We’re endlessly fascinated with what killed the dinosaurs. Sure, we’re all taught that an asteroid slammed into the Earth and made them extinct all at once, but it turns out to be a more complicated process. The fact that their eggs took forever to hatch, climate change killed pretty much everything, and their relentless farting have all been shown to at least potentially contribute to their die-off. And now it turns out there’s another factor, namely that plants evolved defenses against the dinosaurs faster than the dinosaurs could evolve to detect them.
To understand why, researchers Gordon Gallup and Michael J. Frederick start with our tongues. Bitter foods stand out to us in part because the poisonous compounds of most plants taste bitter. The goal of the plant isn’t to poison you, just that you’ll associate the awful taste with the resulting gastrointestinal misery and avoid eating it. But for that to work, you have to be able to taste the bitter compounds, and Gallup and Frederick theorize that dinosaurs simply couldn’t taste the bitter, and thus kept eating poison plants.
Of course, we don’t have the tongues of dinosaurs to study, but we do have their descendants, birds and crocodiles, and it turns out neither of them can taste spoiled or poisonous food; birds learn to avoid bitter food on sight, not taste, and crocodiles just eat it. And, tellingly, right around the time plants started evolving poison compounds as a form of defense, the dinosaurs began to die off. In other words, by the time the asteroid hit, it was just speeding up a process that was already well in motion.
Or, put still another way, M. Night Shyamalan was right when he made that Mark Wahlberg movie about how grass hates us. We’re never hearing the end of this one.