Phonosemantic compound. ⺼ represents the meaning and 古 represents the sound. Based on the original meaning "flesh under the chin of a cow", which later shifted to "beard" (now written as 鬍 in traditional characters). Also used pejoratively to refer to foreigners from central Asia, who tended to have more beards than Han Chinese people. This meaning also shifted to "reckless" and "outrageous".

Evolution

Bronze script

Late Warring States (~250 BC)

Seal script

Shuowen (~100 AD)

Regular script

Modern