OK, so after my post of day before yesterday juxtaposing Grace Liu being a normal inquisitive soul with cool ideas vs. whatever it is she's going on about on her blog, I was watching comments and seeing one after another deleted that inks to her own writing. Duck got one comment to stick.
You know I have a lot of respect for you, but your assertion that raw starches are not ancestral is extremely weak and is in no way supported by the anthropological literature. It's sloppy.
For instance, using 5 "ancestral" species of bacteria that are inherited from non-starch eating primates as proof that raw starch is not ancestral is a logical fallacy. It's very misleading.
Humans eat starch. Primates do not. Therefore, raw starch is not ancestral? I'm afraid you will need to do better than that.
It's well known that USOs are extremely important to human evolution, for millions of years, and it's more than a little odd that you would try to claim that only "cooked" USOs were eaten when they were perfectly safe to eat raw.
Tiger nuts are just one example of a sedge tuber that has had a close relationship with humans since the dawn of humankind. The tiger nut is safe to eat raw and was one of the first cultivated plants in Ancient Egypt. Even today, kids in Europe snack on raw tiger nuts as candy and the Valencians drink their raw horchata as a medicinal superfood.
Paleo Indians at Mashantucket were shown to have yellow nutsedge (weedy tiger nut) starch all over their tools. To suggest that these sedge tubers, which were perfectly safe to eat raw, were somehow only eaten cooked will require far more assertive evidence than a short poorly-researched paragraph engineered to needle your ex-collaborators.
Not only is there overwhelming evidence showing the importance of sedge consumption by our distant ancestors, but there are plenty of studies showing a variety of different sedge tubers consumed by H. Sapiens.
For instance, here is a study that was published last week!
The Middle Stone Age ended ~50–25,000 years ago. To suggest that sedge tubers were only eaten cooked is like suggesting that pecans were only eaten roasted. It's preposterous.
As you can see, there are a wide variety of raw sedge tubers besides tiger nuts out there. I hope you don't plan on trying to discount the raw consumption of every USO that's ever been classified.
I was interested in the new study. Someone found the full text for me right under a tattered pillow with lots of dog hair stuck to it. The abstract is online.
Nuts for dinner? Cladium mariscus in the Middle Stone Age at Sibudu, South Africa
The sedge, Cladium mariscus, has been identified in Middle Stone Age deposits at the shelter Sibudu, South Africa, where the leaves were used as “bedding” – an informal floor covering for various activities. Cladium mariscus nutlets were recovered from layers 73,000 – 39,000 years old and are likely to have entered the shelter on the plants harvested for bedding. This paper explores the possibility that, in addition to the use of Cladium mariscus leaves for bedding, the nutlets were collected for food. The underground storage organs and nutlets of many sedge species are eaten by contemporary people and they are known to have been eaten in the past at other sites. Nutritional analysis of the nutlets and rhizomes of Cladium mariscus indicates their potential as a food source, notwithstanding the small size of the nutlets. Although there is no evidence for the preparation of Cladium mariscus for consumption at Sibudu, the abundant nutlets produced by the plants, their nutritional value and the ease of harvesting the nutlets indicate that they could have been a useful dietary item. At Sibudu, as early as 70,000 years ago, the complicated mastic recipes for hafting stone tools indicate that the shelter inhabitants possessed advanced pyrotechnological skills and sophisticated knowledge of the chemical properties of materials. It is possible that these abilities were applied to the processing of Cladium mariscus nutlets. Such activities could imply an early example of intensive collection and possible processing of a particular plant food.
Beyond that, I think the dogs would bark if I gave out the full text, so you'll have to be satisfied with my confirmation bias, unless you know the same dog owner.
Ripe for the picking, would an abundant, easily harvested and nutritious resource have been ignored by people at Sibudu in the Middle Stone Age? The fruits of the sedge, Cladium mariscus (L.) Pohl subsp. jamaicense (Crantz) Kük fulfil these desirable criteria and were available in the uThongathi River, which flows at the base of the steep cliff in which the rock shelter Sibudu is situated. Approximately 12 km down- stream from Sibudu, the uThongathi River reaches the east coast of South Africa and flows into the Indian Ocean. Although Cladium no longer grows near or downstream from Sibudu, it was present in the past (Sievers & Muasya, 2011) and was used for “bedding” – plant material informally laid down on the dusty, stone-littered shelter floor to provide a clean and comfortable surface for a range of activities (Wadley et al., 2011). In this paper I argue that in addition to the use of Cladium leaves for bedding, Cladium nutlets (< 3 mm, single-seeded, indehiscent fruits) were eaten and that even though it is possible to crush and grind the nutlets between one’s teeth, processing of the nutlets at Sibudu is a possible scenario.
So, they ate them, maybe processed them.
The use of Cladium leaves as an informal mattress need not preclude the use of other parts of the plant for other purposes. Sedge nutlets, corms, tubers and rhizomes are widely reported as food in archaeological and ethnographic contexts, in southern Africa and further afield (e.g. Van Wyk & Gericke, 2000; Simpson & Inglis, 2001; Crawford, 2007; Sievers, 2011) and likely were an important dietary item for hominins even in early Pleistocene times (Van der Merwe et al., 2008; Wrangham et al., 2009; Sponheimer et al., 2013). The prolific production of nutlets on individual Cladium inflorescences indicates that the nutlets are an abundant food source and this warrants analysis of their nutritive value; the rhizomes are more difficult to harvest, but their nutrient values provide useful comparative data.
The evidence extracted from the dental calculus has shown the use of fire, and possibly smoke, in all periods. Cooking on an open fire does not always fully gelatinize starch granules. Variable gelatinization of starch granules following open fire cooking). The Hadza, for example, are known to cook their tubers for a very short time, possibly to facilitate peeling and chewing, while leaving the interior of their food raw . Therefore, despite the raw appearance of the starch granules in the pre-Mesolithic samples, they could have come from food items that had been lightly heated...Some of the ‘char’ observed in the calculus samples may also derive from exposure to fires for non-culinary purposes...In the pre-Mesolithic samples...all these starch granules appear undamaged. In some cases starch granules occurred in groups of two or three, still intact and lodged within remains of the thin cellular wall (Figure 2). This suggests little or no external processing...No diagenetic effects  are apparent and the granules display no evidence of any form of processing or heating either in the presence of water (which leads to swelling) or roasting (which leads to drying and cracking); this suggests the plant food may have been ingested raw or after only little heating.
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