Winning Allies and Poisoning Predators: The Convergent Evolution of Caffeine

Authored by Michael Brandt • 
March 12, 2018

Like many products of nature that humans enjoy on a regular basis – a bird’s song, the taste of an apple, the shade of a tree – caffeine is a happy side effect of a long evolutionary chain that vastly predates humanity.

Before various human societies began ingesting caffeine centuries ago – tea in Asia, cacao in South America, and coffee in Africa – various plants had evolved caffeine to obtain competitive advantages in the world of natural selection.

Poisoning Predators

Caffeine can hurt or kill plants and animals when ingested in sufficiently high doses. Caffeine has a negative effect on insects that ingest it, causing erratic or irregular behavior, or death. In the coffee plant for instance, the leaves and beans have a high enough caffeine content to act as insecticide, warding off predators and pests. As a response, some species, fruit flies for instance, have evolved taste receptors that respond to caffeine, so they know to avoid its bitter taste and dangerous side effects.

A spider’s web made under normal (left) and caffeinated (right) conditions. Caffeine adversely affects spiders’ capacity to produce efficient symmetric webs.

On related note, coffee seeds, when they fall to the ground, bleed caffeine into the soil, preventing nearby plants from germinating. Coffee seeds, which are not adversely affected by their own caffeine content, effectively block potential competitors that would compete with the coffee plant for sunlight, nutrients, and water.

Making use of of caffeine to deter pests, and inhibit the growth of other plants, gives caffeinated plants a competitive advantage in surviving millennia of natural selection.

Winning Allies

The nectar of the coffee plant contains low doses of caffeine. While it’s poisonous in high doses, caffeine in low doses promotes positive habits and behavior in some organisms. Bees and other pollinators can become habituated to the caffeine in a plant’s nectar. Bees find caffeinated nectar to be highly rewarding, and as such, they prefer caffeinated nectar and have an easier time remembering its scent, compared to non-caffeinated nectar.

Bees and other pollinators can become habituated to the caffeine in a plant’s nectar.

Bees distribute pollen grains from one plant to another as they feed on the plants’ nectar.

Just as bees depend on plants for nectar, plants depend on bees to help spread pollen. In order to reproduce, a plant needs to spread its pollen to other plans and/or receive pollen from other plants. When a pollinator, such as a bee, comes to drink a plant’s nectar, it leaves pollen grains from other plants it has recently visited. And when it leaves, it carries that plant’s pollen on to next plant.

Caffeinated plants, by gaining preferential treatment from pollinators, are exposed to a greater frequency of pollen from a greater breadth of plants, which helps the species to reproduce efficiently.

Caffeine Evolved Twice

Caffeine occurs in over 60 plants, including coffee, various tea varieties, cacao (chocolate), and nuts.

Scientists recently (source: Science, Sept 2014) made the discovery that caffeine has actually evolved at least twice, in two separate evolutionary lines.

Caffeine in plants is created through multi-step processes of biosynthesis, involving a series of enzymes that manipulate molecules, through various chemical reactions, into caffeine.

Caffeine is so useful to its producer that it evolved twice.

This caffeine biosynthesis process is significantly different in coffee compared to tea, suggesting that those plants developed the capacity to produce caffeine in separate, but parallel, evolutionary lines. This is called “convergent evolution,” similar to how bats and birds both evolved wings independently, many generations after splitting from their non-winged common ancestor. Convergent evolution means that two separate species have developed a similar solution to a similar problem; simply put, caffeine is so useful to its producer that it evolved twice.

Caffeine For Humans?

The lure of caffeine, and its mentally stimulating effects, has been noted for generations. It’s by pure serendipity that humans have access to caffeine, which plants evolved independently for their own survival.

“A mathematician is a device for turning coffee into theorems – Alfréd Rényi"

In humans, coffee causes psychoactive effects such as increased attention and lucidity. Human have been cultivating and harvesting caffeinated plants at massive scale for centuries – coffee was first discovered in Ethiopia, where indigenous societies ground the coffee with animal fat into something like an energy bar for warriors to increase alertness and stamina.

The appeal of caffeine to humans provides yet another evolutionary benefit to those plants. Humans have poured untold effort into ensuring the survival and propagation of caffeinated plants. From a biological perspective, it’s mutually beneficial symbioses, similar to the bee-plant relationship: humans benefit from caffeine, and caffeinated plants benefit from our efforts to keep their species strong.

Nootrobox SPRINT

One capsule of Sprint by HVMN contains a measured 100 mg of caffeine, about what's in a cup of coffee, to increase energy and alertness. SPRINT compounds the positive effects of caffeine with 1) L. Theanine, an antioxidant in tea that enhances mental focus, especially when coupled with caffeine, 2) B Vitamins to accelerate metabolism 3) Inositol, a de-stresser and 4) Glucoronalctone, a detoxifier.

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HVMN Co-founders Michael Brandt and Geoffrey Woo