10 May, 2013

Sago palms in ancient China

Just now I've read this paper.
  • Yang, X., H.J. Barton, Z. Wan, Q. Li, Z. Ma, M. Li, D. Zhang, J. Wei. 2013. Sago-Type Palms Were an Important Plant Food Prior to Rice in Southern Subtropical China. PLoS ONE 8 (5): e63148. doi:10.1371/journal.pone.0063148
Usually I don't write any comments about any papers into this blog, but this paper is very helpful for our starch studies in Japanese archaeology. That's why I'm writing my impressions here. 

In my opinion, this is a nice paper for exploring plant food prior to domesticated rice.

One of the authors, Dr. Barton is a specialist of starch residue analysis (and a colleague of my supervisor Dr. P. J. Matthews).

Based on their analysing data sets of starch granules and phytoliths, during 3,350-2,470 aBC humans exploited sago palms, bananas, freshwater roots and tubers, fern roots, acorns, Job's-tears as well as wild rice.

In terms of starch residue analysis. 

[Methods]

This paper shows all of sampling procedures and treatments of residue samples as well as how to avoid a contaminated problem "starch granules into sediments".

I haven't looked at sediment samples in my studies yet, and now I'm analysing residues from natural stones for comparing those of archaeological stone tools. I have to do this kind of sediment analyses as soon as possible.

[Taxonomic identification] 

This paper conducts taxonomic identification of starch granules, and its method is not so problematic.

Figure 3 shows starch granules recovered from residues on their sampled stone tools. I haven't seen these shapes of starch granules in my case studies excluding "m", but some of granules can be very similar to starch granules of modern lotus, arrowhead, and water chestnut in my reference starch collection.

In Figure 5, some of extracted starch granules were identified as acorn starches (Quercus sp.). My impression is same as those of the authors. In my Japanese cases, I have found similar morphological features of starch granules taken from Palaeolithic and Jomon stone tools. 

As the most important point, this paper shows a problem of "taro starch". No starch granules from taro were recovered, and the authors present 2 reasons about this result. 

"One reason is the taro granules are too small to detect under the microscope and no phytoiths are produced by this plant. The other reason is that the taro was not be used at the time."

In my archaeological case studies, I haven't seen any taro starch granules. This might be due to the above 2 reasons.

[Conclusion of my comment]

Overall, this paper is a challenge to explore plant food prior to the spread of domesticated rice southwards from the Yangze River region using analyses of starch and phytoliths. Also, it shows all of procedures and interpretations unlike some of recent starch papers. 

Analysing methods and interpretations of starch granules are very similar to my studies, and so these results make me rethink about my case studies in Japan.

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