4 AM
- Honey, I'm hungry.
- Why are you eating so much lately?
Yeah, 4 AM and craving for food, in this latitude we are in that tmei of the year where our head tells us "stockpile some calories! Winter is coming!" [1].
Source. Yet, the ORIGINAL source remains unknown.
Lets round up that humankind became sedentary around 10000 BCE (this is a VERY rough round up, since there's tens of thousands of years from place to place on Earth).
This means -since that time- humankind did not have to worry about "stockpiling calories" because food was no longer as scarce as it was when we where gatherers-hunters. 12000 years without having to worry about "what will we eat today" were just not enough to suppress that feeding frenzy we cope with every, singe, year.
For around 600 human generations we lived and thrived thanks to the abundance of food. If we had the data, a child could memorize his/her entire genealogy back in time until the stone age. After all, some children memorized all 802 Pokemon... 600 names should be a piece of cake.
Around the same time we became sedentary, we domesticated dogs. They've come a long way too, with over 12000 generations in their budget, we helped them "evolve" into useless yap machines.
Today, those yap machines cannot survive on their own. My guess is, in around 12000 human generations, we'll be able to get rid of that unnecessary instinctive hunger we have; this is, in 360000 years.
In the meantime we'll have to rely on a strong will, or in one of these:
Source