They might be smaller than the point of a pin, but pollen grains are packed with information that endures. Pollen trapped in sediment, or fossilised within rocks, can be analysed by paleoclimatologists to chart changes in vegetation and climate going back hundreds of thousands of years. It was pollen that revealed hazel to be the first of the deciduous forest trees to migrate from what is now Asia Minor and send down roots all over the place in the postglacial period. And in the mid 1990s, archaeologists found evidence of Stone Age nut processing on the Isle of Colonsay, Scotland, in the form of a pit filled with hundreds of thousands of burnt hazelnut shells (similar sites have since been found in temperate climates all over the globe). All of which to say: humans have been enjoying toasted hazelnuts for a very long time.
The original wild species of hazel varied from place to place; their subsequent cultivation resulted in many varieties, from low hedgerow shrubs to genuine trees. While the proportions and taste of the nuts vary, too, the form is the same: a fibrous husk containing a small shell with an edible seed (nut) inside.
