写了篇argument（33），请指出错误和建议，万分感谢啊！！！

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ARGUMENT33 - The following report appeared in an archaeology journal.
"The discovery of distinctively shaped ceramic pots at various prehistoric sites scattered over a wide area has led archaeologists to ask how the pots were spread. Some believe the pot makers migrated to the various sites and carried the pots along with them; others believe the pots were spread by trade and their makers remained in one place. Now, analysis of the bones of prehistoric human skeletons can settle the debate: high levels of a certain metallic element contained in various foods are strongly associated with people who migrated to a new place after childhood. Many of the bones found near the pots at a few sites showed high levels of the metallic element. Therefore, it must be that the pots were spread by migration, not trade."
The author points out the fact that high levels of a certain mtallic element contained in various foods has something to do with people who migrated afer they are born and the fact that bones near pots has high levels of the metallic element. Then, the author concludes that the pots were spread by migration, rather than trade. Close scrutiny of each of these facts, however, reveals that none of them land credible support to the conclusion.
Firstly, the argument falsely concludes that the bones' owners were migrated from one same place. Maybe people born in other different regions will have the same metallic element, or it is entirely possible that the native people also had the certain element. The fails to substantiate that the certain metallic element is from a unique region, therefore, there remain possibilities that the bones' owners were from different regions. Without ruling out the possibility above, therefore, the author cannot  confidently conclude that the bones' owners were migrated from one same place after childhood.
Secondly, even it is possible to substantiate that the bones' owners were from the same place, there maybe no relation between the people and the pots. Maybe the pots were left long time after the person were buried at the certain place. The only relationship between them is that the pots and the bones' owners were found in the same place. The author provides no clear evidence that the bones' owners were the host of the ceramic pots. In a word, the mere fact that they were found in the same place hardly suffices to prove that the pots belongs to the bones' owners, at least not without more information about the the relationship between the pots and the bones' owners.
Finally, even assuming that the pots belongs to the bones' owners and the people are migrated from one same place, the author overlooks the possibilities that the pots were not taken from the place where the owners were born. Maybe they are bought in native place, or they are from other places for commercial reasons. But the author dose not provide any clear credible information about the producing area of the pots. If either is the case, it is apparent that the pots are spread by other ways rather than migration, therefore, and it is too hasty to conclude that the pots were spread by migration, not trade.
In conclusion, the assumption that the pots were spread by migration is not well supported. To convince me that the pots were spread by migration, the author must provide clear and reasonable evidence that the people were migrated from one same place and the pots beside them were taken from their hometown, rather than relying on questionable information and deduction. To better evaluate the argument we would need more information about the producing region and the connection between the bones and the pots.

(2009-08-08 23:08:11)