Ancient cheese found smeared on Chinese mummy

To China now, and the discovery of the world’s oldest cheese. Scientists believed that a ‘Caerphilly’ preserved substance dating back 3600 years that they found smeared on the heads and necks of mummies in the Tarim Basin was a dairy product, but it wasn’t until recent advancements in DNA analysis that they were able to say for sure that they were working with kefir cheese. And sequencing the bacterial genes in the kefir grains - which fermented the ancient milk into cheese - has revealed how they have evolved to become better cheese-makers over the past few millennia. The University of Cambridge's archaeologist Emma Pomeroy is an expert on our ancient ancestors and looked at the study for us. As it turned out, the very mummies mentioned in the study were what inspired her to follow the career she subsequently has!

Emma - The mummies described in this study, they come from what's now northwest China. It's called the Tarim Basin. It's part of the Taklamakan Desert. And they're actually quite famous mummies. They're naturally mummified bodies from the Bronze Age. So we're talking about 3,500-4,000 years ago. And they're a population that I heard about when I was quite young. I remember watching a documentary about them and being really excited just by the richness of the culture. So because of the way the bodies were treated once they died, they were put in some kind of coffins, which were then sealed over with cow hides. This has helped preserve not only the bodies but also the clothes they're wearing. So they've got these amazing kind of felt hats and feathers and little booties and things like that. Really fantastic. Interesting too, because as a people they look different to what was expected for that part of China. So a number of the individuals have quite European looking features, perhaps even blonde hair, and were a bit taller than some of the other surrounding populations. So from that point of view, they've been a bit of a mystery and genetic evidence has actually suggested now that they descend, so they're kind of a remnant, of a very ancient kind of Pleistocene , so ice age, population from North Eurasia who actually have very few descendants now. But even at that time they were kind of a pocket left over of people descended from those ancient populations who were different from the other ones surrounding them.

Chris - They didn't migrate in later and established a pocket in the surrounding population. They were there first and got surrounded by what we would call more modern Chinese populations then. So they were there first.

Emma - That seems a very plausible scenario. It seems like the populations that were originally in that very broad area of ancient North Eurasia were ancestral to these populations.

Chris - So these dairy products that they were involved with, why did they end up on the mummies?

Emma - That's a really good question and I think 'we don't know' is the answer. So it's really interesting the sort of chunks of this kefir cheese kind of around the neck and the head area, why it would be there is really hard to answer. And there's a bit of a standing joke in archaeology that if we can't sort of say what something is for, we just say, 'oh well that's ritual.' And possibly that is, I mean sometimes when there isn't a practical explanation for something, symbolic activity, so a meaningful activity that's not necessarily got a functional purpose to it but has some meaning for the population, perhaps in the way they culturally believe you should treat the dead. That's where the behaviour comes from. It's not to say though that every day things that we do don't have a ritual element as well. You think about sort of how we eat, we use certain implements, we lay the table in a certain way. And that all is a kind of ritual in itself. So things can be functional and ritual at the same time. But in cases where we can't see something clearly functional, it suggests that it's something cultural and symbolic.

Chris - And how have the team that have been studying these mummies, how have they pursued this investigation of the cheese?

Emma - What they've done is they've taken small samples of the cheese itself and they've been able to sequence DNA from the bacteria and from the fungi, and actually even from the animals who produce the milk that the cheese was made out of to be able to tell exactly what it is. And from that they can tell that it is kefir cheese. So when you make kefir, the particular kinds of bacteria involved are different from making other kinds of yoghurt or dairy products. Um, and so they can say that this was kefir that's then been made into cheese.

Chris - And does this therefore give us insights into their husbandry techniques, the sorts of animals they had in what sorts of numbers, how genetically diverse even their herds were? What can we learn from that DNA evidence?

Emma - It helps to support some of the other evidence that we have about their lifestyle. And we can see for example, that they're using both goat's milk and cow's milk to produce the kefir. But usually not mixing it together, which is really interesting, you make it from one or the other, we can then see that they are herding and keeping these animals to be able to have access to that milk. And that fits quite well with the other evidence we have. So things like the animal bones that have been found, the cow hides that have been used to produce the burials, some of the clothing and things like that. So what we've built up is a picture of these as sort of nomadic people who are herding extensively. We can also say a little bit about where those herds originated from. So where did those animals originally come from? And we can say that that's likely to have been in the Caucasus, essentially.

Chris - This is being dubbed the world's oldest cheese, it's the oldest surviving specimen. Do we think this is really some of the earliest examples of making cheese or were people probably doing that for much longer?

Emma - We have good evidence that people were actually making cheese for substantially longer. But this is exciting because it is the cheese itself, which is really remarkable and a rare preservation. But for example in Europe we have evidence that comes from pots, say, from ceramic and they've analysed the tiny traces of the substances that were in the pots that have kind of soaked into the ceramic. And from that they've been able to isolate proteins that come from cheese and those data about 7,000 years ago or so. We have evidence from South Asia as well for sort of early cheese making. But yeah, this is perhaps with some from ancient Egypt, some of the earliest actual cheese itself, which is amazing.