The caffeine in coffee beans serves as a toxic substance protecting the seeds of the plant, a form of natural plant defense against herbivory. Caffeine simultaneously attracts pollinators, specifically honeybees, by creating an olfactory memory that signals bees to return to the plant's flowers. Not all "Coffea" species contain caffeine, and the earliest species had little or no caffeine content. Caffeine has evolved independently in multiple lineages of "Coffea" in Africa, perhaps in response to high pest predation in the humid environments of West-Central Africa. Caffeine has also evolved independently in the more distantly related genera "Theobroma" (cacao) and "Camellia" (tea). This suggests that caffeine production is an adaptive trait in coffee and plant evolution. The fruit and leaves also contain caffeine, and can be used to make coffee cherry tea and coffee-leaf tea. The fruit is also used in many brands of soft drink as well as pre-packaged teas.