There are some kinds of foods that are recognized as being extremely nutritive. Some were known in ancient times and are being rediscovered now. some are new. READ MORE http://www.squidoo.com/top_10_superfoods
It may be that in ancient times, primitive people were more prone to eating algae and marine plankton. However, that practice became dormant until just recently, when this practice was rediscovered and re-named "super-foods." Shazzie, the raw food chef in the UK speaks highly of these foods in regaining one's natural vigor.