Month: November 2015

November 2015 in Review

This is an index and summary of the things I’ve talked about over the last month. Links for multi-post subjects go to the first post (even if it’s before this month), you can follow the internal navigation links from there.

Books

Non-Fiction

“The Middle East: The Cradle of Civilisation Revealed” Stephen Bourke. Part of the Thames & Hudson Ancient Civilisations series.

Total: 1

Radio

Prester John – In Our Time episode about this mythical Eastern Christian King.

The Science of Glass – In Our Time episode about glassmaking, both the science of it and the history.

Total: 2

Talks

“New Light on the Narmer Palette with Advanced Digital Imaging” Kathryn E. Piquette – talk at the November EEG meeting.

Total: 1

Trip

Egypt Holiday 2014: Site at el Kab.

Egypt Holiday 2014: el Tod.

Total: 2

“The Middle East: The Cradle of Civilisation Revealed” Stephen Bourke (Part 2)

The next chapter of this book covers the vast swathes of prehistory in the Middle East, taking us from the first migrations of pre-homo sapiens humans out of Africa all the way through to about 6000 years ago just before the first cities of Mesopotamia. Which is rather a lot of ground to cover! So much so that I have split the chapter into two blog posts, the first of which covers the Paleolithic cultures and the second will cover the Neolithic.

The Fertile Crescent

This is not just the story of the Middle East over this period, but also the story of humanity as we go from early humans to modern humans, and from nomadic hunter-gatherer to farmers living in permanent settlements. The introductory 2 page spread for this chapter suggests that one reason everything seems to happen first in the Middle East is due to geography. It’s on a crossroads between Africa, Europe and Asia, so it was the best informed region – all knowledge flowed through there as it spread. And then could be combined with the other new ideas from other areas to produce leaps in technology.

Paleolithic Era

Early humans (Homo erectus) begin to spread outside Africa within a few hundred thousand years of their evolution. The earliest traces of humans date to 2.6 million years ago (in Ethiopia) and the earliest non-African evidence is from Dmanisi in Southern Georgia dating to 1.8 million years ago. These hominids presumably migrated via the Levantine corridor, as the only land route between the two areas. The next oldest site where human tools (and three teeth) have been found is in the Jordan Valley. Judging by the tools found at a wide variety of sites across the Middle East there were three or four different waves of migration out of Africa by Homo erectus. One of these migration waves also provides evidence of the first controlled use of fire – which I think I should’ve known pre-dated modern humans, but if I did know I had forgotten.

The Middle Paleolithic era lasted from around 250,000 to 45,000 years ago, and it was during this period that Homo erectus was replaced by Homo sapiens sapiens and Homo sapiens neanderthalensis. The dominant theory 40 years ago (based on archaeological evidence from Europe) was that first came the Neanderthals and they were then replaced by our own species before 40,000 years ago. Excavations in the Levant have changed this picture significantly. There are Homo sapiens sapiens remains as old as 100,000 years ago at site in the Levant, and Homo sapiens neanderthalensisas young as 50,000 years ago. There have also been skeletons found that display different combinations of characteristics from the two groups. What’s more the tools produced in the various different sorts of sites show no significant difference between the sites in terms of material culture and way of life. So perhaps the two species co-existed (for around 50,000 years or so). The double page spread about this era ends with a set of questions we don’t know the answers to yet – including whether or not the Neanderthals were actually a separate species.

The boundary between the Middle Paleolithic and the Upper Paleolithic (c.45,000-50,000 years ago) is marked by changes in tool technology. The shift was from tools formed as flakes or points to elongated blades which have a better edge-to-mass ratio and can be more efficiently produced. Interestingly as well as a local development of this tool culture (or perhaps brought by newcomers from Africa) there is also evidence of migration* into the area from Europe. The tools these immigrants brought with them are also blade based, but not the same as the ones produced in the Levant. These migrants are relatively restricted to one geographical region and one time period (32,000 to 30,000 years ago). An oddity of the Levantine Upper Paleolithic culture is that there is no evidence of art: no cave paintings, no figurines, no engravings. If I remember right the same is also true of Chinese prehistory … is art another of those ideas that is thought of only rarely and then spreads to become universal? Although having said that, we are very limited in what we can find evidence of – music, singing, dancing, drama and so on aren’t necessarily going to leave traces in the archaeological record.

*I’m not quite sure from the book why they know (if they know) that it’s the tool users that migrated rather than just the technology moving.

The next period of Middle Eastern prehistory is referred to as the Natufian period, and once again it’s characterised by a particular sort of tool. They give a technical description in the book, but basically the main form is small crescent-moon shaped tools for hunting and food preparation. The Natufian period falls into two phases: early from ~15,000-13,000 years ago and late from 13,000-11,500 years ago. This culture shows the first signs of sedentarism – with permanent, year-round villages. The communities still seem to have been hunter-gatherers, which was interesting as I previously thought the general idea was that settlement and agriculture happened the other way round. During the second phases of this period there’s actually more mobility in the communities, but they seem to have more clearly defined territories even if they’re not sedentary. I’m not actually sure what the evidence for this is, they don’t mention it in the book. However the authors do say that the second phase lines up with a signicantly drier period and so perhaps there wasn’t sufficient food at any given site to support a permanent population. Agriculture may or may not have begun during this period (experts are divided) but taming and domestication of the dog were definitely begun by the Natufians.

In contrast to the earlier Levantine cultures the Natufians are art producers. They produced both standalone things (like decorated bowls and slabs as well as figurines) and personal accessories (like necklaces, belts, etc). And the beginnings of trade are visible – for instance artifacts made of Anatolian obsidian have been found in the core Natufian region (the Levant from the Mediterranean coast to the Jordan Valley). Natufian sites also have evidence of the first large scale cemetaries. There isn’t really a pattern to how bodies were treated. Generally the body was buried in a flexed position, sometimes in a single occupant grave, sometimes in a larger grave. Some bodies have decoration and/or ornaments, some graves have carefully place stones, others are just a pit refilled after burial. The book doesn’t speculate at all about potential elite/non-elite distinctions – perhaps it’s clearly random when you look at the data?

< Previous Chapter | Next Chapter >

In Our Time: Prester John

Prester John was the greatest Christian King who never lived. All through the Middle Ages there were persistent legends (sometimes backed up by apparent documentation) about this powerful priest-king in the East who was ready to bring his powerful armies to attack the Muslims in concert with the Western Crusaders. The experts who discussed these legends on In Our Time were Marianne O’Doherty (University of Southampton), Martin Palmer (Director of the International Consultancy on Religion, Education, and Culture) and Amanda Power (University of Sheffield).

They opened the programme with a bit of a discussion about the historical truths in which these legends might’ve been rooted. During the early Middle Ages there was a large Christian population in the Middle East and in India. There’s evidence that Western Christians were in contact with them – for instance King Alfred (of England) sent some people to India. It’s written about as if the journey wasn’t anything particularly special – a long way, and a relatively rare event but perfectly doable. These Christians weren’t from the same branch of Christianity as the Western Church, and the two Churches would’ve regarded each other as heretics. They are sometimes referred to as Nestorian Christians, but that is a bit of a derogatory term and it’s politer to refer to them as the Church of the East or the Syrian Church. The schism between this Church and Western Christianity hinges round a theological point about the nature(s) of Christ. Western Christianity (or monophysitism) holds that Jesus’s human nature was absorbed into his divinity and he had only one nature. However those who followed Nestorious believed that Jesus had two natures that were only loosely connected (this is called dyophysitism) – he was both divine and human and those were separate from each other. So there was a substantial Christian population in the East (probably larger than in the West), which dwindled after the rise of Islam – after which the legends of Prester John began to develop.

The first forms of the legend are known from the 12th Century AD. One of these is an account of a visit to the Pope in 1122 by an emissary from Prester John. It’s not clear to modern scholars what, if anything, this is actually based on – if there was any visit from anyone that got garbled in the reporting or if someone just made it all up. The emissary purportedly says that he has come form Prester John’s kingdom to the east, and that Prester John had been leading a force to aid the Christians at Jerusalem. However the army had been unable to cross a river on the way, and had been forced to turn back. The account of this emissary’s visit gives details of the fabulous force that Prester John had available, and gave hope they would make another attempt to join the Crusaders.

Another early piece of “evidence” for Prester John was a letter that was purportedly sent from Prester John to the Byzantine Emperor in 1165, and subsequently translated into German and forwarded on to the Holy Roman Emperor. This letter goes into detail about what life is supposedly like in the land that Prester John rules. It’s an earthly paradise, full of wondrous beasts. Everyone lives long and virtuous lives, and after death they don’t rot and will return to life at the Day of Judgement. The kings are always called Prester John and combine the roles of secular and religious leaders in one person. The experts on the programme said that it’s extremely likely that this letter was originally written in German – it doesn’t read like translated Greek. There’s also no obvious reason why the Byzantine Emperor would be forwarding his post on to the Germans! The most plausible explanation for the letter is that it’s a piece of propaganda produced by the Holy Roman Emperor’s court. At the time he and the Pope were embroiled in a power struggle, and a document that explained how perfect everything would be if the secular leader of a country was also the spiritual leader was rather useful for the Holy Roman Emperor.

It seems odd to us as modern people to think that these tales of an earthly paradise (of an incredible nature) were so easily believable, but the programme pointed out that during this era there was a large body of literature of tales of wondrous lands beyond the known world. This is the period where maps have areas labelled as where the Doghead people live, and where the people live who have their faces in their torsos. Around the 12th Century and onwards this begins to change, as more people travel and write more accurate travelogues. It’s a slow change though – not all the early travelogues are written by people who’ve actually been where they claimed to be. For instance the author John Mandeville apparently travelled to Prester John’s land and met him – but a lot of other things in Mandeville’s book are made up, and most of the rest appears to’ve been copied from other books. There’s no indication Mandeville actually went anywhere! He’s not the only example of this from the time, either.

The rise of the Mongols changes the legends of Prester John a bit. There are some stories about Prester John being conquered, but other stories suggest that maybe he was never in Central Asia and his land is actually in India. Another blow to the believability of the legends is that travellers visit the Mongols from Europe, and whilst they meet Christians they don’t meet or find any evidence of Prester John. (Nor do they find any wondrous beasts, or Dogheads etc.) They do try and make an alliance with the Mongols against the Muslims, but this doesn’t interest the Mongols.

And later still as China becomes more well known to Europeans it becomes ever more implausible that Prester John and his kingdom could be anywhere in Asia. By the 14th Century AD the legend of Prester John has shifted to Africa, and Ethiopia is the new focal point. As an aside one of the experts (I forget which one) said that you could think of the 14th Century as “the century when Ethiopia discovered the West”. Ethiopia had been Christian since the early AD period, and in the 14th Century they sent emissaries to the Pope and to some of the European kings. They seemed to fit in with some of the Prester John stories – in particular the “long lost Christian Kingdom” aspects of it. And they also seemed to fit other legends about the Queen of Sheba. But the legends still weren’t true. Which apparently didn’t stop European travellers from visiting Ethiopia and asking the rather bemused locals about Prester John.

They finished up the programme by talking about whether or not people actually believed the stories at the time. I think the overall conclusion was that mostly they probably didn’t, it was just a good story or a useful one for propaganda purposes. However there were examples of people who did believe – for instance during the Crusades some commanders made strategic errors because they believed they were about to be joined by Prester John’s army any time now.

In Our Time: The Science of Glass

Glass is odd stuff. We’ve been making it so long that one tends to forget that it’s both artificial and really quite odd. The In Our Time episode about glass talked both the science of glass and glass-making, and the history of it. The experts discussing it were Dame Athene Donald (University of Cambridge, current Master of Churchill College, my old college, but here in her context as a physicist), Jim Bennett (University of Oxford) and Paul McMillan (University College London).

On the programme they intertwined the historical and the scientific discussion, but I thought the joins showed rather more than they usually do and so I’m going to split the threads up in my writeup. We first know of glass manufacturing about 5,000 years ago, by the ancient Egyptians who made beads of it initially. Over time they learnt to make larger and more complex objects like bottles & ornaments. The Romans developed the technology further. They invented most of the techniques that were used before the Industrial Revolution, like glass blowing for example. In ancient Egypt glass was primarily used for decorative or luxury goods, but the Romans used glass for both everyday and finer objects – including wine bottles (which struck me as an awfully modern way to store wine!).

In the Renaissance era the Venetians were famed for making particularly fine quality glass. The city attempted to keep a monopoly on glass-making by keeping their methods secret & forbidding glass-makers to leave the city. Which didn’t entirely work, unsurprisingly. One of their secrets was a way of making very transparent glass which was useful for lenses. Something I learnt from this programme was that spectacles first appear in the 13th Century AD which is much earlier than I’d assumed. Once lenses were being made to correct people’s sight it was only a relatively short step to making lenses for scientific instruments. Glass is part of the Enlightenment’s scientific revolution – not just lenses but also for making scientific instruments or vessels. There is a feedback loop between the demands of the scientific experiments driving new glass making technology and better glass instruments expanding the possible experiments that can be done. Industrial production of glass as we know it today begins in the Industrial Revolution.

The whole of the history discussion was very Eurocentric so I had a little look on wikipedia after we’d listened to the programme to see whether this was a fair reflection of the world history of glassmaking. The answer (based on a tiny amount of effort on my part) is … maybe? Glass making in China appears to’ve arrived late – during the Han Dynasty and probably influenced by trade goods from the Roman Empire. I didn’t find anything about the Americas, so I don’t know if that means they didn’t invent glass making or if no-one cared enough to add it to wikipedia. It’s odd to think that something so ubiquitous today might’ve been discovered once & once only.

Making glass (not good glass, just glass) is deceptively simple. In essence the process is to heat up sand till it melts, and then cool it very quickly and you end up with the transparent solid that we call glass. One of the experts pointed out that the necessary temperatures are those that would be reached by a bonfire on a beach – so it was probably discovered in Egypt by people (briskly) putting out campfires in the desert. Although a large body of empirical knowledge of how to make glass was built up over the next 5,000 years it was only relatively recently that we gained any understanding of what is actually going on, and the science of glass & glass-making is still not entirely understood. It’s actually more difficult to make glass out of pure sand than when there are impurities present, pure sand needs a quicker cooling step. So when making glass other things are often added – like potash or lime.

One of the complicated things about glass formation is that the phase transition from liquid sand to glass is not well defined – which is an oddity in physics. An example of a well defined phase transition is that from liquid water to ice: it happens at 0°C no matter how you cool the water. But the point at which liquid sand becomes glass depends on the precise starting conditions and the precise heating & cooling regimen – and it isn’t predictable using the current state of knowledge. Glass isn’t even a usual solid – it’s not crystalline, and that’s why the speed of cooling is important. If it cools too slowly it will crystalise and you don’t get glass. So instead of the atoms lining up in neat little rows they appear to just stop where they are. This non-crystalline nature of glass is what gives it some of its characteristic properties. It is brittle because there are no planes of atoms able to spread over each other when pressure is applied. I think they also said that the transparency is down to there being more routes for light to take through the structure, but I’m not sure that makes sense to me so I may’ve mis-remembered.

Glass in the technical sense is a broader term than just silicon glass (the stuff we generally call glass). You can make a glass using sugar – that’s what sweets like glacier mints are made of. And something I knew but had never really thought about is that spectacles & things like motorbike crash helmet visors aren’t made from silicon glass. Instead they are made using large polycarbon molecules – these can never crystallise so are much easier to work with. And the glass produced is not prone to fracturing, which is obviously important in those usages. I assume there are other downsides which mean we don’t use these glasses for all applications.

From the title I hadn’t expected this to be as interesting as it was – I didn’t realise how much wasn’t known about glass (nor how unique a discovery it was).