The Cacao Tree Is A Lot Older Than We Thought

Cacao powder and beans. Dionisvera/Shutterstock
Robin Andrews 11 Nov 2015, 16:35

The entire world owes a lot to Theobroma cacao, the tree from which we derive that unrelentingly delicious chocolate of ours. It’ll probably come as no surprise that global chocolate sales for 2016 are predicted to be $100 billion (£66 billion). What may come as a surprise, however, is that the cacao tree evolved at least 10 million years ago, far earlier than previously thought. New genetics research published in the journal Frontiers in Ecology and Evolution reveals that there may in fact be hidden genetic strains of cacao hiding out there that could contain flavors we’ve only previously dreamed of.

Each and every year, the demand for chocolate rises, so growing more and more cacao is essential to the industry. However, there’s a problem: The current crop of cacao shows a distinctly low level of genetic variation. Such a lack of diversity means that organisms are unable to adapt to a changing environment, thus leaving them susceptible to things like the sudden appearance of a new disease, or climate change.

A research team from Bogotá, Edinburgh and Miami, looked into the development of the cacao plant around the Andes, the birthplace of chocolate – an Aztec invention that could be more than 3,000 years old – using genetic analysis techniques to investigate its supposed low genetic diversity. By tracking the changes in the DNA sequences of the cacao tree over time, the researchers could ascertain the evolutionary pathway the tree took. This effectively allows them to look backwards in time to see the genetic variation of the plant over millions of years.

Image credit: A cacao pod. Valentyn Volkov/Shutterstock

This technique – known as molecular phylogenetics – revealed that the plant itself is 10 million years old, with the diversification of the group of tree it belongs to beginning up to 14.3 million years ago. This evolution and subsequent diversification occurred at the same time as the uplift of the northwestern section of the Andes mountain range. This uplift likely forced cooler conditions on the trees that rose with it, provoking them to adapt and transition into different, more adaptable species of cacao tree compared to the ones in the still-warm lowlands.

This type of segregation-induced evolution is known as allopatric speciation; numerous examples of it around the world have been shown to “rapidly” produce new species, and the cacao tree is no exception to this. This early evolution of the species suggests that the tree has had millions of years to become genetically diverse, suggesting that there could potentially be many variants of the tree in the wild hidden across the Americas.

“After 10 million years of evolution we should not be surprised to see a large amount of variation within the species, some of which might exhibit novel flavors or forms that are resistant to diseases. These varieties may contribute towards improving a developing chocolate industry,” Dr James Richardson, a tropical botanist at the Royal Botanic Garden Edinburgh and one of the lead authors of the study, in a statement.

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