Humans arrived in the Kaliko Islands about 7,000 years ago, and within 3,000 years most of the large mammal species that had lived in the forests of the Kaliko Islands were extinct. Previous archaeological findings have suggested that early humans generally relied on both fishing and hunting for food; since archaeologists have discovered numerous sites in the Kaliko Islands where the bones of fish were discarded, it is likely that the humans also hunted the mammals. Furthermore, researchers have uncovered simple tools, such as stone knives, that could be used for hunting. The only clear explanation is that humans caused the extinction of the various mammal species through excessive hunting.

Write a response in which you discuss one or more alternative explanations that could rival the proposed explanation and explain how your explanation(s) can plausibly account for the facts presented in the argument.