Time Has Only Strengthened These Ancient Roman Walls

J. P. Oleson
J. P. Oleson

Any seaside structure will erode and eventually crumble into the water below. That’s how things work. Or at least that’s how they usually work. Scientists say the ancient Romans figured out a way to build seawalls that actually got tougher over time. They published their findings in the journal American Mineralogist.

The walls’ astonishing durability is not, itself, news. In the 1st century CE, Pliny the Elder described the phenomenon in his Naturalis Historia, writing that the swell-battered concrete walls became "a single stone mass, impregnable to the waves and every day stronger."

We know that Roman concrete involved a mixture of volcanic ash, lime, seawater, and chunks of volcanic rock—and that combining these ingredients produces a pozzolanic chemical reaction that makes the concrete stronger. But modern cement involves a similar reaction, and our seawalls fall apart like anything else beneath the ocean's corrosive battering ram.

Something else was clearly going on.

To find out what it was, geologists examined samples from walls built between 55 BCE and 115 CE. They used high-powered microscopes and X-ray scanners to peer into the concrete's basic structure, and a technique called raman spectroscopy to identify its ingredients.

Microscope image of crystals in ancient Roman concrete.
Courtesy of Marie Jackson

Their results showed that the pozzolanic reaction during the walls' creation was just one stage of the concrete toughening process. The real magic happened once the walls were built, as they sat soaking in the sea. The saltwater did indeed corrode elements of the concrete—but in doing so, it made room for new crystals to grow, creating even stronger bonds.

"We're looking at a system that's contrary to everything one would not want in cement-based concrete," lead author Marie Jackson, of the University of Utah, said in a statement. It's one "that thrives in open chemical exchange with seawater."

The goal now, Jackson says, is to reproduce the precise recipe and toughen our own building materials. But that might be harder than it sounds.

"Romans were fortunate in the type of rock they had to work with," she says. "They observed that volcanic ash grew cements to produce the tuff. We don't have those rocks in a lot of the world, so there would have to be substitutions made."

We still have a lot to learn from the ancient walls and their long-gone architects. Jackson and her colleagues will continue to pore through Roman texts and the concrete itself, looking for clues to its extraordinary strength.

"The Romans were concerned with this," Jackson says. "If we're going to build in the sea, we should be concerned with it too."

A Team of Cigarette Butt-Collecting Birds Are Keeping a French Theme Park Litter-Free

iStock
iStock

The six rooks pecking at litter within the Puy du Fou theme park in Les Epesses, France, aren't unwelcome pests: They're part of the staff. As AFP reports, the trained birds have been dispatched to clean up garbage and cigarettes butts from the park grounds.

Rooks are a member of the corvid family, a group of intelligent birds that also includes ravens and crows. At Puy du Fou, an educational amusement park with attractions inspired by various periods from French history, the rooks will flit around park, pick up any bits of litter that haven't been properly disposed of, and deliver them to a receptacle in exchange for a treat. At least that's how the system is set up to work: The full team of six rooks has only been on the job since August 13.

Employing birds as trash collectors may seem far-fetched, but the experiment has precedent. The Dutch startup Crowded Cities recently started training crows to gather cigarette butts using a vending machine-like device. Once the crows were taught to associate the rig with free peanuts, the machine was tweaked so that it only dispensed food when the crow nudged a cigarette butt resting on a ledge into the receptacle. The cigarette butts were eventually removed, and the birds figured out that they had to find the litter in the wild if they wanted to continue receiving their snacks.

Crowded Cities had planned to conduct more research on the method's effectiveness, as well as the potentially harmful effects of tobacco on crows, before bringing their vending machines to public spaces. Puy du Fou, meanwhile, has become one of the first—if not the first—businesses to fully implement the strategy on a major scale.

Even if it doesn't prove to be practical, Puy du Fou president Nicolas de Villiers told AFP that cleaning up the park is only part of the goal. He also hopes the birds will demonstrate that "nature itself can teach us to take care of the environment."

[h/t AFP]

Online Daters Tend to Be Interested in Partners 25 Percent More Desirable Than They Are

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iStock

Online dating may not bring out the best in people (as anyone who’s been ghosted can attest) but it does bring out our optimistic side. A new study suggests that people tend to reach out to fellow online daters who are approximately 25 percent more attractive than they are, according to The Washington Post.

The study, published in the journal Science Advances, looked at online dating messaging behavior from heterosexual men and women in four different U.S. cities. Researchers analyzed how many messages people sent and received in January 2014, how long those messages were, and how many messages went unanswered.

They examined daters in New York City, Chicago, Seattle, and Boston, including age, ethnicity, and education of the users in their analysis, but kept the profiles anonymous and did not read the messages themselves. (The researchers don’t name the particular site they got their data from, merely describing it as a “popular, free online dating service.” From the details, it sounds a lot like OkCupid or a very similar site: one that allows users to answer open-ended essay questions and list attributes like their religion and body type on their profiles.)

To quantify how desirable a person was, the researchers looked at the hard numbers—how many messages someone received, and how the senders themselves ranked on the desirability scale.

Both men and women tend to aim high, messaging someone more desirable than themselves by about 25 percent, on average. For the most part, users didn’t contact people who ranked lower than themselves on the desirability scale. When they did contact people who were hotter, daters tended to write much longer messages than they did when they contacted someone on their own level, so to speak—sometimes up to twice as long. Women tended to use more "positive" words (like "good" and "happy") when they were writing to hotter dudes, while men actually used fewer positive words when talking to hotter ladies. Men in Seattle sent the longest messages, perhaps because of the city’s makeup—in some populations, there are twice as many men there as women, so heterosexual men face a lot of competition. Although wordy messages in Seattle did have a slightly higher response rate, in other cities, the extra time spent typing out missives didn’t pay off. Given that those messages weren’t any likelier to get a response than a short note, the researchers write that the “effort put into writing longer or more positive messages may be wasted.”

The data also showed how desirability in online dating can be influenced by attributes like age, education level, and ethnicity. For instance, at least as far as averages go, older men tended to be viewed as more desirable than younger men until they hit 50. Women’s scores peaked when they were 18 years old (the youngest age when you can join the site) and decreased until age 60.

Even if you aren’t in the pool of the most attractive users, sometimes, aiming high can pay off. “Even though the response rate is low, our analysis shows that 21 percent of people who engage in this aspirational behavior do get replies from a mate who is out of their league, so perseverance pays off,” co-author Elizabeth Bruch explained in a press release.

[h/t The Washington Post]

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