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. Therefore, some climate change or other environmental factors must have caused the species’ extinctions.

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. Therefore, some climate change or other environmental factors must have caused the species’ extinctions.

In this argument, the writer proposed an idea that though many mammals became extinct after the appearance of human in the island, no evidence about the connection between humans and mammals were found and no bones of mammals were discarded in spite of some fish bones discarded so that humans were not the cause of distinction and it was caused by environmental factors.

First and foremost, the argument is based on an assumption that evidence must be found about the connection between mammals and human beings if there were really connections. This assumption can be problematic. If it can be asserted that the assumption is completed true, the argument would be strengthened, and otherwise weakened.

Second, the passage suggested that bones of fish are found but bones of mammals were not so that human beings did not cause the mammals to be distinct. Whether it remains self-evident can be decided by a question whether humans treated bones of mammals and fish in verisimilitude ways. If the answer is no, it means that humans may have eaten both fish and mammals but dealt with the bones differently, for example, leaving fish bones in places that are easy to find but mammal bones where people nowadays have no or little access to so that archaeologists could not find it. If the answer is yes, the argument would be strengthened.

Last but not least, though the reasoning above are all right, we could not draw the conclusion that the distinction of mammals were the result of climate change. Many factors are causing animals to become distinct. For example, invasion of some foreign animals could destroy the food chain, contributing to the result that some animals have no food to eat and finally die out, which can provide an alternative explanation to the distinction.

In conclusion, the argument is not convincing enough due to the assumptions it is based on/ because of the questions to be answered/based on the evidence to be proven/due to the alternative explanations.