Picture a large bowl of fruit salad. What’s in it? You may be imagining apples, oranges, bananas, pears, melons, grapes, peaches, cherries, mangoes, or kiwifruits. What makes these things fruits, anyway? A fruit is simply the part of a plant that holds the seeds. The ripened ovary. Many other foods are botanically fruits, but we eat them “as vegetables” in savory rather than sweet dishes. Try to think of some of those. You might come up with tomatoes, peppers, green beans, avocados, or squashes. Now, if you’re like me, you’ll notice a couple of things when examining the two lists we’ve made. First, your mouth is watering. Second, everything on the first list comes from the Old World, and everything on the second list comes from the New World. Why on Earth would that be?

I realize there are exceptions to this pattern. Pineapples are South American, for example, and cucumbers originated in India. But I think there’s a general trend here. The fruits we eat from Eurasia and Africa are usually sweeter than the fruits we eat from the Americas. There are a few possible explanations. I don’t know for sure which are true, and I’m no historian. But we can evaluate the evidence. And the exceptions will be useful in these evaluations.

You might guess that early Native American horticulturalists had less of a craving for sweet foods than peoples elsewhere. Such an idea is not totally implausible: taste receptor genes do differ somewhat among human populations. But I know of no evidence that sweet teeth vary geographically. In any case, Pre-Columbian farmers did cultivate other plant parts for their sugar content, like agave, jicama, and yacón.

A second hypothesis is that the flora of different continents show innate differences. There is some validity to this. Tomatoes and peppers are from the same family, the nightshades, which occur worldwide but show the greatest diversity of species in the Americas. Intriguingly, eggplants are also in this family and are another exception to the general rule, coming as they do from Asia. If nightshades are just inherently less sweet, that alone could have skewed Mesoamerican cuisine options. But for the most part, ancient peoples everywhere would have had a similar cornucopia of plants to domesticate. Species of apple, grape, raspberry, cherry, plum, and strawberry occur on both sides of the Atlantic. As Jared Diamond argues in Guns, Germs, and Steel (the “Apples or Indians” chapter), there was nothing fundamentally different about either the fruits or the peoples of ancient America, relative to their Eurasian counterparts. Rather, it was the complete ecological package of available plants and animals that determined which folks adopted intensive agriculture. Diamond’s logic implies that scrawny North American crabapples have the potential to become fat, juicy pie-filling along the lines of Honeycrisps. But no one bothered to breed them that way because the local humans weren’t in the orchard business.

The strawberries are an instructive case, and are the plant I know the best from my own research. First of all, they’re not even really fruit. The little yellow things on the outside that you call the seeds are actually the fruits. But we’ll lump the “berries” in with the culinary fruits for now. Wild strawberries occur across the whole Northern Hemisphere, and also dip south in places. For millennia, they have been plucked and gobbled wherever they are found. But the cultivated strawberry sold in stores is an artificial hybrid. It was produced in France in the 1700s from two American species. So is it Old World or New World? It’s both. It’s roots stretch from Canada to Chile, but the fact that we eat strawberries the size of your thumb, not your thumbnail, is a debt we owe to the French. Other fruits have similar stories. Commercial raspberries and Concord grapes, for example, are hybrids between American and European species.

So part of the answer is that Eurasians were apparently more inclined to breed plant ovaries into highly sugary forms. Perhaps such a goal required a stratified society, with a stable upper class whose nutritional needs were secure enough that they could focus on dessert. This seems especially true for fruits that grow on trees, which require years of forethought and oversight. Life didn’t just give us lemons, despite the aphorism. They’re another artificial hybrid. When life gives you wild citrus, thought some ancient Asian aristocrats, make lemons.

Another part of the answer is that, even here in the cosmopolitan United States, we don’t treat all foods equally. We focus on particular favorites, and not always for pragmatic reasons. Again, I’m no historian, nor a psychologist, but I suspect sweet fruit might have special cultural meaning. For foods that are traditionally extravagances, or signifiers of sophistication, we take our cues from Europe. Fruits even pervade our morality parables – think Eve, or the fox and the grapes. It’s also not lost on me that the US produce industry was built by exploiting the Hispanic descendants of this continent’s first farmers. Exactly how connotations of race and social class may have influenced white shoppers is hard to say. But plenty of Western Hemisphere native fruits popular in Latin America, like papayas or prickly pears, have simply never featured heavily in the diets of gringo WASPs. Meanwhile, indigenous US regional treats like pawpaws or salmonberries are seen as chow for hicks or Indians. Thus, these species rarely achieve large-scale production, with the exceptions of blueberries and cranberries. Conversely, there are many varieties of (Old World) banana, some of which, like plantains, are starchy and eaten more like vegetables. But in temperate North America, “banana” means one particular fructose-rich cultivar.

The reasons behind your fruit salad ingredients are more cultural than botanical. You may think you’re freely sampling nature’s wild bounties, but they don’t just occur naturally. And your bowl is still missing a lot of untapped crop diversity. I mean this two ways. First, folks are already eating a lot of delicious things that may be off your radar. If you’ve never tasted soursop, guava, or passionfruit -all three syrupy and South American- I recommend them. Second, humanity’s grand domestication experiment isn’t over. Fruits that we normally don’t even think of as fruits could be bred to be larger, juicier, and sweeter. Maybe even inedible fruits, like the osage orange native to Texas, could be turned into delicacies. You may have heard the adage, “Knowledge is knowing a tomato is a fruit. Wisdom is not putting a tomato in your fruit salad.” I would add that gratitude is recognizing how everything in your fruit salad is only there because someone chose to breed it for sweetness. And ingenuity is asking what it would it take to turn a tomato into another tasty addition.