Similar to the howling of the wolf pack, which is designed to synchronize mood in gregarious animals, yawning would have signalled tiredness to other members of the tribe thousands of years ago.
for more: http://thezenstones.blogspot.com/2011/11/why-is-yawning-contagious.html
Minnesota.
none
Yawning is not a disease.
if rude and yawning are defined as such i don't see any reason why the act of yawning be rude. yawning is physiologic. would urinating and defecating be rude also?
main
Maine
Texas
The cause in not know.
Yawning too much can prove to be fatal. My aunt didn't sleep for a week, kept yawning, and died. You're in trouble
texas
jamaka
Contiguous is pronounced kon teeg yew us