which is traditionally consumed in parts of Uruguay and Argentina, contains less than one percent by weight. Whereas, teas of Camellia sinesis which originated in China contain almost three times the concentration of caffeine than Arabica.
But for humans caffeine is very unique. Thus far we are the only living forms on Earth that readily seek caffeine for both its stimulatory and psychological effects. For all other life forms, caffeine is a potent toxin capable of sterilization, phytotoxicity and antifungal properties. As such scientists believe that caffeine, with its intensely bitter taste, has evolved as a primitive defense mechanism in coffee ensuring its survival in the wild for thousands of years. It’s no surprise then, that the caffeine content of the more “robust” Robusta species is almost double that of the more delicate Arabica. The belief is that as insects attack the coffee cherry, they are deterred by the bitter taste of caffeine and simply move on to other crops.