You probably don’t feel much remorse when you bite into a raw carrot. You might feel differently if you considered the fact that it’s still living the moment you put it into your mouth. Of course, carrots—like all fruits and vegetables—don’t have consciousness or a central nervous system, so they can’t feel pain when we harvest, cook or eat them. But many species survive and continue metabolic activity even after they’re picked, and contrary to what you may believe, they’re often still alive when you take them home from the grocery store and stick them in the fridge.
The most recent evidence of this surprising phenomenon? A new paper, published today in Current Biology by researchers from Rice University and UC Davis, found that a range of harvested fruits and vegetables—including cabbage, lettuce, spinach, zucchini, sweet potatoes, carrots and blueberries—behave differently on a cellular level depending on their exposure to light or darkness. In other words, these fresh produce have an internal “body clock,” or circadian rhythm, just like we do. Previously, Rice biologist and lead author Danielle Goodspeed had found that some plants depend on light cycles and their internal circadian rhythm to fend off predatory insects, at least while still in the ground. In experiments, she had noticed that thale cress plants used reliable daily exposure to sunlight as a basis for anticipating the arrival of insects during the day, and were able to build up reserves of defensive chemicals beforehand, during the night.