The poet Pablo Neruda almost ran out of metaphors singing to the watermelon: “The green whale of summer”, the “chest of water”, “the freshest of all planets”, “the fruit of the tree of thirst”. A slice of watermelon can also be viewed as a page from a history book. The name of the fruit is a derivative of the Arabic sindiyyah, which means “from Sind”, the region of Pakistan from which the plant was supposed to come, as recorded in Dictionary of the Royal Spanish Academy. But it is a red herring. New research suggests a much older and more convoluted history, spanning the Egypt of the pharaohs and dating back to the Nubian farmers who inhabited present-day Sudan more than four millennia ago.
The German botany team Susanne Renner trace the origin of the watermelon as European explorers searched for the source of the River Nile four centuries ago. Renner and his colleagues analyze the oldest historical traces of the fruit: two drawings from Ancient Egypt that suggest that Egyptians already ate watermelon 4,360 years ago. They are illustrations – found in the tombs of powerful figures in the Saqqara and Mair necropolis – that show a kind of elongated watermelons served on trays. A third drawing, found in the kamara papyrus, about 3,000 years old, includes what looks like a small, spherical, striped watermelon on a table. Renner’s group believes it is a Kordofan melon, an ancestral variety that is still grown in Darfur, a war-torn region of western Sudan for nearly two decades. The Kordofan melon is the main suspect of being the dad of modern watermelons.
Renner, former director of the Munich Botanical Garden, argues that the Nubians, protagonists of one of the oldest civilizations of the world, they domesticated the watermelon in the Darfur region and this crop was transmitted northwards, until reaching Egypt. Watermelons, both the sweet variety and a more bitter South African species, reached the Iberian Peninsula already in Roman times, continues the expert, who has just joined Washington University in San Luis (USA). “There is a recipe in Latin from the fourth century to make jam with the South African species,” explains Renner.
The researcher imagines the journey of watermelons around the world, starting from their possible origin in present-day Sudan. “It is known that they arrived in North America shortly after Christopher Columbus’ trip in 1492 and to Brazil because of the slave trade,” he says. The caravans of merchants on the Silk Road would bring sweet watermelons to Asia in Roman or medieval times, the researcher adds. Renner’s team has tried to grow Kordofan melons in the Munich Botanical Garden, unsuccessfully. The botanist, born in the German city of Tübingen 66 years ago, is planning a trip to Khartoum, the Sudanese capital, to try to taste a slice of the alleged father of watermelon.
Renner and his colleagues’ research has not been limited to Egyptian paintings. The team has carried out a genetic analysis of several types of modern watermelons and the Kordofan melon, which has white flesh but not bitter, unlike its relative the cucumber. The scientists’ results, published this Monday in the magazine PNAS, show that the watermelon was gaining red color and sweet flavor throughout the domestication process.
The French Biologist Guillaume Chomicki, co-author of the research, stresses that the Kordofan melon is genetically more resistant to pests than modern watermelons. “These genes have been lost throughout domestication. This means that the Kordofan melon genome could potentially be used to develop disease-resistant watermelons, ”says Chomicki from the University of Sheffield (UK). The researchers propose the use of the revolutionary CRISPR gene editing technique, winner of the Nobel Prize in Chemistry in 2020.
Chomicki, 30, remembers that watermelons suffer from a multitude of pests and diseases, especially fungi and viruses. Farmers use, in addition to fungicides, insecticides to prevent bugs from carrying viruses from one plant to another. Watermelons genetically modified to mimic the resistance of the Kordofan melon “could significantly reduce the use of pesticides,” says Chomicki. China, with 61 million tons per year, is by far the world’s largest watermelon producer, well ahead of Turkey (3.8 million), India (2.5 million) and Brazil (2.3 million). Spain is the fourteenth largest producer, with 1.2 million tons, according to the statistics of the United Nations.
Andalusia grows half of the Spanish watermelons. Biologist Natalia Gutierrez, from the Andalusian Institute for Agricultural, Fisheries, Food and Ecological Production Research and Training (IFAPA), has worked on the development of new varieties of the plant. The specialist applauds the new study, in which she has not participated. “The use in improvement of crosses with wild varieties helps to introgress [introducir] genes of agronomic interest to the cultivated varieties and in this way make them more resistant ”, he explains.
The agronomist Oscar Alejandro Perez, born in Bogotá (Colombia) 32 years ago, has participated in the new genomic analyzes of the different varieties of watermelon. “There is a tendency to think that species are like units with their own identity, but both the Kordofan melon and the red-fleshed watermelon that we consume today have part of their shared genes, they are linked over time,” explains Pérez, from Kew Royal Botanic Gardens, founded in 1759 on the outskirts of London.
Two years ago, the same team published an analysis draft DNA from a watermelon leaf supposedly found in the 19th century inside a 3,500-year-old sarcophagus near the Egyptian city of Luxor. The authors they then proclaimed that that leaf showed that there were already red and sweet watermelons in that period, the New Kingdom of Egypt. Guillaume Chomicki now admits that they were wrong. “When we did the draft, we had not yet dated the blade with carbon-14. We made them and we realized that the leaf was not 3,500 years old, but dated 1871, the year it arrived in the herbarium of the Royal Botanic Gardens of Kew ”, details the French biologist. The team has now found two 3,100 and 6,000-year-old watermelon seeds in Kew’s old botanical collections. His future analysis will continue to reveal the journey through the world of “the round, supreme and heavenly watermelon”, according to the verses de Neruda.
Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.