ARG-031

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, because there is no evidence that the humans had any significant contact with the mammals. Further, archaeologists have discovered numerous sites where the bones of fish had been discarded, but they found no such areas containing the bones of large mammals, so the humans cannot have hunted the mammals. Therefore, some climate change or other environmental factor must have caused the species' extinctions.


Write a response in which you examine the stated and/or unstated assumptions of the argument. Be sure to explain how the argument depends on these assumptions and what the implications are for the argument if the assumptions prove unwarranted.


The article attributes the extinction of several large mammal species on the Kaliko Islands to climate change or other environmental factors. The author reaches this conclusion mainly by excluding the possibility of human impact. Unfortunately, her reasoning rests on several unwarranted assumptions, and more evidence is needed to fully corroborate her claim.


For starters, the author does not believe that humans hunting activity could be responsible for the extinction. For evidence. she points to sites where fish bones had been discarded, assuming that, if humans did hunt large mammals, archaeologists would have discovered similar sites with their remains. However, the author hasn’t mentioned what stage archaeological excavation is in, or how much of the islands they have searched. Perhaps researchers are barely starting this project, and have only recently located the site with the fish bones. In fact. most of the islands have not been thoroughly searched so with a more meticulous examination, they might end up discovering animal bones as well. Also, human traditions might have made archaeological excavation particularly daunting. Since fish are relatively small and easy to transport, humans could have caught the fish and brought them all back to their dwellings consequently, all the fish bones would have been discarded at a central location, relatively easy to discover. In contrast, large mammals are difficult to carry, so humans would have had to slice their meat and discard their bones wherever they were hunted. Consequently, their bones would be so scattered that they would be nearly impossible to uncover. Another possibility is that humans discarded fish bones because they were useless whereas they often kept mammal bones. and turned them into ornaments or weaponry. In short, all these possibilities would explain the lack of apparent evidence for human hunting activity.


Granted that humans did not hunt the mammals it is still rash to exclude human influence as a potential factor. True, as she mentioned there was no evidence of direct contact between humans and other mammals, but since the ecosystem is a tight net, with each knot directly affected by other joints, humans could still have been responsible for the demise of these large mammals without directly hunting them. Humans could have depleted populations of important small mammals that were the main prey of the larger mammals. Human’s slash-and-burn agricultural practices might have eradicated local forests, resulting in loss of habitat for these mammals. Thus, without evidence showing what activities the humans were generally engaged in, it is presumptuous of the author to simply eliminate the possibility of human influence.


Now, granted that there was no way humans could have seriously jeopardized the large mammals' subsistence, directly or indirectly, are climate and environmental factors the only remaining alternatives? The author apparently assumes that there exists no third possibility, when in reality, many other forces could have been in play. The spread of a new virus or bacterial toxin could have eradicated the species. Also, the introduction of non-indigenous plant or animal species could have threatened existing ones by competing with them for local resources. It must be added that these factors could have accompanied the arrival of humans, but they could also have occurred independently. Either way they would have sufficiently explained the large mammals’ disappearance.


In short, while the author’s reasoning is superficially reasonable still suffers from several unwarranted assumptions. Without providing more evidence to justify these presuppositions, her conclusion could be undermined by a series of alternative possibilities.



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