Caterpillars have played a pivotal role in crafting mustard and wasabi.

This is due to what is sometimes called an evolutionary arms race. Like a nuclear one, it involves two parties duking it out over not just hundreds, but in this case millions of years.

Chris Pires, a plant evolutionary biologist from the University of Missouri, explains that around 90 million years ago, the plant species Brassicales developed chemicals called glucosinates to protect them from being eaten by caterpillars. This chemical damaged the caterpillars' internal organs, and therefore prevented the plants from being eaten.

Ten million years later, the caterpillars developed a tolerance for the "mustard oil bomb," and became one of the only species evolved enough to eat it, leading to the development of more evolved caterpillars.

By building an evolutionary tree to map out the development of both species, Pires and his team discovered that over time each party developed a fancier defense, leading to coevolution of both kinds of species. 

For us, these chemical defenses manifest into flavors such as mustard, horseradish, wasabi, and broccoli. The more defensive the chemicals became, the more delicious the flavors.

Cover image: Wikimedia Commons