Recently I have been pondering how we should eat if higher protein increases all-cause mortality and higher carb diets increase all-cause mortality, so I've come up with my seasonality hypothesis: basically we would experience periods of lower carb or lower protein diets historically, which would engage each of these various beneficial pathways we have.
For instance, and this is my hypothesis: we wouldn't eat wooly mammoth for breakfast lunch and dinner every day, we would eat nothing but it for three days, once a month. Dense carbs would come sporadically ("yay, we found a bee hive" twice a year) and fruits (carbs) would blossom in either only spring or fall.