In the following quotation, what is the most likely reason that Orwell mentions the number of chins the pigs had?
"But as the animals outside gazed at the scene, it seemed to them that some strange thing was happening. What was it that had altered in the faces of the pigs? Clover's old dim eyes flitted from one face to another. Some of them had five chins, some had four, some had three. But what was it that seemed to be melting and changing?"