I would like to revisit whether yams are Paleo or not. Yams are one of the
grey-area foods that are not considered Paleo by most, but appear to have
been consumed during the Paleolithic era. I searched past discussions and
did not find the latest evidence and scientific arguments for yams being
Paleo, so I present it below for consideration:


* Wrangham Dates Cooking and Eating of Yams to about 1.8 m ya
  
  Harvard anthropologist Richard Wrangham has proposed that cooking starchy
tubers like yams with fire was the major factor in the evolution of homo
erectus 1.6 to 1.8 million years ago. I am highly skeptical of Wrangham's
views (they fit too nicely with today's politically-correct bias in academia
for one thing), but they are taken seriously so they should be addressed).
[See HUMAN EVOLUTION: Did Cooked Tubers Spur the Evolution of Big Brains?
http://cogweb.ucla.edu/Abstracts/Pennisi_99.html]

* Yam linked to homo erectus finds 400,000 ya and yam digging sticks dated
to 40,000 B.C. by D. G. Coursey, "the preeminent scholar of West African
yams"

> Digging sticks for yams have also been found dating to at least 40,000
> B.C., so these tubers considerably antedated the use of grains in the 
> diet. Coursey 1975, p. 203.

> Erectus finds from northern China 400,000 years ago have indicated an
> omnivorous diet of meats, wild fruit and berries (including 
> hackberries), plus shoots and tubers (such as yams), and various other 
> animal foods such as birds and their eggs, insects, reptiles, rats, 
> and large mammals.

Sources: 
- Coursey, D.G. (1975) "The origins and domestication of yams in Africa."
In: Arnott, Margaret L. (ed.), Gastronomy: The Anthropology of Food and Food
Habits. The Hague: Mouton Publishers. Distributed in U.S. by Aldine
Publishing Co., Chicago, Illinois.
- Coursey, D.G. Yams: An Account of the Nature, Origins, Cultivation, and
Utilisation of the Useful Members of the Dioscoreaceae (London: Longmans,
1967)

* Reasons given by Loren Cordain in 1997 Paleofood discussion for not
considering yams Paleo:

"Inedible" (toxic in their original wild, raw form) and not easily
digestible raw: 
> "The main tubers of agricultural man (potatoes, sweet 
> potatoes, yams, cassava etc) are [were] inedible without cooking 
> because of their high anti-nutrient load and their storage form of 
> carbohydrate. These tubers contain huge amounts of poorly digested 
> starch which becomes more digestible during cooking.  Additionally 
> many, but not all antinutrients are denatured or reduced with cooking 
> and/or processing (soaking in water or leaching in alkaline 
> solutions). The difference between wild edible roots and commercially 
> available starchy tubers is that, the starch content is generally much 
> lower in wild roots and there tends to be more stored sachharides and 
> less toxic antinutrients. Examples of domesticated roots which 
> certainly should be a part of a -modern paleolithic diet- would 
> include carrots, beets, parsnips, radishes, daikon, turnips or any 
> other non-starchy root which is edible and non-toxic in its raw state. 
> Potatoes are clearly inedible in their raw state and there have been 
> more than 30 deaths reported in humans in this century from eating raw 
> potatoes (Slanina P.  Solanine (Glycoalkaloids) in potatoes: 
> toxicological evaluation. Fd Chem Toxic 1990 28:759-61.)."

[Surprisingly, Cordain appears here to admit that starchy tubers are
detoxified by simple soaking--something Paleolithic people were quite
capable of doing. Also, since cooking with fire was available throughout
most or all of the Paleolithic era, Stone Agers could have cooked yams.]

"Yams of African species must be cooked to be safely eaten because various
natural substances in raw yams can cause illness if consumed; the most
common cooking method in Western and Central Africa is fufu. Preparing some
species of yam is a time-consuming process, involving days of pounding,
leaching, and boiling to remove the toxins. Yams may be served fried, boiled
or pounded into a paste." - Wikipedia

> Starchy (high carb), and therefore unhealthy

[Aren't beets fairly starchy too? Ray Audette prohibits beets.]