I consider myself Paleo and love the concept, but there are just so many things about the "Paleo Diet" that simply make no sense. One of them is that tubers (root foods) are great and whole grains are pure evil. The reasoning is that tubers were used by Paleolithic peoples, which is true, and grains are a more recent invention - also (largely) true.
But I have big news for all the Paleo folks who hold to these silly rules: Grains Are The New Tubers! The anti-grain, pro-tuber bias is just silly for two important reasons:
The real truth is that Paleo folks may want to eat tubers and pretend that they are modern hunter gatherers, but, if they're honest, they'll admit that those kind of goods just aren't accessible in general. So what can they do as a rock solid substitute? That's right - just plug in whole grains (sans wheat in my opinion) and they have a "modern tuber". This is why grains have done so well in study after study: they are simply modern foods that are virtually identical to what we are used to eating for aeons. (See my page on The Many Benefits of Grains to Your Sex Life for more information.)
NOTE: I personally avoid wheat, because has been significantly modified - not GMO'd I should point out - and is also higher glycemic. There are other potential immune-related issues associated with wheat as well. For more information, see my page on Wheat Belly Review by Dr. William Davis.
To show you wheat I mean, let's look at two widely accepted Paleo foods: blueberries and sweet potatoes. The Paleo community seems to generally recognized that hunter gatherers ate tubers, which includes sweet potatoes, and berries as common staples. And that makes sense, because these are very healthy foods. Interestingly enough, some Paleo leaders do not like sweet potatoes, but their argument is weak because one very healthy primal culture consumes them as a staple!
Regardless, notice their general macronutrient profile below: calories close to 200; sugars pretty high in the 13-26 gram range; glycemic load quite low and < 20; fiber in the 5-10 gram range; carbs around 40 grams, etc.
Both of these are clearly superhealthy plant foods. Now look at the macronutrient profiles of two whole grains, quinoa and millet:
I am sure that you noticed that these two supposedly wicked and health-destroying grains are almost identical to the Paleo-beloved sweet potatoes and berries. Notice, in particular, that the glycemic load, carbs and fiber levels are all very similar. Furthermore, notice that the grains have 0 grams of sugar!
The point is that if you want to eat "Paleo" or primal, all you really have to do is look for low fat, low glycemic foods. It's really that simple. One of the books that I think is truly Low Fat Paleo and has tons of great information is the The Pritikin Edge . This book on Low Fat Dieting by heavyweight Low Fat leaders allows for low fat meats and total fat more in the 20% range - very similar to many of the supercultures that I spoke of above.
The bottom line is quite worry about which tubers, fruits and/or whole grains are "Paleo". If they are low fat and low glycemic load, then you are in good company almost for sure.