Photo by Ria Tan licensed under CC BY-NC-ND 2.0
Mmm mmm coffee. This wonderful elixir has taken over the world. Though individual tastes and preferences vary, there is no denying that most folks who turn to coffee enjoy its effects as a stimulant. Many an In Defense of Plants post has been written in a coffee-fueled frenzy. Even as I write this piece, I am taking breaks to sip on a warm mug of the stuff. Coffee has plenty of proponents as well as its fair share of nay sayers but the health effects don't really concern me much. Today I would rather talk with you about the shrubs that are behind all of this.
The coffee we drink comes from a handful of shrubs in the genus Coffea. Native to parts of Africa, these shrubs are distant relatives of plants like buttonbush (Cephalanthus occidentalis) and the bedstraws (Galium sp.). The "beans" that we brew coffee from are not beans at all but rather a type of pit or stone found in the center of a bright red berry. Before they are roasted, the "beans" are actually green. Plants in this genus produce an alkaloid compound known as caffeine. Though it may seem strange, the purpose of caffeine is not to stimulate the human nervous system (though it is a wonderful side effect) but rather it is produced as a defense mechanism for the plant. Making this compound is a complex process that involves many metabolic steps within the tissues of the plant. There are certain factions out there who would like to argue that this is proof against evolution but, as always, evidence seems to be the downfall of their argument.
Creationists will tell you that the adaptations we see throughout the living world are too complex to have happened by accident. In reality, there is a vast amount of evidence that disputes this. Caffeine is one such example. It has evolved independently multiple times in many different plant lineages. Looking at the genome of coffee, researchers at the University at Buffalo (my alma mater) found that the genes involved in the synthesis of caffeine did not arise all at once. Instead, the genes duplicated multiple times throughout the history of this genus with each duplication coding for another step in the process of producing the caffeine molecule. The interesting part is that each step of this evolutionary process produced a chemical that was itself useful to the plant. The precursor compounds are bitter and toxic to the kinds of animals that like to nibble on the plant.
As it turns out, the benefits that the plants get from caffeine aren't restricted to defense either. Coffee, as well as other flowering plants such as citrus, produce small amounts of caffeine in their nectar. Researchers at Arizona State University found that bees were 3 times more likely to remember a flowers scent when there was caffeine in the nectar than if there wasn't. This serves a great benefit to the plant producing it because it means that its flowers are much more likely to get pollinated. As it turns out, humans aren't the only species that enjoys a good buzz from caffeine.
Before we get too excited over coffee, we must remember that is definitely has its downside. Worldwide, we humans drink roughly 2.25 billion cups of the stuff every day. In order to produce that much coffee, humans have turned somewhere around 11 million hectares of land into coffee plantations. This has come at an extreme cost to the environment. Also, being a tropical species, the types of habitat used to grow coffee were once lush, tropical rain forests. A majority of coffee consumed around the world is produced in monocultures. Where there once stood towering trees and a lush understory is now an open, chemically-laden field of coffee shrubs. There is hope, however, and it is rising in popularity.
If you enjoy coffee as much as I do, you should certainly consider switching over to shade grown coffee. I have attached a fair amount of literature at the bottom of this post but the long story short of it is that growing coffee is much less harmful to the environment when it is grown in a forest rather than open plantations. The structural complexity of shade grown coffee farms allows a greater diversity of plant and animal species to coexist with one another. Species diversity and richness are significantly higher on shade grown farms than on open field plantations.
So, there you have it. Coffee is as complex as it is interesting. We humans are simply lucky to have stumbled across a plant that interacts with our brain chemistry in wonderful ways. Certainly coffee has benefitted in the long run.
Photo Credit: Ria Tan (http://bit.ly/1pFQD1J)
Further Reading:
http://www.sciencemag.org/content/345/6201/1181.full
https://asunews.asu.edu/20130307_beesandcaffeine
http://s.si.edu/1o6wOaj
http://www.sciencedaily.com/releases/2012/08/120807101357.htm
http://bit.ly/1S6dLVV