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

In above passage, Author state that after arrival of human in kaliko island,the large mammal species that had lived in the forest of island had become extinct.But,further,based on certain survey done by archaeologists, author claim that human can't have been the factor in species' extinction. And assume that there may be some other factor like climate change or environmental factor responsible for species' extinction.Here,author makes the hasty conclusion based on some unwarranted assumption.

First,Author mention that most of the large mammal species of island become extinct within 3000 year after the arrival of human being.But,here author doesn't show any statictical analysis or any graph that indicate decrease in the popullation of large mammals.author also doesn't mention the number of large mammal before 3000 year and number of large mammal after 3000year.Insted of that,author used the words like 'most' which leads to ambiguity.

Second, Author state confidently that human can't have been the factor in species' extinction on the basis of survey done by archaeologists. In this survey, archaeologists have discovered fish bones but they didn't found any bone of large mammal on numerous sites. Here,also,author make a use of ambiguous word like 'numerous’. it doesn't mean that archaeologists examined all the sites on islands.Hence,this may happen that bones of large mammal may be discoverd on the remaining sites.Moreover,author doesn't give any detail information about archaeologists.

Third, Author state that humans aren't responsible for species' extinct and further assume that some climate change or environmental factor must have caused the species' extinction.Here,author doesn't take responsibility for stating the specific factor like rainfall,temperature,any huge disaster or epidemic disease and how these factor led to extinction.Thus, he doesn't provide standard proof but make the assumption confidently.

Thus, the argument is not completely sound. These assumption and evidence doesn't support totally to the conclusion.ultimetly,the argument might have been strengthen if author could have shown the statistical analysis, specific environmental factor responsible for species' extinct, information about archaeologists.