Midtown Blogger/Manhattan Valley Follies: Extreme Tech= The Evolution of Coffee

Friday, September 5, 2014

Extreme Tech= The Evolution of Coffee

Scientists unravel the genetic secrets of caffeine’s evolution in coffee

By John Hewitt on September 5, 2014 at 2:35 pm
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For lack of a better landing site, visiting aliens might logically choose an equatorial location. That way they would have maximal initial tangential velocity should they need to make a quick getaway. Upon noting the region has over 11 million hectares planted with coffee, they might presume that the biofuel du jour that powers our civilization is caffeine. As fate would have it, they wouldn’t need to sequence the coffee genome for themselves to see exactly what is going on — the supplementary text of a new article in Science should give them all they need to know.

Unfortunately for a Type I civilization like us, a genome sequence alone doesn’t really give us much actual knowledge. We now have learned, for example, that different plant sources of caffeine — coffee, tea, kola, or cacao — make the chemical in slightly different ways. Hipster evolutionary biologists cite this as an example of “convergent evolution” which, regrettably, tells us nothing. One useful detail from the study pertains to the enzymes which add methyl groups (the CH3s in the picture below) to xanthine to convert it into caffeine.

In the evolution of the species Coffea canephora (more commonly known as Robusta coffee), the genes for these enzymes have undergone several rounds of the familiar process of copy and modify. These modifications have not only given the enzymes the ability to act on new molecules, but also to have their activity controlled in new ways. For plants that spend a lot of energy synthesizing bucketloads of caffeine, the when, where, and how much to generate are key questions of community survival. Some plants find it useful to concentrate caffeine where creatures will consume it. In many cases this is to kill them, for others it is to reward them — the particular effects enjoyed are made in the dose. [Research paper: DOI: 10.1126/science.1255274 - "The coffee genome provides insight into the convergent evolution of caffeine biosynthesis"]

Putting the caffeine in nectar for example, gives bees a little extra kick, increasing not only the vigor with which they spread pollen but also the persistence in memory of the effort. Putting it in leaves selects the animals that eat them (and vice-versa), and it also inhibits plant competitors when the leaves are later shed upon the ground to caffeinate the surrounding soil.

Robusta (Coffea canephora) beans

But what we as humans want to know is how caffeine works when we put it in us. Common simplistic explanations for caffeine’s effects usually run something like “they act on adenosine receptors.” That novice answer is neither complete nor satisfying. The genome information alone doesn’t add much either — we need more potent incites for that. One sharp observation is that caffeine can intensify the bizarre symptoms of a disease known as Lesch-Nayan syndrome. In this affliction, there is a problem with the enzyme that scavenges the xanthine precursors back into DNA synthesis pathways. The perplexing result of this genetic injury is that in mild forms children go around pinching others, while in severe forms they self-cannibalize their own lips and fingers. If anyone needs an understanding of what is going on it is them.

There are many other anecdotes on the larger systemic effects of caffeine that make good scientific entry points. For example, after a lumbar puncture is done to get a sample of cerebral spinal fluid, the ensuing splitting headache is best alleviated by a quick spritz of caffeine into the IV line. Here caffeine quickly tightens up the vasculature and replenishes the fluid cushion of the brain.
As some note, the adage “I don’t like the drugs but the drugs like me” is only half true. The love-hate relationship with any vice overdone may not be entirely our fault but it is certainly our problem. While caffeine itself is almost magical in the way it suits our physiology, the time-lapse effects of stirring in a bitter pill of 120,000 tonnes per year on our civilization are harder to qualify.