You don't have the necessary information, so you can't know how relevant it is. Diet in the case of past human development may be very relevant to life span. Not knowing how important it is does not equal it not being important.
the methodology of the argument is irrelevant, not the data itself. if we can't pull out and isolate the data, we can't make a (good) argument on the data. but we're not limited to historical studies, we can perform clinical trials which are designed to isolate the relevant variables.
the video i linked was by the study's author as well. he goes through other studies that tried to find the same thing as well as the methodology of the study.
The Battle of the Diets: Is Anyone Winning (At Losing?)
and here's the methodology of the study (the LEARN diet is the one most similar to the USDA food pyramid. but in practice, all the non-Atkins diets ended up grouping together by the end of the trial into "high carb/low fat" with similar ratios):
METHODS
Intervention
Participants were enrolled in 4 cohorts, with the first cohort starting in February 2003 and the last cohort starting in September 2004. Randomization was conducted in blocks of 24 (6 per treatment group) and occurred by having a blinded research technician select folded pieces of paper with group assignments from an opaque envelope. Participants were assigned 1 of 4 diet books: Dr Atkins' New Diet Revolution,8? Enter the Zone,9 The LEARN Manual for Weight Management,18? or Eat More, Weigh Less by Ornish.19
Each diet group attended 1-hour classes led by a registered dietitian once per week for 8 weeks and covered approximately one eighth of their respective books per class. The same dietitian taught all classes to all groups in all 4 cohorts and was rated by participants at the end of the 8-week sessions for enthusiasm and knowledge of the material (rating scale of 1-5, from "strongly disagree" to "strongly agree," respectively). The LEARN program is intended to be a 16-week program and, therefore, the 8 weeks of guidance through this book reflected an accelerated time frame, which was necessary to match the time frame given for the other 3 diet groups. Efforts to maximize retention in the study included e-mail and telephone reminders for appointments, e-mail or telephone contact from staff between the 2- and 6-month and between the 6- and 12-month data collection points, and incentive payments of $25, $50, and $75 for completing the 2-, 6-, and 12-month data collection, respectively.
Each group received specific target goals according to the emphasis of the assigned diet. The Atkins group aimed for 20 g/d or less of carbohydrate for "induction" (usually 2-3 months) and 50 g/d or less of carbohydrate for the subsequent "ongoing weight loss" phase. The Zone group's primary emphasis was a 40%-30%-30% distribution of carbohydrate, protein, and fat, respectively. The LEARN group was instructed to follow a prudent diet that included 55% to 60% energy from carbohydrate and less than 10% energy from saturated fat, caloric restriction, increased exercise, and behavior modification strategies. The primary emphasis for the Ornish group was no more than 10% of energy from fat. Additional recommendations given for physical activity, nutritional supplements, and behavioral strategies were consistent with those presented in each diet book.8?-9,18?-19 The guidelines for the Zone and LEARN diets incorporated specific goals for energy restriction, while for the Atkins and Ornish diets, there were no specific energy restriction goals.
A range of behavior modification techniques were discussed during the 2-month classes. The Ornish and Zone books suggest some stimulus-control strategies but on the whole do not emphasize behavior modification, whereas both the Atkins and LEARN books suggest multiple strategies, such as relapse preparation and planning strategies and goal setting. Overall, the LEARN manual has the greatest emphasis on behavior modification strategies.
re: http://www.proteinpower.com/drmike/obesity/obesity-in-ancient-egypt/
This seems like more bad logic. How many paleolithic remains do they have that are 50year old people? How do they know what Hatshepsut ate? Seems like they can only know what a typical Egyptian diet of the time was. What does the second sentence even mean? And what other factors could there have been for Egyptian rulers to have bad teeth?
to answer the 3rd question in your barrage, "All the conditions that nutritionists today would have us believe would be prevented by Hatshepsut’s diet," means the conventional recommended diet of high in grains (they had it) and low in meats and fats (cattle was spared for labor) and sweets (sugar wasn't invented yet) would lead to a life free of obesity, diabetes, and tooth decay, but Hatshepsut was plagued by all three.
but the rest are really good questions also. we're back to picking apart confounding factors. it is more historical story-making. i guess all i can say is "the methodology of the argument is irrelevant, not the data itself. if we can't pull out and isolate the data, we can't make an argument on the data."
my bad. these type of arguments are so hard to resist. i was just testing you. 
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), and things seemed alright, although we don't know for sure, but since consuming excess sugar like HFCS, things have gone bad. It may be simplistic, and it's nothing new, but it makes a lot of sense. In that respect though, cutting out on rice or pasta entirely seems excessive too, but who knows. 
