Watermelon is off the menu for me. Just a couple of bites and I am in the emergency room with anaphylactic shock. That being said, I hear wonderful things about the fruit. As a science journalist I also hear lots of bad news about the future of watermelons. The crux of the problem is that melons are facing a host of new diseases and pests as the climate warms and may soon go extinct. Fortunately, a team of researchers have just identified help for the watermelon by studying ancient Egyptian art.
Already a sweet success.
Image courtesy of Dr Lise Manniche.
The researchers behind this work started by engaged in an extensive genetic analysis of domesticated watermelons from around the world and compared what they found to the genetics that they obtained from six other melon species. They also had historians on their team who examined ancient artistic depictions of melons (we're talking about stuff like Egyptian art) to try and understand when the fruit's flesh became red, when it gained its iconic green stripes and when it developed a sweet flavour.
All of this work revealed that the Sudanese Kordofan melon, which has whitish pulp and does not taste terrible*, is the closest relative of the modern watermelon and is likely the precursor of all domesticated watermelons. The researchers think that early farmers likely cultivated variants of this melon and that it obtained its sweet flavour and reddish colour over time. As for when the watermelon actually became sweet, the team identified illustrations from two Egyptian tomb paintings dating to around 4,450 years ago portraying oblong fruit with dark green stripes on trays and tables with other sweet foods like grapes, suggesting that watermelon as we know it, had come to be by that time.
While this might all sound rather academic, it is not. The watermelon of today has been extensively bred to be sweet and easy to grow. All of the genes that the plant once had for fighting off diseases and insects of days long ago have been lost. It is for this reason that identifying the Kordofan melon as the wild relative of the watermelons is such a big win for botanists looking for disease and pest resistant genes that can be brought into this crop to keep it healthy as the planet goes to hell. You can read more in The Economist article that I wrote on this here.
*Yeah, I know that isn’t selling much but most wild melons need to be boiled with sugar to be edible. The Kordofan can at least be eaten raw.