Ruminants like cows have developed an unusual way of digesting their food: they ingest plants, give them a rough chewing and then swallow the half-chewed mash before regurgitating it repeatedly and continuing to chew. This has clear advantages: the regurgitated mushy food contains much less hard grit, sand and dust than the food that they first ingested. This protects the teeth from being ground down during the chewing process. This may explain why the crowns of the teeth of ruminants are less pronounced than those of other herbivores.
