Dan Bolton
Dan Bolton, STiR editor
What if we and tea are meant to be evolutionary companions?
The thought is inspired by a hint that mankind’s long affair with tea led the plant to change in ways pleasing to the humans who tend it.
Researchers who successfully mapped the tea plant genome found it incredibly complex, much more so than coffee or cacao. The tea plant evolved during the same 50 million year period as modern human DNA, which it resembles in complexity at 3 billion base pairs compared to mankind’s 3.2 billion base pairs. (See Unraveling the Tea Genome)
Unexplained is why tea contains an unusually large percentage of genes that turn up in multiple places along the helical chain. Two-thirds of the plant’s genes are “retrotransposen sequences” designed to subtly alter the expression of nearby genes. Mapping their location suggests this adaptation is primarily to create desirable flavonoids and caffeine, which protect the plant from assault by insects.
In his book, The Botany of Desire: A Plant’s-Eye View of the World, author Michael Pollan describes how some plants adapt their adaptability to humans. He cites the example of the apple, a tree that produces a bitter fruit in the wild.
“High in the hills of Kazakhstan, where the ancestors of malus domestica trees first began experimenting with the shape and color of their fruit, you can find an astounding variety of examples of what the apple could have been, from large purplish softballs to knobby green clusters. But through its countless journeys over the Silk Road many thousands of years ago, carried by generations of wayfarers, the apple adapted to meet the needs of its traveling companions, evolving to become a portable, durable conduit for sweetness,” writes Pollen.
He explains that mankind has a special relationship with psychoactive plants that affect our thoughts and perceptions like coffee, tobacco, and tea. These plants contain molecules that cause changes to the biochemical processes that go on deep inside our brains. The relationships between them and the people who use them has evolved over time, both influencing and reflecting the values of the societies in which they are used.
Prof. Zeno Apostolides, at the University of Pretoria, writes that “understanding the tea genome will allow breeding of new cultivars with unique flavors, e.g. low or high caffeine for different market segments, slow fermenters for green tea, fast fermenters for black tea, high theanine for the umami taste or high catechins for health properties. The achievements will be made possible by classical breeding and selection, without any genetic modification of the tea plant.”
Perhaps this is exactly as the plant intended!
As Pollen reminds us: “We give ourselves altogether too much credit in our dealings with other species.”