Analyzing the contents of a 500-year-old medicine horn from Eastern Cape Province, South Africa.

The discovery of organic residues in or on ancient artifacts presents exciting opportunities for archaeologists. Analysis of such residues has suggested purposes as cosmetics, adhesives, medicines and even poisons, with the majority apparently derived from Plants. The earliest organic residues date from about 200 000 years ago, and apparently reflect Plants chosen for the Insect-repellent smoke they produced when burned,. This marks the beginning of a long history of Humans utilizing the chemical properties of Plants, which has enabled us to move out of Africa and colonise every continent except Antarctica. The oldest of these studied residues come from Southern Africa, where we have a record of Human Plant usage spanning almost the entire history of our species, and including a wide range of uses, though, surprisingly, including very few residues associated with medicines.

Traditional African medicine is still widely used on the continent, and is heavily dependent on Plants, something which was recorded by the earliest European visitors to the continent, and which therefore was probably the case long before their arrival. Unfortunately, from an anthropological point of view, traditional African medicine practitioners are flexible and adaptable in their approach to Plant selection, and today use many Plants imported from other parts of the world, something which makes it hard to assess which Plants might have been used in medicine in the remote past. This is complicated by the fact that not all traditional medicines are effective, with only 33 of the 166 Plants used in traditional medicine in Eastern Cape Province today having been shown to have pharmacological effects. This is not simply a sign of incompetence on the behalf of the practitioners of this medicine, but rather a slightly different perspective on how Plants are used, with much medicine being used to protect against, or treat the effects of, harmful magic rather than disease.

The lack of archaeological evidence makes it hard to assess how old modern traditional medicine practices are, and how (or if) they have changed over time. The remains of Plants which would be considered to have medicinal properties today have been found associated with archaeological sites dating back to the Middle Stone Age in South Africa (i.e. more than 130 000 years old), although it not possible to say if they were being used for medicinal purposes, or how they were used if they that was their purpose.

In a paper published in the South African Journal of Science on 31 January 2023, Justin Bradfield of the Palaeo-Research Institute at the Universityof Johannesburg, Stephan Woodborne of iThemba LABS, Jeremy Hollmann of the Rock Art Research Institute at the University of the Witwatersrand, and Ian Dubery of the Research Centre for PlantMetabolomics and the Departmentof Biochemistry at the University of Johannesburg, describe a 500-year-old medicine horn found in a rock shelter on a farm in Eastern Cape Province, South Africa, the results of an analysis of its contents.

The horn was discovered on a farm called La vie D’Antan, in the Langkloof Mountains, about 40 km to the north of Plettenberg Bay, and about 40 km to the east of Uniondale. The object is a Cattle horn sealed with  leaves, which contained a solid residue, thought likely to have been a liquid or gel when the horn was deposited, due to its orientation. This residue was readily soluble, making it suitable for gas chromatography-mass spectrometry analysis.

The horn container after excavation (large inset) and at two stages of the recovery of the parcel: (A) the parcel tightly bundled with Boophane disticha leaves and grass, wrapped together with plant fibre rope and (B) partially unwrapped exposing the horn container. (C) and (D) The location of the rock shelter on the farm La vie D’Antan. Bradfield et al. (2023).

The site from which the horn was recovered is a rock shelter with rock art, about 3 m high and cutting 3 m deep into the conglomerate Enon Formation. The shelter has a shallow floor deposit, which is only a few centimetres thick, within which the horn had been deposited. The horn was discovered after apparently being exposed by Animal activity, and removed by a passer-by to prevent further damage. It was sealed with a bundle of Century Plant, Boophane disticha, leaves and Grass, which were attached to the horn by a twisted Plant-fibre rope. The leaves of the Century Plant are known to have antiseptic properties, which may have helped to preserve the horn and its contents; the same leaves were used to bind the 2000-year-old Kouga Mummy, which was discovered about 10 km from the La vie D'Antan site. The site also produced a few shards of ceramic, but no signs of ever having been occupied, The area around the site contained numerous Everlasting Plants, Helichrysum spp., and Ragworts, Senecio spp., both of which are sometimes used to make teas in Southern Africa.

The rock shelter is within a conglomerate made up of sandstone boulders, which is covered by between 20 and 30 paintings, executed in red and yellow ochre paints, apparently made with a brush (with the exception of some handprints), and depicts Human figures armed with hunting equipment, and a range of Animals, most of which are hard to identify, but which include at least one Eland and one Antelope. This art is fairly typical of the San people who occupied the region before being largely driven out by Dutch settlers in the late eighteenth century; similar art has been found at two other rock shelters within 2 km of the site.

Examples of rock art from La vie D’Antan and neighbouring sites. Images have been digitally enhanced using colour deconvolution. The original colour is a red hue. Bradfield et al. (2023).

Prior to the eighteenth century, the area was occupied by hunter gatherers who belonged to the San ethnic group, and pastoralists from the Khoi ethnic group, who typically owned large herds of Sheep and Cattle. By 1775 much of the land had been partitioned among Dutch settlers, with the few remaining Inqua Khoi largely being employed as herdsmen on Dutch owned farms. A mixed population, descended from San and Khoi refugees and deserters from the Dutch army (which included non-European conscripts from colonies in Africa and Asia) may have survived in the mountains as late as the 1880s, but the last independent San bands disappeared in the 1760s. Little is known about this hunter gatherer population, though they were resident in the area for at least 10 000 years, and used a technology which modern archaeologists classify as Later Stone Age.

The Kouga Mummy was found about 10 km from the La vie D'Antan rockshelter, and comprises a man aged between 30 and 40 and thought to be a member of the San ethnic group due to his stature, and dated to about 1930 years before the present. The Mummy was wrapped in the leaves of a Century Plant, and covered with a mass of twigs and branches, which may have formed a burial basket. Within the leaf-bindings were found some Century Plant bulbs, as well as some beads made from marine shells. The feet of the Mummy had been bound, and the last joint of the left little finger removed, both burial customs known to have been practiced by some San societies. The burial site was covered by a painted stone slab.

The Kouga Mummy. Albany Museum.

The use of horns as medicine containers is fairly common across Africa as a whole, but somewhat unusual in Southern Africa, where the shells of Tortoises or the eggs of Ostriches have been the favoured traditional containers. A number of Cattle horn snuff containers attributed to Sotho or Shona makers are housed in the collection of the British Museum, but these date from the nineteenth century. The Harvard Peabody Museum has similar containers, reportedly from southern Tanzania or northern Zimbabwe, but again from the nineteenth century. Bradfield et al. also note having found reference to a medicine horn collected in the Belgian Congo between 1890 and 1930, on which they could find no further information, possibly in reference to this specimen from the Welcome Collection. They also note that some San groups living in the Kalahari use horns to store medicine, as do the Bemba of Zimbabwe, althought the Kalahari San generally use Duiker horns to store medicine used against witchcraft, while the Bemba use  a variety of Antelope horns, including Duiker and Bushbuck, 

Bradfield et al. first examined the contents of the horn under a light microscope, finding a mixture of Insect and Plant remains in the surface layer. The majority of the Insect remains could not be identified with any confidence, but were not inconsistent with having come from Dermestid Beetles (Skin Beetles) a group which are known to have been attacking the Horn and its contents when it was found, though some scales of Lepidopteran Insect (Butterfly or Moth) wings were also found. Beneath the surface the residue contained no Insect or Plant remains, and comprised a shiny brown crystalline substance which dissolved readily in water and smells faintly of Liquorice. 

Micrographs showing (A) Insect epithelial tissue; the glossy, reflective surface and absence of visible phytolith structures under ultraviolet light suggest Insect origin rather than Plant; (B), (C) elongated tissue structure, possible Plant tracheids; (D) fragment of an Insect wing; (E)–(G) Lepidoptera wing scales; (H)–(K) probable Insect setae; (L), (M) crystalline-looking fragments of the tacky main container residue; and (N), (O) the solute of the tacky residue after dissolving in water. Note the absence of other obvious tissue structures. Bradfield et al. (2023).

Gas chromatography-mass spectrometry analysis of the brown residue revealed it to be a mixture of organic compounds, with the largest proportion being mono-methyl inositol and its isomers, as well as lupeol, and lesser amounts of  di- and tri-terpenes, a sterol derivative and fatty acid methyl ester. Curiously, no volatile aromatic associated with a Liquorice smell was found.

Inositol is a natural polysaccharide sugar synthesized in plant cells and used in the production of plasma lipo-proteins to aid cell growth. It is produced by a range of Plants, including Legumes and Citrus fruits, and used in medicines used to control diabetes, and treat  high cholesterol, bronchopulmonary dysplasia and various mood disorders, as well as to reduce the symptoms of polycystic ovarian syndrome. Importantly, it is considered to be a pharmacologically stable compound, upon which it is impossible to overdose.

Mono-methyl inositol and inositol isomers are produced by a number of Southern African plants used medicinally, including the Balloon Pea, Sutherlandia frutescens, an antioxidant which has traditionally been used to wash wounds and treat eye infections, as well as as a tonic to treat rheumatism and pulmonary ailments and boost immune function, the Honeybush, Cyclopia intermedia, from which an antioxidant rich tea is made, which is held to have anti-inflammatory and possibly cancer-fighting effects,  Lotonius laxa, and Bluebellvine, Clitoria ternatea, which is not used in medicine in Southern Africa today, but which is used in Asia to treat sexually transmitted diseases and anxiety.

Lupeol is a pentacyclic triterpenoid produced by a wide range of Plants, and is commonly a constituent of resins and plant waxes. Medicinally, it has anti-inflammatory and antimicrobial properties, and is used in some cancer treatments. In Southern Africa it is produced by a number of Plants, including the Namaqua Rock Fig, Ficus cordata, the Kokilaksha, Asteracantha longifolia, which is used by the Pedi people of northern South Africa as a treatment for rheumatism, urinary tract infections, and jaundice, as well as an aphrodisiac, as well as by a number of species of Euphorbia, 

Kaurenoic acid is an antibacterial compound produced by a variety of Plants, which is particularly effective against Gram-positive Bacteria such as Listeria, Staphylococcus and Streptococcus. It has also been shown to offer some protection against liver damage. Again, this is produced by a number of Plants found in Southern Africa, including the Bears Foot, Arctopus sp., the medicinal use of which has been recorded since the 1770s, as a treatment for gout, various infections and respiratory ailments, Alepidea sp., which has been used to treat colds, coughs, sore throats, influenza, and abdominal cramps, and Aster bakeranus, which has been used to treat venereal diseases, urinary tract infections, chronic coughs, and intestinal complaints.

Another chemical present is cyclolanostenol acetate, which can be produced by a variety of Dicotyledonous Plants and Animals. Notably, in Southern Africa, it is produced by Rafnia amplexicaulis, which has been used to make a tea used to treat pulmonary conditions, and as a substitute for liquorice. 

Small amounts of three decanoic acids were found within the resin. These are are produced by a range of Plants held to have medicinal compounds. Also present were hexadecane and octadecanoic acid, both of which have antifungal, antibacterial, and antioxidant properties.

While all of the identified chemicals are produced by a range of Plants across Southern Africa, Bradfield et al. feel confident in narrowing the field to plants found close to the site where the horn was discovered. When this is done, three species stand out as being highly likely to have contributed to the contents of the horn; the Prostrate Purslane, Corbichonia decumbens, which comprises 75% mono methyl inositol, 17% hexadecenoic acid and 16% octadecanoic acid, and which is liquefied for use as an emetic by members of the Zulu people today, the Liquorice Plant, Glycyrrhiza glabra, which contains 28% of mono-methyl inositol, 3.4% octadecanoic acid, and 4.9% hexadecenoic acid, which is widely used by traditional medicine practitioners across Africa, but which has generally been assumed to have been introduced to the continent by Europeans, and the Horse Gram, Macrotyloma uniflorum, which also contains mono-methyl inositol, hexadecanoic acid and octadecanoic acid, and which, while not used in African traditional medicine today, is used in India as an antioxidant and a treatment for insulin resistance. Another possibility is Mikania sp., which contains lupeol and kaurenoic acid, and which is used to treat Snake bites and venereal disease today.

Bradfield et al. conclude that the horn contains a mixture of extracts from at least two plants, almost certainly intended to have a medicinal use. The major components of this mixture are used to treat a wide range of ailments today, either by drinking or applying as an ointment; San people today often apply ointments to small cuts intentionally made for that purpose, which may also have been the case when the horn medicine was in use. There is no way to know what ailment(s) the mixture found in the horn was actually intended to treat, or whether that treatment would have been of any benefit to the patient. The medicine contains a number of active ingredients, but the medicine maker is likely to have had a world view very different to our own, including a belief in supernatural as well as (or instead of( physical causes for ailments, which would have affected the choice of ingredients to be used in a medicinal potion in ways difficult for us to understand.

Notably, two plants found to be growing abundantly in the area around the rock shelter today, Helichrysum sp. and Senecio sp., are both used in traditional medicine today to treat both physical and spiritual ailments, are unlikely to have been components of the medicine, based upon the gas chromatography-mass spectrometry analysis, although both the medicine and Helichrysum sp. have a Liquorice-smell, so it is possible that this was a component of the medicine but not detected instrumentally for some reason. The alternative explanation, that the Liquorice-smell derives from the Liquorice Plant, Glycyrrhiza glabra, runs counter to the current belief that the Plant was introduced to Africa by Europeans, although this Plant matches the chemical contents of the horn much more closely, and other Plants thought to have been introduced to Africa by Europeans have subsequently been shown to have been on the continent before Europeans arrived. 

The careful wrapping and burial of the horn and its contents implies that this was a valued object. It is likely that it was buried in the rock shelter with the intention that its owner would return and retrieve it at some point, but never did so. Similar finds of items probably buried for storage purposes have been found elsewhere in Southern Africa, for example a full hunting kit was found  Eland Cave in the Drakensberg Mountains. Other than this item, the rock shelter contains only a few ceramic shards and the rock paintings, with no indication that it was ever used as a dwelling. 

As far as Bradfield et al. are aware, the horn from the La vie D'Antan rock shelter is the oldest medicine container ever discovered in Southern Africa. The occupation of the region where the horn was found appears to have been ephemeral after about 2000 years ago, with nearby rock shelters at Boomplaas, Nelson Bay Cave and Matjes River, all of which were once occupied, having been abandoned during the first millennium AD. The information available does not allow the identification of the medicine-maker. The art in the rock shelter is clearly of San origin, but there is no evidence that the horn and the paintings were contemporary in origin. The choice of a Domestic Cattle horn would seem to imply the medicine was left by a Khoi herder, but there is no real reason to assume this. The San people sometimes kept Cattle, and even if this was not the case, the horn could have been acquired by a San medicine maker through scavenging, theft, or trade. Bradfield et al. note that nineteenth century records from the Western Cape state that the Khoi and San peoples there shared a belief in a mythical being called the Water Bull, which resembled a Domestic Bull, and which had horns with magical healing properties. 

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Examining stone tools for evidence of Rice harvesting in the Neolithic of the Lower Yangtze River Basin.

Rice cultivation is believed to have originated with the Neolithic Shangshan (上山) Culture in the Early Holocene of the Lower Yangtze Valley Basin, between about 10 000 and 8200 years before the present. The Neolithic Rice-farming tradition of this region persisted for several millennia, culminating in the Liangzhu (良渚) Culture of about 5300-4400 years ago. Archaeologists have tried to study this process in a variety of ways, although most investigations have concentrated on changes to Rice Plants over this time, or else changes in cultivation practices and their impact on the landscape.

In a paper published in the journal PLoS one on 7 December 2022, Jiajing Wang of the Department of Anthropology at Dartmouth College, Jiangping Zhu of the Pujiang Museum, Dongrong Lei of the Longyou Museum, and Leping Jiang of the Zhejiang Provincial Institute of Cultural Relics and Archaeology, and the Department of History of Science and Scientific Archaeology at the University of Science and Technology of China, present the results of a study of early Rice cultivation in the Lower Yangtze Valley that concentrated on the stone tools used by these early farmers to harvest Rice.

Harvesting techniques in themselves apply selective pressure to a cultivated crop. Most Cereal crops have lost the ability to shatter their own seed cases, effectively making them dependent on Human intervention. This development in early cereal crops has been widely linked to the use of sickles as a harvesting tool, as this selects for seeds with a tougher rachis (section of the stem to which the seed is attached), something only found in a small proportion of wild Cereal Plants. This fits well with the development of Cereal crops in the Fertile Crescent, where the onset of Cereal cropping is marked by the appearance of hundreds of flint sickles. However, these tools are absent at the Neolithic sites of the Lower Yangtze where Rice cultivation originated. This has raised the possibility that the initial cultivation of Rice was marked by a different form of harvesting, such as see picking or plucking and beating. Evidence to support such theories, however, is lacking.

Excavations of Shangshen Culture (10 000-8200 years before present) and Kuahuqiao (跨湖桥) Culture (8000-7000 years before present) culture sites in the Lower Yangtze River Basin have produced hundreds of crudely made flaked stone tools in the core-and-flake tradition widely found in South China during this interval. These have been recorded variously as scrapers, burins, or drills, based upon their shape, but little thought has been applied to their purpose. Wang et al. observe that many of these blades have sharp edges which would be suitable for harvesting crops, and, in order to test this hypothesis, analysed use-wear marks upon 52 of these blades, as well as examining them for phytolith residues. 

Phytoliths are produced by plants as a way of handling silica absorbed with water from the soil. Most plants produce phytoliths to some extent, but Monocotyledons, such as Grasses and Palms, which utilise phytoliths both as structural support and a defence against herbivores (silica phytoliths quickly wear down the teeth of animals which lack specific adaptations to deal with them), produce phytoliths which can often be used to identify the maker to genus or even species level. Rice Plants produce three highly distinctive types of phytolith, double-peak husk cells, Oryza-type bulliform leaf cells, and scooped parallel bilobates, which can make tools which have been used to work Rice easy to identify.

Cereal harvesting produces both distinctive wear traces upon a tool, and leaves a residue of plant tissues. Examination of stone tools that have been used to cut Poaceaen Plants (Grasses, Reeds, etc.) reveal that this activity produces a particularly distinct pattern of striations and polished areas, and that this remains constant across a variety of stone types that would have been available to Neolithic farmers in East Asia. 

The Shangshan Culture are thought to have been the first people to have cultivated Rice, and to have built permanent settlements in the Lower Yangtze River Valley. To date, Archaeologists have uncovered 19 settlements associated with the Shangshan Culture. The Kuahuqiao Culture dates from slightly later in the same area, and used many of the same technologies, but also engaged in more intense landscape modification with specialised Earth-working tools.

Wang et al. obtained stone tools from two sites in Zhejiang Province; Shangshan, the type location of the Shangshan Culture, and Hehuashan, which has both Shangshan and Kuahuqiao layers. The Shangshan settlement covered an area of about 30 000 m², and includes dwellings, storage and midden pits, and possible burials. It has produced a diverse stone tool assemblage, including flaked stone tools (82% of the material), grinding stones (15%) and polished stone tools (3%). Hehuashan is located about 80 km to the southwest of Shangshan, on a small hill, and is divided into two areas, the East and West. East Hehuashan has an (excavated) area of about 600 m², and includes houses, pits and Shangshan-style stone tools and ceramics, while West Hehuashan has an excavated area of about 150 m², including houses, pits, ditches, and Kuahuqiao-style stone tools and ceramics.

Archaeological background. (a) Location of Shangshan and Hehuashan. (b) Cultural history and rice domestication process in the Lower Yangtze River region. Wang et al. (2022).

At both sites, chipped flake tools form a significant part of the total lithic assemblage (82% at Shangshan and 57% at Hehuashan). At both sites these tools seem to have been made when needed, and discarded after use, with attempts at retouching being rare. None of these blades resemble the sickle blades developed in the Neolithic of the Fertile Crescent, or the denticulate sickles of the Huai River Valley of China (developed by the Peiligang (裴李崗) Culture of Henan Province in central China between 9000 and 7000 years before present, and thought to have been used to harvest Grasses and Rushes). These tools are made from locally available rock, including vitric tuff, river pebble, porphyry, and sandstone, with the blades made by the two cultures essentially identical in form.

The tools analysed in the tests came from the collections of the Pujiang and Longyou museums. Twenty tools were selected from the early phase of the Shangshan Culture (10 000 to 9000 years before present), eighteen from the late phase of the Shangshan Culture (9000 to 8200 years before present), and fourteen from the Kuahuqiao Culture (8000 to 7000 years before present). These averaged 42 mm in length and 42.8 mm in width, suggesting that they were hand held tools.

A selection of stone flakes analyzed in the study. (a)-(h) Flakes from the Shangshan culture; (i)-(l) Flakes from the Kuahuqiao culture. Red dots delineate working edges. Wang et al. (2022).

Use wear analysis of these tools suggested that they had been used for five different tasks; harvesting Siliceous Plants (i.e, Grasses or Reeds) (30 tools), cutting Animal tissue (7 tools), processing hard materials (10 tools), scraping woody material (6 tools), and an unidentified function (13 tools). 

Tools used for cutting Siliceous Plants generally have an uneven finish, with fine and uneven striations, and and extensive patches of polishing, on both raised and scored areas. Of the 30 tools in this category, 22 have striations perpendicular or diagonal to the cutting edge of the tool, suggested as being indicative of cutting or scraping, while 14 have striations parallel to the cutting edge, probably caused by slicing, and six have both.

Use-wear traces from cutting Grass. Wang et al. (2022).

Tools used to cut the soft tissues of Animals tend to develop patches of highly polished surface, but lack the striations produced by cutting Plant matter or hard material.

Use-wear traces from cutting Animal tissues. Wang et al. (2022).

Stone tools used to scrape woody material develop a rough polish on sinuous domed areas, with occasional deep, tapering striations perpendicular to the cutting edge.

Use-wear traces from scraping wood. Wang et al. (2022).

Scraping hard materials such as Animal bones produces a level topography and rough polish on a stone tool, with deep, even striations. The polished areas are concentrated on the highest parts of the tool, with reticulated areas between.

Use-wear traces from scraping Animal bones. Wang et al. (2022).

Interestingly, while the tools had all been identified as simple, single edged, single function tools, analysis of the striations identified secondary cutting edges on thirteen of them. These typically had a principle cutting edge with a low-angled concave surface, and a more steeply convex secondary cutting edge. In these tools the concave surface showed signs of having used to process Grasses, while the convex surface appeared to have been used to cut Animal tissues.

Fifty of the fifty two tools analysed yielded phytoliths, the vast majority of which came from types of Grass. These included silate or sinuate elongates from Grass leaves, stems, and inflorescences. More specific material included ouble-peak husk cells, Oryza-type bulliform leaf cells, and scooped parallel bilobates, all diagnostic of Rice, as well as Reed-type bulliforms, Sedge achenes, and articulated quadrilobates, which are associated with Panicoid Grasses (the group which includes Sugarcaine, Maize, Sorghum, and Switchgrass). This suggests strongly that a high proportion of the tools were used in the harvesting of Grassy crops, including Rice.

Phytolith morphotypes recovered from flakes from Shangshan and Hehuashan flakes. (a) Double-peak (Oryza, Rice); (b) Oryza-type bulliform (Oryza, Rice); (c) Scooped parallel bilobate (Oryzeae); (d) Reed-type bulliform (Phragmites); (e) Sedge achene (Cyperaceae); (f) Articulated quadrilobate (Panicoideae); (g) Rondel (Poaceae); (h) Saddle (Poaceae); (i) Scutiform, elongate sinuate, and rectangular (Poaceae). Wang et al. (2022).

The composition of the phytolith assemblage does, however, change significantly between the Shangshan and Kuahuqiao tools. In the Shangshan material, double-peak Rice husk phytoliths are found on 71% of the tool assemblage, while in the Kuahuqiao material this falls to 7%. The reverse trend for Rice leaf/stem phytoliths, which were recovered from 34% of the Shangshan tools, but 57% of the Kuahuqiao tools. The phytoliths of Reeds and Sedges also increased, with both being recovered from 8% of the Shangshan tools, while Reed phytoliths were found on 43% of the Kuahuqiao tools and Segde phytoliths on 29%. These changes probably reflect increased landscape management and a change in harvesting technique.

Wang et al. found a significant correlation between the abundance of phytoliths and wear patterns on blades, with blades showing wear patterns associated with Grass processing yielding a significantly higher proportion of Grass phytoliths. Furthermore, of the 30 blades interpreted as having been used in harvesting activities, 28 yielded Rice phytoliths. Comparing the phytolith and wear-use data suggests that the blades were used in two ways, as finger knives used to reap the panicles (seed clusters) at the top of the Plant, and as sickles used to cut the stems at their base.

Schematic representation of the use-wear traces and phytoliths from Rice-harvesting finger knives and sickles. Wang et al. (2022).

The best example of a blade used to cut Rice using the finger knife technique is specimen SS-10, a flaked blade made from a river pebble, with a slightly convex working edge 58 mm in length. This tool has numerous fine striations perpendicular to the blade edge, interpreted as indicative of cutting or scraping Grass. The blade edge of this tool yielded a large number of phytoliths of the Rice glume double-peak type, suggesting that it has been in direct contact with Rice seeds. In combination, this is interpreted as evidence of being used to cut the panicles at the top of the Rice Plant during harvesting.

In contrast, specimen HHS 38 is interpreted as having been used in sickle harvesting. The blade of this tool has a convex surface about 92 mm in length, with many fine striations parallel to its cutting edge, thought to be indicative of slicing or sawing through plant matter. This tool yielded no phytoliths associated with Rice husks, but numerous phytoliths with morphotypes associated with Grass leaves and stems, including Oryza-type bulliforms and scooped parallel bilobates from Rice leaves. This combination of sawing-type striations and leaf and stem phytoliths is considered to be indicative of cutting Rice stems close to the ground with a sickle-action.

Use-wear traces from rice harvesting flakes. (a) and (b) Use-wear traces from Artifact SS-10 exhibit fine striations perpendicular or diagonal to the cutting edge, suggesting a transverse motion. (c) and (d) Use-wear traces from Artifact HHS-38 are dominated by striations parallel to the cutting edge, suggesting a slicing motion. Wang et al. (2022).

Wang et al.'s findings strongly support the hypothesis that these flaked stone tools were used in the harvesting of Rice. Furthermore, they demonstrate a shift in the way in which Rice was harvested which had not previously been suspected. In the Shangshan Culture Rice appears to have predominantly been harvested using a finger-knife technique to remove seeds from the top of the Plant, while the use of sickles to cut the stems was rare, while in the Kuahuqiao Culture the use of sickles appears to have become the predominant method of harvesting Rice.

Although the materials from which tools are made have changed, both finger-knife and sickle harvesting of Rice have persisted into modern times. The finger-knife technique allows the farmer to repeatedly revisit the same Plant, which seems unduly arduous, but can be useful under conditions where the seeds of the Plant do not all ripen at the same time. This technique reduces the number of panickles (seed husks) that shatter during harvesting, thereby maximising the amount of Rice recovered from each Plant. Sickle harvesting enables the farmer to quickly cut through bunches of stems, gathering the entire harvest rapidly, with the seeds subsequently separated from the stems and leaves, which can be used for fuel or Animal feed. The choice of tool can be driven by spiritual beliefs as well as practical considerations, with many Southeast Asian cultures having resisted the introduction of the sickle for a long time, as sickles were perceived as harming the soul of the Rice, and therefore being less pleasing to the Rice Goddess.

Little is known (or is likely to be known) about the spiritual beliefs of the earliest Rice farmers of the Lower Yangtze Basin, but it is possible to make a comparison between the change in Rice harvesting technique and the process of domestication. The wild progenitor of modern East Asian Rice, Oryza rufipogen, grows in swampy wetlands, where its seeds ripen unevenly, and are shed into the (often deep muddy water. Trying to harvest this Plant with sickles has been shown to be very difficult experimentally, while a better yield can be achieved with finger knives. This would presumably also have been the case in the Early Holocene, when the process of Rice domestication began. Samples of Rice spikelets from Huxi, a late Shangshan Culture site, dated to between 9000 and 8400 years before the present, included only 8.7% non-shattering husks, which are predominant in modern Domestic Rice. This presumably indicates that the Rice fields of the Shangshan people were dominated by a type of Rice with unevern ripening and self-shattering husks, better harvested with the more selective finger knife technique. 

The succeeding Kuahuqiao people had a much more developed farming culture, originating about 8000 years ago, in which Rice was cultivated in managed Grass-Reed swamps, where water flow was controlled by irrigation systems and periodic burning was used. This system is thought to have been used to cultivate multiple wetland and forest Plants together, and to have promoted more synchronous Rice growth, making the harvesting of bundles of stems with a sickle a more viable option. At the Kuahuqiao type site (which gives its name to the culture), one of the key finds was a bunch of Rice stalks cut squarely at the base, something most likely to have been achieved with a sickle technique.

This adoption of sickle harvesting appears to have been roughly synchronous across several cultures in Ancient China about 8000 years ago. At the Peiligang Culture Jiahu Site in Henan Province, denticulate sickles begin to appear in large numbers during Phase III, which has been dated to between 8000 and 7500 years before the present. Wear use analyses carried out on these blades has suggested that they were used to harvest Grasses, and phytolith analysis of deposits from the site's residential areas suggests that Rice stalks were being brought into the settlement.

While finger knife harvesting requires more time within the Rice field, the product it produces is relatively 'clean' and requires little post-harvest processing. Sickle harvesting on the other hand, is likely to introduce more 'weeds' into the yield, which need to be removed later. The Kuahuqiao blades yield significantly more Sedge phytoliths than the Shangshan blades, which is probably evidence of a common weed being harvested alongside the Rice. There is also an increase in the number of Reed phytoliths at this time, but this may reflect the use of the new sickle technology to harvest an Reed stems as an additional crop. Items made from Reed stems have not, to date been discovered at any Kuahuqiao sites, but the use of Reeds in the Chinese neolithic is well documented at later Hemudu (河姆渡) Culture sites such as Tianluoshan, dated to about 7000 years ago, and the Hemudu type-site, dated to about 6000 years ago.

Both finger knife and sickle harvesting would produce selective pressure for non-shattering husks in Rice. With finger-knife harvesting, the Plants would be revisited numerous times, with the last crop obtained each year presumably contributing most to the seed crop saved for the following year. Since the final crop will include the highest proportion of non-shattering genotypes (which ripen slower), this would lead to a higher proportion these genotypes in each crop. With the introduction of sickle-harvesting, seeds with self-shattering husks would be more likely to be lost between the harvesting site and the processing site, effectively removing themselves from the domestic Rice genepool, applying another selective pressure in favour of non-shattering husks. 

Given these pressures, it is somewhat surprising that the domestication process for Rice took as long as it did (about 5000 years). This probably relates to the knowledge level of the farmers themselves, who would not have considered they were involved in a multi-generation domestication process, but rather have been concentrating on each years crop. Such farmers would not have intentionally selected non-shattering husked Rice as a seed crop, and may not always have selected their seed crop from the last harvest of the year. Furthermore, they are highly unlikely to have cleared a virgin plot to farm each year, so that self-seeded Rice, with self-shattering husks, would have been present in each year's crop.

For the Shangshan and Kuahuqiao cultures, Rice was probably only a small proportion of the diet, supplementing wild-gathered foods such as Acorns. This process of domestication proceeded through the following Hemudu Culture, with Rice probably not becoming fully domestic until the onset of the terminal-Neolithic Liangzhu Culture, considered to have been the first culture in southern China to form centralised states, about 5300 years ago.

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Cutting the Gordian Knot of tree-ring timelines in the East Mediterranean Bronze Age, and looking for a date for the Santorini/Thera eruption that destroyed the Minoan civilization.

Tree-ring records constructed from ancient wooden timbers can provide calendar-dated frameworks to underpin archaeological and palaeoenvironmental chronologies beyond the reach of written evidence. They can provide securely dated records of construction, abandonment, and trade across different cultural regions while simultaneously providing calendar-dated, annual resolution records of contemporary climatic variability. As such, they represent an invaluable resource for studies of past human and environmental interactions and for the resolution of complex chronological issues. However, for certain key geographic regions and time periods, the only tree-ring records preserved are not calendar dated to the exact year but rather, 'float' in time, dated with less precision and accuracy by radiocarbon wiggle-match dating (a dating method that uses the non-linear relationship between Carbon¹⁴ age and calendar age to match the shape of a series of closely sequentially spaced Carbon¹⁴ dates with the Carbon¹⁴ calibration curve). While this approach can produce excellent results for certain time periods, limitations of the method include multiyear error ranges and the fact that calibrated date ranges may shift forward or backward in time depending on which iteration of the international radiocarbon calibration curve is used for calibration. The full benefits of the annually derived tree-ring record for establishing rigid archaeological chronologies for cultural interaction plus the impacts of climatic or geological events on ancient civilizations can be fully realized only by securely fixing such records in a precise and accurate calendar-dated range.

In a paper published in the Proceedings of the National Academy of Sciences of the United States of America on 30 March 2020, Charlotte Pearson of the Laboratory of Tree-Ring Research, Geosciences, and the School of Anthropology at the University of Arizona, Matthew Salzer, also of the Laboratory of Tree-Ring Research at the University of Arizona, Lukas Wacker of Ion Beam Physics at Eidgenössische Technische Hochschule Zurich, Peter Brewer, again of the Laboratory of Tree-Ring Research at the University of Arizona, Adam Sookdeo, also of Ion Beam Physics at Eidgenössische Technische Hochschule Zurich, and of the Chronos ¹⁴Carbon-Cycle Facility at the University of New South Wales, and Peter Kuniholm, once again of the Laboratory of Tree-Ring Research, and the School of Anthropology at the University of Arizona, present the results of an attempt to resolve a Bronze Age floating tree-ring record in the Eastern Mediterranean, using using timbers taken from a chamber surrounding the grave of a predecessor of King Midas in the Phrygian capital city of Gordion (modern day Yassihöyük, Turkey).

Map to show the proximity of the Gordion site to Thera, the main direction of fallout of the Thera ash, and other locations. Pearson et al. (2020).

This record is one of a group of interlocking tree-ring series from the ancient East Mediterranean, which when first published as a dated sequence, ncluded wooden timbers from 22 archaeological sites in central Anatolia (Turkey) spanning the years from approximately 2220 to 718 BC. The Gordion part of this sequence was subsequently redated multiple times, with each redate necessitating a reevaluation of the associated archaeological evidence. Aside from being the key to dating a number of critical archaeological sites in the East Mediterranean, the tree-ring series from Gordion has an extra relevance in that it is the only tree-ring record from the ancient Mediterranean that fully spans the period during which all scholars would agree that the Minoan eruption of Thera occurred. This event provides a pivotal marker horizon through which the chronologies of ancient Egypt, the Levant, Greece, and Anatolia could be linked. Dating this tree-ring series to a fixed point in time rather than a shifting calibrated range would, therefore, offer significant new opportunities for dating the eruption and the synchronization point that it offers because it is possible that the tree rings hold an anatomical or chemical marker for the event, which could be used to further refine the dating. This is particularly important as radiocarbon dating for Thera is impeded by a plateau in the radiocarbon calibration curve between about 1620 and 1540 BC.

In particular, if a chemical response related to environmental changes brought about by the eruption could be identified in the wood, as has been observed in both the lake environment at Gölhisar and in the Speleothem record (deposits of secondary minerals that can be dated from their isotope content) in Sofular cave on the Black Sea coast, then it might be possible to suggest a more exact date for the event. While there are many factors that can lead to disturbances in the anatomy of tree rings, there are only a few that can lead to major chemical changes in the environment.

In an earlier attempt to trace the Thera eruption, Pearson et al., published in a paper in the Journal of Archealogical Science in 2009, conducted elemental analysis on a wide growth-ring anomaly from one of the tree-ring site chronologies overlapping with the Gordion record (Porsuk in southern central Turkey). In that study, they found significant changes in elemental chemistry associated with a wide growth-ring anomaly, which was then dated to about 1650 BC; at the time, this was within the possible radiocarbon range suggested for the Thera eruption, at odds with certain lines of archaeological evidence. The elemental response was consistent with what might be expected from a volcanic event but as noted at the time, also consistent with what might be expected following a forest fire. The date for this elemental change and growth response is now outside the possible range for the Thera eruption, although it may originate from some other unidentified eruption; such as the Yali-Nisyros volcano, at the eastern edge of the Aegean volcanic arc. The revised radiocarbon ranges for Thera-relevant materials suggested by Pearson et al. in the earlier study indicate that the majority of the 16th century BC should now be searched for evidence of the eruption.

Left: The 854 anomaly in sample C-TU-POR-3, from Porsuk in southeast Turkey; right: a similar (though extended) growth-ring anomaly from a tree which grew about 30 km from Katmai Volcano, Alaska. The tree in question was inundated with a few feet of pumice following the 1912 AD eruption of Novarupta, attributed to Katmai. The pumice killed or suppressed low vegetation cover, enhancing conditions for established trees. Inset: a short growth anomaly from a single application of fertilizer to a tree in an experimental forest. Pearson et al. (2009).

In the new study, a combination of two approaches was used for improving and securing the date range for the floating tree-ring series from Gordion. First, Pearson et al. compared a sequence of annual Carbon¹⁴ measurements from single rings of the Gordion series with a contemporary time series of annual Carbon¹⁴ from absolute, calendardated Bristlecone Pine, Pinis spp., and Irish Oak, Quercus spp., across the period 1700 to 1500 BC.

Similar applications have relied on detecting the presence of significant rapid excursions in the annual tree-ring Carbon¹⁴, in particular the largest of these discovered so far an approximate 1.2% change between the years 774 and 775 AD. This event has also been used to provide an independent verification of the calendar dating for established multiregional tree-ring records and to synchronize tree-ring Carbon¹⁴ with Berylium¹⁰ (which forms by spallation of nitrogen and oxygen in the atmosphere and precipitates onto and into surface layers) in the ice cores. In the case of the 774/775 AD marker event, the potential is clear, but for time periods where no such dramatic markers are present, like 1700 to 1500 BC, a different strategy has to be applied. Pearson et al. make use of less pronounced and consequently, less secure Carbon¹⁴ time markers for a proposed annual Carbon¹⁴ pattern-matching approach..

Second, this is tested using an anticorrelation between tree growth response to the same volcanic forcing events in both the Mediterranean Juniper, Juniperus spp., trees and calendar-dated North American Bristlecone Pine. This test uses a well-established temporal association between high-elevation Bristlecone Pine frost rings and large-scale volcanic eruptions. It has been clearly demonstrated that latewood frost rings in Bristlecone Pine occur the year of or the year following a volcanic event, and this causal connection has been strongly confirmed across the last 2500 years. Beyond this period, Bristlecone tree-ring chronologies are accurately dated to the calendar year for over 5000 years, and therefore, the record of precisely dated Bristlecone response to volcanism covers the period across which the Juniper sequence lies according to both conventional radiocarbon wiggle matching and the annual Carbon¹⁴ pattern-matching approach used by Pearson et al.

In western Turkey, the years of or following many of the same major volcanic eruptions that affected Bristlecone growth in the more recent period are marked by wide growth rings in Austrian Pine, Pinus nigra. This indicates that an increase in May–June precipitation caused more favorable growth in this region as part of a chain of climatic disturbances associated with Northern Hemisphere cooling following major mid- or northern latitude volcanic eruptions. Assuming that similar climatic forcing prevailed during the Bronze Age and knowing that Pine and Juniper tree-ring chronologies from this region show strong interspecies correlation, Pearson et ai. hypothesised that wide rings in the floating Juniper sequence should correlate with calendar-dated frost events in Bristlecone Pine and that, if so, this could provide a means to test the annual Carbon¹⁴-matching approach and to refine to a fixed tree-ring date based on synchronization with the calendar-dated Bristlecone record (in a similar approach to previous studies that used Bristlecone Pine frost rings as fixed date volcanic markers to refine dating for volcanic acidity layers in ice cores).

Finally, Pearson et al. report the chemical study of this newly secured tree-ring sequence with the objective of seeing if any chemical indicator could be found that might help to further constrain the dating possibilities for the Thera eruption.

Annual Carbon¹⁴ measurements were made on 186 consecutive years (relative years 834 to 1019) of the 1028-year Gordion Juniper sequence (which starts with relative year 737). These measurements into the IntCal13 Radiocarbon Age Calibration Curve using the OxCal 4.3 radiocarbon calibration program to provide an end date for the entire calibrated tree-ring chronology, within an 8-year range: 758 to 751 BC at 95.4% confidence level. This was in good agreement with previous wiggle matching of 128 decadal or 11-year blocks spaced over 987 years of the same Juniper sequence, which placed the end of the tree-ring sequence at 751 BC +6/–8 at a 95.4% confidence level. A chi-squared (χ²) test (used to determine whether there is a statistically significant difference that is unlikely to be due to chance alone between expected frequencies and observed frequencies) for the Mediterranean Carbon¹⁴ time series vs. the weighted mean of the annually resolved combined Oak and Pine data placed the last ring of the Mediterranean sequence at a more precise date of 745 ± 4 BC (95.4% confidence level); this is statistically slightly younger (10 ± 6 years) than when the same data are wiggle matched to IntCal13. Pearson et al. considered the position using the annual Carbon¹⁴ data as significantly more reliable as it is a result of comparing fine structure that is not available in IntCal13, which is primarily based on decadal data. Using the fine structure yields dating results free from the regional or laboratory offsets that may be combined in the coarser-resolution calibration data. The reasonably close agreement of the results via the different methods does, however, demonstrate that, for wiggle matches spanning multiple decades, the improved curve shape offered by the annual Carbon¹⁴ data may have a relatively small effect on the final calibrated date range.

Positioned relative to an end date of 745 ± 4 BC the visual correlation of the annual data around the increased production event of circa 1528 BC is clearly evident. The Gordion data more closely agree with the annual Oak and Pine data than with IntCal13 and show the same offset from the curve as shown by the other annual data between 1650 and 1540 BC. They are also valuable in providing an annually based record of Carbon¹⁴ fluctuation from the Mediterranean region in this time period relevant for the Thera eruption. While no large-scale localized offsets in Carbon¹⁴ are evident, for the years where contemporary Oak, Pine, and Juniper measurements from the same laboratory can be directly compared (1680 to 1580 BC), the Mediterranean Juniper is offset from the Irish oak by +9.0 ± 3.5 Carbon¹⁴ years, whereas they are only +3.4 ± 2 Carbon¹⁴ years different from the North American Pine. While this slight difference is within the stated measurement errors, it is possible that the closer agreement between the Pine and Juniper may reflect a shared, more southerly latitude than the Irish Oak. These data agree with previous findings that there is no major regional offset in the period. Pearson et al. also note that the data indicate that, around the period of lower solar activity (around 1600 BC) and during the period of more rapid Carbon¹⁴ production (roughly 1540 to 1528 BC), there is no significant difference between the multiregional annual Carbon¹⁴ data, which might be related to growth season. Pearson et al. do, however, note the possibility of a localized excursion in Carbon¹⁴ around 1548 BC. This requires further investigation as, if it is not an analytical outlier, it could represent an influx of  'old carbon' into the environment, potentially consistent with a volcanic eruption such as Thera.

The validity of the dated position produced by chi squared analysis (745 ± 4 BC at a 95.4% confidence level) and supported by annual Carbon¹⁴ pattern matching around the 1528 BC Carbon¹⁴ excursion was then independently tested using the previously described correlation between years of known eruptions, calendar-dated Bristlecone Pine frost-ring years, and wide tree rings in Mediterranean sequences. Pearson et al. hypothesised that, if their temporal placement of the Juniper chronology was correct at 745 ± 4 BC, then it should show wide rings in the year of or following a Bristlecone Pine frost ring. On this basis, superposed epoch analysis (a statistical tool used in data analysis either to detect periodicities within a time sequence or to reveal a correlation, usually in time, between two data sequences) was used to test the significance of the effects of a mean tree-ring response to the proxy record of volcanic forcing across the full Bronze–Iron Age Juniper chronology in the adjusted position suggested by this study. In this position, the superposed epoch analysis analysis showed significantly wider rings than would be expected by chance in the Mediterranean chronology in the year following a Bristlecone frost ring. This nonrandom association provides strong corroborative evidence for the annual Carbon¹⁴ position to, in fact, be correct to the year. Within the 4 years on either side of the 745 BC dating placement, no other positions provide this strong association. This provided additional support that the position of the Gordion chronology determined by the chi-squared analysis is indeed correct to within 1 year and allowed Perason et al. to derive an exact calendar-dated position for the tree-ring series.

Having arrived at a secure date range for the tree-ring series, Pearson et al. made multiple scans using a desktop ATLAS Micro-X-ray Fluorescence unit across the transverse surface of a subsample of GOR-76. The scans covered the period from circa 1630 to 1500 BC. These revealed a single major disturbance of the element Calcium around 1560 BC. The exact onset of the change may be as early as 1562/1 BC, and the effect appears to last until around 1557 BC. Other analytical techniques will be used to refine this temporal association. Calcium is an essential element in wood that is needed to support fundamental biological functions, including cell membrane stability and stress response. Declines in tree-ring Calcium have previously been associated with drought; however, in this case, the growth rings that feature the depletion are not unusually narrow (as would indicate drought). A forest fire response is also a possible explanation, and this can manifest as either an increase of Calcium as it becomes more available for uptake after burning or as a depletion where areas of the sample are scarred but again, the tree-ring growth pattern does not indicate a growth release or scar typical of fire impact.

A high-resolution X-ray fluorescence scan of the transverse section of GOR-76 featuring an unusual depletion of the element Calcium. The mapped area was identified as the only significant elemental anomaly in the 16th century BC growth rings from this sample. This scan shows that a calcium depletion occurs from around 1562 to 1558 BC and is centered on an unusually wide, slightly pale in colour growth ring at 1560 BC. A similar wide, pale ring occurs in 1550 BC but does not indicate the same degree of depletion. Pearson et al. (2020).

Alternatively, Calcium can be reduced in tree rings following foliar exposure to acid mist or other such precipitation. Therefore, the finding of a Calcium depletion is consistent with the impact of volcanically induced acid deposition [reported in lake sediments as a result of the Thera eruption. On its own, this Calcium response in a single tree might not be worth reporting; however, the date around which it occurs makes it worthy of further discussion because 1560 BC also coincides with evidence for volcanic impact indicated in two other records. Subfossil Pine trees from a calendar-dated record in Finnish Lapland indicate a possible eruption immediately preceding 1560 BC in the form of a negative departure in Carbon¹³ (drop in the proportion of Carbon¹³ relative to Carbon¹²), which has been shown to correlate with periods of reduced visibility due to volcanic acid fog. The high-altitude Bristlecone pine record also includes an indicator year at 1560 BC along with 4 other years in the 16th century BC when unusually narrow growth or frost-damaged cells are recorded. These dates (1597, 1560, 1546, 1544, and 1524 BC) are all indicative of major volcanic eruptions, the origins of which are not yet known. The coincidence of these two additional records around 1560 BC makes further investigation essential. The apparent increase in old carbon around 1558 BC also requires further exploration as, although the tree grew several 100 km from the eruption, this too could hypothetically connect with the Thera eruption, and all potential indicators should be explored. We note, however, that 1560 BC is more recent than indicated likely for the chemical change associated with the Thera eruption at Sofular cave and older than is indicated likely for the event via certain lines of archaeological evidence Nevertheless, these findings clearly merit further careful investigation to define better the onset and duration of the response and to see if it can be replicated in other trees and expanded via the detection of other more clearly volcanogenic (or otherwise) elemental markers.

Pearson et al.'s study shows that, even in the absence of a large-scale interannual Carbon¹⁴ excursion (such as at 774/775 AD), comparing the fine structure in annually derived Carbon¹⁴ time series via a range of approaches can offer a way to improve the dating precision and accuracy possible for floating tree-ring sequences previously dated by conventional radiocarbon wiggle matching to the IntCal calibration curve. First, critically, matching based on two annual Carbon¹⁴ time series (one of which is calendar dated via dendrochronology) offers a dated position for the floating sequence, which is fixed. This differs from modeled dates via conventional radiocarbon wiggle matching, which may change with new iterations of the calibration curve. Second, chi-squared testing of longer annually based time series can refine dating for floating tree-ring sequences to a precise year within a ± 4-year range, and this can be visually tested and confirmed across small-scale Carbon¹⁴ features (such as at 1528 BC). Third, as is the case in this study, additional proxy information can be used to refine the dating further. We found that other tree-ring associations strongly suggested that the dating indicated by the annual Carbon¹⁴-matching approach yielded a result that was in fact accurate to within 1 year. This combination of methods opens up opportunities to anchor floating tree-ring sequences in time outside the capacity of standard dendrochronological techniques, demonstrating potential to fill in a range of critical temporal and geographic gaps in the tree-ring record.

Anchoring the Gordion tree-ring series more securely in time is an important contribution to improving timelines in the ancient East Mediterranean and maximizing the potential of this record as a paleoenvironmental resource. The first step toward this is the identification of the calcium anomaly around 1560 BC, which while clearly requiring replication and much further substantiation, opens up potential that may now be pursued toward finding an exact date for Thera.

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Phoenix dactylifera: Seeking the origin of the historic Judean Date Palm, using genetic analysis of germinated ancient seeds.

The Date Palm, Phoenix dactylifera, a dioecious species (in dioecious plants each individual produces either male or female flowers only) in the Arecaceae (formerly Palmae) family has a historical distribution stretching from Mauritania in the west to the Indus Valley in the east. A major fruit crop in hot and arid regions of North Africa and the Middle East and one of the earliest domesticated tree crops, archaeobotanical records suggest that the earliest exploitation and consumption of Dates is from the Arabian Neolithic some 7000 years before the present. Evidence of cultivation in Mesopotamia and Upper Arabian Gulf approximately 6700 to 6000  years before present support these centres as the ancient origin of Date Palm domestication in this region, with a later establishment of oasis agriculture in North Africa. 

The current date palm germplasm is constituted by two highly differentiated gene pools: an eastern population, consisting of cultivars extending from the Middle East and Arabian Peninsula to northwest India and Pakistan and a western population covering North Africa and sub-Saharan Africa. Introgressive hybridization by a wild relative in North African Date Palms has been proposed as a source of this differentiation.

Date palms in the southern Levant (modern-day Israel, Palestine, and Jordan), situated between eastern and western domestication areas, have historically played an important economic role in the region and were also of symbolic and religious significance. The Kingdom of Judah (Judea) that arose in the southern part of the historic Land of Israel in the 11th century BC was particularly renowned for the quality and quantity of its dates. These so-called 'Judean Dates' grown in plantations around Jericho and the Dead Sea were recognized by classical writers for their large size, sweet taste, extended storage, and medicinal properties. While evidence suggests that Judean Date culture continued during the Byzantine and Arab periods (4th to 11th century AD), further waves of conquest proved so destructive that by the 19th century, no traces of these historic plantations remained. 

In Jume 2008, Sarah Sallon of the Louis L. Borick Natural Medicine Research Center of the Hadassah Medical Organization, Elaine Solowey of the Arava Institute of the Environment at Kibbutz Ketura, Yuval Cohen and Raia Korchinsky of the Department of Fruit Tree Sciences at the Volcani Research Center, Markus Egli and Ivan Woodhatch of the Radio-Carbon Laboratory at the University of Zurich, and Orit Simchoni and Mordechai Kislev of the Mina and Everard Goodman Faculty of Life Sciences at Bar-Ilan University, published a paper in the journal Science in which they reported the germination of a 1900-year-old Date seed recovered from the historical site of Masada, a Herodian fortress overlooking the Dead Sea, built the second half of the first century BC, and destroyed in 70 AD.

(A) Ancient date seeds from Masada. (B) Germinated seedling age 3 months, showing normal development of simple juvenile leaves. Height is 15 cm. (C) Age 7.5 months, some leaves showing white patches. Height is  31 cm. (D) Age 26 months, normal seedling development with compound leaves. Height is 121 cm. Guy Eisner in Sallon et al. (2008).

In a second paper published in the journal Science Advances on 5 February 2020, Sarah Sallon, still of the Louis L. Borick Natural Medicine Research Center of the Hadassah Medical Organization, Emira Cherif and Nathalie Chabrillange of the Institut de Recherche pour le Développement at the Université de Montpellier, Elaine Solowey, still of the Arava Institute of the Environment at Kibbutz Ketura, Muriel Gros-Balthazard of the Center for Genomics and Systems Biology at New York University Abu Dhabi, and the Institut des Sciences de l’Evolution at the Université de Montpellier, Sarah Ivorra and Jean-Frédéric Terral, also of the Institut des Sciences de l’Evolution at the Université de Montpellier, Markus Egli, still of the Radio-Carbon Laboratory at the University of Zurich, and Frédérique Aberlenc, also of the Institut de Recherche pour le Développement at the Université de Montpellier, present the results of a follow-up study in which six additional ancient date seeds from archaeological sites in the Judean Desert were germinated, bringing to seven the number of ancient genotypes genetically analyzed using molecular markers. In addition, morphometric analysis (a tool used by palaeontologists, archaeologists, anthropologists and forensic pathologists to analyse and compare specimens, by taking numerous measurements of an object such as a bone or shell, and comparing both these measurements and ratios between measurements to those obtained from other specimens in order to establish relationships between them) was used to compare the size and shape of ungerminated ancient date seeds with modern varieties and wild Dates.

This study, which confirms the long-term survival of Date Palm seeds, provides a unique opportunity to rediscover the origins of a historic Date Palm population that existed in Judea 2000 years ago. The characteristics of the Judean Date Palm may shed light on aspects of ancient cultivation that contributed to the quality of its fruit and is thus of potential relevance to the agronomic improvement of modern Dates.

Of the hundreds of ancient date seeds and other botanical material recovered from excavations carried out in the Judean Desert between 1963 and 1991, 32 well-preserved Date seeds from the archaeological sites of Masada, Qumran, Wadi Makukh, and Wadi Kelt were planted in a quarantine site at Kibbutz Ketura. Of these, six ancient seeds germinated and were further identified by the following designations: Masada: 'Adam'; Qumran: 'Jonah', 'Uriel', 'Boaz', and 'Judith'; and Wadi Makukh: 'Hannah'.

Map of Judean desert sites where ancient seeds were discovered. Discovery sites are circled in red. Sallon et al. (2020).

On visual inspection, no specific observation linked the ability of these seeds to germinate compared with those that failed to germinate. Before planting, the ancient Date seeds had been weighted, and their length was measured, with the exception of those seeds from Masada, (including Adam, the germinated seed), which unfortunately were not measured. No statistically significant differences were found between germinated and ungerminated seeds in either weight or length.

Morphology of six germinated ancient Date seeds before planting. (A) Adam, (B) Jonah, (C) Uriel, (D) Boaz, (E) Judith, (F) Hannah, and (G) HU37A11, an unplanted ancient Date seed from Qumran (Cave FQ37) used as a control. Scale bars, 0.5 cm. (A) has no bar size as unmeasured before planting. Guy Eisner in Sallon et al. (2020).

Radiocarbon ages were determined for the ancient Date seeds germinated in the new study and also for the Date seed ('seed 3' or 'Methuselah') germinated in the original work. These ages were obtained from seed shell fragments found clinging to the rootlets of germinated seedlings during their transfer into larger pots (3 to 17 months of age). The values were recalculated to take into account contamination by modern carbon incorporated during seedling growth previously shown to reduce measured radiocarbon age by approximately 250 to 300 years, equivalent to 2 to 3% modern carbon. On the basis of these calculations, Methuselah, germinated in the previous study, and Hannah and Adam in the current study are the oldest samples (first to fourth centuries BC), Uriel and Jonah are the youngest (first to second centuries AD), and Judith and Boaz are intermediate (mid-second century BC to mid-first century AD).

Germinated ancient date seedlings. (A) Adam (110 months), (B) Jonah (63 months), (C) Uriel (54 months), (D) Boaz (54 months), (E) Judith (47 months), and (F) Hannah (88 months). Guy Eisner in Sallon et al. (2020).

Eighteen ancient Date seeds that failed to germinate were recovered from the potting soil and compared with modern seeds derived from 57 current date palms of which 48 are cultivated varieties and 9 are wild individuals. Ancient seeds were significantly larger in terms of both length and width (length 23.66-31.58 mm, width 9.67-11.09 mm) than both current cultivar (length 15.90-25.30, width 7.31-9.24) and wild Date Palm seeds (length 13.30-20.08, width 6.62-7.54). Ancient seeds were, on average, 27.69% wider and 38.37% longer than the combined current samples (wild and cultivated).

When only compared to the cultivars, the ancient Date seeds were still larger: 24.55% wider and 34.06% longer. However, the contrast in seed size is even more marked when comparing ancient seeds and current wild Date Palms: The Judean Date Palm seeds were, on average, 39.55% wider and 65.48% longer than current wild samples.

Analysis of seed shape diversity in current and ancient date seeds using principal components analysis performed on seed outlines confirmed visual observation that modern cultivated seeds were more diverse in size than ancient ones but similar in shape. Ancient seeds displayed an elongated shape similar to current cultivated samples.

The sex of the six germinated ancient Date seedlings in the new study were as follows: Judith and Hannah are female genotypes and Uriel, Jonah, Boaz, Adam, and Methuselah (seed 3) from the previous study are male genotypes. Through microsatellite genotyping, three levels of genetic inheritance were investigated to highlight geographic origins|: (i) inheritance transmitted by both parents to progeny, obtained by microsatellite markers showing western and eastern patterns of the ancient seed’s genomes; (ii) inheritance transmitted from mother to progeny through the chloroplast genome, reflecting maternal lineage origin by reporting chloroplastic minisatellite eastern or western alleles; and (iii) inheritance transmitted from father to son through the Y chromosome, reflecting paternal lineage origin by reporting male specific sex-linked eastern or western alleles.

Structure analysis revealed that distribution of the germinated ancient Date seeds was within previously described eastern and western Date Palm gene pools. Methuselah, Hannah, and Adam are the most eastern genotypes, although they also show ancient western contributions requiring numerous generations and highlighting ancient crosses. Boaz and Judith are the most admixed, with almost equal eastern and western contributions reflecting more recent crossings. Jonah and Uriel are the most western genotypes with the most western parental lineages.

To shed light on genetic diversity of the ancient dates, basic population genetic parameters were estimated and compared to modern reference collections. The ancient genotypes showed an allelic richness value with a relatively high diversity for such a small sample size (seven genotypes) compared to values of other countries sampled. Genetic relationships between the ancient Date and current varieties show Methuselah and Adam close to eastern modern varieties Fardh4 and Khalass, respectively, assigned to current Arabian Gulf varieties; Hannah and Judith related to modern Iraqi varieties Khastawi and Khyara, respectively; and Uriel, Boaz, and Jonah, the most western genotypes, related to modern Moroccan varieties, Mahalbit, Jihel, and Medjool, respectively.

In the new study, six ancient Date seeds, in addition to the seedling obtained in the previous study were germinated. All the seeds were approximately 2000 years old and had been previously recovered from archaeological sites in the Judean Desert, a rain shadow desert of about 1500 km² located between the maquis-covered Judean Hills and the Dead Sea.

Little is known about the mechanisms determining seed longevity; however, it has been related to the ability to remain in a dry quiescent state. Low precipitation and very low humidity around the Dead Sea could have contributed to the longevity of the ancient Date seeds, which may be an adaptation of Date Palms to extreme desert conditions fostering seed dispersion. Their remarkable durability, however, may also be connected to other extreme environmental conditions in this area; at 415 m below mean sea level, the Dead Sea and its surroundings have the thickest atmosphere on Earth, leading to a unique radiation regime and a complex haze layer associated with the chemical composition of the Dead Sea water. However, since no visible evidence in the study was linked to seed germination and, accordingly, to their long term survival, further investigations are needed to understand the basis of Date Palm seed longevity.

Among the world’s oldest cultivated fruit trees, Phoenix dactylifera is the emblematic of oasis agriculture and highly symbolic in Muslim, Christian, and Jewish religions. Closely connected to the history of Human migrations, the first cultivated varieties of Phoenix dactylifera are thought to have originated around Mesopotamia and the Upper Arabian Gulf some 6700 to 6000 before the present. In Judea, an ancient geopolitical region that arose during the 11th century BC in the southern part of the historic Land of Israel, and situated at the cross roads of Africa, Asia, and Europe, the origins of Date Palm cultivation are unknown. However, from historical records, a thriving Judean date culture was present around Jericho, the Dead Sea, and Jordan Valley from the fifth century BC onward, benefitting from an optimal oasis agriculture environment of freshwater sources and subtropical climate.

Described by classical writers including Theophrastus, Herodotus, Galen, Strabo, Pliny the Elder, and Josephus, these valuable plantations produced Dates attributed with various qualities including large size, nutritional and medicinal benefits, sweetness, and a long storage life, enabling them to be exported throughout the Roman Empire. Several types of Judean Dates are also described in antiquity including the exceptionally large 'Nicolai' variety measuring up to 11 cm.

In the new study, ancient seeds were significantly longer and wider than both modern Date varieties and wild Date Palms. Previous research has established that both fruits and seeds are larger in domesticated fruit crops compared with their wild ancestors, suggesting that the ancient seeds were of cultivated origin, most likely originating from the region’s date plantations. Furthermore, an increase in seed size has been linked allometrically to an increase in fruit size, corroborating the historical descriptions of the large fruits grown in this region.

Genotypes of the germinated ancient date seedlings cover a large part of present-day Date Palm distribution area, findings that reflect the variety, richness, and probable influences of the historic Judean Date groves. Microsatellite genotyping shows a relatively high diversity, with eastern and western gene pool contributions, allelic richness, and genetic proximity to current varieties cultivated in the Arabian Peninsula, Iraq, and North Africa. Although the sample size is small, a predominance of eastern female lineages (six of seven) indicates that eastern female varieties grown from local germplasm were probably clonally propagated from offshoots to maintain desirable fruit qualities. Male lineages, mainly western (four of five), suggest that genetically different or 'foreign' males were used for pollination. This assumption is supported by first century texts, indicating that substantial knowledge existed in ancient Judea 2000 years ago regarding the most suitable males for pollination of female Date Palms.

Sallon et al.'s results reinforce the historical narrative that a highly sophisticated domestication culture existed in ancient Judea. Local farmers with an interest in maintaining genetic diversity in their Date plantations and anthropogenic pressures leading to selection on fruit dimension and other desirable traits used cross-breeding with foreign (genetically different) males to develop a rich collection of varieties.

These findings suggest that Judean Date culture was influenced by a variety of migratory, economic, and cultural exchanges that took place in this area over several millennia.

In Israel, the oldest remains of Phoenix dactylifera are wood specimens 19 000 year old from the Ohalo II site on the Sea of Galilee. Recovery of carbonized Date seeds from Chalcolithic and Early Bronze Age sites (4500 to 2900 BC) in the Judean Desert, Jordan Valley, and Jericho, and early Iron Age sites in Israel (12th to 11th century BC) suggest that Human exploitation and consumption of Dates occurred at this time. However, it is unclear whether these samples, which are relatively few in number and of very small size, are derived from ancient wild populations, as suggested by morphometric studies of modern wild Date populations or represent an early stage of the domestication process.

In Sallon et al.'s new study, although the sample size is too small to claim a trend, on a gradient from east to west genetic contributions, the older the germinated seeds are on radiocarbon dating, the more eastern is the nuclear genome. In this respect, Methuselah, Adam, and Hannah (first to fourth centuries BC) have a predominantly eastern nuclear genome and eastern maternal lineage, their relationship to modern varieties from the Arabian Gulf and Iraq suggesting that they belong to the same eastern genetic background.

The Phoenix dactylifera cultivated by the inhabitants of Judea at that time therefore appears to be from the eastern gene pool, possibly growing locally and related to oasis populations, of which relict populations were recently found in Oman.

Elite female cultivars may also have been introduced to ancient Israel from these regions, consistent with a pattern of Human intervention and possibly active acquisition of Date palm varieties. Established trade links are documented with Arabia and the Persian Gulf from at least the 12th century BC. Babylonian Date Palm cultivation in southern Mesopotamia (most of modern Iraq), originating some 6000 before the present, used deportees from ancient Judea following its conquest in the sixth century BC. After the collapse of the Neo-Babylonian Empire, returning exiles may have brought this specialized knowledge and selected cultivars back to Judea; a Date variety 'Taali' cultivated in both Judea and Babylon is mentioned in the Talmud. 

Western genetic admixtures in the germinated seedlings and their proximity to current cultivated date varieties from Morocco also suggest that ancient Judean Date Palms were the result of germplasm exchanges with this area and of multiple crosses. Introgression of eastern genomes into western ones are common, detected in varieties from Algeria, Morocco, Mauritania, and particularly east-west junction areas like Egypt. In the latter, eastern contributions from the Persian Gulf, detected in ancient Egypt Date seeds from 1400 BC to 800 AD, reveal a chronological pattern of change in agrobiodiversity and the possible emergence of a western form in the Roman period.

Introgression of Date Palm western genomes into eastern ones, however, is far lower, their presence in the current study reflecting west to east exchanges.

The origins of these exchanges are unclear; however, archaeological evidence indicates that North Africa, Near East, and Mediterranean cultures were clearly linked during the Neolithic in the southern Levant (approximately 11 700 to 7300 years before the present) and were associated in Jericho with the earliest origins of food production and fundamental changes in human subsistence strategies.

Phoenicia, a maritime trading nation occupying the coastal areas of modern northern Israel, Lebanon, and Syria (1500 to 300 BC), was also historically associated with cultivation and trade of Date Palms. Sallon et al. speculate that later west to east germplasm exchanges to this region may have been associated with domesticated varieties originating in Phoenician City States in North African (e.g., Carthage in present-day Tunisia), where oasis agriculture appeared relatively late in the archaeological record.

The most western genotypes in Sallon et al.'s study (Uriel and Jonah) are also the youngest seeds (mid-first to mid-second AD), coinciding with established trade routes linking this region to North Africa and supporting evidence for date consumption in the latter 2000 years ago. This period coincides with Judea’s well-documented wars against Rome (66 to 73 AD and 132 to 136 AD) and deportation and displacement of its population. The ancient seeds in the current study were found in the Judean Desert, historically a place of refuge due to its steep cliffs and inaccessible caves. The loss of political autonomy and the final collapse of Judea have been postulated as causing major disruption to labor intensive practices associated with Date cultivation. Elite cultivars no longer conserved by vegetative propagation (offshoots) were gradually replaced by seedling Date Palms producing fruits displaying considerable variation within the progeny. Although Phoenix dactylifera can live for more than 100 years and date groves in this region are thought to have persisted for several more centuries, they were already rare by the 11th century and had been entirely replaced by seedling populations or feral, wild trees producing only low-quality fruit by the 19th century.

Sallon et al.'s new study study sheds light on the origins of the Judean Date Palm, suggesting that its cultivation, benefitting from genetically distinct eastern and western populations, arose from local or introduced eastern varieties, which only later were crossed with western varieties. These findings are consistent with Judea’s location between east-west Date Palm diversification areas, ancient centers of Date Palm cultivation, and the impact of Human dispersal routes a this crossroads of continents.

Given its exceptional storage potentialities, the Date Palm is a remarkable model for seed longevity research. Investigations on the molecular mechanisms involved in long-term protection in the dried state have important implications on plant adaptation to changing environments and for biodiversity conservation and seed banking. As new information on specific gene-associated traits (e.g., fruit colour and texture) is found, Sallon et al. hope to reconstruct the phenotypes of this historic Date Palm, identify genomic regions associated with selection pressures over recent evolutionary history, and study the properties of dates produced by using ancient male seedlings to pollinate ancient females. In doing so, Sallon et al. hope they will more fully understand the genetics and physiology of the ancient Judean Date Palm once cultivated in this region.

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