I have found that if I let my potassium, calcium and magnesium levels
fall too low, I get heart pounding. When I take a handful of sesame
seeds (210mg Calcium per 1 oz) and have 1 avocado (1096 mg potassium)
the pounding goes away within a few hours. These are the richest sources
I can find for these minerals for their relative carb values. Some
people appear to be able to go for long periods without any symptoms.
Some may never develop symptoms(?). Seafood, especially sardines and
salmon, are good sources of calcium and potassium. With sesame seeds and
avocados not being available on a wide scale to hunter gatherers (surely
not?), is it not possible that the susceptible people may have an
ancestory that was coastal and relied more on fish. eg. Scottish, Irish?
If this was not the case then people would have had to have eaten
relatively large amounts of vegetables to get these minerals. This
would  increase the carb count substantially. With what is
known/speculated about high carbs and disease, the fish sources seem
more plausible to me. Is this correct?