Peruvian excavation

Chris - This week we're exploring the science of archeology, first up Lawrence Owens from the University of London; you've been to Peru and looked at ancient civilisations but how old are the people that you've been trying to understand?

Lawrence - The ones I'm working on are about two and a half thousand to one thousand years old, but they get much older now of course.

Chris - How do they fit into our understanding of how mankind covered the earth and migrated to various places and then took up residence in these various countries?

Lawrence - Well of course the big question is migration from Asia because South American population came across from Asia originally and we're not quite sure when. So these kinds of projects are addressing human variation to see how much variation there is and therefore how long they've been there.

Chris - So looking at their genetic ancestry to see if you can understand who went where when?

Lawrence - Basically yes, first you find out what they were and when you've found out what they were, you need to find out who they were and a bit more about them.

Chris - So these people that lived in Peru, you've already said "Asia" so how would they have got there?

Lawrence - They would've come across the straits during the last Ice Age we think, but of course its much more complex than we originally believed - naturally, as everything is in science - so actually various migrations; there was one much earlier and one much later and so we're talking maybe 15,000 years ago. Someone is arguing that there's a site there from 30,000 years ago, so we're not really quite sure yet but we'll get there in the end.

Chris - So these individuals decided to lock up their dead in sort of time capsules for us to discover today. They mummified them; why were they doing that?

Lawrence - There's various beliefs, the oldest mummies in the world are in fact from Chile and they used to carry them around with them as they're family members and they didn't want to leave them behind. They used to do all kinds of weird things; de-flesh them, tie them together with mud and strips of cloth, then dress them in their own clothes and a lovely mask painted red or white or black, and tow it around for a thousand years or so.

Chris - So these individuals obviously weren't rooted to the spot, they weren't living in settlement so that's why they wanted that mobile mummy if you like?

Lawrence - That's right - a mummy for all seasons! Yes and so they were carrying them around with them for a very long time. But of course these were fisher folk; they're living on the coast in Chile. Later on, maybe two or three thousand B.C. People started settling down and that's when the really flamboyant architecture and so forth linked to mummies, started to appear.

Chris - So what did they actually do in terms of preserving them, how did they in Peru? We've asked about Egyptian mummies, but how did Peruvian mummies end up getting preserved, what did they do?

Lawrence - Often, accidentally they used to bury them in hot sand and that was all it really took. In some cases, the body has been modified; its has been partly de-fleshed or the innards have been taken out or things like that. They never got to the same level of sophistication, if you like, as the Egyptians did with draining the brain out of the nose and all the other disgusting things they used to do.

Helen - So do we think this was a deliberate thing or did they just bury them in the sand like we bury people near where we live today - was it accidental or did they really try to preserve the bodies for a reason?

Lawrence - I find the thing is in both Egypt and Peru as far as you can make out, mummification appears to have happened originally by accident and people then capitalised on that and went on further. So yes, originally it was partly accidental but as time went by and particularly towards the Inca Empire they really made efforts to go the full hog.

Chris - How well preserved are they?

Lawrence - Some of them are phenomenally well-preserved. I mean, the Ice Maiden for example from the top of the Andes is absolutely stunning - she looks as though she could get up and walk away and she's 800 years old or so. Some of them are a bit dicey to be honest, some of the ones from my site are terrible but they're still very informative and so you can find out a great deal about them.

Chris - Can you get DNA from them?

Lawrence - You can.

Chris - Is it good quality DNA?

Lawrence - So far there seem to be good signs, there is no contamination and so forth and so it looks as though we could have a very promising data set from there.

Chris - And does it give you any clues as to the kinds of things they ate, died from, that kind of thing?

Lawrence - Well the DNA - we're normally looking at it for variation purposes, just to see where they came form and what was going on. But things like what they died from are more my area, rather than doing all the genes and all the complex stuff I like to rely on the bodies themselves. I'm looking at their teeth, their bones and their stature and everything else about them to find out what they were all about.

Chris - So what kind of clues can you get from bones and teeth as to what happened to people?

Lawrence - Oooh, how long do you have? Loads of things. Basically you can find out everything about somebody you would find out from talking to somebody apart from their name. You could find out everything about them and also things they wouldn't want you to know and so you're going on a blind date almost and asking all these random searching questions. You can also find out things like how much they actually weigh, how old they actually are and things like that which you could really necessarily ask on a blind date and so its quite intriguing.

Helen - Are you getting a good cross section of the population in these mummies? Or is it perhaps just the elite classes which were getting mummified or are you really getting an idea of what everyone was up to? Is it that everyone was put in the ground in this way?

Lawrence - Well the poshest burials if you like are in these nice and very showy tombs and so we naturally know they're from a certain scree of social group. In my site there is 80,000 burials and people came from all over South America to be buried there. Its as important to pre-Hispanic groups as say Mecca is to Muslims today or Jerusalem to Christians. Therefore we have virtually all parts of society, all of whom wanted to come and be buried or to consult the oracle at this site.

Chris - So looking at the bones and things, what sorts of diseases did people have then and did they die from things different to what we would expect people who were living there to die from today - if you look at modern, contemporary populations there?

Lawrence - Yes, of course in the olden days you have to bear in mind that most causes of death you cant really ascertain. The fever that could knock you on the head in a couple of days wouldn't really happen anymore. Also of course you have to bear in mind that diseases would suddenly arrive, say with the explorers from Europe, and that wiped out millions maybe up to nine million people in total.

Chris - So when we went to South America what did we give these people?

Lawrence - The common cold would be enough, 'flu, in many cases they died in huge numbers with sores.

Chris - Measles?

Lawrence - Measles, anything at all like that.

Chris - Smallpox presumably?

Lawrence - Smallpox as well, but the thing is these usually leave little sign on the bone unless you do a genetic test. In the pre-Hispanic period they died from things like syphilis which they did have there before we got there, so not all to blame. Tuberculosis and of course lots of inter-personal violent things like Leishmaniasis which is something worth avoiding.

Chris - Parasite.

Lawrence - Yes, its a nasty parasite indeed. All kinds of afflictions.

Chris - How did the bones tell you that?

Lawrence - In the Leishmaniasis we actually do genetics on it and you can actually isolate it but you can also look at certain morphology and pathology of the face and it rots away the entire middle of the mouth.

Chris - What about syphilis, doesn't that destroy the nose?

Lawrence - Syphilis can destroy various bits of you. There's four diseases in syphilis and so various levels of severity. It starts of with a nasty looking acne on the skull if you can imagine that. It goes all the way through to venereal syphilis which takes away most of your face and leaves your face an entire mess.

Helen - Sounds quite disgusting. I've got an email here from Louise Brownley who asks; is it true you've come across cancerous skulls which shows that historically humans have lived with diseases that we might today not imagine existing with, if so does it really tell us anything about medicine and palliative care that happened at that time.

Lawrence - Yes of course and if you zip back far enough, Neanderthals nearly 60,000 years ago they were taking care of each other and people were living to a ripe old age, in their fifties and sixties a very long time ago indeed. We're designed to live about 30 years and so obviously they were being taken care of with a withered arm and a withered leg. When it comes to Cancer for instance, these things turn up and it reflects the kind of lifestyles they were having and so cancer only appears in certain built-up groups living in a crowded area. There is indication that they had surgery of some sort like trepanation for example - boring holes in your skull - and the champion trepanation chap had 16 operations and survived all of them.

Helen - My goodness! That's incredible!

Chris - Do we have any clues as to why they did that? Did they do it because they happened to believe that there was something evil going on inside this person and therefore accidentally they discovered and stumbled upon drilling holes in people's heads to let the pressure out when they thought they were letting out something different. Or did they genuinely understand the medical basis for drilling holes in people's heads?

Lawrence - There are cases of hydrocephalus for example, so people have water on the brain and then people had drilled holes in the vague hope that it might make their heads a normal size and shape and of course it didn't work. But most cases its rather hard to figure out actually, but trepanation happened in Africa up until the '60s and '70s. There's actually a famous case of a chap called "hat on hat off" who had no skull left above his eyes at all. His entire skull was missing and his brain was pulsing under the skin, they'd actually taken nearly of his over 20 years of operation and he said the cause was headaches that's why he'd had it.

Chris - He did afterwards that's for sure!

Lawrence - I would've thought so.

Chris - John in Norwich would like to know exactly how you work with the mummy, they must be very fragile, he speculates.

Lawrence - They're very fragile, so it really depends upon the preservation. Some of them are really robust and I mean relatively, I mean there's a very good one right here in Cambridge for example. Generally what you do is you have to lay them out and you use endoscopy or radiography to examine what's inside them. Then you do a very minute study of everything that is exposed, look at it under UV light to try and work out tattoos for example. I've found tattooed individuals at my site. Then you go through, if things are showing like teeth and bone you can score morphological characteristics and the pathology , look at their teeth and work out what they ate. Then you can look at - if you're lucky - to work out what they died from take tissues samples for DNA analysis. Its quite comprehensive.

Chris - So given all this analysis and your latest set of excavations in Peru, how has this changed your understanding of who these people were, what they were doing, how they got there and where they went?

Lawrence - That's a big question!

Chris - Its four actually but you don't have to answer them all at once.

Lawrence - I'll do my very best. The thing about proving in archeology is that lots of it is to do with the archaeological materials like temples and buildings, pottery and gold and silver and what have you. So in this case we're looking at migrations of people from around the place, from the Amazon, from the Andes, even from the Caribbean coming to this site. Looking at the kind of things that affected them and so they're dying in their thirties, they were about four foot two believe it or not up to about five foot two, five foot three and so they're really and so they're really quite short.

Chris - Just poor diet did that?

Lawrence - Maybe partly, also genetically speaking people in Peru are generally short. I mean I stick out like a sore thumb there because I'm six foot seven so I have a hell of a time trying to get clothes for instance. We're using isotopes now so we can work out that people are coming for thousands of miles, all over South America just to visit this site. Its quite impressive in that way.

Helen - We sort of touched on some of the maybe odd sides of society and we've got an email here from Sam who says "Is it true that children were often buried alive? And if so what can we learn about such behaviour?" Is that true?

Lawrence - I'm afraid that's true, yes indeed. It had some fairly humble beginnings, back in 600AD-ish. But the people who really loved to get their kids and do nasty things to them were the Incas and they would take them up and the would believe that - they're called capacocha burials - they would take the most perfect child and it was an honour for the family and the girl (generally a girl). They would dress her in her finery and take her up a mountain, generally give her some bitter elixir to drink, which would naturally contain a poison. Then they would put her in a tomb, she would fall asleep because it would be a drug obviously and they would literally wall her in and leave her there.

Helen - So are they actually killing her with the poison or were they just knocking her out until they walled her in and left her there?

Lawrence - Both actually occurred. Sometimes there was blunt force trauma so they actually got hit, other times they just died from the poison itself.