Two articles have come out recently that I’ve seen mentioned in both the regular news and around the blogging world. As a scientist, when I see ‘popular’ media pieces about things like this, I like to go back to original research article. Often what you see reported is a bastardization of the actual research. These two articles are no different.
Hopefully in the next day or two I’ll get to this one:
Revedin A., B. Aranguren, R. Becattini, L. Longo, E. Marconi, M. M. Lippi, N. Skakun, A. Sinitsyn, E. Spiridonova, and J. Svoboda. 2010. Thirty thousand-year-old evidence of plant food processing. Proceedings of the National Academy of Sciences 1-5.
But today I’d like to discuss this one:
Summerhayes G. R., M. Leavesley, A. Fairbairn, H. Mandui, J. Field, A. Ford, and R. Fullagar. 2010. Human Adaptation and Plant Use in Highland New Guinea 49,000 to 44,000 Years Ago. Science 330:78-81.
It doesn’t appear this article is open access. What this means to those of you in the non-science world is that if you want to read this actual article, you’ll have to do some work to get it. The best some of you may be able to do is read the abstract on the journals page. I might be able to hook people up with the pdf if they are interested.
I’m going to attempt to summarize some of the work discussed in this paper and the conclusions and implications it has.
People colonized New Guinea sometime around 50,000 years ago, likely a bit after that. Evidence is not well preserved from this era making work like this difficult. The earliest sites researchers have found are from around 49-43000 years ago. During this time, the climate would have been much cooler, by about 5-10 degrees Celsius. In the sites examined, old tools and starch grains were found.
First, the tools. One major finding were waisted axes. These tools were likely used to clear plant material to either help sunlight reach growing food bearing plants or other useful plants. On some of the tools found, starch grains were found. Translation: some form of agriculture/farming happened in this region.
A word about grains. This is NOT referring to grains in the common usage. This is a scientific usage referring to how plants store starches/carbohydrates, as small globular grains (think tiny sand like things, inside the plant cell). Most of the grains they found were identified to be in the yam genus. The researchers also found Pandanus nutshells, known for containing nutritious seeds. Two simple pieces of evidence point to these findings coming from human sources. 1. Proximity to charcoal, bone fragments and tools (all human associated). 2. No rodent gnaw marks on the seeds.
Unlike what you may have read in the common media about this being some evidence for grain consumption and ‘Go ahead, eat bread!’, this is NOT the conclusion drawn by the authors. First, they state “The preservation of food plant species in open sites of this age is remarkable, and the analysis confirms that Pandanus and yams were used for subsistence in this valley from the time that the earliest colonists arrived”. This does NOT translate to ‘We ate bread’. It translates to – we ate nutrient dense nuts and complex carbohydrates from yams.
The last paragraph is so interesting to me that I’m just going to copy the entire this here:
“Our data show that people occupied a New Guinea valley at 2000 m above sea level soon after their arrival in Sahul (1). As the climate cooled, the optimal growing conditions for yams would have occurred at lower altitudes. This may indicate that Pandanus was the most important staple at this time and help explain the late Pleistocene abandonment of the highland sites. Foraging into this high-altitude environment would guarantee a high return in plant fat and protein to complement local animal foods, the starch-rich yams from lower altitudes, and those foods not preserved in the archaeological record.”
There are a few things I hope you get out of that last paragraph. The first is that Pandanus was likely a major portion of their diet. They also could only grow yams at lower elevations, so as the climate cooled they had to move further down in elevation. And lastly, yams and Pandanus nuts were PART of their diet. The last part of the last sentence? “… and those foods not preserved in the archaeological record”? That’s really important here. We do know A LOT about our evolution from the archaeological record. But there is a lot we don’t know because not everything preserved well. Think about it. If your people are dying out, is your last thought going to be about preserving your heritage so that future people can study you? No, you’re likely thinking about ways you can help your people survive. If some of your tools and such survive for 50,000, so be it.
What I really want you to get out of this whole article is the simple fact that during this period of human evolution, we ate starch rich foods and nuts. Along with a bunch of other foods. Pretty simple.
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