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 had become extinct. Yet humans cannot have been a factor in the species' extinctions, b

According to the argument, the author suggests that humans cannot have been a factor in the species' extinctions. At first glance, the argument seems persuasive; however, unsubstantiated assumptions lead me to conclude that this argument is flawed on many grounds.

First and foremost, the author assumes that no evidence indicates that humans did not have any significant contact with the mammals. However, we cannot corroborate that humans had no contact with the mammals solely because there is no evidence. What I mean is that, it is plausible that humans did affect the mammals and there were evidences, but archeologists have not found those yet. Even if there has been no evidence in the Earth, it is still possible that humans led the extinction indirectly. For example, they could have all foods for the mammals or get rid of their habitats by deforestation. Thus, the author needs to take into consideration other possibilities that can led the extinctions.

Secondly, another assumption the author makes is that we can deduce that humans did not hunt the mammals because no mammal bones in the conjectural human habitats. Yet we also cannot substantiate that humans did not hunt the large mammals like the aforementioned reason. It is likely that scholars have not found those bones yet. Also, since we do not have solid information on the mammal bones, it is also possible that bones of large mammals can be corrupted more easily than the bones of fish can. This is sound in that the extinction is occurred more than 4,000 years ago. Therefore, it is far-fetched to say that humans did not hunt the large mammals because there is no evidence on that.

Last but not lease, the author falsely assumes that he can conclude that some climate change or other environmental factor must be yielded by the nation, not by humans. However, it is illogical due to the possibility that humans made the climate change or other environmental factors. As I mentioned in the first paragraph, people could make those changes indirectly. For example, they made a mistake caring their fire so they generated a huge fire in the forest. Or they could hunt all the small animals which are the prey of the large mammals. In these cases, since humans made the environmental changes, humans still can be the reason of the extinctions. Therefore, the author should rule out this assumption to make the soundness of the conclusion.

In brief, the argument is illogical in many respects. In order to bolster the argument, the author needs to eliminate unsubstantiated assumptions that humans did not made the extinctions because there is no evidence and the assumption that other environmental factors are only due to the nation.