Carrying capacity,population density and the later Pleistocene expression of backed artefact manufacturing traditions in Africa

As is the case today, both climate variability and population density influenced human behavioural change in the past. The mechanisms underpinning later Pleistocene human behavioural evolution, however, remain contested. Many complex behaviours evolved in Africa, but early evidence for these behaviours varies both spatially and temporally. Scientists have not been able to explain this flickering pattern, which is present even in sites and regions clearly occupied by Homo sapiens. To explore this pattern, here the presence and frequency of evidence for backed stone artefact production are modelled against climate-driven, time-series population density estimates (Timmermann and Friedrich. 2016 Nature 538, 92. (doi:10.1038/nature19365)), in all known African Late Pleistocene archaeological sites (n = 116 sites, n = 409 assemblages, n = 893 dates). In addition, a moving-window, site density population estimate is included at the scale of southern Africa. Backed stone artefacts are argued in many archaeological contexts to have functioned in elaborate technologies like composite weapons and, in the African Pleistocene, are accepted proxies for cultural complexity. They show a broad but sporadic distribution in Africa, prior to their association with Homo sapiens dispersing into Europe 45–40 ka. Two independent population estimates explain this pattern and potentially implicate the interaction of climate change and demography in the expression of cultural complexity in African Pleistocene Homo sapiens.This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.     

The Calcaneum—On the Heels of Marsupial Locomotion

The potential for making functional interpretations from a single postcranial element for marsupials was investigated through morphometric analysis of the calcanea of 61 extant species from Australia and New Guinea. Extant species were grouped into locomotor categories and a canonical variates analysis was carried out on measurements of their calcanea. A relationship between measurements of the calcanea and the locomotor behavior of species was found, allowing for prediction of locomotor behavior from calcaneum morphometrics. This was applied to fossil marsupial taxa, from early–late Miocene/?Pliocene deposits at Riversleigh, in an attempt to determine their locomotor behavior. Hopping (saltatorial) taxa are distinguished from quadruped terrestrial taxa and taxa capable of climbing (arboreal and scansorial) by their relatively longer tuber calcis and wider calcaneal head, by their dorso-ventrally thicker calcaneal head, and by their calcaneocuboid facet being less steeply angled antero-posteriorly. Taxa capable of climbing are distinguished from quadruped terrestrial taxa by their shorter tuber calcis relative to the calcaneal head and by their smaller calcaneo-astragalar facet. The locomotor categories distinguished in this study (arboreal/scansorial, quadruped terrestrial, and saltatorial) highlight differences between species in their use of available substrates and thus are informative with regards to the structural components of their habitat. The results of this analysis can be used, in combination with other data, to make inferences about the habitats of paleocommunities at Riversleigh through the Miocene. The calcaneum is a dense and very robust element and, therefore, has a good chance of being preserved. This method provides a quick and easy way of inferring locomotion and has a wide potential for application to many fossil deposits because it requires only a single element.     

Microbiological transformations of nabilone, a synthetic cannabinoid.

A screening program was conducted to find microorganisms that modify the synthetic cannabinoid nabilone. After purification, the products from three cultures were analyzed by spectral methods to determine their chemical structures. An optically active 9S-hydroxy-6aR,10aR-trans cannabinoid was isolated from a culture of an unidentified soil bacterium designated A24007. From Bacillus cereus cultures were isolated a 9S,6'-dihydroxy-6aR,10aR-trans cannabinoid, a 9S-hydroxy-6'-keto-6aR,10aR-trans cannabinoid, a 9-keto-6'-hydroxy-6aS,10aS-trans cannabinoid, and a 6',9-diketo-6aS,10aS-trans cannabinoid. All of these products were optically active, as was a 9S-hydroxy-6aS,10AS-trans cannabinoid also isolated from B. cereus cultures. A series of acidic products were isolated from cultures of Nocardia salmonicolor. All of these products contained a carboxylic acid group at the terminal end of three-position alkyl side chains having varying numbers of carbon atoms. Two of the acidic products contained a 9-keto group, whereas all other carboxylic acid products were 9-hydroxy cannabinoids. The array of products obtained from incubation of nabilone indicates the usefulness of microbial transformations in the preparation of new cannabinoids.     

Long-acting contraceptive agents: design of the WHO Chemical Synthesis Programme

The great demand for improved long-acting injectable steroid contraceptives, particularly in developing countries, and the relative lack of interest from the pharmaceutical industry to develop such products stimulated WHO to launch a synthetic and screening programme to find improved, safe and acceptable injectable preparations. More than 210 esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) and levonorgestrel (D-(-)-13 beta-ethyl-17 alpha-ethynyl-17 beta-hydroxygon-4-en-3-one) have been prepared in university-based research laboratories situated mainly in developing countries, and then screened by NICHHD in animal models. The following three compounds, levonorgestrel butanoate, cyclopropylcarboxylate and cyclobutylcarboxylate, proved to be particularly long-acting when administered as microcrystalline suspensions. The overall strategy of this research and development programme is described.