Passage Summary: We see ancient paintings of war starting only when humans began farming, so farming must have been what caused war to start.

Conclusion: Warfare likely originated as a consequence of the shift toward agricultural societies.

Reasoning: Artistic depictions of war are present in all civilizations from the Neolithic period onward but are entirely absent in the records preceding that era.

Analysis: The author is making a significant leap from the absence of evidence to the evidence of absence. This argument relies on the necessary assumption that if warfare had existed before the Neolithic period, those people would have actually created paintings or engravings of it. Without this link, it is possible that pre-Neolithic people were quite violent but simply didn't feel like drawing their battles. Look for an answer that bridges the gap between the existence of an activity and the existence of artistic records of that activity.