In fact Clocks are one of the oldest inventions of the human mind. 4000 years ago in Babylon water clocks (clepsydra) were used. Also in old China. http://www.nist.gov/pml/general/time/images/water_1.gif
There is a 2050 year old Horologia tower in Athen ("Tower of the Winds"):
"This structure tracked a 24-hour day using both sundials and mechanical hour indicators"
Humans have been around for more than 200,000 years (up to 2.5 million years, depending on how you define the term "human"). So even 4,000 years ago is relatively recent on the scale of human history.
"This structure tracked a 24-hour day using both sundials and mechanical hour indicators"