The invention of farming
How did the Neolithic invent farming, and how has it changed since then? Georgia Mills spoke to Cambridge University's Howard Griffiths...
Howard - So when farmers crop land for too long you tend to get that one crop uses similar amounts of nutrients year on year, so you tend to get progressive impoverishment of the soil, and also you tend to get a buildup of pathogens. So the two things tend to mean that progressively yields tend to decline with time.
Georgia - Right. So if I’m having a field of wheat that I wanted to run through year after year, the wheat would eat the same nutrients again and again out of this soil that wouldn’t have any way of replenishing them, and the same diseases that like the wheat as well would be building up year on year?
Howard - Yeah. And it’s exactly what we see in East Anglia here where we have a take-all which progressively reduces wheat yields and that’s why we have to rotate crops.
Georgia - So what’s crop rotation?
Howard - Well basically it means that, under the current example, you grow a single crop perhaps for two years at most before switching to another crop to allow the soil to recover.
Georgia - How does the soil get its nutrients back?
Howard - Well, two ways really. One is that the increased weathering brings in more nutrients from the bedrock and that is, of course, helped by the roots which actually help to digest some of the rocks where the acid water’s going down though. Otherwise through fertilisers that come in. Some naturally as a result of lightning bringing in nitrogen. Others, of course, through manures and that’s where progressively early man probably would have learnt fairly quickly that some form of manuring would aid crop productivity.
Georgia - And so if you replace wheat with something else then also the bacteria or whatever it was that was feasting on the wheat would have nothing to eat and, hopefully, disappear as well?
Howard - Yes, that’s the general idea. Yeah, it just gives a break and so then the land is healthier and more nutrient-rich ready for the crop when you replant it.
Georgia - How long does it take for soil to recover between wheats?
Howard - Well, as I say, currently I think it’s in the region of about a year or so, or a year or two following intensive cropping. Although I believe in the East of England there are some farmers that are able to get through this rather impoverished time and can grow wheat continuously, but it tends to result in lower yields.
Georgia - And this is exactly why the archeologists think the settlements were moving around the landscape. They had only just started to farm so hadn’t hit upon this idea of crop rotation, but they were finding their yields were less and less each year. So after using up all the land around the settlement, it was time to move on. But what kind of things where they farming? Back to Howard…
Howard - Okay. Well, the early evidence suggests that we started to select early wheat varieties. There’s one variety called Einkorn which, as it sounds, it just has a single grain in its ear.
Georgia - Wheat’s quite surprising because if you look at wheat and I guess you don’t realise you can turn it into tasty, tasty bread and pasta. It doesn’t look sort of immediately useful. I’d much rather something I can eat straight away.
Howard - Well, like all of these things, one wonders how much of this was found by accident in conjunction with leaving grains near the fire and so on. But we do know that the early Neolithic man had breads and had found ways of grinding grains to make flour. So it rapidly became adopted I think as a staple diet. We have wheat and barley were early domesticates, but also things like poppy and flax, and some legumes as well so lentils and vetches and so on. Those were the earliest crops.
Georgia - How have those crops themselves been changed by our repeated farming of them? Would they be recognisable I suppose?
Howard - That’s an interesting question. So the extent as to whether the seeds have actually increased. What we certainly have managed to do is select grains with increasing yields but, at the same time, we’ve been able to build on a number of chance hybridisations whereby two grasses accidentally merge their genetics - genetic bases - and that led to this hybrid effect with increased yield. And that has ultimately led us with the characteristic wheat ear that we now recognise; whereas if you saw one of those early wheats you’d scarcely recognise it as a crop that we’d recognise as wheat today.
Georgia - In terms of the farming itself, how’s that developed in the last 10,000 years? I imagine quite a bit.
Howard - Well, indeed. There’s a lot of debate in the UK about the extent that the forests were initially cleared in what’s the Stone Age. But I think, in the UK certainly, we think that the chalk was cleared first, which would have been the uplands because it’s the lighter soil so it’s easier to plough with early stick ploughs and so on, and that would have been cultivated initially. The argument goes that it was only later, about 1,000 years BC or so, that the iron-shod plough came in from Belgium and so on, and that then led to the heavier clays being tilled.
Georgia - What is tilling?
Howard - Basically, it’s a question of having cleared the basic forest. It’s then a question of creating a seed bed because what growing crops is all about is creating a monoculture. And in fact, funnily enough, some of the earliest Neolithic sites have seeds of weeds very characteristic as well, so sort of speedwells that we characteristically find in our flowerbeds and so on today. Presumably, they were weeds that were growing amongst the crops, the barley and wheat, that was being cultivated by those earliest farmers.