Panicum spikelets from the Early Holocene Takarkori rockshelter (SW Libya): Archaeo-molecular and -botanical investigations

This paper deals with the extraction, amplification and sequencing of ancient DNA (aDNA) from spikelets of wild cereals dated at ca. 9000 cal yr BP, representing the most ancient plants with preserved genetic material from the Sahara desert. The sub-fossil records were collected from the archaeological excavation carried out at Takarkori, an archaeological site located in south-western Libya. Morphological and genetic analyses were made on 100 well preserved dried spikelets. Ten DNA extraction protocols were performed to evaluate nucleic acid recovery in terms of DNA yield, purity and amplification success of the chloroplast barcode region matK. The extraction protocol that returned the most suitable DNA to be amplified is the Kistler and Shapiro (2011: J Archaeol Sci 38: 3549-3554) modified protocol. In our study, the results from matK amplification suggested that four specimens are the most appropriate number of spikelets for these analyses. DNA was then used for PCR amplifications of four chloroplast barcode genes: rbcL, matK, trnH-psbA and trnL. A phylogenetic analysis shows the strict relation between the archaeological specimens and modern Panicoideae, supporting the morphological identification. The results indicate that spikelets have a close relation to Panicum laetum Kunth, a wild cereal still collected in tropical Africa.     

Glacial refugia of temperate, Mediterranean and Ibero-North African flora in south-eastern Spain: new evidence from cave pollen at two Neanderthal man sites

Aim To locate glacial refugia of thermophilous plant species in Spain. Location Two south‐eastern Spanish Neanderthal man sites in Murcia; namely, the inland Cueva Negra del Estrecho del Río Quípar and the coastal Sima de las Palomas del Cabezo Gordo. Methods We use pollen found in cave sediments as a source of palaeobotanical and palaeoecological information. The findings are discussed with regard both to animal remains from both sites, and also to other refugia in south‐eastern Spain and elsewhere in the Iberian Peninsula. Results Both sequences show persistence of abundant mesothermophilous trees during the last glacial stage, suggesting both localities were reservoirs of phytodiversity and woodland species. At both sites, deciduous and evergreen oaks are the most abundant components, followed by a wide variety of deciduous trees and sclerophyllous shrubs, including Ibero‐North African xerothermic scrub near the coast. Conclusions Incomplete information underlies a common misapprehension that Iberian glacial refugia were confined to southernmost parts of the peninsula. A rather different picture of Quaternary refugia emerges from consideration of pollen sequences from caves (and other inputs such as macroscopic charcoal, spatial genetic structure of present‐day populations, faunal remains, and present‐day distribution of thermophilous species). This picture offers a view of numerous viable areas for woodland species in southern Spain, in addition to others in the mountain ranges, both in continental central Spain and those of northern Spain: these stretch from the Mediterranean coast of Catalonia to the westernmost extent of the Bay of Biscay.     

Palaeovegetational reconstruction based on pollen and seeds/fruits from a Bronze Age archaeological site in Tuscany (Italy)

Abstract

A reconstruction of the vegetation surrounding the Bronze Age archaeological site of San Lorenzo a Greve (Florence) based on pollen and seed/fruit records is presented. Pollen analysis suggests the presence of prevailingly open and damp landscapes, typically occurring on alluvial soils. Patches of woodland, mostly formed by deciduous Quercus, Ulmus, Salix, were alternated to the grasslands. Vitis also probably grew in these damp thickets together with Alnus and Hedera. The forests on the hilly slopes included deciduous Quercus, Carpinus betulus, Corylus, Cornus mas, and Sambucus nigra. Where the soil was well drained, Ostrya carpinifolia and Mediterranean evergreen elements such as Q. ilex and Viburnum tinus grew. In the landscape scenario reconstructed by pollen analysis, seeds/fruits indicated the presence of specific plants which produce a low amount of pollen: they are seldom recorded in pollen spectra but their fruits were commonly gathered in prehistory.     

Paleoethnobotany: Modern Research Connecting Ancient Plants and Ancient Peoples

Paleoethnobotany is a growing subdiscipline of archaeology that utilizes information from numerous other disciplines to show the relationships between ancient plants and ancient peoples. The two primary disciplines that underlie paleoethnobotanical research are archaeology and botany. As such, the results of ongoing botanical research on taphonomic processes, genetic identification of ancient plant types, pollen analysis, phytoliths analysis, and seed identification directly affect the strength of paleoethnobotanical models of past human behavior. Preserved seeds form a significant portion of the archaeobotanical record. They represent not only the environment that was present when they were deposited but also a connection to the activity and culture of ancient people. Using the type of archaeobotanical remains and the archeological context of the remains, paleoethnobotanists study a diverse range of topics. These topics include, but are not limited to, the use of plants in ancient cultures, the development and rise of agriculture, and the relationship between agriculture and settlement patterns.     

The history of the Portulaca oleracea aggregate in the Emilia-Romagna Po Plain (Italy) from the Roman Age to the present

Portulaca oleracea L. is a cosmopolitan synanthropic species, of uncertain origin, known in Italy since the Roman Age. The aim of this work is to reconstruct the history of P. oleracea aggregate in the Emilia-Romagna Po Plain, by discovering the microspecies that have lived in this region. A qualitative study was carried out to determine the microspecies documented in the archaeological sites of Emilia-Romagna, from the Roman to Medieval/Renaissance periods. A comparison between archaeological seeds and recent and present records was made by sampling in historical herbaria and field collections. Seven different microspecies were identified: Portulaca papillatostellulata, P. trituberculata, P. cypria, P. sativa, P. oleracea (all hexaploid); P. granulatostellulata and P. nitida (both tetraploid = 4x). They are distinguished on the basis of seed coat morphology. The findings in archaeological sites and in the present collections are discussed. Two independent events of European colonization could be proposed: First to arrive were the hexaploid (6x) species, followed by the tetraploid species. In future, the application of similar analyses to the well-preserved archaeobotanical remains of purslane, particularly the microspecies from America, could be a good way to understand the history of this interesting species aggregate from a chronological and geographical standpoint.     

Domestication rates in wild-type wheats and barley under primitive cultivation

Man's first cereal crops were sown from seed gathered from wild stands, and it was in the course of cultivation that domestication occurred. This paper prcsents thr preliminary rrsults of an experimcntal approach to the measurement of domestication rate in crops of wild-type einkorn wheat exposed to primitive systems of husbandry. The results indicate that in wild-type crops of einkorn, emmer and barley (a) domestication will have occurred only if they were harvested in a partially ripe (or near-ripe) state using specific harvesting methods; (b) exposure to shifting cultivation may also have been required in somr cases; and (c) given these requirements, the crops could have become completely domcsticated within two centuries, and maybe in as little as 20–30 years without any form of conscious selection. This paper (1) considers the possible length of delays in the start of domestication due to early crops of wild-type cereals lacking domestic-type mutants; (2) examines the combination of primitive husbandry practices that would have been necessary for any selective advantage to have been unconsciously conferred on these mutants; (3) considers the state of ripeness (at harvest) necessary for crops to be able to respond to these selective prcssures; (4) outlines field measurements of the selective intensities (selection coefficients) which arise when analogous husbandry practices are applied experimentally to living wild-type crops; (5) summarizes the essential features of a mathematical model which incorporatcs these measurements of selection coefficients and other key variables, and which describes the rate of increasc in domestic-type mutants that would have occurred in early populations of wild-type cereals under specific combinations of primitive husbandry practices; (6) considers why very early cultivators should have used that combination of husbandry methods which, we suggest, unconsciously brought about the domestication of wild wheats and barley; and (7) concludes by considering whether these events arc likely to have left recognizable traces in archaeological remains.     

Tree mortality in the African Sahel indicates an anthropogenic ecosystem displaced by climate change

Aim Widespread reports of disappearing tree species and senescing savanna parklands in the Sahel have generated a vigorous debate over whether climate change or severe human and livestock pressure is principally responsible. Many of the tree taxa in decline are closely associated with human settlement and farming, suggesting that the parkland ecosystem may not be a natural vegetation assemblage. The aim of this study is to assess the possibility that human activities promoted the spread of taxa with edible fruit into dry Sudano‐Sahelian areas during high‐rainfall periods in the climate cycle. Location West African savannas (Mali, Burkina Faso, Ghana, Togo, Benin). Methods Cultivated savanna parklands and adjacent forests and transitional landscapes were inventoried at 27 sites in five countries. All trees with basal diameters > 10 cm were counted within 500‐m² belt transects. Species composition and abundance were contrasted between three landscape classes to assess the degree of influence exerted by traditional human management. Twentieth century rainfall data were averaged for two sets of weather stations encompassing the north–south range of typical parkland tree species. Rainfall trends were used to evaluate the putative impact of climate change on edible and/or succulent fruit species at the northern limit of the parkland savanna zone. Results Species composition and spatial distribution data indicate that the parkland ecosystem is significantly shaped by human activities. Indigenous land management favours edible‐fruit‐yielding taxa from the wetter Sudanian and Guinean vegetation zones over Sahelian species. Rainfall isohyets at the northern range limits of parkland species shifted southwards in the late 20th century, crossing the critical 600‐mm mean annual rainfall threshold for Sudanian flora. Relict vegetation and historical records indicate that the Sudanian parkland system extended in the past to near 15° N latitude in middle West Africa, compared with 13.5° N today. Main conclusions The current loss of mesic trees in the Sudano‐Sahel zone appears to be driven by the sharp drop in rainfall since the 1960s, which has effectively stranded anthropogenically distributed species beyond their rainfall tolerance limits.     

Prehistoric Chronology of the Common Bean in the New World: The Linguistic Evidence

Glottochronology and the comparative method of historical linguistics provide a linguistic approach for dating the common bean ( Phaseolus vulgaris L.) that both complements and supplements archaeological dating techniques such as accelerator mass spectrometry (AMS). For example, the comparative approach reveals that prehistoric languages of eastern North America having glottochronological dates earlier than 700 B.P., such as Proto-Iroquoian (2700 B.P.), lacked words for bean. Protolanguages of the region with glottochronological dates younger than 700 B.P. had bean terms. These linguistic results accord with the AMS finding that beans do not become archaeologically visible in the region until around C.E. 1300. The earliest AMS date for beans of Mesoamerica is around 2300 B.P. This date is considerably younger than glottochronological dates for prehistoric languages of the area, such as Proto-Mayan (3400 B.P.), for which bean terms are posited. Linguistic findings for protolanguages of Mesoamerica suggest that the regional bean chronology is considerably older than that indicated through archaeological dating.     

Looking beyond history: tracing the dispersal of the Malaysian complex of crops to Africa

In his 1959 book, Africa: Its Peoples and Their Culture History, George P. Murdock suggested that a Malaysian complex of crops dispersed to Africa in ancient times across the Indian Ocean along the Sabaean Lane. The Malaysian complex comprised bananas, sugarcane, taro, three yam species, rice, Polynesian arrowroot, breadfruit, coconut, areca palm, and betel leaf. Except for rice, arrowroot, and potentially taro, most of these crops were domesticated in the Island Southeast Asia-New Guinea region, from where they dispersed to Africa. Our reassessment of agronomic, archaeological, classical, genetic, and historical sources shows that we need to go beneath standard historical narratives to recover a much more ancient and complex history of crop introductions to Africa. Despite considerable uncertainty and fragmented research, we were able to conclude that the Malaysian complex of crops did not arrive in Africa as a complete assemblage at one time or along one route. Multiple lines of evidence suggest that these crops arrived in Africa at different times and followed different pathways of introduction to the continent.