Can you solve the mystery of Brazil’s time-traveling capital?

Forensic cartography 101: Explain what Brasilia is doing on this map of 1920s South America.

  • "Forensic cartography" is dating a map by the age of its borders.
  • All evidence points to this undated map of South America to be from the 1920s.
  • So why does it feature Brasilia, the new capital of Brazil, which was only built in the 1950s?
Keep reading Show less

What’s wrong with the internet? We’d rather “display” than communicate.

Jonathan Rauch explains why the internet is so hostile to the truth, and what we can do to change that.

Sponsored by the Institute for Humane Studies
  • Disruptive technologies tend to regress humanity back to our default mode: deeply ingrained tribalism.
  • Rather than using the internet to communicate, many people use it to display their colors or group affinity, like tribespeople wearing face paint. Fake news spreads faster than truth in these tribal environments.
  • How can we solve this problem without censorship? Platforms like Facebook and Google are tilting the playing field to be more pro-truth by asking people to stop, think, and take responsibility.
Keep reading Show less

Marchetti’s Constant: The curious principle that shapes our cities

How the half-hour commute and motorised transport changed our cities into huge metropolises.

  • The average commute, from antiquity to now: half an hour
  • That's Marchetti's Constant, and it informs the growth of our modern cities
  • But we're stuck in traffic, and waiting for the next great leap forward.

The curious constant

Image source: public domain

Charles T. Harvey, president of the West Side & Yonkers Patented R.R., New York City's first elevated railway, demonstrating in 1867 that a car would not fall off the track.

What do the citizens of ancient Rome have in common with those of modern Atlanta? The duration of their daily commute: an hour, at most. No matter whether we move on foot or by car, half an hour either way is about as long as we're prepared to travel to and from our place of work.

That timeless truism is called Marchetti's Constant, and it has a curious effect on the size of our cities. For as our modes of transport improve, the result is not that our commutes shrink, but that the distance between our homes and places of work increases. That, Jonathan English explains in a fascinating article over at CityLab, is why ancient Rome was tiny, and modern Atlanta is huge.

When in Rome

Ancient Rome, walking city

Image source: David Rumsey Map Collection courtesy Stanford University Libraries, CC-BY-NC-SA; image credit: David Montgomery/CityLab

Even when it was the biggest city in the world, Rome was tiny by modern standards.

For most of history, walking was the main way to get around cities. Since a mile (1.6 km) is about as far as you can walk in half an hour, that's the maximum radius of a pre-modern city. Actually, ancient Rome is a good example: for several centuries at the start of the Common Era, it was the world's biggest city. Yet its one million inhabitants were packed like Latin-speaking sardines into an area with a diameter of just two miles.

That's about the same distance as from the Bastille to the Louvre, the extremities of medieval Paris. And, as Jonathan English remarks in his article, "the historic City of London is named the 'Square Mile' for a reason." Up until the Industrial Revolution, urban growth meant cities got denser rather than bigger, leading to horrific levels of overcrowding. Escape to the country was a luxury available exclusively to the very rich — only they could afford both a rural mansion and an urban pied à terre.

The advent of modern transport brought the ideal of an escape from the city within reach of ever greater numbers of city-dwellers — but the effect was ultimately self-defeating: the growing size of the urban exodus meant they brought the city with them. But that change didn't happen overnight: our current cityscapes are the result of centuries of experiments with transportation modes — always with Marchetti's Constant as a yardstick for growth.

Philosopher on the bus

Medieval Paris, walking city

Image source: Analyse Diachronique de l'espace Urbain Parisien: Approche Geomatique, Open Data Commons Open Database License 1.0; image credit : David Montgomery/CityLab

Medieval Paris was a bit smaller than Rome, a thousand years earlier.

  • The first public transit system was introduced in Paris in 1662 by none other than Blaise Pascal, the philosopher. His system of horse-drawn buses followed a set schedule, along fixed routes, for a distance-based fare. However, the system wasn't much faster than walking, and collapsed after 15 years due to increased ticket prices.
  • In 1830, Liverpool and Manchester were connected by the world's first steam-powered public railway. Railways caught on quickly in major cities across the world. Moving people at speeds of 10 miles or more per half hour, railways allowed those who could afford it to live in "railroad suburbs" along the stops outside the city proper. Examples include Philadelphia's Main Line suburbs and West London's Stockbroker Belt.
  • From the 1880s, the introduction of electric trams and "safety bicycles" (i.e. not the high-wheeled penny-farthings) extended the commuter range of more lowly-paid workers. They now could travel in half an hour to 4 miles. This enlarged the potential size of cities from a diameter of 2 miles (i.e. 3 square miles) to a diameter of 8 miles (i.e. 50 square miles). Over the next decades, cities all over North America, and to a lesser extent Europe, adopted tram networks, and started sprouting new suburbs.
  • Elevated trains, suspended above their straight streets avenues, further spurred the growth of American cities. These "el trains" and later subways, allowed the working class to live as far as 8 miles from their places of work. This allowed New York to spread out north to cover the entirety of Manhattan, for example.

Going Underground

London, rail city

Image source: David Rumsey Historical Map Collection, CC BY-NC-SA; image credit: David Montgomery/CityLab

London was one of the first cities to transcend the ancient limits of urban development.

  • Lacking an American-style grid, London's streets were not amenable to elevated trains. Because they couldn't go up, they went under, and in 1863, the first London Underground line opened. The 'Tube' would soon become instrumental for spreading out the city over the surrounding counties, eventually annexing large parts of them. The county of Middlesex was almost entirely absorbed by Greater London (see #605), and disappeared off the map.
  • In 1908, Henry Ford launched the Model T, the first mass-produced car. Despite its eager adoption by the middle classes, the automobile did not create huge urban growth in the 1920s and 1930s. That's because the roads, built for non-motorized traffic, quickly choked up. Only after WWII would cars would start to transform cities — thanks to the introduction of expressways, which allowed people to move to and from cities with greater speed.
  • After WWII, urban planners developed two competing methods to finally overcome the problem of inner-city overcrowding. The mainly European method, developed by Le Corbusier, was to concentrate people in free-standing high-rise towers, set in parkland ringing the old city centers.

Welcome to Chicagoland

Chicago, Street-car city

Image source: Harvard Map Collection, Harvard College Library; image credit: David Montgomery/CityLab

The sprawl of 'Chicagoland' was made possible by the street car.

  • The predominantly American method, developed by Frank Lloyd Wright, was based on the car, and proposed dispersing the population over a much wider area, on individual plots of land — a recipe for what has become the classic American suburb. This model allows for a 20-mile commute in 30 minutes, and that extends the metropolitan diameter to 40 miles. An "expressway city" can thus cover more than 1,250 square miles.
  • In the 1970s, Wright's model proved so successful that North America's inner cities emptied out; except for its African-American inhabitants, kept out of the suburbs by various means of institutional discrimination. These days, the standard commute in North American metro areas takes around 26 minutes — about the same as that of the average citizen of ancient Rome.
  • In the last few decades, the dispersal model has become the victim of its own success: traffic has multiplied, slowed down and become congested. Los Angeles, Atlanta, and other "expressway cities" have hit maximum capacity.

Sprawl ad infinitum?

Image source: U.S. Census; image credit: David Montgomery / CityLab

The dispersal model, the latest (and perhaps ultimate) phase of urban expansion.

So, what's next after 'stuck in traffic'? Jonathan English suggests three technological solutions, with varying degrees of feasibility:

  • First option: high-speed rail. Downsides: very expensive, and facing "formidable ideological opposition" — at least in North America.
  • Second option: self-driving cars. Downsides: still a pipe dream, will not improve road capacity, and may even increase congestion.
  • Third option, and the most viable one: telecommuting. Working from home is already technologically feasible and holds "the greatest promise" for enabling Wright's vision of the complete dispersal of population. But employers are resistant: they want their staff on-site, their physical presence the ultimate guarantee for productivity.
Here's another idea: how about we reduce commutes and congestion by re-densifying the hollowed-out inner cores of our major cities? This too is neither easy or cheap, but the alternative is "sprawl ad infinitum,"and that, argues Jonathan English, has a huge environmental cost.
Keep reading Show less
Sponsored by the Institute for Humane Studies
  • For society to stay open and free, you don't need to eliminate prejudice. You need the opposite: All kinds of prejudice pitted against each other.
  • Intellectual diversity helps society as a whole learn the truth. And as long as society has rules that force ideas to be openly tested, the intolerant will not gain the upper hand.
  • "In America it's legal to be intolerant. It may not be right. It may not get you accepted or respected. But absolutely it's legal and it should be legal," says Jonathan Rauch.
Keep reading Show less

A murder map of Denmark

Lovers deadlier than gangsters, first comprehensive Danish homicide study since 1970s shows

  • Danes love tv crime, but rarely commit (and barely study) murder
  • The typical Danish murder involves knives and relatives, study reveals
  • Wealth of stats can help forensic scientists - and lawmakers

One map, 1,417 murders

A murder map of Denmark

Image: Ruland Kolen / Dagbladet Information

A geographic representation of all 1,417 murders committed in Denmark from 1992 to 2016.

Scandinavians love bloody murder. On their tv screens at least: if they're not binge-watching the latest, locally-sourced Scandi noir crime thriller, they'll happily re-watch Morse, Vera, Barnaby, Taggart or any other of the mostly British (and strangely often mononymous) homicide procedurals clogging up all channels, any day of the week.

That massive, if passive, interest in killing must somehow serve as an antidote for its active pursuit, because the Nordics are among the least murderous countries worldwide.

In 2017, Denmark had a rate of 'intentional homicide' of just 1.20 per 100,000 inhabitants, which is among the lowest in the world (1). Given its relatively small population (5.8 million), that translates to a mere 71 murders that year. The other Nordics have similarly low stats: also in 2017, Finland also had a murder rate of 1.20 (69 Finns finished), in Sweden it was 1.10 (113 Swedes silenced), in Iceland 0.90 (just 3 Icelanders iced) and in Norway 0.50 (28 Norwegians neutralised).

The only major countries doing better than that were Indonesia (0.40, i.e. 1,150 murders) and Japan (0.20, for 306 homicides). The United States trends to the other side of the spectrum (2), with a murder rate of 5.30 in 2017, which translated into 17,284 intentional homicides (3).

With murder rates this low and home-grown crime dramas as popular as they are, it could be argued that there are more fictional murders on screen in the Nordic countries than actual ones. It's certainly true that the actual murders - outshone and perhaps outnumbered by their fictional counterparts - get less attention.

Societal value

Toe-tagged body in a morgue

Image: Ralf Roletschek / FAL 1.3

Objectified information helps forensic scientists transcend their own knowledge of previous cases.

Enter Asser Hedegård Thomsen from the Institut for Retsmedicin (Institute of Forensic Science) at Aarhus University. He is conducting the first comprehensive analysis of Denmark's murder statistics since the early 1970s. For his Ph.D. thesis, to be completed next year, he has spent five years examining each and every one of the 1,417 murders committed in Denmark in the quarter century from 1992 to 2016.

Why? "When autopsying a murder victim, forensic scientists use their own knowledge of previous cases to reach their conclusions. My analysis is helpful because it is objectified information, extending beyond personal knowledge", Hedegård Thomsen told the Danish newspaper Dagbladet Information, which devoted an entire supplement to his findings.

But there is also a broader, societal value in a close reading of all those autopsy reports, the paper editorialises: "Even if murder is relatively rare here (in Denmark), it remains the ultimate crime against society, and the one that is punished most severely. That's why knowledge on this topic is so relevant: if murder is to be discussed, prevented or legislated on, it's important to do so based on facts."

X marks the spot

A murder map of Denmark

Image: Dagbladet Information

More chilling than 'The Killing': a real-life murder map of Denmark.

So, what does murder in Denmark look like? According to this map, one X for the location of each murder, a lot like Denmark itself.

Murder density is highest where most people live: first and foremost in the capital, Copenhagen (the white blob, bottom right). Odense (middle, bottom) is also easily visible. Smaller areas of overlapping crosses correspond to other Danish cities such as Esbjerg, Aarhus and Randers.

But killing happens in enough places for the geographic outline of the entire country to become visible. The densely populated islands of Sjælland (on which Copenhagen is located), Fyn (Odense) and Lolland can be clearly discerned. A few murders in Skagen, the northern tip of Jutland, help identify the Danish mainland.

One isolated cross north of Odense seems to indicate a solitary murder on the small holiday island of Samsø. The bunch of x'es to the right represent the island of Bornholm, at greater distance from the rest of Denmark, halfway between Sweden and Poland.

Typology of violence

CIA World Factbook map of Denmark

Image: CIA / Public domain

For reference, an actual map of Denmark

Perhaps more interesting to coroners (and legislators) is the study's typology of violence and victims.

Stabbing was the most frequent cause of death (33.2%), followed by shooting (22.2%), blunt-force trauma (21.9%) and strangulation (17.6%). Since most murders happen at home, Denmark's favourite murder weapon is the kitchen knife. Access to guns is strictly regulated in Denmark, otherwise death by gunshot would probably be the larger category.

Familiarity breeds contempt - and worse: 44% of all killings happen within families. No less than 77% of all female murder victims die at the hands of a relative, and just 24% of men. Spousal homicide is the biggest single subcategory of all murders (26.7%), and 79% of its victims are women. In fact, more than half of all female murder victims are killed by their (former) significant other. For men, that figure is just 9%.

The second-largest category are drink- and drugs-related murders. Here, 97% of the victims are male. Gangland killings and other crime-related murders - which receive wide media attention - are a distant third.

Three out of four murders take place at a home (rather than out on the street), two-thirds occur between 6 pm and 6 am, and most happen on a Friday or Saturday. Monday is the least lethal day of the Danish week.

'Ideal' victim profiles

A set of knives and other kitchen utensils

Image: Kent Wang / CC BY-SA 2.0

Line up the usual suspects...

Based on the 1,417 murder cases in Denmark from 1992 to 2016, Mr Hedegård Thomsen has established three profiles for the 'ideal' Danish murder victims.

  • The average murdered Danish male is between 18 and 50 years old, is killed on a Friday night by a drinking buddy with a kitchen knife, either at his own home or that of a friend.
  • The typical female murder victim in Denmark is between 30 and 39 years old, and is killed at home by her partner or her ex, out of jealousy or because of separation issues. She is either knifed or strangled.
  • Murder victims under 18 years are as often boys as girls, most often killed by a relative - in 75% of cases by their father or another man.

While studying a quarter century of murder must have made for much grim reading, even in a relatively peaceful society like Denmark, there is at least one positive conclusion: the murder rate is dropping to ever lower levels. The annual figures zig and zag up and down, but the trend line goes from just under 80 murders in 1992 to just over 40 in 2016.

This may partly be the result of better care and, thanks to mobile phones, faster reaction times. But other factors may be at work. Perhaps, if the quality of fictional murders on Danish tv keeps increasing, it will be much harder to spot the country's outline on the homicide map of the next 25 years.

Keep reading Show less

NASA camera captures Amazon fires

Satellite movie shows clouds of carbon monoxide drifting over South America.

Image: NASA/JPL-Caltech
Strange Maps
  • The Amazon fires were captured by the AIRS camera on the Aqua satellite.
  • A movie clip released by NASA shows a huge cloud of CO drifting across the continent.
  • Fortunately, carbon monoxide at this altitude has little effect on air quality.
Keep reading Show less

Yet another American divide: 'crunk' vs 'bible studies'

How deep are America's cultural fault lines? Depends on which data you crunch.

Image courtesy of Boyd L Shearer Jr / OutrageGIS
Strange Maps
  • America is a divided nation, but perhaps its divisions are as much in the eye of the beholder.
  • This map charts the geographic fault lines between 'crazy drunk' America and 'bible study' America.
  • Strangely, Las Vegas falls in the latter category – and Salt Lake City in the former.
Keep reading Show less

Is this the world map of the future?

North America and Europe peripheral on China's 'vertical world map'

Strange Maps
  • Europe has dominated cartography for so long that its central place on the world map seems normal
  • However, as the economic centre of gravity shifts east and the climate warms up, tomorrow's map may be very different
  • Focusing on both China and Arctic shipping lanes, this vertical representation could be the world map of the future
Keep reading Show less