Where Did Watermelon Originate? Genetics Answers Age-old Mystery

Ancient Egyptian tombs show people believed to be eating watermelon, or its predecessor, for dessert. That's a clue

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The traditional Israeli beach snack of watermelon with feta cheese.
The traditional Israeli beach snack of watermelon with feta cheese.Credit: Tomer Appelbaum
Ruth Schuster
Ruth Schuster

Where did the watermelon come from? Inquiring minds want to know, and now maybe they do.

We did know that millet was domesticated in ancient China, and barley, oats and wheat in Mesopotamia or thereabouts. The goat and sheep were also brought into our fold in the Middle and Near East, too. But the watermelon?

When or where we started to farm watermelon is entirely unclear. But archaeologists suspect certain images in Nile Valley tombs dating to about 4,360 years ago were exactly this fruit – or rather, its predecessor. It was eaten as a dessert, the team writes. The ancient pictures of the putative watermelon are a key pointer.

Competing hypotheses for the feral fruit’s origin ranged all over Africa – including the northeast, the Sahel savannas. And now a team, publishing in PNAS, believes it has the answer.

It is helpful in this context to know that we were hunter-gatherers until very recently. The Neolithic agricultural revolution was evidently a protracted, irregular affair, not a linear progression. The earliest stabs may have been as early as 23,000 years ago in the Galilee, but starting to “properly” settle down and growing stuff more regularly seems to have been around 12,000 years ago. And early farmers also sustained the family with hunting and gathering. It isn’t that there was a eureka moment from which time we settled down, grew crops and hassled herbivores, sometimes with the help of the dogs that actually may have been domesticated way earlier.

As for the watermelon’s mysterious domestication, the detective work into the fruit’s past was based on the iconography but, crucially, also on genomic information on the various members of the Citrullus family. The goal: To find the closest relative of the domestic watermelon, Citrullus lanatus, subspecies vulgaris.

And the genetic studies pointed at the Sudanese Kordofan melon as the closest relative of the domesticated watermelon. It could be the fruit from which the watermelon we know today descended. Or not; we can’t be sure, but it’s the leading candidate at this point.

The Kordofan melon has a whitish pulp but despite the propensity of the family’s feral fruits to be bitter, it isn’t.

The Sudanese Kordofan melon.Credit: Shan Wu
An Israeli ad for the "Hebrew" watermelon (but only where you saw that particular sign). Credit: GPO

The feral watermelon

What difference does it make if we know or don’t know the origin of a given food? The original species could be an important resource for future watermelon breeding programs, for instance – and yes, they exist. “Identifying them, however, is difficult because of extinction, hybridization and the challenge of distinguishing them from feral forms,” explain Prof. Susanne Renner of the University of Munich and colleagues.

“Our analyses imply that early farmers brought into cultivation already non-bitter watermelons, different from other domesticated Cucurbitaceae crops such as cucumber,” the team writes.

In Israel, the watermelon is beloved and popular, but hardly a staple. In central Asia, however, it’s one of the 10 most important crops, the team explains.

Genetic diversity is an excellent thing. It gives the creature – from cockroach to chimp to banana, more options to potentially survive change in different conditions.

We mention the banana purposely. The yellow fruit beloved and sold the world wide consists almost entirely of the Cavendish variety, which is under near-worldwide attack by a pernicious fungus that could even doom it to extinction – as it did the Cavendish’s predecessor, the Gros Michel. The rub is, the world is farming Cavendish clones, not a wide range of bananas, some of which might resist the disease (which is called Fusarium wilt). In April, Bloomberg reported on the fear in the world’s biggest banana exporter, Ecuador, as its neighbor Peru faces an outbreak of the deadly disease (to the bananas, not the eaters).

Beachgoers enjoying watermelon in the sea, in Israel.Credit: Tomer Appelbaum

You can grow watermelons from cuttings, but the point of knowing the fruit’s origin is to expand the options for breeding hardy stock. The researchers note that the Kordofan and watermelon are both non-bitter, and add that both the sweetness typical of the fruit today, and its pink color, ensued thanks to breeding for these traits.

You can even obtain watermelon with yellow flesh inside. It lacks lycopene (that gives the red hue – yes, the same compound as in tomatoes) but is richer in beta-carotene, which is cool. Some might feel it’s unnatural, even creepy. Well, the yellow watermelon preceded the pink one and if anything, according to FarmFlavor, the yellow one may be sweeter in flavor.

Do not adjust your screen: this watermelon is yellow.Credit: Dudu Magal

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