All posts by Tim De Chant

Fruit salad trees

Ferris Jabr, writing for Scientific American:

In an episode of Matt Groening’s animated science fiction sitcom Futurama, Leela offers her friend Fry an unusual housewarming gift: a bonsai tree sprouting tiny bananas, melons and plums. “It’s a miniature fruit salad tree,” she explains.

Here’s the thing: fruit salad trees are real.

Grafting isn’t just for making fruit salad, either. We do it all the time with bonsai, adding branches where there were none to achieve a certain aesthetic. Here’s another fun bonsai trick: air layering.

What Drove Early Man Across Globe? Climate Change

Christopher Joyce, reporting for NPR:

Anthropologists believe early humans evolved in Africa and then moved out from there in successive waves. However, what drove their migrations has been a matter of conjecture.

One new explanation is climate change.


Ingvar Kamprad of Ikea fame seems to have caught a case of the Walt Disneys. Like the wealthy animator, the Swedish furniture magnate is dipping his company’s toes into urban development. But don’t expect slavish reproductions of the big box stores, as Doug Sanders reports at the Globe and Mail:

As the Ikea people repeatedly tell anyone who will listen, this place will not be an Ikea. There will not be Poäng armchairs adorning the living rooms and Billy bookcases covering the walls. The houses will not require Allen keys to assemble. Meatballs in lingonberry sauce will not be served at the restaurants. And there will not, the company insists, be an Ikea store anywhere in or near the neighbourhood.

And like Disney, Ikea plans to keep a close eye on what happens in the development:

“We would have a fairly firm line on undesirable activity, whatever that may be. But we also feel we can say, okay, because we’ve kept control of the management of the commercial facilities, we have a fairly strong hand in what is said in terms of the activities that are held on site.”

Despite Ikea’s protestations, this sounds exactly like a Disney development.

(Via Design Decoded.)

The Anti-Skyscraper Law That Shaped Sydney, Australia

Matt Novak:

While researching a column I wrote recently for BBC Future about fighting the skyscraper fires of tomorrow I came across a fascinating anti-skyscraper law from 1912 that would have a lasting impact on Australia’s largest city. Fearing that fighting fires was nearly impossible in tall buildings, Sydney passed the Height of Buildings Act of 1912, limiting new buildings to just 150 feet tall. As a result Sydney spent almost half a century growing predominantly outward rather than skyward.

Farm bill falls flat on climate

Mark Hertsgaard, with an op-ed for the New York Times:

Indeed, instead of helping farmers take common-sense measures to limit their land’s vulnerability to extreme weather, the legislation would simply spend billions more on crop insurance — sticking taxpayers with the bill. “It’s like giving a homeowner cut-rate fire insurance but not requiring fire extinguishers,” Jim Kleinschmit of the Institute for Agriculture and Trade Policy told me in an interview.

Marchetti’s constant, or why the 30 minute commute is here to stay

Shanghai Transrapid maglev

“How far should you live from work?”

I pondered that question a few weeks ago after perusing American Community Survey data compiled by Charlie Gardner. It showed that most people in most metro areas in the United States tended to commute about 30 minutes each way to work, give or take a few. That adds up to about an hour of commute time per day. As I looked into it further, I found a lot of research that corroborated the surprising similarity of people’s commute times.

But in all ten research papers I used to footnote that article, I was missing one. Eric Fischer pointed me toward a 1994 treatise—for lack of a better term—by Cesare Marchetti. He posited that one hour per day is as long as people have been willing to travel. Ever. Since the dawn of human society.

At least, that’s what Marchetti hypothesized. He did have some data to back it up, though it wasn’t his own. It was Yacov Zahavi’s. Zahavi was a transportation engineer who consulted for the U.S. Department of Transportation and World Bank in the 1970s and early 1980s. As part of his work for the DOT, he came up with what he called the Unified Mechanism of Travel Model, or UMOT. Zahavi produced a string of reports and papers on UMOT, which he hoped would shake up how transportation planning was done in cities.

In the process of developing UMOT, Zahavi collected many juicy tidbits of data. One observation was that as people earn more money, they spend an increasing percentage of their income on everyday travel, up to about 13 percent. That number seemed to be both a hard ceiling and firm floor once households earned above a certain amount (about $50,000 in 1976). The richer you got, the more you spent in real terms. But the percentage remained the same.

Another bit—the one that inspired Marchetti—was that people in the United States and the United Kingdom traveled about 1 hour per day. (Astute readers will notice that a 30 minute commute to work—the number most studies have settled on as the “average” commute—adds up to precisely that amount at the end of the day.) Zahavi also noticed that even though some people could travel faster—by car rather than bus, for example, they still spent the same amount of time traveling. They just traveled farther to work—a trend which more recent studies have also uncovered.

Zahavi’s data is compelling, but in Marchetti’s hands it quickly became a universal constant. If so many people in Zahavi’s study (mostly in the developed world of the 1950s and 1960s) traveled the same amount per day, Marchetti reasoned that humans must have an innate desire to travel at most and at least 1 hour per day. Boom. Marchetti’s constant.

Zahavi’s data wasn’t the only leg he had to stand on, though it certainly was his sturdiest. Cave men and Greek villages were another. Marchetti pointed out, “Walking about 5 km/hr, and coming back to the cave for the night, gives a territory radius of about 2.5 km and an area of about 20 km2. This is the definition of the territory of a village, and … this is precisely the mean area associated with Greek villages today, sedimented through centuries of history.”

Marchetti—not one to think small, apparently—then used his new universal constant as a jumping off point to explore the future of tomorrow. How fast would a transportation system need to be to serve a city of 100 billion people? An average speed of 150 km/h sounds about right. Can you turn Switzerland into one giant city? Sure, so long as you run maglev trains in sealed tunnels sucked free of atmosphere. What about if you linked Paris and Casablanca with a maglev, too? “[A] woman in Casablanca could go to work in Paris, and cook dinner for her children in the evening.”

Not a man to leave a logical extreme unreached, Marchetti realized that at some point in the future everywhere on Earth will be 30 minutes from your front door. “With mach-7 airplanes and matching Maglevs, a world city is also possible. The assimilation of the technologies in political terms, however, will take some time.”

Details. In the meantime, enjoy your 30 minute commute.


Marchetti, C. (1994). Anthropological invariants in travel behavior, Technological Forecasting and Social Change, 47 (1) 88. DOI: 10.1016/0040-1625(94)90041-8

Zahavi, Yacov. 1976. “The Unified Mechanism of Travel (UMOT) Model.”

Photo by Lars Plougmann.

Related posts:

How far should you live from work?

Tell me how much you drive, and I’ll tell you where you live

Drive a lot? Housing density may not be to blame

Suburban lions

Stephanie M. Dloniak, reporting for the New York Times:

As difficult and exciting as capturing the lions was, a more imposing question now loomed: What do you do with them?

We nearly always frame the problem as lions moving into cities and suburbs. But the reality is, we’ve moved into their territory.

Crowdsourced maps reshaping geography

Michael M. Grynbaum, reporting for the New York Times:

Barry F. Hersh, a professor at the Schack Institute of Real Estate at New York University, said online maps were only the latest tool in a long line of technology influencing geography. “The telephone company once decided which neighborhood you were in,” he said.

Baby steps

Tim Landis, writing for The State Journal-Register:

The first test runs of 110-mph passenger trains in Illinois are scheduled to begin by the end of this month. But speed is only one piece of the test. Transportation regulators and Amtrak also will monitor an automated system of crossing gates and lights intended to accommodate trains, motorists and pedestrians. If the system works as expected on the Amtrak line between Dwight and Pontiac, plans are to extend the upgrades to the remainder of the route downstate. The target is to begin faster service between Chicago and St. Louis in 2015.

How Fungi May Create the Amazon's Clouds

Veronique Greenwood, reporting for Discover Magazine:

The clouds in the Amazon, just like everywhere else, consist of water vapor clinging to tiny clumps of carbon compounds. In forested areas, the carbon compounds are byproducts of plants’ metabolism; in populated areas, they are often from human pollution. Most of the time, atmospheric chemists can see the carbon clumping taking place; when the microscopic bits reach a certain size, they are able to attract and hold water. In the Amazon, the clumps seem to appear out of nowhere, nearly fully formed. No one has ever been able to catch them in the act of coming together.

Until now.

This is a perfect example of why we should keep hammering away at seemingly impossible questions. It would be easy to throw our hands in the air. But these scientists didn’t, and now we know something new.

Feeding 9 billion

David Biello, writing for Scientific American:

Can the world’s existing farmlands provide enough crops to satisfy the hunger of the nine billion people—up from seven billion currently—that demographers predict will be living on the planet by the mid-21st century? Or will more and more forests and other ecosystems have to be cleared to feed all the extra mouths? A new study, published in Nature on August 30, suggests that increasing deforestation could be avoided provided farmers made better use of water and nutrients on land currently under cultivation around the globe.

Wise fertilizer use and targeted intensification. Sounds about right.

Drought forcing animals to scour cities for food

Jack Healy, reporting for the New York Times:

With their natural food sources ruined by drought, animals are descending from mountains and mesas, desperate to eat whatever they can find before the winter freeze comes.

There isn’t much to go around.

Why wood pulp is world's new wonder material

Will Ferguson, writing for New Scientist:

[Nanocrystalline cellulose] will replace metal and plastic car parts and could make nonorganic plastics obsolete in the not-too-distant future, says Phil Jones, director of new ventures and disruptive technologies at the French mineral processing company IMERYS. “Anyone who makes a car or a plastic bag will want to get in on this,” he says.

Scientists have known about nanocrystalline cellulose, or NCC, for a while now. The news here is that the U.S. Forest Service’s has built a factory to produce the stuff. It’s cheap, strong, and renewable. The article says tech, auto, and defense companies are curious about NCC, but think of what architects are going to do once they get their hands on the stuff. 

(Aside: NCC is transparent. Yes, my fellow Star Wars nerds, transparisteel is real. It just happens to be made from wood.)

High-tech ghost town remains unbuilt

Remember that ghost town that was to built in the New Mexico desert? The one that was to be a test bed for all sorts of wiz bang technologies that could revolutionize real, populated cities? Turns out the developer has put off construction “due to some very complicated and unforeseen issues with acquiring the land.” Mmm hmm. And it has nothing to do with the fact that the price tag ballooned from the $200 million it was to cost when I first wrote about it?