Men first began wearing clothes shortly after Adam ate the apple Eve gave to him from the forbidden tree. After they were forbidden from the Garden of Eden, they began to wear cloths or robes to cover themselves. Further on in history, it was not until the late 1700s that it became fashionable and acceptable for men to wear full length trousers. John Quincy Adams was the first US president to wear long trousers, rather than knee-high britches.
Pants or trousers popped up during the late 19th century. It was started to be seen in clothing ads from the late 19th and early 20th century. The inspiration for the design most likely came from the three-piece ensemble worn by men in Europe in the 15th century.