with forest, fynbos and lower Orange River Valley regions approximated. The fynbosregion is indicated by the solid outline, the forest region by the small dotted outline and the lower Orange River Valley by the dashed outline. Black lines indicate approximate latitude markers and the star indicates the approximate location of Koffiefontein. Cameron & Pfeiffer (2014).

The bones used in the study came from burials at Koffiefontein and Augrabies Falls, both are thought to date from around the beginning of the historical period in South Africa, with the Koffiefontein burial dated to about 390 years ago (i.e. about 1620). The bones are thought to have come from small bodied herder-foragers, belonging to the same San ethnic group as the coastal population, and also reliant on stone-aged technologies, though this population is thought to have had contact with other ethnic groups using different technologies, and is likely to have had some degree of genetic and technological exchange. The Orange River Valley has a seasonally arid climate, with vegetation intermediate between the Sweet Grassveld and Karoo types.

The inland hunter-foragers were found to have higher upper limb strength than the coastal populations. This is contrary to predictions, since it was presumed that herding would reduce the need for intense upper limb activity compared to hunting. This increased strength was seen in both male and female herders (whereas in the other populations the males had higher upper limb strengths), and Cameron and Pfeiffer suggest that this may be linked to increased effort going into foraging in a semi-arid environment where there was competition with other groups (such as farmers who supplemented their livelihoods by some foraging).

Both sexes showed some upper limb asymmetry in the Orange River population. This was less than seen in males from the forest population, but greater than seen in males from the fynbos population. The cause of this is unclear, but it is thought to be unrelated to hunting, suggesting that foraging activity can play a greater role in the development of upper limb-bone asymmetry than previously thought.

The Orange River Valley population showed a similar level of lower sexual dimorphism to the fynbos population, with well developed, robust lower limbs in the males but not the females. This suggests a similar division of mobility-related labour between the two populations, but does not give any insight as to what it was. It was previously assumed that the fynbos males were travelling further afield than the females in pursuit of game, but this is less likely to have been the case amoung pastoralist herders, where the entire community is assumed to have moved with the herds.

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One of the traits that is used to determine that fossil primates are part of the Human lineage, rather than that which leads to Chimpanzees and Bonobos (our closest relatives) is the structure of the ankle. Because of this palaeoanthropologists have tended to assume that the abandonment of an arboreal lifestyle for a life on the open plains of Africa was the defining ecological change that led our ancestors to diverge from those of the Chimps and Bonobos, and that hominids with human-like... Skull closure in the Taung Infant.                 The Taung Infant was discovered by workers at the Buxton Limeworks near Taung, South Africa in 1924 and described in a paper in the journal Nature by palaeoanthropologist Raymond Dart in 1925. It is the partial skull and endocast of the brain case of a three to four year old Australopithecus africanus, the first...
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A new species of Tulip from Anhui Province in eastern China.

Tulips of the genus Amana are found in eastern Asia. They are very similar to the Tulips of Western Asia and Europe, which are placed in the genus Tulipa, differing only in the presence of bracts on the upper part of the flowering stem, and not all botanists have recognised the two genera as distinct. However modern genetic studies appear to support the separation of the two groups, as closely related but distinct genera with different geographical ranges.

In a paper published in the journal Phytotaxa on 27 August 2014, Bangxing Han of the Research Center of Research and Development of Traditional Chinese Medicine at West Anhui University and the National Resource Center for Chinese Materia Medica at the China Academy of Chinese Medical Science, Ke Zhang of the Department of Pharmacy at Anhui University of Chinese Medicine and Luqi Huang, also of the National Resource Center for Chinese MateriaMedica at the China Academy of Chinese Medical Science, describe a new species of Tulip from Ningguo County in Anhui Province, eastern China.

The new species is named Amana wanzhensis, meaning ‘from Wanzh’, though no explanation of this is given. It is a 15-30 cm high perennial herb growing from 1.5-2.5 cm bulbs, producing white flowers with brown stripes and green bases in February and March. It is widespread around the town of Xianxia, where it grows in moist Bamboo forests and meadows, at altitudes of 600-800 m above sea-level.

Amana wanzhensis.Yun-Xi Zhu in Han et al. (2014).

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Peruvian Lilies, Alstroemeriaceae, are a small group of flowering plants found across Central and South America, the islands of the Caribbean and the Falklands. The are members of the Lily order, Liliales, and have relatives in Australia and New Zealand. Some...

Plants in the genus Allium are found throughout temperate regions of the northern hemisphere, with a few species from Africa and South America. The genus includes a number of important food plants, including Onions, Garlic, Leeks, Chives and Shallots. The number of species in the genus is disputed, but there are probably around 750 valid described forms.

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Wednesday, 22 October 2014

The role of aquatic polymers in transmitting disease in coastal ecosystems.

Toxoplasma gondii is a protozoan parasite that affects humans, and many other animals, across the globe. While it causes disease in many organisms, it reproduces only in Felids, particularly in Domestic Cats, with oocysts (egg-like cysts) being shed in Cat faeces spreading the disease to many other organisms (some of which are subsequently eaten by Cats). The response to infection is variable; in humans it can cause illness and even death, but many people appear to become infected without ever suffering symptoms.

The disease has been recorded in a variety of Marine Mammals off the coast of California, including Sea Otters, which appear to be particularly vulnerable, and there have been a number of cases of Humans becoming infected after consuming seafood or simply coming into contact with seawater in California. While it is possible for Toxoplasma gondii oocysts to reach the sea in runoff from land, the rate of infection seen in Californian Marine Mammals is hard to explain; oocysts can persist in the environment for years, but should still be at a far lower concentration in the sea than can explain the infection rates seen.

In a paper published in the Proceedings of the Royal Society SeriesB: Biological Sciences on 8 October 2014, a team of oceanographers, ecologists and epidemiologists from the University of California, Davis and University ofCalifornia, Santa Cruz, led by Karen Shapiro of the One Health Institute and Department of Pathology, Microbiology and Immunology at the School ofVeterinary Medicine at the University of California, Davis, describe the results of a series of investigations into the role of marine polymers in the transmission of Toxoplasma gondii in Californian coastal ecosystems.

Marine polymers are a diverse group of sticky organic chemicals produced by organisms for a variety of reasons, including defence (many organisms have a protective mucous coating), feeding (filter feeding and detritus consuming organisms often use mucus to aggregate small food particles into manageable clumps) and movement (such as the mucus trails left by Snails). They form drifting marine aggregates (marine snow), which tend to sweep up small particles in the water, aiding the settling of such particles onto the seafloor or other surfaces.

Firstly Shapiro et al. tested to concentration of Toxoplasma gondii oocysts in seawater with varying concentrations ofmarine polymers, finding that high concentrations of such polymers could raise the concentration of oocysts by up to 80%. This indicates that oocysts entering the marine ecosystem are highly likely to become associated with marine polymer aggregations, concentrating the infective particles, if causing them to settle out more rapidly (which is not a bad thing for the oocyst, settling close to shore where it may be consumed by a potential host is better than drifting into the open ocean where it will eventually die).

Toxoplasma gondii oocyst (arrow) associated with a TEP-embedded aggregate under DAPI epifluorescence. Shapiro et al. (2014).

Next Shapiro et al. looked at the ability of the Turban Snails Chlorostoma brunnea, Chlorostoma montereyi and Promartynia pulligo to absorb and transmit Toxoplasma gondii oocysts; it has previously been observed that Sea Otters that favour Turban Snails are more at risk of Toxoplasma gondii infection than those living in the same areas that favour other prey. The Turban Snails live on Kelp plants, where they consume mucus from the surface of the Kelp; the mucus is excreted by the Kelp as a defence, allowing the transmission of dissolved marine nutrients but excluding potentially harmful microorganisms. Shapiro et al. found that Turban Snails start to excrete Toxoplasma gondii oocysts in their faeces about 10 days after being exposed to a source of food contaminated with the oocysts, and that these oocysts are significantly concentrated in the faeces relative to the food.

Ventral surface of Turban Snail with enlargement of scraping radula. Shapiro et al. (2014).

Based upon these experiments Shapiro et al. propose the following mechanism for the transmission of Toxoplasma gondii in Californian coastal waters: The oocysts of the organism enter the water through runoff from the land at low concentrations, but are concentrated in floating aggregations of marine polymers. These aggregations may be consumed in the water column by filter feeding Fish such as Sardines, or settle out of the water column and be consumed by filter feeding shellfish such as Clams, both of which facilitate transmission to Humans via seafood.

In the specific case of Otters the chance of infection is significantly raised by the consumption of Turban Snails, which feed upon mucus on the surface of Kelp Plants (where the oocysts are likely to have become concentrated) and further concentrate the oocysts within their bodies.

Two mechanisms are proposed whereby polymers can mediate transmission of terrestrial pathogens in coastal ecosystems (depicted here for a modelzoonotic protozoan parasite, Toxoplasma gondii). Pelagic polymers such as TEPs may enhance the association of pathogens with sinking macroaggregates, while benthic exopolymer substances (EPS) can trap pathogens within sticky biofilms. Both mechanisms are likely to increase the probability ofpathogen entry into the marine food web through aggregate-consuming invertebrates such as Bivalves or surface scraping Molluscs such as Snails. Ingestion ofcontaminated prey items can then lead to pathogen exposure in susceptible hosts, including threatened California Sea Otters and Humans. Shapiro et al. (2014).

See also…

At least 467 people have died in an outbreak of  Ebola Hemorrhagic Fever in West Africa that began in February this year. The disease initially appeared in the remote border area between Guinea, Sierra Leone and...

Bull Kelp, Durvillaea antarctica, is a large Brown Algae forming dense colonies of fronds up to 8 m long on otherwise exposed rocky shores on the coasts of South America, New Zealand and the islands of the...

John Snow was a nineteenth century London doctor, who is widely credited with the discovery of the transmission mechanism of Cholera, a severe and often fatal infection of the small intestine caused by the bacterium Vibrio cholerae. In Snow's time our understanding of microbiology was in its infancy...

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