Passage Summary: We found cow bones in a dry area where no other big animals lived, even though people were there. Since wild cows would have needed water holes that attract all sorts of animals, these cows must have been raised by the people.

Conclusion: The bovines found in this arid region were domesticated, indicating that the local people were not just hunter-gatherers.

Reasoning: The region was dry and lacked other large mammals; since natural water sources would have attracted a variety of large animals, the bovines must have been provided water by humans.

Analysis: The argument relies on a 'Gap' between the absence of other animals and the conclusion of domestication. It assumes that if the water were natural, other large mammals would have inevitably left remains there. It also assumes that the bovines couldn't have survived on some resource that other large mammals couldn't use. Look for an answer that confirms the bovines' survival was dependent on human-controlled water or that other animals would have definitely been present if the water were naturally occurring.