Maps tell us so much more than how to get from A to B, or where C is in relation to D. They can be tools of power and snapshots of history, and reveal the fears and prejudices of their age, says historian Jerry Brotton.
A remarkable thing about maps is people's resistance to the most basic fact of mapmaking - they can never be completely objective, accurate images of our world.
Talk to any mapmaker and they will tell you that the mathematics of mapping the globe onto a flat piece of paper mean that some form of distortion, manipulation and selection will always occur because, to put it simply, you cannot square the circle.
But for most people who use maps in their everyday lives - on sat navs, phones, online map applications, even the good old-fashioned Ordnance Survey - the idea that maps are partial, selective images of the world is extremely unsettling.
Maps can be used to challenge history
Almost unconsciously we expect maps to help us move around the world, whether getting to Tokyo or just finding the way to the nearest Italian restaurant. They give us a feeling of security that the big, wide world is somehow manageable and navigable.
But throughout history, maps have usually been more interested in providing people with that basic sense of security, before trying to get them from A to B. Each society tends to get the world map they deserve, one which manages to summarise and define a particular society's hopes and fears, prejudices and beliefs.
Throughout time, different cultures produced radically different images of the world. None of them could be labelled "right" or "wrong", they all simply reflected a culture's preoccupations.
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BBC Four's Maps: Power, Plunder and Possession will be repeated on 4,6 and 7 May
A map of China called the Yujitu was made in 1136. It was carved on stone and stood in a Chinese schoolyard to instruct bureaucrats to learn about Chinese geography and history. To our modern eyes it looks remarkably modern and accurate - the outline of China is quite clear, and there seems to be a grid showing latitude, longitude and scale.
But you quickly discovered the map made some basic errors. The course of the Yellow River was wrong, and another river, the Heishui, apparently didn't even exist. But the river did exist in a book called the Yugong, the story of a mythical Chinese ruler called Yu, who saved China from Noah-like floods in the 21st Century BC. The map's title, Yujitu, translates as "Map of the tracks of Yu".
In other words, it is a map designed to follow the mythical text, even when it knew the Yugong was inaccurate. Geographical realism gave way to a mythical story of the foundation of China, which was more important to the scholars and teachers who used the map than the exact location of a particular river's course - especially as most people who saw the map would never travel far enough to see the river.
South at top
West of China at about the same time, Christian and Muslim scholars were creating very different maps of the whole world. They also conformed to their particular theological beliefs, rather than the pursuit of cartographic accuracy.
The world is round. Maps are flat
Just as the Yujitu was being made, the Muslim mapmaker Muhammad al-Idrisi was working on his own world map in Sicily. The result showed the earth with south at the top, because for Idrisi, Mecca and the Arabian Peninsula was now the symbolic centre of the world. Around his map's edges is a Koranic inscription that suggests this is a world made in Allah's image.
Just over a century later, Christian world maps like the Hereford mappamundi rotated the world 90 degrees, to put east at the top. On the Hereford map, the sacred city of Jerusalem lies at the heart of the map, with the Garden of Eden in Asia sitting at the top of the map, with Christ looking down from the map's frame.
Both these maps were telling believers to think of the life beyond the earthly one. The results were very different, but they made sense according to the specific theology of the two religions.
In the West, maps continued to reflect particular cultural preoccupations, even when they ostensibly claimed to be about scientific accuracy and navigating from A to B. The infamous Mercator Projection of 1569 distorts the world at the north and south poles, to ensure navigational accuracy when sailing east to west.
The Henricus Martellus World Map dates from 1489
This was the most important issue for merchants and statesmen following the establishment of the sea routes to India and the new world of America in the late 15th Century.
Even today, Google Earth manipulates the first image of the earth that you see when you log on. But is it any surprise? How can you show a three-dimensional globe on a two-dimensional computer screen without choosing a projection that mimics how we imagine we see the earth from space?
All of this might sound unsettling, but we should see this as an opportunity - not an anxiety. As online mapping increasingly pervades our everyday lives, we need to be a bit sceptical about how maps are being used to shape our behaviour.
In the past they wanted us to accept a particular religion, or embrace a specific political ideology. Today they are more likely to be encouraging us to buy things as we zoom virtually around the globe.
But that doesn't mean they're any less powerful, or selective, than they've ever been.
Below is a selection of your comments.
I maintain a very large digital map for a telecoms company by using and referencing information from many "accurate" sources including original drawings, GPS maps, state produced online maps, and websites such as Google maps. Almost every thing on this map is a compromise of differences between all the different sources of information. For practical purposes everything is where it is suppose to be, but geographically no map will ever be precise.
Simon Davies, Jacksonville, FL, US (ex-pat Brit)
We all rely on the accuracy of maps but you should remember that maps are drawn with deliberate errors to protect the authors copyright if someone copies them without permission. The series 'Tales from the Map Room' showed some examples including a village in Wiltshire that did not exist but could be traced through copied maps for several hundred years. Other examples are the wriggles in the OS copy of the map of Basingstoke that caught the AA out and an error in the A-Z that was "discovered" & corrected on a TV series.
John Murrell, Carshalton
Surely it's pushing it to say there's no "right" and "wrong" where maps are concerned, if by right we mean, as rational people would, the most accurate representation we can manage of the objective truth of the world around us. Deliberate misrepresentation takes you beyond mapmaking into mythmaking - and gives you a map that is objectively wrong.
Robert Bargery, London UK
Maps also have historical shown the effects of physical barriers on an age before the coming of steam power, flight etc. I remember a particular map of Great Britian from around the 12th-13th Century from an English chronicle, that showed Scotland as much smaller county. Not only that the south of the vast "Sea of Scotland" was much bigger than the mountainous north. Their was only one bridge across the "Sea". The "Sea of Scotland" was in fact only the River Forth and the Bridge was at Stirling, but with out modern travel it may as well have been a Sea. The small size of the North was mainly because vast tracts had obviously not been visited regularly from our friends from the South (unlike now!!!!).
Neil Wilkie, Perth
The thing I find most fascinating about ancient maps are the areas of the old maps drawn completely differently from how they would be today. If you look at the Henricus Martellus map Africa and the peninsula where Thailand etc are are greatly over-exaggerated towards the south. I wonder if this came from explorers going on expeditions to these areas and finding seemingly never-ending desert, forest or bush land.
I bet we've all seen maps from the US that start on the International Date Line and go round the world eastwards to the Polish border, missing out the USSR completely.
Eric Hall, Pionsat, France
It is true that choices have to be made to display a globe on a flat surface, provided these are explicitly stated and adhered to this does not mean that the map is not objectively correct. This is not the same as saying that the size of a landmass should be determined by the population living there (or some other social criteria). What you then have is a graphical representation of the social data, not a map.
Michael Barnes, Milton Keynes, UK
It's funny that I've also been thinking about maps recently. This article summarised the reason for the existence of so many different maps throughout the world over time. I realised that the intellectual knowledge, progress and mindset of a particular society in a given time could be seen by the maps they produce (therefore also parts of its history). The examples given above provide for excellent support.
With advances in 3D rendering, it will be interesting to see how this plays into our reading of maps - it may not be long before we do not have to flatten our maps, but rather observe them in their full beauty.
Ai You, Oxford, United Kingdom of Great Britain and Northern Ireland
"Just over a century later, Christian world maps like the Hereford mappamundi rotated the world 90 degrees, to put east at the top. On the Hereford map, the sacred city of Jerusalem lies at the heart of the map, with the Garden of Eden in Asia sitting at the top of the map, with Christ looking down from the map's frame. "
Are you sure that this was a "Christian" thing, rather than European? This type of map has been described by many as "sunwise", marking the rising of the sun as the first key point of navigation. The Scottish Gaelic for south is to this day the same as the word for right - "deas" - and the word for clockwise (which is "sunwise" if your clock is a sundial) is derived from this - "deiseil", literal rightward, as the sun travels to the observer's right to pass through the south of the sky. "Deiseil" also happens to mean "ready", which underscores the importance that the sun had in Celtic culture.
Furthermore, prehistoric monuments - the most ancient "maps" in Europe - are aligned to the sunrise and sunset at the solstices and the equinoxes. Before the invention of the magnetic compass, north-south alignment would only have been easy to measure against a firmly established east-west reference line.
There is a great deal of sociological information in maps, but this article overextends that. The sunwise map, based on the position of sunrise as the primary reference, is the oldest and most natural way of describing the world. There is nothing more to it than that.
Níall, Edinburgh, Scotland
Even Google Earth in the 21st Century includes non-existent bodies of water! Do a search for "Bervie Water", near where I live, and check the map (which shows water...) and the satellite (which doesn't...).
Alan Marson, Aberdeen, Scotland
Years ago I can remember seeing an East German world map. It looked very similar to the maps I was used to, it was only when I looked at it I noticed that it didn't have the East/West German border and there were other subtle differences, such as the Falklands being called the Malvinas. Maps don't just represent geography, they also represent political ideas.
I have noticed that an increasing reliance on sat-nav is reducing people's use of maps and their consequent spatial awareness. Many are unaware of where they have been en route and how these places relate to one another. This is bad news and will result in large numbers of people losing an important ability developed over thousands of years. As an analogy look at how technology has reduced many people's ability to handle numbers and their relationship to one another. When an error is made on the calculator or PC they simply fail to spot it as their arithmetic perception is so poor.
John Stratford, Chester, UK
It's only since World War II that people have become as mobile, as Mr Stratford imagines. Throughout those "thousands of years" millions of people hardly travelled from the parish where they were born. That's how it will be again, once fossil fuels run out.