The fact that such lovely things as a mellow cup of tea or a luxuriant espresso exist can make it feel like the universe was made, in some small way, for you. But of course caffeine evolved for some other purpose. Why do plants produce it?
New research on caffeine revealed a surprise: Whatever the reason it exists, it’s effective enough to have arisen twice in nature. A study published on Sept. 4 in Science shows that the ability to produce caffeine evolved once in coffee, and a second time, completely independently, in tea and cacao.
The study was codirected by Victor Albert, a genome scientist at the University of Buffalo, and it compared the genetic code of the robusta coffee plant with the genetic code of tea and cacao plants. The researchers found that robusta plants use one kind of enzyme—known as a methyltransferase—to produce caffeine, while tea and cacao plants use another. Two organisms using different genetic instructions to achieve the same end is an example of convergent evolution, and the odds of it happening are long.
Evolutionary biologists theorize that caffeine may be protective; when caffeine-laced leaves drop to the ground, they contaminate the soil and prevent other plants from sprouting in the vicinity. Another explanation is one that might feel quite familiar to many of us, Albert explained to Nature: “Caffeine habituates pollinators and makes them want to come back for more.” The founder of Starbucks couldn’t have known it, but plants beat him to his business idea by eons.
Kevin Hartnett is a writer in South Carolina. He can be reached at firstname.lastname@example.org.