Coffea arabica makes up a vast majority of the coffee produced in the world with Coffea canephora (robusta) coming in at a distant second. Unfortunately, the world’s favorite variety of coffee is a picky plant requiring very specific growing conditions. Altitude, drainage, shade, and temperatures have to be perfect for these plants to succeed.
Headlines warn about the imminent danger facing coffee plantations around the globe due to climate change. Changing temperatures and drought conditions are pushing farms to higher elevations, diseases such as coffee leaf rust are running rampant, and pests such as the coffee borer beetle are proving difficult to eliminate.
To give the delicate Coffea arabica the best chance at survival, geneticists and farmers are looking to the not-so-distant past for answers.
Thanks to modern genomic analysis techniques, we know the first C. arabica is descended from C. canephora (robusta) and C. eugenioides which are originally from Ethiopia and South Sudan. 1
As the story goes, the first person to notice the benefits of coffee was a goat herder named Kaldi. He observed his goats were more energetic after eating the berries from a certain tree, and they would stay awake all night. Eventually Kaldi and others discovered the beans have the same effect on humans which sparked the human obsession with coffee. 2
Sometime during the 14th century, coffee seeds from the forests of Southwestern Ethiopia were brought to Yemen. Slowly but surely, farmers began cultivating coffee but it wasn’t until a few hundred years later that the coffee beans made their way out of Yemen.
Coffea arabica was essentially unknown outside of the Arab world until about 400 years ago and many of the subsequent “Out-of-Yemen” accounts were well documented.3
From the late 17th century to the early 20th century, Coffea arabica began spreading around the globe.
The French were some of the first to try smuggling coffee seeds from Yemen. There are three separate accounts of them attempting to cultivate the plant on Bourbon Island off the coast of Madagascar.
The “Bourbon” variety of coffee was bred on the island for 200 years before French missionaries spread the seed to parts of mainland Africa where it is still grown today.
The “Typica” variety of C. arabica was bred in India after an Indian monk named Baba Budan smuggled the seeds out of Yemen in 1670. The seeds were eventually sent to Indonesia and coffee was cultivated throughout the Indonesian islands.
The Dutch finally sent one single “Typica” coffee plant from Indonesia to a botanical garden in Amsterdam. This single coffee plant produced the “Typica” varieties that propagated in the Americas starting in the 1700’s linked closely to the colonization routes of the French, Dutch, and English.4
All this from a single plant! Almost every subsequent variety of C. arabica that we grow today around the world comes from the very small gene pool of these two varieties.
The place of origin, the hub of coffee diversity, lies in Southwestern Ethiopia and for centuries, was an impenetrable expanse of land under the control of the Kingdom of Kafa from 1390-1897.5
It wasn’t easy for people to take coffee genetics out of this part of the Ethiopian jungle. As a result, the C. arabica that was cultivated in Yemen and then spread around the world represents a very small portion of the wild coffee genetics. This is a classic example of what geneticists and biologists call a “bottleneck event”.
C. arabica is a scrawny picky plant because it has been inbred since it was taken out of the Ethiopian jungle in the 1300’s. In inbred animal populations, such as German Shepherds, a lack of genetic diversity has given the dogs a propensity for abnormal hip development.
Many “purebred” dogs suffer from a lack of genetic diversity in their pedigree but inbreeding isn’t just a problem for animals . Plants suffer from the same consequences of inbreeding. This is why C. arabica is so much more susceptible to coffee leaf rust, the coffee borer beetle, and the shifting climate.
Genetic diversity is the key to adaptation and C. arabica doesn’t contain much genetic diversity. We picked C. arabica because when brewed, it is a superior cup of coffee compared to its relatives.
Even today, there are certain varieties of Arabica plants that have a smaller yield, are susceptible to pests and disease, but the beans make an incredible cup of coffee that fetch great prices per pound in the world market.
Organisations like worldcoffeeresearch.org are combining modern genetic analysis with older Coffea species and varieties to create a strong plant that still produces high quality beans.
Interestingly enough, C. canephora (robusta),although not preferred for its taste, has shown resistance to many of the problems facing the C. arabica species. By luck, in the 1920’s, a natural cross occurred between the two species on the island of Timor creating the well-known “Timor-hybrid”.
A bee could have simply decided to hop from an Arabica plant to a Robusta plant or vice versa. The “Timor-hybrid” plant was resistant to rust thanks to its Robusta parent and the beans only took a slight dip in quality from the Arabica parent.6
That plant was the result of chance but luckily, breeders are much more precise in their approach.
Imagine the resistant qualities of coffee species that have lived in the jungles of Ethiopia for millennia. Part of their success in the jungle relied on producing tasty coffee beans to spread their seeds but a greater part of their survival as a species was rooted in their ability to fight pests and disease.
There are occasional articles discussing the incredible taste of non-Arabica species such as C. eugenioides7 and tasty varieties of C. canephora8so it isn’t hard to imagine a superhero coffee species hiding in the Ethiopian jungle.
The future of C. arabica can follow a number of paths. Some scientists are going back to the species birthplace in Ethiopia to identify coffee plants with resistance to disease, pests, and a changing climate. Their hope is to breed these species with C. arabica in order to acquire these resistant genes but retain the quality taste of the Arabica coffee.
Other scientists are focusing on crossing C. arabica and C. canephora (robusta)with the hopes that the genes responsible for superior flavour are blended with resiliency. Some scientists are simply going back to Yemen to see if older varieties of Coffea arabica are stronger genetically.
Regardless, the world’s favourite species of coffee will need to undergo some genetic alterations to be better prepared for the challenges ahead.9 There just isn’t enough diversity in C. arabica alone to fight the future implications of a changing climate.
1. A great, recent scientific article on coffee genetics can be found here: Scalabrin, S., Toniutti, L., Di Gaspero, G. et al. A single polyploidization event at the origin of the tetraploid genome of Coffea arabica is responsible for the extremely low genetic variation in wild and cultivated germplasm. Sci Rep 10, 4642 (2020).
2. See Giorgio Milos, “Coffee’s Mysterious Origins”, The Atlantic, August 6, 2010
3. One of the best 20th century accounts of coffee history: Sylvain, P. G. Some observations on Coffea arabica L. in Ethiopia. Turrialba. 5, 37–53 (1955).
4. See “History of Typica and Bourbon”, World Coffee Research, https://varieties.worldcoffeeresearch.org/info/coffee/about-varieties/bourbon-and-typica
5. Amnon Orent. (1970). Refocusing on the History of Kafa prior to 1897: A Discussion of Political Processes. African Historical Studies, 3(2), 263-293. doi:10.2307/216217
6. See the “T8667 Catimor” page on WorldCoffeeResearch.org under the “History” section. https://varieties.worldcoffeeresearch.org/varieties/t8667#:~:text=Timor%20Hybrid%20is%20a%20natural,rust%20resistance%20into%20the%20variety.
7. See the article about C. eugenioides: Liz Clayton, “Meet The Species Eugenioides, Coffee’s Weird Delicious Uncle”, Sprudge, August 31, 2015
8. See progression made with C. canephora: Kelly Stein, “Brazil Bets on Specialty Conilon”, stir-tea-coffee.com, February 28, 2018
9. Alex Scott, “Why the end of the world’s most popular coffee could be nigh”, Chemical & Engineering News, Volume 96, Issue 7, February 12, 2018