What do you call an animal that eats both plants and meat?

An omnivore, which is what we are, and the anatomy shows the compromise. Our teeth include cutting incisors, tearing canines and grinding molars; a specialist carnivore has no grinding surfaces and a specialist herbivore has no serious canines. Our gut is intermediate in length - shorter than a herbivore's fermentation system, longer than a cat's.

The strategy costs something. A koala eating one thing can afford a simple gut and a small brain; an omnivore must recognise, remember and judge an enormous range of possible foods, several of which will kill it. That is thought to be part of why omnivores tend to be behaviourally flexible and good at learning - and it produces the omnivore's dilemma, the anxious relationship with novel food that shows up in humans as both neophobia and cuisine.

The category is also leakier than it sounds. Deer eat birds; cows eat chicks; hippos, textbook grazers, have been filmed scavenging carcasses. Pandas kept a carnivore's digestive system and switched to bamboo. Diet is what an animal does, not what it is built for, and the two agree less often than the textbook categories imply.