Marianne Sommer

Injectable materials with magnetically controlled anisotropic porosity.

We propose a method to create aligned porosity in injectable materials by using magnetically responsive microrods as pore forming sacrificial templates. Rod alignment occurs through the application of an external magnetic field after injecting the material into the desired end location. Removal of the sacrificial templates through dissolution or resorption generates porosity in deliberately tuned orientations after injection, offering a powerful method to design the porous architecture of injectable materials.

3D Printing of Hierarchical Silk Fibroin Structures

Like many other natural materials, silk is hierarchically structured from the amino acid level up to the cocoon or spider web macroscopic structures. Despite being used industrially in a number of applications, hierarchically structured silk fibroin objects with a similar degree of architectural control as in natural structures have not been produced yet due to limitations in fabrication processes. In a combined top-down and bottom-up approach, we exploit the freedom in macroscopic design offered by 3D printing and the template-guided assembly of ink building blocks at the meso- and nanolevel to fabricate hierarchical silk porous materials with unprecedented structural control. Pores with tunable sizes in the range 40-350 μm are generated by adding sacrificial organic microparticles as templates to a silk fibroin-based ink. Commercially available wax particles or monodisperse polycaprolactone made by microfluidics can be used as microparticle templates. Since closed pores are generated after template removal, an ultrasonication treatment can optionally be used to achieve open porosity. Such pore templating particles can be further modified with nanoparticles to create a hierarchical template that results in porous structures with a defined nanotopography on the pore walls. The hierarchically porous silk structures obtained with this processing technique can potentially be utilized in various application fields from structural materials to thermal insulation to tissue engineering scaffolds.

Silk fibroin scaffolds with inverse opal structure for bone tissue engineering.

Abstract How scaffold porosity, pore diameter and geometry influence cellular behavior is‐although heavily researched ‐ merely understood, especially in 3D. This is mainly caused by a lack of suitable, reproducible scaffold fabrication methods, with processes such as gas foaming, lyophilization or particulate leaching still being the standard. Here we propose a method to generate highly porous silk fibroin scaffolds with monodisperse spherical pores, namely inverse opals, and study their effect on cell behavior. These silk fibroin inverse opal scaffolds were compared to salt‐leached silk fibroin scaffolds in terms of human mesenchymal stem cell response upon osteogenic differentiation signals. While cell number remained similar on both scaffold types, extracellular matrix mineralization nearly doubled on the newly developed scaffolds, suggesting a positive effect on cell differentiation. By using the very same material with comparable average pore diameters, this increase in mineral content can be attributed to either the differences in pore diameter distribution or the pore geometry. Although the exact mechanisms leading to enhanced mineralization in inverse opals are not yet fully understood, our results indicate that control over pore geometry alone can have a major impact on the bioactivity of a scaffold toward stem cell differentiation into bone tissue.

Human tools of the European tertiary? Artefacts, brains and minds in evolutionist reasoning, 1870–1920

This essay explores evolutionary reasoning and notions of progress at the turn of the twentieth century by focusing on the various interpretations used to understand eoliths. These ‘dawn’ (Greek eos) ‘stones’ (Greek lithos) were contested objects and I focus on three geographic episodes in which they were used to support scientific, and sometimes socially inspired, accounts of human origins. Particular attention is paid to the work of Gabriel de Mortillet (1821–98), James Reid Moir (1879–1944) and Henry Fairfield Osborn (1857–1935).

‘An amusing account of a cave in Wales’: William Buckland (1784–1856) and the Red Lady of Paviland

In 1823 the first Reader of Geology at Oxford University, William Buckland (1784–1856), unearthed the human skeleton known as the ‘Red Lady’ in Paviland cave, south Wales. While the Red Lady is valued today as a central testimony of early Upper Palaeolithic humans in Britain, Buckland considered the skeleton as of postdiluvian age, meaning from after the biblical Deluge. Rather than viewing Buckland as either obscurantist or as having worked entirely within ordinary scientific practice, the paper focuses on how he managed to create an institutional and conceptual space for his geology at one of the centres for the education of the Anglican clergy, and on the impact the sometimes paradoxical demands had on his interpretation of prehistoric human relics, the Red Lady in particular. Buckland was famous if not notorious for his peculiar humour, the distracting and cathartic qualities of which, it will be argued, served as strategy in the advancement of unorthodox ideas or for glossing over inconsistencies.

Biology as a Technology of Social Justice in Interwar Britain: Arguments from Evolutionary History, Heredity, and Human Diversity

In this article, I am concerned with the public engagements of Julian Huxley, Lancelot Hogben, and J. B. S. Haldane. I analyze how they used the new insights into the genetics of heredity to argue against any biological foundations for antidemocratic ideologies, be it Nazism, Stalinism, or the British laissez-faire and class system. The most striking fact—considering the abuse of biological knowledge they contested—is that these biologists presented genetics itself as inherently democratic. Arguing from genetics, they developed an understanding of diversity that cuts across divisions of race, class, or gender. Human diversity rightly understood was advantageous for societal progress. Huxley, Hogben, and Haldane did not hold identical political ideals, but they all argued for democratic reforms and increased planning geared toward greater social equality, and they did so under the label of scientific humanism. Huxley took issue with the notion that evolutionary history does not carry any moral lessons for human societies. Rather than being its antithesis, evolution was the basis of human sociality. In fact, the entire future progress of individuals and communities toward a democratic world order needed to be founded on the cosmic principles of evolution—a process that had to be guided by the biological expert with a strong sense of social responsibility.

Seriality in the Making: The Osborn-Knight Restorations of Evolutionary History

The author and illustrator, Charles R. Knight (1874–1953), has like no other artist shaped the scientific, artistic and popular images of prehistoric animals and men. Again and again, he visualized and performed the story of “life’s pageant through the ages” by means of a series of images. The most impressive was undertaken in the second half of the 1920s for the Chicago Field Museum, for which Knight produced a series of 28 murals for a new gallery showing the fossils of extinct vertebrates. These murals were to be a splendid display of the history of life on earth, from its beginnings, through the age of amphibians, reptiles and mammals, up to the age of man (although no humans were depicted). However, this commission piqued the feelings of Henry Fairfield Osborn (1857–1935), who as curator of vertebrate palae ontology (1891) and later president (1908) of the American Museum of Natural History in New York (hereafter AMNH) had revolutionized the way in which fossil vertebrates were displayed. It was Osborn who had made it possible for locals and visitors alike to be stunned by the dynamic mounts of the skeletons of fossil reptiles and mammals. And it was Osborn who had combined science and art to bring to life the long-gone creatures in their behaviour and ecology. No doubt Osborn regarded Knight — the genius of palaeontological reconstruction — as to no small degree his creation. After all, it was due to Osborn that Knight had opened up the field of ‘palaeoart’ in the mid-1890s, painting fossil animals as realistically as living animals could be caught on photographs. It was through Knight’s work at the AMNH that the artist achieved worldwide fame. In fact, Osborn considered his share in Knight’s paintings to be considerable, so considerable that he spoke of the images as OsbornKnight restorations. Osborn’s layout of the epochs in the history of life at the AMNH was not as compactly serial as Knight’s mural project for the Field Museum. Rather, the development of vertebrate life was stretched out through entire halls: the ages of reptiles, mammals and man. Within each hall, the visitor encountered static scenes of life in the respective age as well as visualizations of development. There were other structuring devices at work than chronological order, as for example the reconstruction of scenes from particularly rich sites; the exhibits also reflected Osborn’s interests, such as the evolution of the proboscidea and titanotheres. Nonetheless, seriality was incorporated in the design of the halls, and it also ordered the work processes that led to their profuse decoration. Osborn firmly subscribed to his New-York élite’s credo of efficiency, and wanted to make the process of bringing evolutionary history before the eyes of the museum visitors as rational as possible. This included the collection

Population-genetic trees, maps, and narratives of the great human diasporas

From the 1960s, mathematical and computational tools have been developed to arrive at human population trees from various kinds of serological and molecular data. Focusing on the work of the Italian-born population geneticist Luigi Luca Cavalli-Sforza, I follow the practices of tree-building and mapping from the early blood-group studies to the current genetic admixture research. I argue that the visual language of the tree is paralleled in the narrative of the human diasporas, and I show how the tree was actually mapped onto the surface of the earth. This visual and textual structure is mirrored in the liberal discourse of unity in diversity that has been criticized as running counter to the socio-political effects of human population genetics. From this perspective, one may ask how far the phylogenetic diagram in its various forms is a manifestation of the physics of power that according to Michel Foucault consists in mechanisms that analyse distributions, movements, series, combinations, and that uses instruments to render visible, to register, to differentiate and to compare. It is one among other disciplinary technologies that ensure the ordering of human diversity. In the case of intra-human phylogenetic trees, population samples and labels are one issue. Another is that the separated branches seem to show groups of people, who have in reality been interacting and converging, as isolated. Often based on so-called isolated peoples, molecular tree diagrams freeze a hierarchical kinship system that is meant to represent a state before the great historical population movements.

Visibility matters: Diagrammatic renderings of human evolution and diversity in physical, serological and molecular anthropology

Images are at the heart of strategies of persuasion. They render certain aspects visible and leave others unrepresented; and they may shape processes of scientific reasoning and imagination. By tracing diagrammatic images in the anthropological sciences throughout the 20th century, the contributions to this special issue highlight some dominant pictorial traditions for rendering human evolution and diversity visible. This article aims to provide an overview of and an introduction to the special issue ‘Visibility Matters’.

„Wer sind Sie wirklich?“ – Identität und Geschichte in der ‚Gensequenz‘

Heute mögen uns die Versuche der physischen Anthropologie des 19. und frühen 20. Jahrhunderts, den biologischen Typ des widerstandsfähigen und freiheitsliebenden Schweizer Homo alpinus an der Form des Schädels festzumachen, allenfalls zu einem Lächeln verleiten. Oder wen interessiert noch, ob das Band, das die SchweizerInnen der Gegenwart mit den antiken Völkern verbindet, die einst auf dem heutigen Schweizer Boden hausten, ein kulturelles oder biologisches ist? Jene, die mit dem rassenhygienischen Paradigma der frühen Zürcher Anthropologie (insbesondere unter Otto Schlaginhaufen) vertraut sind, dürften auch wissen, wieso sie solche Fragen nicht stellen. Die Pfahlbauer genießen zwar wieder große Popularität, sie werden uns in den Medien und in Ausstellungen gar als unsere Vorfahren vorgestellt, aber so richtig ernst wird das wohl auch vom breiten Publikum nicht genommen. Wer diese Annahmen teilt, wird erstaunt sein, auf der Website einer Schweizer Firma auf die Frage zu treffen: „Haben Sie keltische, jüdische oder germanische Wurzeln?“1 Noch unerwarteter ist die Methode, mittels welcher diese Frage angegangen wird, lädt doch die Firma Gentest.ch dazu ein, die eigene Identität genetisch bestimmen zu lassen. Die Basenabfolge bestimmter DNA-Regionen des Kunden sollen sowohl das Geheimnis seiner Geschichte als auch das seiner Zugehörigkeit in sich tragen. Die tatsächlichen und potentiellen Anwendungen der medizinischen Genetik – wie etwa Präimplantationsdiagnostik, Embryonenselektion, Klonen, genetische Modifikation und personalisierte genomische Medizin – haben von Seiten der Wissenschaftsforschung und in Öffentlichkeiten viel Aufmerksamkeit erhalten, wobei gegensätzliche Einschätzungen formuliert werden. Die genomische Medizin wird mit der Gefahr des genetischen Determinismus und Rassismus, der Diskriminierung aufgrund des