Supertypes?

In school we've learned about supertypes. I don't know if the raw
translation is correct so here is an example:
Supertype human with the attributes name,age,size.
Now I can derrive types from it... For example -> employe with even more
attributes like personal id.

Can I realise this in PostgreSQL? And if yes, would anybody please
explain how, or point me to the right documentation?

Thanks and regards, Christian Marschalek