Jay Gatsby famously says in The Great Gatsby “Can’t repeat the past? Why of course you can!” He’s a larger than life character in a novel, of course, and (of course) he’s wrong anyway. But in good times or bad, most people would turn back the clock if they could. The past often shines more brightly than the future; it’s fixed and known, and though we can’t relive it, we look for reassurance in connections with it.
These connections take many forms. Some people find them in genealogy, some through country dancing, Civil War reenactments, or whatever. I have friends who grow heirloom tomatoes, in part (I believe), to find this connection with the past. They say that heirloom tomatoes have unique qualities (and histories) not found in “modern” tomatoes and that they taste so much better than the grocery store ones. All true, I suppose; I have grown heirloom tomatoes myself, and almost anything that you grow in your own backyard tastes better than what you buy at the grocery store.
Heirloom crops, tomatoes in particular, are very popular. Seed Savers Exchange offers 4713 varieties of tomato heirlooms alone. So called “heirlooms” are traditional varieties or landraces that were originally selected, grown and passed down within families or local regions. There are literally thousands upon thousands of heirloom tomatoes that are largely unique and distinct from one another from around the world.
Tomato was probably domesticated in Mexico from wild Peruvian stock with fruit similar to what we think of as “cherry” tomato. The first record of cultivated tomato comes from the Spanish who found it consumed at the time of the conquest of Mexico in the early 16th century in a limited area from Central America north to Mexico City. When tomato came into cultivation is unknown, but large fruit types had already developed by the time the Spanish appeared in Mexico and possibly before domestication.
The cultivated tomato (Solanum lycopersicum L.) is a member of the Solanaceae family. Solanaceae contains around 3000 species of both the Old and New World origin, many agriculturally important; worth mentioning are eggplant, from China, and tomato, potato, and pepper, from Central and South America. All wild tomatoes, with the exception of one species found on the Galapagos Islands, are native to mainland South America in a region of the Andes that includes parts of Colombia, Ecuador, Peru, Chile and Bolivia.
All forms of cultivated tomato are self-fertile and exclusively inbreeders—barring human intervention or other extraordinary circumstances, individual tomato flowers do not cross pollinate each other. Wild tomato species, in contrast, are both self-fertile and self-infertile. With human aid, most of the wild species (thirteen or seventeen, depending on the classification scheme) can interbreed with cultivated tomato.
Domestication of tomato was brought about by inbreeding and intensive selection for desirable traits, in both Mexico and Europe, but this imposed genetic uniformity on cultivated tomato. And if, indeed, the large-fruit types arose before domestication, those large-fruit plants would certainly have been chosen as the progenitor of cultivated tomato. When these plants, which would have been few and possibly genetically identical, were taken from the Andes to Mexico and then to Europe, tomato was isolated from its source of genetic diversity and what evolutionary biologists call a “genetic bottleneck” resulted. Despite the obvious variety in fruit shape and size, flavor, local adaptation, color and aroma, traditional cultivated tomatoes are genetically impoverished with less than 5% of the genetic potential of their wild cousin. Different varietal names may have been applied to genetically very similar lines. Thus, the proliferation and increase in number of heirlooms over time. The variation that exists in these heirloom tomatoes today is mostly the result of rare spontaneously occurring mutations, such as those that induced the large-fruit types.
Tomato was brought back to Europe by the Spanish and was first consumed in Spain and southern Italy in the mid 16th century (this we know from tomato recipes and shopping lists). By the end of that century, tomato had spread to most of the rest of the Mediterranean region and England and much of the rest of continental Europe. By the 17th century, the Spanish had introduced tomato to their North American outposts in Florida, Texas and California. From there, it gradually found its way to Colonial America, which also received different varieties with the floods of immigrants from Europe. In Colonial America, tomato was eaten rarely in the mid 18th century and commonly by the mid 19th century. Since its arrival in Spain nearly 500 years ago, human selection of desirable and valuable traits in all the regions where tomato was grown has produced an array of varietal types adapted to local climates and incorporated into local cuisines.
While heirloom tomatoes represent a fantastic source of valuable traits, there are distinct advantages to hybrid plants, where the aim is to combine the best characteristics of two inbred lines (one of which is perhaps an heirloom). And in the early part of the 20th century, universities and later private companies began formal tomato hybrid breeding programs. Hybrid tomatoes are tailored specifically for uniformity of such traits as yield, type of desired fruit (canning vs. fresh market), shelf life, disease resistance and climate. Because there’s more work involved in producing hybrid seed, the seed is more expensive. And, unlike inbred heirloom seed, hybrid seed does not breed true and must be replenished each year. But despite the additional expense of hybrid seed, the advantages have led most growers, especially commercial growers, to choose hybrid tomatoes over inbred lines like the heirlooms. The first really successful hybrid tomato was Burpee’s ‘Big Boy’, introduced in 1949 and still popular today.
In contrast to traditional, heirloom tomatoes, wild tomatoes exhibit a tremendous amount of genetic diversity. This is especially true of some of strictly self-incompatible species (obligate outbreeders). Wild tomatoes carry a wealth of genes. Within the next 10 years or so, the complete sequence of the tomato genome will have been determined. And as our knowledge of the structure and function of tomato genes increases, it will become progressively easier for tomato breeders to “design” new cultivars that combine traits of traditional, inbred tomatoes with wild-species traits such as resistances to pathogens, pests, and environmental conditions as well as elevated nutrient content, a current breeding goal.
If like my friends, you enjoy growing heirloom tomatoes (for whatever reason), by all means continue to treat yourself. But don’t overlook the great hybrid tomatoes that are currently on the market. And look to the future because the best tomato varieties are yet to come.