Inferring cultural reproduction from lithic data: A critical review

The cultural reproduction of lithic technology, long an implicit assumption of archaeological theories, has garnered increasing attention over the past decades. Major debates ranging from the origins of the human culture capacity to the interpretation of spatiotemporal patterning now make explicit reference to social learning mechanisms and cultural evolutionary dynamics. This burgeoning literature has produced important insights and methodological innovations. However, this rapid growth has sometimes led to confusion and controversy due to an under-examination of underlying theoretical and methodological assumptions. The time is thus ripe for a critical assessment of progress in the study of the cultural reproduction of lithic technology. Here we review recent work addressing the evolutionary origins of human culture and the meaning of artifact variation at both intrasite and intersite levels. We propose that further progress will require a more extended and context-specific evolutionary approach to address the complexity of real-world cultural reproduction.     

Entwicklungsgeschichtliche untersuchungen an einer Blattmutante vonHyoscyamus niger L.

Summary The leaf shape of the mutantfiliformis (fil) ofHyoscyamus niger L. is strongly modified by external factors (like nutrition and light) as well as by the height of insertion. The name filiformis refers to thread-like leaves which always occur in the inflorencence; they may also be formed in the vegetative region, especially under short day conditions. Other leaves may have a small rhombic blade or a larger blade with irregular edges and deep incisions. Even pinnate leaves have been found. In contrast to the leaves of normalHyoscyamus, all mutant leaves (hypsophylls included) have a stalk-like basal portion that seems to be homologous to the basal part of the normal blade. This mutant is caused by one recessive factor which is linked neither toann nor topall.the submarginal initials of the normalHyoscyamus blade were always found dividing according to the periclinal-anticlinal type, while in the mutant the activity of the submarginal initials frequently resulted in a primarily biseriate mesophyll (so-called double-edged segmentation).This is apparently the first time that gene control of the mode of submarginal blade growth has been observed. Further differences between mutant and normalHyoscyamus concern the venation, the lengths of palisade cells and of stomata guard cells, the frequency of stomata per mm², and the thickness of the blade.

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Inversionen und chromosomale Strukturtypen bei Drosophila subobscura Coll

Zusammenfassung 1. Auf Grund der Untersuchung von zahlreichen Stämmen von Drosophila subobscura, die aus Köderfängen in der Natur an verschiedenen Orten in Österreich, Oberitalien, der Schweiz, England und einigen außereuropäischen Ländern abgeleitet worden waren, wurde ein Verzeichnis aller bisher bei dieser Art festgestellten natürlichen Inversionen gegeben, wobei die Anordnung des strukturell homozygoten Stammes Küsnacht als Standardanordnung diente.2. Durch den Vergleich von Stämmen, durch deren Kreuzung mit dem Standardstamm, durch die Ableitung von Inzuchtlinien aus verschiedenem Ausgangsmaterial und deren Kreuzung mit bestimmten Stämmen wurde die Zahl und der Bau der chromosomalen Strukturtypen ermittelt, auf deren Koexistenz in der Population die Mannigfaltigkeit der beobachteten Inversionsbilder beruht.3. Die Verteilung der Inversionen auf die verschiedenen Chromosomen des Satzes ist nicht zufällig. Auch die relative Länge der Inversionen scheint nicht rein zufallsmäßig zu sein.4. Bei den Bruchstellen der Inversionen finden sich auffallend oft Koinzidenzen, bis zu 5 Bruchstellen an einem Ort eines Chromosoms. Wie eine statistische Überlegung zeigt, können diese nicht zufallsmäßig bedingt sein. Es werden einige hypothetische Deutungsmöglichkeiten dieses Phänomens vorgelegt.5. Es wird die phylogenetische Ableitung der Strukturtypen der verschiedenen Chromosomen diskutiert.Mit 7 Textabbildungen.     

Effects of temperature and photoperiod on flowering in Hyptis brevipes

Few tropical species have been tested for their flowering response under controlled conditions. Hyptis brevipes Poit, is an annual herb, commonly found in wet margins of streams and ponds, being considered a weed for some perennial plantations in Brazil. Under experimental glasshouse conditions, this species proved to be an obligate short-day plant. Flowering was delayed when photoperiods longer than 8 h were given, the critical photoperiod being between 12 and 13 h. When both temperature and photoperiod were controlled, at 20°C a longer protoperiod (by almost 1 h) is still inductive compared to 25 and 30°C. The number of short-day cycles required for full induction is relatively high and dependent upon temperature; at 20°C or above, 10 cycles are adequate, but at 15°C, more short-day cycles are needed. The number of inflorescences formed as well as the floral index vary according to daylength × temperature × inductive cycle number, allowing flowering to be assessed quantitatively. Long days are inhibitory to flowering, either suppressing it completely (when symmetrically intercalated among 24 inductive cycles) or preventing the floral index from increasing.     

Molecular basis of intercellular adhesion in the biofilm-forming Staphylococcus epidermidis

The Staphylococcus epidermidis genes icaABC are involved in the synthesis of the polysaccharide intercellular adhesin (PIA), which is located mainly on the cell surface, as shown by immunofluorescence studies with PIA-specific antiserum. PIA was shown to be a linear β-1,6-linked glucosaminoglycan composed of at least 130 2-deoxy-2-amino-D-glucopyrano-syl residues of which 80–85% are N-acetylated, the rest being non-N-acetylated and positively charged. A transposon insertion in the icaABC gene cluster (ica, intercellular adhesion) led to the loss of several traits, such as the ability to form a biofilm on a polystyrene surface, cell aggregation, and PIA production. The mutant could be complemented by transformation with the IcaABC-carrying plasmid pCN27. Transfer of pCN27 into the heterologous host Staphylococcus carnosus led to the formation of large cell aggregates, the formation of a biofilm on a glass surface, and PIA expression. The nucleotide sequence of icaABC suggests that the three genes are organized in an operon and that they are co-transcribed from the mapped ica A promoter. Ica A contains four potential transmembrane helices, indicative of a membrane location. The deduced Ica A sequence shows similarity to those of polysaccharide-polymerizing enzymes, the most pronounced being with a Rhizobium meliloti N-acetylglucosaminyltransferase involved in lipo-chitin biosynthesis (22.5% overall identity and 37.4% overall similarity). This similarity suggests that Ica A has N-acetylglucosaminyltransferase activity in the formation     

Upper cretaceous rudist and stromatoporid associations of Central Oman (Arabian Peninsula)

Summary Rudist and stromatoporid associations of the Campanian from Central Oman are nearly monospecific. They are dominated byDurania aff.nicholasi, Vaccinites vesiculosus, Torreites milanovici or phaceloid and massive stromatoporids. Several other rudist genera play a secondary role. The thickness of the associations is rarely more than one metre. Solitary corals do not occur in the associations. Colonial corals are less common, although they are up to 1 m high and show considerable diversity. There are no binders. The reef structure indicates variable hydrodynamic conditions. They are always associated with very shallow water. The pureDurania aff.nicholasi patches with large colonial corals andTorreites milanovici are presumably the most rigid structures. The near monospecific associations ofVaccinites vesiculosus are widely distributed. Although mostly preserved in situ, strong currents, presumably caused by tropical storms, have repeatedly impaired and interrupted growth. The specific growth characteristics of the shell of some rudists, especially the radiolitids, enable an estimation of the individual lifespan. Frameworks of approximately 1 metre thickness probably developed in ±100 years. The sediments of the complete sections are predominantly bioclastic.