There is no agreed upon definition of "cecum." The cecum is a pouch-like structure in the lower intestine where the large intestine begins. It is thought to aid in the digestion of plant material, but its exact function is not fully understood. Humans do have a relatively small cecum compared to other apes, but it is not clear if this is due to our diet or our evolutionary history.

There are several possible explanations for why humans might have a relatively small cecum. One possibility is that our diet does not require a large cecum to aid in digestion. Another possibility is that the cecum has shrunk over the course of human evolution as we have adapted to a diet that is less reliant on plant material. Finally, it is also possible that the small size of the human cecum is simply a result of our anatomy and is not related to diet or evolution.