The modern tomato, a staple in kitchens worldwide, has undergone a remarkable transformation from its humble origins. Today’s diverse array of tomatoes, varying greatly in size, shape, and color, might lead one to wonder about the appearance of its wild ancestor. The journey from a small, unassuming berry to the plump, juicy fruit we commonly recognize is a testament to centuries of natural processes and human influence.
The Original Tomato: A Look at Its Wild Form
The most probable ancestor of the cultivated tomato is Solanum pimpinellifolium, often referred to as the currant tomato. Its fruits are quite small, typically pea-sized or currant-sized, measuring about 0.5 to 1.5 centimeters in diameter. These tiny berries usually mature to a bright red or orange color, clustering on the vine.
The wild currant tomato possesses a less substantial pulp and a higher proportion of seeds. The taste profile tends to be more tart or even bitter, though some wild types can be sweet. These ancestral tomatoes are native to the western Andean regions of South America. They thrive in diverse environments, from arid coastal lowlands to isolated valleys in the high Andes, demonstrating considerable hardiness.
The Journey of Domestication: Human Selection
While the wild tomato originated in South America, its primary domestication and cultivation occurred in Mesoamerica. Indigenous peoples, such as the Aztecs and Mayans, began cultivating tomatoes as early as 500 BCE. This early cultivation marked the beginning of human selection, a process that gradually reshaped the tomato over generations.
Early cultivators would have favored plants that produced fruits with more desirable traits. They selected for characteristics like slightly larger size, improved taste, or reduced bitterness, replanting seeds from these preferred plants. This continuous process of artificial selection slowly led to an increase in fruit size and a shift in other physical attributes. After the Spanish conquest in the 16th century, domesticated tomatoes were introduced to Europe and spread globally.
Key Transformations: How Appearance Evolved
Domestication brought about significant changes in the tomato’s appearance. The most striking transformation was the dramatic increase in fruit size, evolving from tiny berries to the large varieties commonly seen today. Genetic research has identified genes responsible for this change, notably the fw2.2 gene, which played a substantial role in increasing fruit weight by affecting cell number during development.
Beyond size, human selection led to a remarkable diversity in color. While wild forms were predominantly red or orange, cultivated varieties now exhibit a spectrum of colors including yellow, purple, black, and striped patterns. This expanded palette resulted from various genetic mutations affecting pigment production. The shape of the tomato also diversified considerably, moving from a uniformly round, berry-like form to a wide array of shapes, such as oblong, pear-shaped, beefsteak, and plum, driven by culinary preferences.
Cultivated tomatoes also developed more fleshy pulp and fewer, smaller seeds, making them more palatable and versatile. Traits related to ripening were also selected, leading to more uniform ripening, aiding harvesting and transportation. This contrasts with the often patchy ripening observed in wild tomatoes. The thousands of tomato cultivars available today illustrate the extensive changes from human selection.