Is this thing still on? Excellent. A big meeting is scheduled for next week in St Petersburg, Russia, to consider new discoveries about some of the holdings at the Pavlovsk Experiment Station and, perhaps, the station’s future, so it seemed like a good idea to make sure that this site was up and running and ready to broadcast whatever intelligence it might receive. As ever, it’s easy to make contact. Rather than just clearing my throat, though, here’s some substance.

African rice, Oryza glaberrima, differs in many respects from Asian rice, O. sativa. Yields are lower, partly because the seeds shatter more easily from the plant, although African rice is better able to withstand stress. The grains are often coloured red rather than white. And it may well be more nutritious, partly because it is harder to polish than Asian rice, and polishing removes essential micronutrients. Certainly average protein levels are higher. And Africans say it fills them up properly, which might indicate a lower glycemic index (not that the official glycemic index contains anything as useful as either O. glaberrima or African Rice among its entries).

African rice has of course been crossed with Asian rice to create the wildly successful NERICA (NEw RICe for Africa) varieties, and some might think that it’s game over for pure African rice, but there’s still a lot to be learned.

The history of its domestication has been confused. Jack Harlan originally suggested that it was domesticated by selection from O. barthii, the wild ancestor, at many places across its wide range. Archaeological evidence suggested a more circumscribed area, around the Middle Niger delta in what is now Mali, although given the relatively late date of the remains found there — around 500 years BCE — the possibility remains that it had been introduced from elsewhere.

A new DNA study by Chinese scientists confirms that African rice was domesticated in the Middle Niger delta and that the original selection may have taken place just once. The scientists sequenced DNA from 20 samples of O. glaberrima and 20 samples of O. barthii, looking at the detailed sequence of 14 unlinked genes. While there was some variation in the diversity of the individual genes, overall the wild relative samples were about four times more diverse than the cultivated samples. That said, the actual diversity of both species is very low indeed, lower than all previously sampled crops and their wild relatives.

An obvious explanation for the low genetic diversity of O. glaberrima would be a genetic bottleneck during its domestication from a small initial population of O. barthii. … [T]he extremely low nucleotide diversity in African rice can be explained by severe bottleneck during domestication, with high value of the bottleneck intensity … which is consistent with its single origin in west Africa.

O. barthii and O. glaberrima are both largely self-pollinating, which would also account for the low genetic diversity. As for the place of domestication, there were 7 O. barthii samples that were clustered closely with all the O. glaberrima samples. All 7 were from previously postulated centres of domestication, three from the Middle Niger delta and two each from brackish mangrove areas of Guinea and the upland areas between Sierra Leone and Ivory Coast. There was no evidence for the kind of multiple domestication proposed by Harlan. More extensive sampling, the authors say, might reveal the precise place where O. glaberrima originated.

Quite apart from the satisfaction of knowing a little more about the origin and domestication of an important crop, this research is also important because in revealing the lack of genetic diversity within African rice and its wild progenitor, it provides insights into how best to conserve the diversity of both species and also suggests that the wild relative might still be able to donate important characteristics to African rice and, perhaps, to NERICA varieties too.

Edible bananas have very few seeds. Wild bananas are packed with seeds; there’s almost nothing there to eat. So how did edible bananas come to be cultivated? The standard story is that some smart proto-farmer saw a spontaneous mutation and then propagated it vegetatively. Once the plant was growing, additional mutants would also be seen and conserved. In fact this “single-step domestication” is considered the standard story for many vegetatively-propagated plants, such as potato, cassava, sweet potato, taro and yam. And while it may be true for those other crops, evidence is accumulating that it may not be the whole story for bananas.

Edmond de Langhe and his colleagues pose a question: Did backcrossing contribute to the origin of hybrid edible bananas? And their answer is, “yes, we’re pretty sure it did”. Truth be told you could probably count the number of people who are really interested in (and able to fully understand) the details of how they got there on one hand. For the rest of us, here’s my take on it.

The hybrid bananas they refer to, our edible bananas, are almost all the results of a cross, either between two wild species, Musa acuminata (A for short) and M. balbisiana (B), or within just one of the species that nevertheless gave rise to a plant that doesn’t need pollen to trigger the growth of a fruit (it is parthenocarpic) and doesn’t itself usually make seeds, although it may produce pollen. Some cultivated bananas are diploid, with two A chromosomes, just two are AB, and none, of more than a thousand, is BB. The rest are all triploid, with three sets of chromosomes: AAA, AAB and ABB with, again, no BBB. Stay with me.

On that basis, Simmonds and Shepherd put the characteristics of the two wild relatives at the opposite ends of a 15 point scoring system to characterise all bananas. Unfortunately, the bananas themselves don’t fall neatly into the categories one might expect them to.

De Langhe and his colleagues looked at the chromosomes and DNA in more detail, using important observations that were not available to Simmonds and Shepherd. Most importantly, for bananas where the parentage is known with certainty, the mitochondria are inherited from the father, or pollen parent, while the chloroplasts come from the mother, or ovule parent. There is also good evidence for exchange among the A and B chromosomes in banana varieties, which would also explain the failure of many varieties to sort neatly under the Simmonds and Shepherd scheme. This kind of evidence allows De Langhe and colleagues to propose alternative, more complex routes to the seedless bananas of today.

Most of these involve a more-or-less fertile AB hybrid being fertilized by A pollen, and then a little nuclear DNA jiggery-pokery (meiotic restitution) and perhaps some rearrangement of the DNA. And that could happen — and more importantly could be noted — if those proto-farmers were growing their newly found edible bananas in close proximity to their wild relatives, as they would have been in southeast Asia. Something very like that is going on today among cassava farmers, for example; they allow volunteer seedlings, the product of sexual reproduction between already favoured clones and wild relatives, to flourish in their fields and then select among them. Banana farmers could easily have done the same.

The details really are not for the faint-hearted; they do, however, make sense of most of the observations on bananas today, including the rarity of certain chromosome combinations and the anomalies in the banana scoring system. And the paper goes out of its way to suggests methods that might verify the backcross hypothesis, including various approaches to direct examination of the DNA.

The big question, of course, is “what does any of this matter?”. And the surprise is that it really does. Banana breeding is difficult at the best of times; no seeds, no pollen, you can imagine. But if the backcross hypothesis is true, then the current approach to banana breeding, which De Langhe et al. describe as “substituting an A genome allele by an alternative derived from a AA diploid source of resistance or tolerance to biotic and abiotic stress”, might be misguided. If the chromosomes are not “pure” A or B, and if backcrosses were involved in the origin of banana varieties, maybe breeders should look again at some of the diploid offspring from their crosses and see whether they could be further backcrossed to come up with types that are more use to farmers.

“Abyssinia is, apparently, the native land of donkeys,” Vavilov states flatly. well, maybe.

Two relatively recent studies shed light on the domestication of the donkey. A 2004 paper by Albano Beja-Pereira and his colleagues, published in Science, looked at the molecular evidence. The researchers conclude that the donkey was domesticated twice, once from the Nubian sub-species of wild ass (Equus africanus africanus) and once from the Somali wild ass (E. a. somaliensis). Asian half-ass species (E. hemiones and E. kiang) made no contribution to the modern donkey. The timing of domestication could not be estimated from the DNA, but the authors do say that both events took place in Northeast Africa, which for them comprises Egypt, Sudan, Somalia, Ethiopia and Eritrea. Vavilov was right on the money.

The other study is a more conventional examination of old bones by Fiona Marshall and the late Stine Rossel and their colleagues, published in PNAS in 2008. The researchers looked in detail at foot bones from 10 ass skeletons dating to about 5000 years ago, and found in a pharaonic complex at Abydos in Middle Egypt. Although the bones were similar in some respects to those from wild asses, in others they seemed to be midway between asses and donkeys. The clincher is that “all of the Abydos skeletons exhibited a range of osteopathologies consistent with load carrying”. In other words, they were being used as beasts of burden, and that damaged their bones — 5000 years ago. That they were buried with the Pharoah suggests these animals were of great significance. As Marshall said:

“This is the first evidence for donkeys carrying loads, which is important because they were the first transport animal … absolutely the first loads off humans’ backs to create land transport routes, the earliest trade routes between Egyptians and Sumerians and so on. … It’s very likely that having land-based transport of this kind actually helped to integrate the state, which was the world’s first and earliest nation-state.”

Vavilov had clearly been strongly influenced by his host in Algeria when he wrote that “Here it is to some extent possible to solve the riddle of the origin of some cultivated plants. It was just here that Trabut found the interesting wild bean mentioned above, Vicia pliniana (Trabut) Muratova, which undoubtedly is genetically especially closely related to the cultivated forms of the small-seeded, black beans of Afghanistan and India.” Although he doesn’t say as much, he seems to be implying quite strongly that the “wild” Vicia pliniana, found and described by Trabut, is indeed the ancestor, or a very close wild relative of, the cultivated bean V. faba. Alas, this seems not to be the case. V. pliniana is no more than a synonym for V. faba subsp. faba var. minor.

Some of the foremost experts on Vicia taxonomy have reviewed the “confused” taxonomic relations of the fava bean with its allies, and have concluded that “after extensive taxonomic investigation the progenitor has not been identified.” Given how much interest there has been in the species in recent decades, it seems unlikely that the ancestral species has been found yet not recognized. So perhaps it has not yet been found. If the wild relative does exist, it is likely to be growing either in the Near East or in Afghanistan, “where the most primitive forms of V. faba occur”. The Near East has been scoured by collecting missions. That leaves Afghanistan. Maxted and his colleagues describe the country as “seriously under-collected” and urge that “forage legume collections in this area should be given a high priority.” There are, of course, other priorities there right now, but that shouldn’t stop a visit by an intrepid Seed Hunter at some point.

Why does any of this matter? Because faba beans matter. According to FAO, in 2006, 2.6 million ha were planted and 4.6 million tonnes were harvested, with about 1.05 million ha planted with faba bean in China alone. Ethiopia, Morocco and Australia cultivate 427,719, 169,000 and 153,000 ha, respectively. Unlike other grain legumes, world trade in faba beans is significantly lower, with most produce consumed locally, where it is an important source of protein. Breeders and farmers looking to improve the performance of faba beans could turn to wild relatives, but the known wild relatives have different numbers of chromosomes from the cultivated types, and the survival of crosses is very poor. The true progenitor might act as a bridge to transfer useful traits from wild relatives into cultivated V. faba.

As for the existing diversity in the species most closely related to V. faba, things are not looking good. Nigel Maxted and Shelagh Kell, in a comprehensive report on crop wild relatives for the FAO Commission on Genetic Resources recommend:

• the establishment of new reserves in Syria and Turkey for the active conservation of V. faba‘s closest wild relatives;
• systematic collection of those wild relatives for genebank conservation;
• a continued hunt for a possible true ancestor, focussed on southeast Turkey, Iran and Afghanistan;
• on-farm projects to conserve the existing diversity of faba beans, “particularly in areas with less developed agriculture”;
• and a specific effort to relocate and collect one of V. faba‘s most primitive relatives, V. faba subsp paucijuga, which might still be found in Afghanistan, India and Pakistan.

That’s enough to be getting on with.

Olives, unlike many other species, were probably brought into cultivation repeatedly, largely by taking extra care of wild specimens that had good qualities. Perhaps these were propagated and planted in areas where they could be tended. Some were abandoned, or their fruits were allowed to go feral, as it were. Some deliberate hybridizations took place too, among wild, cultivated and feral parents. All of which makes unravelling the history of the olive fraught with difficulties. Given the olive’s economic importance, scores of studies have examined every aspect of its biology, but I don’t think I’ve ever seen a generally-accepted narrative of its past. Scholars are still hard at it, and among the more intriguing sources of data on the topic are the really ancient olives one sees around the place. In his journal, Vavilov noted that:

All of old Jerusalem is a complex museum, where each street and every house represents a page from the biblical history. In the garden of Gethsemane centuries old olive trees are still preserved.

Are they centuries old? An interesting section in a column in the Israeli newspaper Ha’aretz examines this and other fascinating aspects of genetic diversity in that country. I’m reprinting that relevant section in full here because I’ve had links from Ha’aretz break in the past.

A tree grows in Galilee by Ronit Vered

All the olive trees participating in this research project are endowed with old gray “eyes” encircled by time-engraved wrinkles, and powerful trunks sculpted in knots and gnarls. What have these eyes seen and how long have their “owners” existed? No one can say for sure.

People who live nearby and love them fiercely are convinced that these trees saw King Herod and Jesus wander these hills and watched as they dipped pita into the oil extracted from their fruit. Scientists, even the greatest romantics among them, are more reserved; the common wisdom is that olive trees cannot live more than 700 years. Their age is a tough riddle to crack: ancient roots develop new extensions and play havoc with chronological estimates, and the rings of the trunk cannot be counted without felling these sculptures wrought by nature.

A “toddler” of 700 or an old-timer of 2,000, the ancient olive tree next to Moshav Hadid, a cooperative village near Lod, is a spectacular embodiment of the spell cast by its kind on tillers of the soil, writers and painters alike. The ancient tree in the courtyard of Beit Jamal, a monastery near Beit Shemesh, is its equal in beauty and majesty, and there are other trees like them – in the Carmel hills, in Jerusalem’s Ein Karem, Beit Jala and Jenin.

In the past year, leaf samples have been taken from hundreds of ancient olive trees in Israel and the Palestinian territories for DNA testing, as well as samples of the fruit to examine the quantity and quality of the oil. The tests are being done as part of a new project dedicated to research and preservation of the ancient indigenous species of olive. These olives are not likely to be found in land tended by modern farmers, but still exist in older groves tended according to traditional methods.

This project is being conducted by the Agriculture Ministry’s Volcani Center, at Beit Dagan, with the participation of researchers from the Israel Plant Gene Bank, the Hebrew University of Jerusalem, the Palestinian Authority and Mainz University in Germany. Since the 1990s, various studies have demonstrated the healthful qualities of olive oil, global consumption of it has doubled and the prestige of the Mediterranean kitchen has soared. However, authorization to publish in the Israeli media a joint project related to olive trees was not forthcoming on the Palestinian side. Olive trees, as everyone knows, apparently do not bring hearts and minds together in the Middle East.

In any event, American journalist Mort Rosenblum declared olives have oiled the wheels of civilization, in his fascinating 1998 book “Olives: The Life and Lore of a Noble Fruit” (North Point Press), which tells the story of one of humanity’s most important fruits. Rosenblum chose to begin his worldwide odyssey of the olive tree and its fruit on the Mount of Olives in Jerusalem: This immediate area and the eastern Mediterranean basin in general are thought to be the sites of the olive tree’s domestication 6,000 years ago.

The ancient regal trees that can still be found in the hills of Galilee, Jerusalem and the northern West Bank, are a treasure trove not only of information about the past, but also of meaningful insight into the future. The gene pool of these trees – the product of natural selection of many thousands of years – attests to the traits they developed to adapt to the local habitat. If scientists succeed in isolating the genes responsible for these traits, they will be able to utilize them via a process of natural hybridization and thereby create improved new-old cultivars.

A study conducted in Israel in the mid-20th century documented 27 names of local olive species. More modern research, though, divides them into four main groups. Some traditional strains have disappeared over the years, and with them genetic information and the ability to identify them. Globalization and advanced agricultural techniques created a preference for new strains that provide higher output for farmers, among them Barnea and Ma’alot, developed by the Volcani Center, and for imported cultivars such as Picual (Spain) and Picholine (France) – sometimes at the expense of flavor and nutritional benefits. Traditional local species, embodying the long history of olive-tree cultivation in Palestine, have been neglected. Now the scientists are trying to turn back the wheel of history.

The olive tree is not the only indigenous flora that interests local researchers these days. Stored in dark rooms and at controlled temperatures of about minus-20 degrees Centigrade in the cellars of the Israel Plant Gene Bank (part of the Volcani Center’s Institute of Plant Sciences) are thousands of seeds of indigenous wild plants. The Israel Plant Gene Bank was founded three years ago, inspired by a global trend toward intensified research of indigenous flora, particularly plants used for food, industry and medicine, because they are crucial natural resources, which individual states must preserve.

An international charter to which Israel is a signatory seeks to right historical wrongs in this realm, on several fronts. It stipulates preserving biodiversity and genetic diversity in areas where open spaces are disappearing under swaths of concrete, and gathering and preserving information regarding traditional agricultural techniques dating back thousands of years, from developing countries plundered by Western states in the colonial and postcolonial eras.

In the meantime, lying in peaceful repose on their cold beds, are valuable seeds from basic edible plants and spices “born” in this region – among them wild wheat, oats, chickpeas, white mustard and black mustard. Dozing nearby in sealed jars are seeds of the Asteraceae family, rescued from damp habitats that face immediate danger of extinction, and also seeds of Salvia eigii from Mount Carmel, a rare plant which has almost disappeared. All of them await researchers and scientists who will decode their genetic information as part of projects like that involving olive trees and other studies currently under way in the gene bank – one on Eruca sativa, commonly known as arugula.

Basmati means many things to many people. Some translate it as the prosaic “full of aroma”. Others as the more fanciful “Mother of all Aroma” or “Queen of Fragrance”. But no matter how you render the word, which is Hindi, it is inseparably associated with India. India, however, is not the original source of fragrance in rice. And Basmati is not an Indica variety. A recently published study of The origin and evolution of fragrance in rice suggests that this highly valuable trait arose first in the Japonica group of rice, characterized by short, sticky grains, and later apparently found its way into the Indica group, with their longer, fluffier grains.

The origin of rice itself is still in dispute. Vavilov believed that its home lay in India, in the foothills of the Himalayas. For a while the fashion was for a dual, independent origin, Japonica in China or Japan, Indica in India. More recent studies, of archaeobotany and molecular evidence, suggest a single origin of the shattering gene — the crucial mutation that keeps the ripe grains attached to the stalk — in Japonica types in southeast China, passing into the Indica types as a result of pollen flow.

Sub-population structure in rice. Colour relates to the chloroplast type, and is not strictly relevant here.

A few words first about rice types (see pic above). Japonica and Indica (conventionally given an initial capital) are the two major varietal groups. Within them, five sub-groups have been identified on the basis of various measures; indica and aus, members of the Indica group, and then in the Japonica group tropical japonica, temperate japonica and the enigmatic Group V, which despite being a member of the Japonica group often has long, fluffy grains. Basmati types belong in Group V.

Fragrance itself had been linked to one of the rice chromosomes back in 1938, and more recently to mutations at a locus called BADH2. The mutant allele, known as bdh2.1 (lower case, because it is recessive) has an abnormally short BDH2 protein that doesn’t work properly; putting a working copy of the BDH2 allele (upper case, because it is dominant) into fragrant rice abolishes its fragrance.

Scientists from Cornell University and the International Rice Research Institute looked for the bdh2.1 allele in 176 samples of all types of cultivated rice that were genetically and geographically a very mixed bag. It was most common in Group V varieties (60% are aromatic), then in tropical japonica (15%) and then in indica (6%). No aus or temperate japonica varieties were aromatic. The researchers then sequenced the DNA of an even larger panel of 242 samples. They were looking for patterns called haplotypes. In the process of sexual reproduction, DNA from the two parents is swapped around, and the block that is exchanged can encompass several genes and DNA markers. If two varieties, for example, share a common haplotype around a gene of interest, then it is likely that they inherited the gene from a common ancestor fairly recently, because the haplotype has not been broken up in the meantime.

Looking at the DNA immediately on either side of the BDH2 locus, there were two types of haplotype pattern. Three patterns were characteristic of all Japonica varieties. Five others were characteristic of Indica varieties. But, every single fragrant variety had one of the Japonica haplotypes, regardless of which sub-group it came from. That suggests “a single origin of the badh2.1 allele in a Japonica-like genetic background”. It also creates a conflict between the mass of data, which place fragrant Jasmine varieties in the Indica group, and the BDH2 haplotypes, which say it is a Japonica. The team widened their area of interest to include a larger stretch of DNA on either side of the BDH2 locus. The same pattern emerged. In all fragrant varieties the bdh2.1 allele was surrounded by Japonica DNA.

The likeliest explanation is that the fragrant allele arose in a Japonica ancestor some time after the split between temperate japonica (no fragrant types) and tropical japonica and Group V, and then as a result of pollen flow made its way into some indica types, where it was strongly selected because it was so desirable. Possibly the mutation arose in a Group V ancestor and then spread in the same way to tropical japonica and indica types. Group V and Indica varieties overlap geographically across South Asia to a considerable extent, which would have provided the conditions needed for the Japonica DNA flanking the BDH2 locus to make its way into Indica rice.

There is a great deal more of interest in the paper, including other BDH2 alleles besides bdh2.1 that confer fragrance, and a couple of samples that are fragrant but that do not have a bdh2 allele. And there’s a paradox that the authors clearly identify as important:

It is noteworthy that despite the apparent importance of hybridization and gene flow during rice evolution, opposing forces have maintained the genetic divergence among the subpopulations of O. sativa. Solving this paradox will require future research to identify the key factors that contribute to subpopulation isolation, as well as to provide insight into the dynamics of genetic exchange among these groups.

I wonder whether any of the rice accessions collected by Vavilov on his journeys through Asia will contribute to our future understanding of rice domestication and evolution.

As with pigs, Vavilov speculated that chickens might have been domesticated independently in the Near East and in southeast Asia. That seems wide of the mark. The best evidence to date suggests that red jungle fowl (Gallus gallus) in a small area of Thailand were the ancestors of all modern chickens, with a bit of input from the grey junglefowl (G. sonneratii) thrown in for good measure, and a yellow skin.

A bigger flap concerns the chickens of South America, and in particular the question whether they arrived from east or west. The conventional view is that the chicken is a post-Columbian bird in the Americas. Some scholars, however, argued that old breeds of Chile — for example the Araucana, with their blue-green eggs, and the Passion Fowl — spring from Asian birds that arrived across the Pacific from Polynesia.

Once again, scientists turned to DNA for answers. They found that native Chilean birds had DNA that put them firmly with the birds of Europe and India. Furthermore, they said that an “apparently pre-Columbian” specimen from Chile and pre-European specimens from Polynesia shared the same background with European and Indian birds.

The proponents of the pre-Columbian chickens fought back. “We present additional data supporting the interpretation of Storey et al. showing that evidence for pre-Columbian chickens at the site of El Arenal, Chile, is secure.”

To which the first bunch replied that the pre-Columbians “concede that there is no direct genetic support for Polynesian–South American contact. However, they claim that linguistic, archaeological, and ethnohistoric evidence supports Polynesia as the most likely source of the El Arenal-1 chickens. We disagree on two grounds.”

It is clear, however, that some chickens from Easter Island are not European, share their ancestry with chickens “from Indonesia, Japan, and China and may represent a genetic signature of an early Polynesian dispersal”.

Science marches forward.

Vavilov wrote of the need to “reveal the genius of the people and to tear down the Chinese wall of isolation”. The Western scholar who best came to embody that idea was Joseph Needham, with his massive project Science and Civilisation in China. The volume on Agriculture, published in 1984, contains much on kaoliang, extracted below.

Cultivated sorghum (S. bicolor or Andropogon sorghum) is an African domesticate. Archaeological evidence suggests that it reached India soon after -2000, but the date of its introduction to China remains uncertain. Remains of sorghum have been reported from several neolithic, Chou and Han sites in North China, but their identification as sorghum is not universally accepted, and possible references in early texts are far from unambiguous.

Chinese sorghum is nowadays generally referred to as kao liang, literally ‘tall millet’; this name appears for the first time in the Wang Chen Nung Shu of +1313, but the plant was more commonly known in pre-modern times as shu shu, ‘Szechwan millet’ (Fig. 220), a name still in common use today in the South and West of China. The term shu shu first appears in the +3rd-century Po Wu Chih, which reads: “If a field is planted with shu shu for three years, then for seven years after there will be many snakes (ti san nien chung shu shu, chhi hou chhi nien to she)”. But even if the text is authentic (the Po Wu Chih has long since been lost except in quotation, and is full of later interpolations), the identification of shu shu with sorghum is not certain. The Chhi Min Yao Shu, in its section on exotic plants, quotes the late +3rd-century Kuang Chih which refers to a cereal called ta ho, ‘great millet’, introduced to China from Su-the-kuo (probably Sogdiana), over ten feet tall and with seeds like mung beans, as well as to a cereal called ‘willow millet’ (yang ho), as tall as rushes, which it says was the same as the ‘Szechwan millet’ (pa ho) or ‘tree millet’ (moo chi) of the Central States. These plants do sound similar to kaoliang, which is characterised by its tall stems ten feet high, huge panicles and comparatively large seeds. In Wang Chen’s description of shu shu, written in 1313, which definitely refers to sorghum, he says: “the stalks are over ten feet high and have panicles as large as a broom. The grain is black as lacquer and like frogs’ eyes.” Sorghum was known in both India and the Arab world well before its introduction to China, and coming from either place Szechwan would be a likely point of entry; the name shu shu means ‘Szechwan millet’, as does the term pa ho given in the Kuang Chih, which adds some weight to Wang Yü-Hu’s proposal that yang ho and pa ho be identified with sorghum. Even Hagerty, who doubts any introduction of sorghum into China proper before the Southern Sung, concedes that it may have been known in parts of Szechwan at a much earlier period.

Hagerty says that the earliest unambiguous references to sorghum are to be found in the Yuan texts, though he believes on linguistic grounds that the grain may have been introduced into Northern China during the Southern Sung, while Ping-Ti Ho says that the first unmistakable botanical description is given in the +1175 edition of the Hsi-An Chih, the history of Hui-Chou prefecture in Southern Anhui written by the famous natural historian Lo Yuan. On the other hand, both Amano and Wang Yü-Hu refer to a Northern Sung text, the Pei Meng So Yen, which describes the general Chu Wen on campaign in North China in c. +910, coming with his troops to a deep channel. They thought that their way forward was barred until they saw that shu shu stems had been piled up in the channel to make a passage (hu chien kou nei shu shu kan chi i wei tao), which Chu and his troops were able to cross on horseback. The shu shu in this passage almost certainly refers to kaoliang, the stems of which were often used for such purposes, and Wang deduces that kaoliang was already cultivated in North China in the early +10th century. A still earlier introduction into China or its border regions is suggested by the fact that the kaoliangs are morphologically related to Sorghum bicolor, the most primitive and least specialised of the early major races of sorghum, and appear to represent a Chinese variant of some early bicolor race.

Be that as it may, whenever sorghum was introduced into China proper, we can say for certain that it was reasonably familiar to Yuan and Ming writers. Wang Chen describes its uses as follows:

The grain can be hulled and eaten, and anything left over fed to livestock. It is a famine food. The tips of the stems can be made into brooms and the straw woven into trays, plaited to make fences or used to provide fuel No part of the plant need be thrown away.

However, we have already seen that Wang Chen described the grain as being ‘black as lacquer’, and in modern China the dark varieties of sorghum, red, brown or black, are considered too bitter for human consumption and are used only for fodder. White and Yellow sorghum, on the other hand, are considered reasonably palatable and sweet. Although sorghum is mentioned in the Wang Chen Nung Shu, Nung Cheng Chhuan Shu and other post-Yuan treatises, it is not until 1760 that the San Nung Chi, a Szechwanese work, gives a detailed account of its cultivation techniques, which are generally very similar to those of millets, and one suspects that sorghum occupied only a very small fraction of the cultivated area until population pressure mounled n the 18th and 19th centuries. Sorghum gives good yields on poor soils and was therefore usually grown on land not suitable for wheat and millet. Hsü Kuang-Chhi remarked on its flood-resistant qualities and its suitability for low-lying land, saying that once autumn had begun, even if the water rose in the fields to a height of ten feet the crop remained undamaged. Sorghum is therefore an ideal crop for marginal land, providing a coarse but edible staple as well as abundant supplies of straw for fodder, fuel and handicrafts. The grain can also be used to distil wine and a fierce spirit, and Wagner claims that up in 90% of the kaoliang crop was used for this purpose in Yunnan and Szechwan. Grain yields are comparable to those of Chinese millets, in the region of 800 to 1000 kg/ha, though the early 18th-century Nung Tshan Ching claimed yields of 2 shih/mu, equivalent to approximately 1900 kg/ha, but the yields of straw are double those of millet, varying from 1500 to 3000 kg/ha, a very important consideration in impoverished areas.
It seems probable, then, that sorghum was a relatively uncommon crop in China in the Yuan and Ming, but that as population pressure mounted during the Chhing it came to occupy an increasingly large proportion of the cultivated area. Not only could it be used to reclaim areas of marginal land too poor for millets or wheat, but eventually it even replaced millet in many areas, for although it was less esteemed as food, its straw was more abundant and extremely valuable; Wu Chhi-Chün was already deploring the replacement of millet by kaoliang in the Northwestern provinces in the mid-19th century. Kaoliang was cultivated principally in the Northeastern provinces, where marshy areas were common and the climate was less severe than in the Northwest; there millets could best withstand the aridity and low temperatures. Even so, when Buck   carried out his agricultural surveys in the 1920s and 1930s, kaoliang occupied only 4.7% of the cultivated area of China, whereas 9.4% was planted with millet. In recent years, particularly in the period 1960-76, kaoliang has replaced traditional Chinese millets in large areas of North China, presumably as a result of policies emphasising the expansion of rice cultivation for human consumption and that of kaoliangs and maize for animal fodder, but already there is a visible tendency to revert to the cultivation of millet, which the Northern Chinese much prefer as food to kaoliang.
That sets Vavilov straight. Kaoliang is not a millet, at least not taxonomically. But with the recent publication of the full sorghum DNA sequence, is it too much to hope that a definitive family tree for the economically important sorghums of the world will soon emerge?

Vavilov was correct when he said that pigs were independently domesticated in China and in the Near East. But the real story is even more complicated than that. In Vavilov’s day, the idea was that pigs had been domesticated from wild boar in the Near East and then carried with them by Neolithic farmers as they spread westwards across Europe. Then a study of DNA from nearly 700 pigs, ancient and modern, wild and domesticated, put paid to that idea. Instead of farm pigs beings most closely related to one another, as one might expect if they were descended from a single domestication (or two, allowing for a distinct event in China) the farm pigs were most closely related to the wild boar of the surrounding area.

As Keith Dobney, one of the study leaders, commented in 2005:

Our study shows that domestication also occurred independently in central Europe, Italy, Northern India, South East Asia and maybe even Island South East Asia. The spread of farming into these areas during the Neolithic seems to have kick-started local independent domestication of wild boar.

However, later work by the same group of scientists complicated the picture still further. Looking at 545 samples of pig and boar specimens from across western Eurasia showed that domesticated pigs from the Near East were definitely present in Europe, and had reached Paris by about 6000 years ago. Local boar too had been domesticated by this time, possibly encouraged by imitation. Those local domesticates then quickly replaced the breeds from the Near East, perhaps because they were already adapted to local conditions.

The net result is that, at least before the global spread of industrial super-pigs, surviving breeds of local pigs trace their ancestry to wild boar in the same region, not just in China and the Near East, but in five other centres too.

I like to think Vavilov would be thrilled at the new insights being provided by the marriage of molecular biology and archaeology.

Vavilov, in his travels through Japan and India, mentions two different plants that are eaten only when infected, or diseased. One is Zizania latifolia (Chinese wild rice) which, he says, is “grown for its diseased, inflated leaf sheaths”. The other is one of the arrowhead species, Sagittaria trifolia, “grown for its diseased, globular rhizomes”. This triggered a memory, which I’ll get to, of the importance of diseases in the domestication of crops, but first I thought I would try to find out more.

Of diseased Sagittaria, there is almost nothing on the internet. I myself used to grow S. latifolia, known to some of the indigenous people of North America as wapato. Disease was never an issue in getting a good harvest.

Food Plants of China, by Shiu-Ying Hu, has some information about Zizania. Gu-hei-sui-jun consists of the enlarged young stems of a swamp grass infected by the fungus Ustilago esculenta, which he calls Zizania smut. “The crop is harvested just before the sporification of the pathogene. A slight sign of black threads visible at the broken surface brings the price down. Before cooking, the shoot must be peeled.” Hu also says that while the diseased plant is harvested from the wild in Jiangsu, it is cultivated in paddies in Sichuan. “In cultivation, the plants seldom flower; the cucumber-like infested shoot harvested before any black vein appears, used as a delicacy.” Hu adds, “the taste and texture is reminiscent of mushroom and bamboo shoot”. Grass and fungus; not surprising, really.

Corn smut

Corn smut, or huitlacoche, is absolutely delicious, the basis of some very interesting Mexican recipes even today, and a great reason to cultivate Teosinte. And if you were cultivating Teosinte, how much easier it would have been to see the single plant that had big, accessible grains on its malformed mutant ears.

Flickr photo by Zampano, used with permission.