It turns out that some of our favourite condiments came about because of a bitter feud between plants and animals. All's fair in love and war …
Next time you put a dollop of wasabi on your sushi, say a little 'thank you' to the humble caterpillar.
Believe it or not, caterpillars played a huge evolutionary role in developing the pungent flavours in our favourite condiments, including mustard, horseradish and wasabi. And it turns out they've been at it for millions of years.
Here's the science: about 90 million years ago, plants began to defend themselves from snacking critters by producing chemicals called glucosinolates, which were toxic to bugs.
However, according to a new study published in Proceedings of the National Academy of Sciences, caterpillars and other bugs built up defenses to protect themselves against these glucosinolates, forcing plants to work even harder to develop stronger and sharper chemicals (like blow-your-head-off horseradish).
According to Chris Pires, a plant evolutionary biologist and one of the study's lead authors, this "evolutionary arms race" led to the dramatic and dominant flavours we associate with spicy sauces like mustard and wasabi and even vegetables like radishes and cauliflower.
The research began with Pires and his team lining up the evolutionary family trees of Brassicales (flowering plants including cabbages and mustard).
They discovered that every time the plants evolved a new type of glucosinolate, their family tree would branch out and entirely new copies of their genes would be created. This led them to deduce how sharp-flavoured plants and caterpillars have co-evolved in tandem and how the bugs evolved to diversify themselves.
Cool stuff. Or actually, hot stuff.
"Why do you think plants have spices or any flavour at all?" asks Pires, "It's not for us." So it seems the mustard kick you like to add to your ham sandwich has a function in evolution, too.