You may never have heard of the plant Brassica Oleracea, but you've definitely eaten it.
Six vegetables you can find in any grocery store and which most people eat on a regular basis are actually all from this one plant. Over the last few thousand years, farmers have bred Brassica Oleracea into six "cultivars" that eventually became many of the vegetables we eat.
This one plant was selectively bred over hundreds of years to create dozens of wildly different vegetables. By selecting and breeding plants with bigger leaves, or larger buds, the different cultivars (also known as subspecies) were created.
Kale, collard greens, and Chinese broccoli were created by making the leaves of the ancestor plant's leaves bigger, and were the first brassica domesticated, sometime before 300 BCE. Collard greens were developed in Europe, while Chinese broccoli was domesticated in China.
Red, green and savoy cabbages were created from a kale cultivar (likely the European collard greens) in the 1200s by selecting for a large terminal bud — the growing end at the top of the plant. The leaves are tightly wound around a short, wide stem (the cabbage's core).
Brussels sprouts are like tiny cabbages, except they grow from the buds along the plant’s stem. They first hit the scene in the 1200s as well.
Kohlrabi was created by selecting for a thicker stalk in a kale plant around the 1400s.
Broccoli was created from a kale predecessor in the 1500s by selecting for the larger flower clusters, which are then harvested before they bloom. Cauliflower was developed from one of hundreds of broccoli varieties.
The amazing evolution of Brassica Oleracea just goes to show: Humans have been tinkering with the genetics of our food for much longer than we've been creating what are now known as genetically modified foods, or GMOs. These new lab techniques just let us do it in a more precise and directed way.