The excavations at Howick revealed a layered series of hearths within the Mesolithic house. The remains preserved within these hearths allow us a unique glimpse into our very distant past.
Shells of hazelnuts, well preserved because they had been charred, provided some of the most important evidence for both the way in which the house had been used, and for how long. The massive number of shells suggest that huge quantities of these nuts were being gathered and preserved here. Could this indicate the house was in permanent occupation? Some hearths seem to have been dedicated solely to this task also raising the possibility that the site was a seasonal production facility, annually preserving a stock of food for the winter.
Radiocarbon dating relies on measuring the radioactive carbon absorbed during their lifetime by all living things. When life comes to an end the absorbtion also ends and the radioactive carbon within the organic remains begins to decay. However this decay happens at a predictable rate. By measuring the radioactive carbon residue we can begin to measure the age of organic material. However this picture can become a little confused. A tree, for example, will absorb its carbon throughout its life, with the result that the inner ring of a large tree may be hundreds of years older in radiocarbon terms that the outermost ring that grew the year the tree died.
This is where nuts become very useful. Nuts grow and get picked (or fall) in one season. This is all part of being a nut and makes them ideal for accurate radiocarbon dating. From an archaeological point of view it also helps if you have a good number of well preserved samples. Like at Howick...
It was realised that the nut shells uncovered at Howick offered a unique dating opportunity. There were thousands of samples to choose from and the best part was that there was a sequence of hearths from inside the house, one on top of the other. Fate smiles upon the archaeologist at Howick and even allows some of the hearth layers to be separated by layers of clean sand.
So, at Howick, we have a definite order in which the dates from individual hearths should fall. This would help to narrow down the range of each date. Had 20 samples from the interior of the house been dated without knowledge of their order, then the best that could probably have been hoped for would have been to say that the house fell within a 400- or 500-year date range. With the information from the sequence, possible only because the house had been so carefully excavated, we are able to state that the house was built in about 7,600 BC and, even more remarkably, that it had been lived in for perhaps as long as 100 years.