Plants taste bitter because they have chemicals that make animals sick, so animals learn to avoid them.

The study shows that the bitter taste in hops comes from natural plant chemicals that trigger a 'this might be toxic' signal in our bodies, which is exactly how plants evolved to keep animals from eating them.

The study says plants have natural chemicals that make them taste bitter and can interfere with digestion—these are the plant’s way of protecting themselves from being eaten, which matches the claim.

Animals that eat lots of bitter plants developed better bitter taste sensors over time—this proves that the bitterness is a warning sign from the plant to keep animals from eating it.