It turns out that coffee is special [Greg Laden's Blog]

But you knew that already.

The Coffea canephora Genome has been sequenced. This is probably more important than the Human Genome project because humans are completely useless first thing in the morning, but coffee is very important first thing in the morning.

Some important plant evolution involves wholesale duplication of large parts of the genome. This does not appear to be the case with coffee. Rather, diversification of single genes characterizes the genome, so, according to the paper reporting these results in Science, “…the genome includes several species-specific gene family expansions, among them N-methyltransferases (NMTs) involved in caffeine production, defense-related genes, and alkaloid and flavonoid enzymes involved in secondary compound synthesis.”

Also of great interest is the apparent fact that caffeine related genes either evolved separately from, or engaged in the important work of making caffeine separately from similarly functioning sets of genes in tea and cacao (chocolate). I had always suspected tea was … different.

So, not at all unexpectedly, the most important molecule on earth evolved more than once!

Elizabeth Pennisi also has a writeup here.