What is the origin of the idiom "keep one's ear to the ground" and when to use it?

The idiom "keep one's ear to the ground" originates from the practices of native American trackers and scouts, particularly from Plains Indian tribes. These individuals would press their ears to the ground or place their ear against the earth to detect vibrations and sounds from a distance. By doing so, they could be alert to the approach of people, animals, or other significant events. It is used to describe the act of staying well-informed, being attentive to current developments, and actively seeking information or news in a specific field or area of interest.