What’s wrong with this sentence? Most style manuals agree that there is a problem here. When two independent clauses are connected with a comma without a conjunction, a comma splice is the result. An independent clause is a clause that can stand alone as a sentence. There are several ways to resolve this situation. The easiest way to fix the problem is to separate the two clauses into two sentences.
Pirates have nasty attitudes. This is frequently the result of wearing their pants too tight.
Another way to resolve this problem would be to combine the two clauses with a conjunction such as or, but, or and. The addition of the conjunction makes one of the clauses dependent on the other.
Pirates have nasty attitudes, but this is frequently the result of wearing their pants too tight.
A third way to fix the problem is to use a semicolon. This is only possible if the clauses are independent. Semicolons are frequently misused so be careful with them.
Pirates have nasty attitudes; this is frequently the result of wearing their pants too tight.
For a clear and succinct description of how to use a semicolon, visit The Oatmeal