How a Tree of the Past Can Help us Make the Chocolate of the Future

               It seems that every article about chocolate begins with a reference to its ubiquity and intoxicating nature. Perhaps there is no other way to remind the reader what is at stake with a food so bound in nostalgia and lust. In keeping with the tradition, I have selected a quote by Simian Sethi, author of Bread, Wine, Chocolate: The Slow Loss of Foods We Love. She describes chocolate as “the stuff of life and love — celebrated, debated and imbued with far more than calories”. But as the title of her book suggests, cacao, the raw material to make chocolate, is among a growing list of foods threatened by our changing biological, chemical, and physical planet. Warmer temperatures lead to evaporation rates too high for the sensitive plant and increase the prevalence of fungal and insect pests. Soils in cacao growing regions are nutrient-depleted, and extreme weather events jeopardize water stability. Scientists across the globe are working to address these concerns by developing delicious, highly productive, resource-efficient, and disease-resistant varieties. Knowledge of the botanical and natural history of the cacao plant is critical for this research because understanding how the plant has historically evolved can help us design a plant for the future.

               All chocolate starts as a seed inside the fruit of a Theobroma cacao tree. Recent DNA analysis suggests this specie originated – with slightly different genetic makeups – in both the Peruvian Amazon River Basin and the foothills of the Venezuelan Andes. Humans initially cultivated the crop for the sweet pulp that coats the seeds, and ancient Mesoamerican civilizations were the first to prepare and consume the seeds themselves. The human expansion of the plant ever since has largely influenced its current genetic diversity.

               Starting during the end of the 1600s, the Spanish brought cacao eastward to present day Philippines, Java, and Indonesia, and the Portuguese later brought cacao to West Africa (which would later become the world’s largest supplier of cacao). The above map outlines the botanic origin of Theobroma cacao in striped red as well as major transoceanic movements of the plant. Due to temperature and humidity constraints, Theobroma cacao must be cultivated within 20 degrees north and 20 degrees south of the equator. This range is indicated on the map above with the dotted horizontal lines for the Topic of Cancer and Tropic of Capricorn. Due to the unfortunate inverse correlation between proximity to equator and wealth, the regions suitable to growing cacao are also some of the poorest.

spread-of-the-cacao

               Starting during the end of the 1600s, the Spanish brought cacao eastward to present day Philippines, Java, and Indonesia, and the Portuguese later brought cacao to West Africa (which would later become the world’s largest supplier of cacao). The above map outlines the botanic origin of Theobroma cacao in striped red as well as major transoceanic movements of the plant. Due to temperature and humidity constraints, Theobroma cacao must be cultivated within 20 degrees north and 20 degrees south of the equator. This range is indicated on the map above with the dotted horizontal lines for the Topic of Cancer and Tropic of Capricorn. Due to the unfortunate inverse correlation between proximity to equator and wealth, the regions suitable to growing cacao are also some of the poorest. {Photo sourced here}

               The cacao variety originally cultivated in Mesoamerica, later titled Criollo, enjoyed a subtle and complex flavor profile and was the first variety to supply the exploding global demand. But at some point in the 18th century (the exact date is unknown), a new source of genes was introduced into the world’s commercial cacao stocks when Iberians discovered cacao growing wild in the South American mainland. The natives knew it as a fruit, but it had never been made into chocolate. This variety, called Forastero, has a harsh, bitter and sour flavor with no secondary notes, but boasts higher yields and greater disease resistance. After a series of disease epidemics over cacao groves in Trinidad, farmers reestablished the crop with the Forastero variety. These plants were then crossed with some of the remaining Criollos and a hybrid, called Trinitario, was born. However, it is important to consider that even before human intervention, Criollos crossed and backcrossed with Forasteros hundreds or thousands of times to form subvariants. DNA analysis is the only way to unscramble these gene mixes and recent analysis actually challenges the traditional belief that Criollos, Forastero, and Trinitario are the only genetic grouping. Forasteros are now classified into 9 unique groups, and as cacao DNA research continues, classification will be further fine-tuned (however, rapid deforestation in cacao habits risks eradication of varieties before we have the chance to discover them).   

               Each Theobroma cacao variety has its own unique characteristics from the size, color, and smoothness of the pod to the shape, flavor, and fattiness of the seed. Understanding the botanical development and characteristics of each variety allows scientists to select for specific traits and assemble a crop suitable for our changing environmental conditions. DNA analysis also allows scientists to test progeny for certain alleles rather than waiting 10 year for them to mature.

Over the last centuworld-crop-populationry, cacao under cultivation has become more uniform and has lost its adaptation to niche environments and specific areas. The genetic base is steadily narrowing, and Criollo, and its superior flavor profile, holds a dwindling share of the world’s cacao supply. The visualization to the left is the current global distribution (across the three antiquated variety categories) of cultivated cacao. {Graphic sourced from Scharffen Berger Chocolate Maker}  

               In addition to understanding genetic varieties, research on cacao’s botanical history helps us understand its current ecological systems. For example, large modern cacao plantations suffer from pollination rates which are substantially lower than those of wild trees. This in turn leads to lower pod yields. When researchers looked at this phenomenon in the context of the Theobroma cacao tree’s natural history, the problem became clear. The tree is exclusively pollinated by midges, a fly that likes to lay its eggs on wet decomposing matter not present in neatly manicured plantations. Considering the natural ecosystem surrounding cacao could also help identify biocontrol species and other plants adapted to shade the sun-sensitive cacao tree. Cacao’s botanical history is especially useful compared to other crops that must reseed every year. Because of cacao’s longer generations, modern cacao is quite similar compared to wild cacao.

               I am not the first to claim that the Theobroma cacao specie is at risk and requires new cultivation varieties and techniques. Due to chocolate’s almost universal adoration, any news article on the topic goes viral. One especially well written article by Bloomberg Markets titled “To Save Chocolate, Scientists Develop New Breeds of Cacao” goes into more detail than this short blog post about new varieties scientists have developed (the article can be found here). But the botanical history of how the Amazonian plant became a $100 billion per year global industry often goes untold in these narratives about the future. It was the years of selective breeding and understanding of the plant’s biological nuances that gave rise to today’s industry. And as we face climate change and its multitude of siblings, an understanding of the past is critical to constructing the future.

Bibliography

“Cacao Bean Varieties.” Scharffen Berger. http://www.scharffenberger.com/our-story/about-cacao/bean-varieties/.

“Chocolate from the New World.” Indigenous and Non Indigenous Plants and Animals (web log).

Coe, Sophie D., and Michael D. Coe. The True History of Chocolate. New York: Thames and Hudson, 2013.

Motamayor, et al. “Cacao domestication I: the origin of the cacao cultivated by the Mayas.” Heredity 89, no. 5 (May 14, 2002): 380-86. doi:10.1038/sj.hdy.6800156.

Presilla, Maricel E. The new taste of chocolate: a cultural and natural history of cacao with recipes. Berkeley: Ten Speed Press, 2009.

Schatzker, Mark. “To Save Chocolate, Scientists Develop New Breeds of Cacao.” Bloomberg.com. November 14, 2014. https://www.bloomberg.com/news/articles/2014-11-14/to-save-chocolate-scientists-develop-new-breeds-of-cacao.

Scott, Michon. “Climate & Chocolate .” Climate.gov. February 10, 2016. https://www.climate.gov/news-features/climate-and/climate-chocolate.

Sethi, Simran. Bread, wine, chocolate: the slow loss of foods we love. New York, NY: HarperOne, an imprint of HarperCollinsPublishers, 2016.

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