Look in the bottom right corner of this painting. If you've never seen a watermelon like that before, you're not alone. This 17th-century painting by Giovanni Stanchi, courtesy of Christie's, shows a type of watermelon that no one in the modern world has seen.

Stanchi's watermelon, which was painted sometime between 1645 and 1672, offers a glimpse of a time before breeding changed the fruit forever.

James Nienhuis, a horticulture professor at the University of Wisconsin, uses the Stanchi painting in his classes to teach about the history of crop breeding.

"It's fun to go to art museums and see the still-life pictures, and see what our vegetables looked like 500 years ago," he told me. In many cases, it's our only chance to peer into the past, since we can't preserve vegetables for hundreds of years.

The watermelon originally came from Africa, but after domestication it thrived in hot climates in the Middle East and southern Europe. It probably became common in European gardens and markets around 1600. Old watermelons, like the one in Stanchi's picture, likely tasted pretty good — Nienhuis thinks the sugar content would have been reasonably high, since the melons were eaten fresh and occasionally fermented into wine. But they still looked a lot different.

That's because over time, we've bred watermelons to have the bright red color we recognize today. That fleshy interior is actually the watermelon's placenta, which holds the seeds. Before it was fully domesticated, that placenta lacked the high amounts of lycopene that give it the red color. Through hundreds of years of domestication, we've modified smaller watermelons with a white interior into the larger, lycopene-loaded versions we know today.

Of course, we haven't only changed the color of watermelon. Lately, we've also been experimenting with getting rid of the seeds — which Nienhuis reluctantly calls "the logical progression in domestication." Future generations will at least have photographs to understand what watermelons with seeds looked like. But to see the small, white watermelons of the past, they too will have to look at Renaissance art.

Update: No, it isn't just unripe or underwatered

Since this article was first published, people have responded on Reddit and other social networks with a couple of questions: Couldn't this just be an unripe or underwatered watermelon? Or is it one with hollow heart, which can look similar? The pictures readers submit look pretty convincing:

To check, I contacted professor Todd Wehner, a professor at North Carolina State University who studies watermelon breeding.

At first glance, the photos look a lot like the painting. But the Stanchi painting gives us a clue with its black seeds, which Wehner says indicate the melon was ripe:

"In the painting, the black seeds indicate that the fruit has reached maturity," Wehner says. "If they had waited longer for harvest, the fruit would have continued to break down, the flesh would have gotten softer and stringier, and the sweetness and redness would not have improved much." A melon that wasn't ripe wouldn't have those black seeds.

"Museum paintings are an interesting method for studying old cultivars [varieties], and the one you indicated certainly shows the sort of watermelons that Europeans had to eat in the Middle Ages during their summer harvest season," Wehner says. "We have cultivars like that one in the painting available to us now from our germplasm collections [a sort of genetic sample library that includes many different varieties]."

He notes that those samples, when grown today, have "large white areas, low sugar content, [and] frequent hollow heart." Hollow heart can cause a starring appearance somewhat similar to an unripe or underwatered melon.

Curiously, readers also noted some paintings from the same time period of normal-looking watermelons, including Brueghel's "Still Life of Fruit and Flowers." However, the diversity of watermelons available doesn't disprove that uncultivated watermelons, like the ones in Stanchi's painting, were significantly different from the ones we consume today. Brueghel's watermelon may have been all red — but Stanchi's ripe watermelon was considered worthy of being painted as well. Over time, breeding helped us define the ideal watermelon.

And that process of breeding continues today. It was only over a long history of cultivation that a normal watermelon came to look less like Stanchi's and more like Brueghel's.

Read more: Here's what 9,000 years of breeding have done to corn, peaches, and other crops