I think it will be difficult to untangle the causes of core metabolic adaptations. Farming not only increased carbohydrate availability, it also substantially changed the nature of metabolic demands by turning people into draft animals, and changed the seasonal ebb and flow of fat cells. If you want to understand adaptation to diet, look at the systems around unique, rare dietary components. Lactase is the famous example. Another one might turn out to be the vitamin C conservation and disposal systems; some diets are close to deficiency, while others are far beyond sufficiency and require active disposal of the excess.

Selection on dopaminergic signaling systems will probably also be informative. They govern not only motivation and planning (fill that stomach now versus save the seed corn for next season's crops) but digestion and metabolism. Dopamine receptor agonists often both brighten mood and cause weight loss, while antagonists are famous for destroying motivation and inducing obesity and insulin resistance.

As a recent Diabetes2 "operator", I often think about two aspects that are not mentioned here:
1. Some think that "diabetes2" is often better thought of as "metabolic syndrome" (in the same way that global warming is probably more accurately called "climate change") because it is so often connected to disturbance in other feedback loops like management of fats in the body or blood pressure. It might be a form of early aging, system breakdown.

(I like the stress theory, having always chosen occupations with high adrenaline components and usually showing high cortisol in blood tests.)

2. The element of environmental contamination (maybe Teflon in pans or rising ag chemical levels or dioxin -- so many are very small amounts but globally pervasive.)

I also think that the marketing opportunities offered by the diabetes "pandemic" are seriously interfering with both individual health and good science, mostly in the US.

Prairie Mary

Some think that "diabetes2" is often better thought of as "metabolic syndrome"

thems fightin' words! :)

some people also think "metabolic syndrome" isn't worth studying because it's made up of so many different disturbances. the hypothesis, of course, is that the biological networks underlying type II diabetes, obesity, high blood pressure, and all the other components of metabolic syndrome are all interconnected, and hopefully overlap significantly. that remains to be seen.

a note to people who commented on this post yesterday and notice they seem to have disappeared-- a blogger snafu lost the post and your comments. sorry.

I'm taking metformin, which I'm told affects not just insulin efficiency, but also high androgen syndromes and fluid management in the body. To me, that suggests a whole cascade of molecule loops -- but I'm not a scientist and I can understand that isolating ONE effect is the general idea.

No one in my family tree has diabetes, but several female ancestors have bald heads/hairy chins and strong startle reactions even in safe situations.

Prairie Mary