Evolution of the Grain Dispersal System in Barley.

About 12,000 years ago in the Near East, humans began the transition from hunter-gathering to agriculture-based societies. Barley was a founder crop in this process, and the most important steps in its domestication were mutations in two adjacent, dominant, and complementary genes, through which grains were retained on the inflorescence at maturity, enabling effective harvesting. Independent recessive mutations in each of these genes caused cell wall thickening in a highly specific grain "disarticulation zone," converting the brittle floral axis (the rachis) of the wild-type into a tough, non-brittle form that promoted grain retention. By tracing the evolutionary history of allelic variation in both genes, we conclude that spatially and temporally independent selections of germplasm with a non-brittle rachis were made during the domestication of barley by farmers in the southern and northern regions of the Levant, actions that made a major contribution to the emergence of early agrarian societies.

First wave of cultivators spread to Cyprus at least 10,600 y ago.

Early Neolithic sedentary villagers started cultivating wild cereals in the Near East 11,500 y ago [Pre-Pottery Neolithic A (PPNA)]. Recent discoveries indicated that Cyprus was frequented by Late PPNA people, but the earliest evidence until now for both the use of cereals and Neolithic villages on the island dates to 10,400 y ago. Here we present the recent archaeological excavation at Klimonas, which demonstrates that established villagers were living on Cyprus between 11,100 and 10,600 y ago. Villagers had stone artifacts and buildings (including a remarkable 10-m diameter communal building) that were similar to those found on Late PPNA sites on the mainland. Cereals were introduced from the Levant, and meat was obtained by hunting the only ungulate living on the island, a small indigenous Cypriot wild boar. Cats and small domestic dogs were brought from the mainland. This colonization suggests well-developed maritime capabilities by the PPNA period, but also that migration from the mainland may have occurred shortly after the beginning of agriculture.

Early agricultural pathways: moving outside the 'core area' hypothesis in Southwest Asia.

The origins of agriculture in the Near East has been associated with a 'core area', located in south-eastern Turkey, in which all major crops were brought into domestication within the same local domestication system operated by a single cultural group. Such an origin leads to a scenario of rapid invention of agriculture by a select cultural group and typically monophyletic origins for most crops. Surprisingly, support for a core area has never been directly tested with archaeological evidence. Over the past decade a large amount of new archaeological and genetic evidence has been discovered which brings new light on the origins of agriculture. In this review, this new evidence was brought together in order to evaluate whether a core region of origin is supported. Evidence shows that origins began earlier than previously assumed, and included 'false starts' and dead ends that involved many more species than the typical eight founder crops associated with the core area. The rates at which domestication syndrome traits became fixed were generally slow, rather than rapid, and occurred over a geographically wide range that included the North and South Levant as well as the core area. Finally, a survey of the estimated ages of archaeological sites and the onset of domestication indicates that the domestication process was ongoing in parallel outside of the core area earlier than within it. Overall, evidence suggests a scenario in which crops were domesticated slowly in different locations around the Near East rather than emanating from a core area.

On the Origin of the Non-brittle Rachis Trait of Domesticated Einkorn Wheat.

Einkorn and emmer wheat together with barley were among the first cereals domesticated by humans more than 10,000 years ago, long before durum or bread wheat originated. Domesticated einkorn wheat differs from its wild progenitor in basic morphological characters such as the grain dispersal system. This study identified the Non-brittle rachis 1 (btr1) and Non-brittle rachis 2 (btr2) in einkorn as homologous to barley. Re-sequencing of the Btr1 and Btr2 in a collection of 53 lines showed that a single non-synonymous amino acid substitution (alanine to threonine) at position 119 at btr1, is responsible for the non-brittle rachis trait in domesticated einkorn. Tracing this haplotype variation back to wild einkorn samples provides further evidence that the einkorn progenitor came from the Northern Levant. We show that the geographical origin of domesticated haplotype coincides with the non-brittle domesticated barley haplotypes, which suggest the non-brittle rachis phenotypes of einkorn and barley were fixed in same geographic area in today's South-east Turkey.

Chromosomal passports provide new insights into diffusion of emmer wheat.

Emmer wheat, Triticum dicoccon schrank (syn. T. dicoccum (schrank) schÜbl.), is one of the earliest domesticated crops, harboring a wide range of genetic diversity and agronomically valuable traits. The crop, however, is currently largely neglected. We provide a wealth of karyotypic information from a comprehensive collection of emmer wheat and related taxa. In addition to C-banding polymorphisms, we identified 43 variants of chromosomal rearrangements in T. dicoccon; among them 26 (60.4%) were novel. The T7A:5B translocation was most abundant in Western Europe and the Mediterranean. The plant genetic resources investigated here might become important in the future for wheat improvement. Based on cluster analysis four major karyotypic groups were discriminated within the T. dicoccon genepool, each harboring characteristic C-banding patterns and translocation spectra: the balkan, asian, european and ethiopian groups. We postulate four major diffusion routes of the crop and discuss their migration out of the Fertile Crescent considering latest archaeobotanical findings.

How fast was wild wheat domesticated?

Prehistoric cultivation of wild wheat in the Fertile Crescent led to the selection of mutants with indehiscent (nonshattering) ears, which evolved into modern domestic wheat. Previous estimates suggested that this transformation was rapid, but our analyses of archaeological plant remains demonstrate that indehiscent domesticates were slow to appear, emerging approximately 9500 years before the present, and that dehiscent (shattering) forms were still common in cultivated fields approximately 7500 years before the present. Slow domestication implies that after cultivation began, wild cereals may have remained unchanged for a long period, supporting claims that agriculture originated in the Near East approximately 10,500 years before the present.