A break from the normal Pyromaniac Chef Blog. It’s not written by Kathryn and it’s not about cooking as such. However it is about fire, but from an Archaeological perspective.
The morning started at the Archaeology Department building and when we’d all assembled, we walked over to the Harris Gardens, a lovely part of the University campus, that I’m ashamed to say I haven’t visited before. We were introduced to Rob, a member of the Archaeology Dept staff, Becky, a PhD student and Mark, an undergraduate student.
Rob started by discussing the role of fire. Why was fire important to our ancestors? Cooking seemed to be the obvious one, though it seems it took us 100,000 years to figure that out, but also warmth, warding off predators, as a social centre for people to gather and light to extend the working day were others. As a result it’s thought that this is a major part of the reason why the human race has evolved to have the average of 8 hours of sleep regardless of where in the world they live, whereas all other primates adapt to the number of hours of daylight. There is evidence that early man was using fire 200,000 years ago but that signs of cooking can only be traced back 60 or 70 thousand years ago when tool use was first discovered. That’s not to say that we didn’t cook our woolly mammoth steaks over fire before then, but that there is no evidence of that happening.
The archaeologists then took us through the various ways of starting fires. Despite what we might think today, lighting fires was actually quite difficult for our ancestors to do. We were shown samples of fire lighting materials, including bull rush seeds, paper birch bark and the lovely named King Alfred’s cakes, a type of fungus. Mark also showed us the different tools he has been using to try and start fires. Iron Pyrites (the substance you might know as fool’s gold), flint, a modern day fire steel and the good old stick rubbing method.
(The University Facilities management had obviously felt somewhat nervous about the request to start fires in their grounds, but after the various Risk Assessments had been done, granted them permission to build some small fires in the corner of the Harris Gardens.)
Mark started by trying the stick method. This involves cutting a notch in the side of a flat piece of soft to medium hardness piece of wood. This is to allow the hot ash to fall down and collect on the side of the ‘plank’. Next a hard wood stick is cut. The stick is then spun using the palm of the hands to burn a hole in the plank just above the notch. As the stick is spun more and more a pile of hot ash starts to form and is collected on top of a pile of dry material where it should eventually get hot enough to start smoking. It’s quite a long process at the best of times, but in colder, damper weather, it is next to impossible to get a fire going this way. I watched the San people of Botswana start a fire this way last summer and it took them about 5-10 minutes, in much warmer, dryer conditions, so he really had no chance. Mark, used a variation on this theme using a simple bow to speed up the spin of the stick. After two attempts, with lots of smoke but definitely no fire, he moved on.
Using the modern day fire steel and a King Alfred cake next, he managed to catch a spark. Obviously well practised by now, Mark managed to coax the cake to smoulder and added some reed seed heads to help get the fire going. Eventually, after much encouragement, huffing and puffing, (with Mark getting a lot of smoke in the face) the kindling caught light and we had a fire.
This all hammered home the point that starting a fire wasn’t easy, so once a fire was lit it was important to keep it going. This had a huge social impact on early humans, as they had to trust someone to stay with the fire to keep it going while they went off hunting and gathering, while whoever was looking after the fire had to trust the rest would come back with food. There is also the effort required to gather enough fuel to sustain the fire. A Swiss study using GPS trackers to record the distance covered by a group of volunteers collecting fire wood from a forest found that as much effort was expended searching for the fuel as was gained from it in eating the cooked food prepared on the fire.
Then Becky started to talk to us about the archaeological evidence for fire. It is difficult to find as much of it ends up being burnt! The ash is then blown or washed away. There may be traces of animal bone, burnt grain and flint tools etc. but these are very small and difficult to find. Hence Becky has been looking at other ways to determine whether a fire has been set, by testing the effects of fire on the sediment underneath it, using clay soils, fluvial sand and coastal sand. The fire causes chemical changes that can be picked up by magnetic susceptibility testing and it also causes a change to a more reddish colour, dependent on the iron content of the sediment.
However on the clay sediment this typically only extends a few millimetres down. Hence it is very unlikely that we will ever find an ancient fire site on this type of ground. Fluvial (or river) sand looks like our best bet as the fire impacted on the structure of the sand to a much deeper level. She is also looking at the effects of repeated fires on the same base. She uses temperature probes to determine how hot the sediment under the fire gets at various depths. For consistency they were also using the same fuel, seasoned birch wood, each time.
Then time for some hands on experience. They had set a couple of fires the day before and had cooked a couple of fish and some pork chops on them (hunted down in the local supermarket). We were invited to have a rummage around using sophisticated tools (i.e. the blunt end of a toothbrush) to see what we could find in the cold remains. Various bits of bone and flint were pulled out, but it was obvious they were very delicate and would not have survived very long, certainly not thousands of years after the event.
We were then taken back to the lab, and were shown various samples of burnt bone, burnt flint shards and sediment samples from previous fires.
What was obvious throughout was the draw to the fire Mark had started earlier. There were always a couple of people sat round it, practicing with the flint and steel and trying to light their own fires. It wasn’t a particularly cold day either. Humans are just drawn to fire it seems, and some of us (like me) particularly like cooking on it.