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The Yanghai Tombs near Turpan, Xinjiang-Uighur Autonomous Region, China have recently been excavated to reveal the 2700-year-old grave of a Caucasoid shaman whose accoutrements included a large cache of cannabis, superbly preserved by climatic and burial conditions. A multidisciplinary international team demonstrated through botanical examination, phytochemical investigation, and genetic deoxyribonucleic acid analysis by polymerase chain reaction that this material contained tetrahydrocannabinol, the psychoactive component of cannabis, its oxidative degradation product, cannabinol, other metabolites, and its synthetic enzyme, tetrahydrocannabinolic acid synthase, as well as a novel genetic variant with two single nucleotide polymorphisms. The cannabis was presumably employed by this culture as a medicinal or psychoactive agent, or an aid to divination. To our knowledge, these investigations provide the oldest documentation of cannabis as a pharmacologically active agent, and contribute to the medical and archaeological record of this pre-Silk Road culture.

The time course of cannabinoid accumulation in the leaves of individual plants of three Cannabis accessions was determined by gaschromatographic analysis in greenhouse-grown plants. The total amounts and the concentration ratios of CBD, THC and CBG were determined; two accessions (an experimental hybrid, (21R £ 15R) £ NL, and plants from a seized seed lot) were found chemotypically uniform, with all plants belonging to chemotpe II (mixed) and I (high THC) respectively. The Carmagnola accession showed chemotypic heterogeneity, with a majority of plants belonging to chemotype III. The CBD/THC and CBG/CBD ratios were shown to be largely constant in the leaves, since 28 and until 103 days after sowing, and consistent with the ratios determined on mature inXorescences. CBD and THC maximum amounts in the leaves showed a peak in the leaves around 80 days from sowing, and were shown to be simultaneous during the growth period, irrespective of the chemotypes. Callus cultures were obtained from all the Wve diVerent chemotypes (I, II, III, IV, V), and GC analyses were performed. Independently of the type and amount of cannabinoids in the mother plants, it was conWrmed that callus cultures of Cannabis were not able to produce detectable amounts of any cannabinoids.

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SummaryHere we studied the organization of genetic variation of the common bean (Phaseolus vulgaris) in its centres of domestication.We used 131 single nucleotide polymorphisms to investigate 417 wild common bean accessions and a representative sample of 160 domesticated genotypes, including Mesoamerican and Andean genotypes, for a total of 577 accessions.By analysing the genetic spatial patterns of the wild common bean, we documented the existence of several genetic groups and the occurrence of variable degrees of diversity in Mesoamerica and the Andes. Moreover, using a landscape genetics approach, we demonstrated that both demographic processes and selection for adaptation were responsible for the observed genetic structure.We showed that the study of correlations between markers and ecological variables at a continental scale can help in identifying local adaptation genes. We also located putative areas of common bean domestication in Mesoamerica, in the Oaxaca Valley, and the Andes, in southern Bolivia-northern Argentina. These observations are of paramount importance for the conservation and exploitation of the genetic diversity preserved within this species and other plant genetic resources.