Coffee is a domesticated plant that is grown all over the world within the “coffee belt” where it does not freeze at night in the winter. However, it was not a plant that was imagined and developed by modern botanists. It grew in the wild where it was first discovered in ancient Ethiopia in Northeast Africa. Coffee does not have the sort of sweet fruit that typically attracts animals who then eat the fruit and subsequently spread the seeds in their excrement. Rather it as a bitter, stimulating fruit which one would think would be ignored by grazing animals. To better understand how coffee evolved we might look at the evolution of flowering plants in general.
When Did Flowering Plants First Appear?
Roughly 140 million years ago in the Cretaceous era when dinosaurs ruled the land flowering plants of angiosperms first appeared. Prior to that time plants spread their pollen by air and their seeds simply fell to the ground around the plant. With flowering plants came insects that visited the flowers to harvest the sweet pollen and unknowingly spread pollen from plant to plant. Along with flowers, these plants brought fruit that animals ate because it was generally sweet and nutritious. Animals roamed around and when they eliminated they unwittingly spread the seeds of the fruit of the flowing plant. This new set of relationships was sufficiently beneficial to plants insects, and animals that angiosperms became the dominant form of plant life that we see today. So how does coffee with its bitter fruit fit into this picture?
The Evolution of Specific Traits of Angiosperms
The way plant evolution works is that a randomly occurring trait of a plant increases its odds of surviving and spreading. This commonly occurred with the fruit of plants being sweet, which encouraged animals to eat the fruit and subsequently to spread seeds within the fruit. Over time fruit became sweeter and sweeter and plants that increased this trait spread more rapidly than ones that did not evolve in the same manner. How does this apply to how coffee plants evolved?
Coffee Plants in the Wild
Geneticists tell us that coffee has been growing in the wild for millions of years. They established themselves at high altitudes where there was plenty of rain. According to legend, the first human to recognize that there was something unique about coffee was an Ethiopian goat herder named Kaldi who noticed that his goats were very energetic after they had grazed on coffee plants. The story goes on to say that Kaldi took coffee beans to a local monastery where the monks learned to roast the coffee beans and make coffee. From there the beans, plants, and drink moved on to ancient Yemen, throughout the Ottoman Empire and across the world. From the story we assume that goats learned by chance to eat coffee beans for the “high” they experienced rather than for any sweetness of the coffee cherries. If we believe this, then the “high” becomes the step that encourages consumption of coffee berries and the goats would have spread coffee beans or seeds in their scat. That fits with the way that flowering plants evolved and makes sense for the persistence and spread of coffee in the wild. It also makes sense that any coffee plant that by chance evolved more caffeine production would become more attractive to grazing animals like goats thus creating a positive feedback loop that would favor evolution of coffee plants similar to was growing in the wild in Kaldi’s day and age.