...sweet potatoes are generally orange tubers that are the root of a plant that is similar to a morning glory(they are in that family), they are native to south america, they are also considered night shades....
The sweet potato "belongs to the family Convolvulaceae" (
http://en.wikipedia.org/wiki/Sweet_potato), not solanaceae, aka nightshade (
http://en.wikipedia.org/wiki/Nightshade) like white potatoes (
http://en.wikipedia.org/wiki/Potato).
Like you said, true yams are native to Africa and Asia. The so-called "yams" most commonly sold in the USA are actually a variety of sweet potato:
"Why the confusion?
In the United States, firm varieties of sweet potatoes were produced before soft varieties. When soft varieties were first grown commercially, there was a need to differentiate between the two. African slaves had already been calling the ‘soft’ sweet potatoes ‘yams’ because they resembled the yams in Africa. Thus, ‘soft’ sweet potatoes were referred to as ‘yams’ to distinguish them from the ‘firm’ varieties.
Today the U.S. Department of Agriculture requires labels with the term ‘yam’ to be accompanied by the term ‘sweet potato.’ Unless you specifically search for yams, which are usually found in an international market, you are probably eating sweet potatoes!" http://www.loc.gov/rr/scitech/mysteries/sweetpotato.html....african yams must be cooked before consumption
It seems so--at least for the varieties that are commonly cultivated. Does anyone know if African yam flour (elubo) is edible cold (raw)? I only found this, which suggests that the elubo is always cooked, but I wonder if it really has to be:
Another method of consumption is to sun dry the raw yam pieces. When dry, the pieces turn a dark brown color. This is then milled to create a powder known as "elubo" in Nigeria. The brown powder can be prepared with boiling water to create a thick brown starchy paste known as "amala". This is also consumed with the local stews and sauces. http://en.wikipedia.org/wiki/Yam_(vegetable)
Some wild tubers can be eaten raw. For example, the long yam (Dioscorea transversa) of Australia can be eaten raw:
http://www.youtube.com/watch?v=UwklPPEDbWM&feature=channelVideo subject: Australian aborigines
2:14 the goodfellow (long yam, Garrbarda, Dioscorea transversa) "can be eaten raw"
The Hadza only briefly roast their tubers or eat them raw:
"After a few minutes of roasting, a Hadza grandmother splits the charred orbs to expose the softened flesh of the nutritious, starchy tubers." (ibid)
Tubers eaten by the Hadza are usually roasted for about 5 min (Mallol et al., 2007). Nevertheless, they are quite willing to eat them raw. Hadza women often say they roast them because it makes them easier to peel. This reason for roasting is also noted in the ?lm ‘‘The Hadza’’ (Hudson and Woodburn, 1966). However, the Hadza sometimes say roasting tubers makes them taste better (though to us the change in taste is slight). (Tubers as Fallback Foods and Their Impact on Hadza Hunter-Gatherers,
http://www.anthro.fsu.edu/people/faculty/marlowe_pubs/Tubers%20as%20Fallback%20Foods%20and%20Impact%20on%20Hadza%20AJPA.pdf)
According to the report, the most common wild African tubers that the Hadza eat raw (and lightly roasted) are the tubers of legumes, rather than Dioscorea (yam) herbaceous vines, and include:
Staple Hadza Yams (All Edible Raw)Hadzane name - Scientific name; Notes
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Matukwayako - Coccinea surantiaca or aurantiaca
Penzepenze - Vigna sp. (Papilionoidea Leguminosae); leguminous plants whose flowers have butterfly-shaped corollas
//Ekwa hasa - Vigna frutescens; Perennial prostrate or climbing herb, growing from a woody rootstock; hatitat is seasonally burnt grassland and woodland (
http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=132190); sweet and juicy and can be eaten raw ("Early Hominids Dug Food from the Ground," New Scientist Dec 12, 1985); woody perennial legumes
Do’aiko/Shakeako - Vigna macrorhyncha; woody perennial legumes with round, potato-like tubers; sweet and juicy and can be eaten raw ("Early Hominids Dug Food from the Ground," New Scientist Dec 12, 1985)
Shumuwako - Vatoraea pseudolablab; sweet and juicy and can be eaten raw ("Early Hominids Dug Food from the Ground," New Scientist Dec 12, 1985); woody perennial legumes
------------------------------
Although the Hadza eat game meat regularly, they also collect berries, honey and several types of tuber. [Anne Vincent, a postgraduate student at the University of California at Berkeley] is in no doubt that with the aid of simple technology--digging sticks--and with a reasonable but by no means excessive amount of work, these people get good value for their tuber-digging efforts. The tubers need little preparation before eating; they can be eaten raw though the Hadza mostly prefer to roast them slightly, and they represent a very good and reliable source of nutrients throughout the year, if needed (World Archaeology, vol 17, p 131).
Tubers of five species of woody perennial legumes are collected (mostly by women) in Vincent's study area around Mangola near the seasonal Barai river and floodplain. All are rich in carbohydrates, are juicy and sweet, and need only peeling before being eaten raw or roasted.
Those of Vigna macrorhyncha and Vatovaea pseudolablab (called by the Hadza do'aiko and shumuko) are rounded--rather like potatoes--and grow no deeper than about 50 centimetres. Vigna frutescens has elongated tubers which the Hadza call // ekwa hasa or // ekwa gadabi [I believe the //'s are click sounds] according to which side of the river the plant grows. The Hadza women need to dig, sometimes down to 1.5 metres, to find these tubers, but can still obtain up to 5 kilograms or more of them for each hour's work. Each kilogram of tuber contains an average of 780 calories. The digging sticks take about 4 minutes to make with the aid of a steel machete, and last for about eight digging trips.
The women think nothing of walking upt to 8 kilometres from camp to dig roots, to gather berries and collect water[,] although, usually they need to go less than 5 kilometres to do so. ("Early Hominids Dug Food from the Ground")
Some domesticated tubers can also be eaten raw, such as jicama (also a legume tuber), yacon, Jerusalem Artichoke and Chinese Artichoke (if you are intolerant of inulin beware that these tubers contain lots of it).
http://www.youtube.com/watch?v=n4wWdXctTHkhttp://www.youtube.com/watch?v=SFmGvzDfvew&feature=relatedSo at least five of the species of tubers that can be eaten raw are from legumes: jicama, Vigna sp., Vigna macrorhyncha, Vatovaea pseudolablab, Vigna frutescens. By Ray Audette's definition of Paleo (anything that you could obtain naked, with nothing more than a sharp stick--in other words, unprocessed foods that can be eaten raw), these legumes would appear to qualify as Paleo and thus his and Dr. Cordain's exclusion of all legumes from the category "Paleo" may be incorrect based on Ray's definition. However, just because you can eat something raw, with nothing more than a sharp stick to obtain, doesn't necessarily guarantee that it's healthful (peanuts and green beans are also legumes that can be eaten raw and most Paleos agree that they're not healthful), but it is interesting that the Hadza eat legume tubers as staple foods.
Ancient African hominins probably ate tubers long before the advent of cooking. Researchers analyzed the teeth of Australopithecus anamensis, "a hominid that lived in Africa 4.2 to 3.9 million years ago," and hypothesized that it "consumed a lot of root vegetables, nuts, insects [such as termites] and some meat [and probably mushrooms]." ("Early Humans Skipped Fruit, Went For Nuts"
http://news.discovery.com/human/human-ancestor-diet-nuts.html) 3.9 mya is well before even Wrangham's extreme early claim of hominin cooking (roughly 1.8 mya).
http://www.youtube.com/watch?v=GMvprzmkz9o&feature=player_embeddedVideo dramatization, in Spanish, of Australopithecines digging up and eating raw underground storage organs and then scavenged meat.
Translation of a comment from Spanish:
"When there is the seasonal fruits and tubers roots [a primate] group seeks to replace them. The Australopithecus [dominated by adapting] a varied diet [and had] different adaptations for feeding: hands became agile and dexterous since they no longer were used for walking, thick enamel on teeth [developed] to help them withstand [tough], dirty food, and grit. The australopithecines may have used basic tools such as digging sticks. They were not born with that skill."
'Australopithecus occupied a very similar environment to Paranthropus but had a varied diet all year round - including fruits, tubers, probably some insects, termites and animal prey,' says Dr Gabriele Macho, honorary professor in palaeoanthropology at the University of Bradford. ....
[T]he Australopithecus had all-purpose teeth, suited to vertical crunching and lateral grinding. 'Their teeth were more versatile and more resistant to wear,' she adds. 'Their diet probably included tough vegetables and tubers soiled with dirt, as well as some meat.' Such a high-quality diet was the pre-requisite for the subsequent evolution of our large brains. (What did early humans eat? 10 August 2009,
http://planetearth.nerc.ac.uk/news/story.aspx?id=502)
Some scientists believe that humans have more salivary amylase than other primates like chimps because our ancestors ate more underground storage organs:
"John Novembre et. al. reported in the October 1, 2007 issue of Nature Genetics that human saliva has significantly more of the enzyme amylase compared to chimpanzees. Amylase breaks down starches into glucose which can be readily used by the cells of the body. With more amylase, humans get more useable calories from starchy vegetable foods such as tubers, corms, and bulbs. The authors suggest that this would have been a distinct advantage for early humans because these foods are readily available. They believe that natural selection favored additional copies of the gene responsible for amylase production (AMY1) in our early hominin ancestors but not in apes." (Analysis of Early Hominins, anthro.palomar.edu/hominid/australo_2.htm)
Even chimps eat raw tubers:
"Chimpanzees prefer to dig for tubers and roots even when aboveground snacks are plentiful. ... Anthropologists had thought the roots and tubers only served as fallback foods for chimps during the dry seasons when sustenance was scarce." (Did our ancestors prefer meat, or potatoes? Findings show that our relatives liked to dig up underground foods,
http://www.msnbc.msn.com/id/21775270/ns/technology_and_science-science).