- Almost (?) all vertebrates can taste sour, despite not having much value in cueing nutritional or safety info, meaning it developed in the common ancestor – probably in the early fishlike creatures so they could detect the acidity of water
- Humans are an oddity in not being able to generate vitamin C – which is probably why we like eating sour foods
- Herbivorous pandas have lost the ability to taste umami and carnivorous cats have lost the taste for sweetness
Eons is a neat show.