Why is 「人口」 used to denote population?


I'm just curious at the appearance of 「口」 that makes this word mean
"population". Why should it be 「口」 as opposed to any other body part or
anything else? Is there a definitive reason or story associated with this
word? If 「口」 is used as a counter then why couldn't 「個」 replace it? If I'm not
mistaken doesn't 「個」 refer to individuals more so than 「口」?




In old Chinese--where Japan borrowed the term--口 was a counter for people.
More specifically, it referred to the number of people needing food. English
has this construction too: the number of "mouths" (=people) to feed.

As for 個, it generally refers to individual non-animate items.




In old Chinese--where Japan borrowed the term--口 was a counter for people.
More specifically, it referred to the number of people needing food. English
has this construction too: the number of "mouths" (=people) to feed.

As for 個, it generally refers to individual non-animate items.

