While it is clear that humans populated almost all areas of the planet, it is rare to find even land-locked cultures where fish was not consumed. Humans preferentially settled by oceans, lakes and rivers, and not much has changed to this day in our settlement patterns. There is a good chance we have the fabulous brains that we do because we hung out by rivers and oceans and ate pretty much anything that moved around in those waters. So whether our ancestors were aquatic apes, river apes, or shore-dwelling apes, we found a ready supply of what our brains needed in the water. Had human populations on the planet remained at 950 million or so, then our brains’ love of seafood, lakefood and riverfood would not likely have outstripped supply.