Starch Grains and Seed Grinding

What did early humans eat? Well, probably they ate a lot of different things, depending on where they lived, just like modern hunter-gatherers. Humans have a remarkable ability to subsist on everything from frozen seal meat to flowers, and the diet that makes us healthiest combines several different kinds of food.

So here's a more precise question: how greatly did the adoption of agriculture change the diets of the first farmers? The basis of farming in most parts of the world is grain -- wheat, rice, corn -- so farmers eat a lot of grain. How much grain did hunter-gatherers eat, especially in those areas where farming was invented? Possibly quite a lot. The basic evidence for this is prehistoric grinding stones, which are quite common on pre-agricultural sites; above is one my crew found on a site in Washington, DC.

A new study out this week in PNAS offers further evidence for grain grinding in the Paleolithic, around 30,000 years ago. The authors studied possible grinding stones from three sites, one each in Italy, Russia, and the Czech Republic. They were looking for starch grains, and they found grains that they say derived from both grasses and the roots of a marsh plant similar to cattails. The identification of starch grains is a cutting edge technology right now. Starch grains are microscopic lumps of starch that most starch-storing plants create; they should be chemically very stable in neutral soil (not too acidic or basic), and different plants create grains of differing shapes. So this is a very promising new technology for studying past diets and environments. But I caution everyone that the technology is new and others that seemed equally promising (e.g., protein residue analysis) have proved to be misleading.