relation between ontology

Hi, Dear folks,

Can OWL "unite" all the ontologies? Or OWL is just a way to represent ontology on the Web?

In OWL, there are subClassOf, subPropertyOf, etc. From first sight, it seems that OWL can unite at least some ontology. But giving an simple example.

Suppose someone developed an ontology by OWL, in which "humans" is a class and has "hasGender" as a property (value=male/female). A man could be an instance of "humans" which "hasGender" of "male". It can work well.

Suppose anther expert developed an ontology by OWL too, in which "humans" and "animals" are classes, but "females" and "males" are classes too (can be attached to both "animals" and "humans"), and "men" is just two subclass of both "humans" and "males". It may work too.

But the problem here is HOW to unite these two different OWL files which tell the same ontology?

Thank you!

Yongchun