Sentence:  Whether modern, industrial man is less or more warlike than his hunter-gatherer <WSD>ancestors</WSD> is impossible to determine. The machine gun is so much more lethal than the bow and arrow that comparisons are meaningless. 
Meaning of the word marked with <WSD> tags:  (Family members) One from whom a person is descended, whether on the father's or mother's side, at any distance of time; a progenitor; a forefather.